Co-reporter:Wen Song, Baoyu Gao, Yu Guo, Xing Xu, Qinyan Yue, Zhongfei Ren
Microporous and Mesoporous Materials 2017 Volume 252(Volume 252) pp:
Publication Date(Web):1 November 2017
DOI:10.1016/j.micromeso.2017.06.019
•Corn stalk based modified magnetic ion exchange resin was prepared in this study.•This study provides a rapid adsorption uptake for perchlorate.•Perchlorate removal by resin mainly includes ion exchange and physical absorption.•This novel magnetic resin could achieve rapid separation from effluents.In this work, a novel corn stalk based modified magnetic biopolymer ion exchange resin (CS-MAB) was prepared and used to remove perchlorate from aqueous solution. The physicochemical characteristics of CS-MAB were observed by SEM/EDS, BET, TEM, VSM, and XPS. The saturated magnetization and average pore diameter of CS-MAB were 3.82 emu/g and 4.83 nm. In adsorption batch experiments, the optimal adsorbent dosage and pH value for perchlorate removal are 1.0–1.5 g/L and 3.0–10.0. The adsorption kinetics fitted well with intraparticle-diffusion model in the first 90 min, and pseudo-second-order model in 90–360 min, which suggested that the potential mechanisms of perchlorate removal are physical adsorption and ion exchange reaction between ClO4− and Cl-containing groups of CS-MAB. Based on the analysis of Langmuir model, the maximum adsorption capacities of CS-MAB are 119.05 mg/g, 126.58 mg/g and 178.57 mg/g at 20 °C, 30 °C and 40 °C, respectively. The column adsorption of perchlorate could be described well by Thomas model, and the co-existing ions would restrain the perchlorate adsorption by the order of SO42− > Cl− > NO3−. Chemical and biological technologies both can be used to effectively regenerate CS-MAB with the efficiency of 70%–90%.Download high-res image (292KB)Download full-size image
Co-reporter:Shiping Xu, Xiang Sun, Yuan Gao, Min Yue, Qinyan Yue, Baoyu Gao
Journal of Solid State Chemistry 2017 Volume 253(Volume 253) pp:
Publication Date(Web):1 September 2017
DOI:10.1016/j.jssc.2017.05.001
•Solvent property is important for the solvothermally synthesized TiO2 products.•Interface separating titanium precursor with aqueous phase is a determining factor.•Dielectric constant of solvents is also very important.•Low solution pH is helpful for the formation of rod-like building block structures.One-step solvothermal method has been proved to be a simple and efficient route to synthesize three-dimensional (3D) hierarchical TiO2 microsphere structures, but discrepant properties of the solvent media had been claimed as the major factors determining microstructures and properties of the final products. In this study, several typical solvents, including alkane, aromatic hydrocarbons, halohydrocarbon, ketone, organic acid, mono- and dihydric alcohols, were selected to comprehensively investigate the effect of solvents on the morphology, crystal structure, specific surface area, porous property and light harvesting capability of the final products. According to the experimental results, a good interface separating titanium precursor with aqueous phase in the reaction solution, created by non-polar solvents, or polar solvents which are immiscible with titanium precursor, was the decisive factor for the formation of quasi-3D urchin-like TiO2 microspheres self-assembled from one-dimensional (1D) nanostructures, and concentrated H+ induced by organic acid medium was also helpful. Meanwhile, without the liquid-liquid interface or extremely low solution pH, anatase TiO2 sphere structures with big specific surface area comprising of nanoparticles or nanosheets would be formed, and performed well in photodegradation of pollutants in water.A good interface separating titanium precursor with aqueous phase is the determining factor to form 3D ordered TiO2 microspheres self-assembled by 1D nanostructures via solvothermal reaction.Download high-res image (393KB)Download full-size image
Co-reporter:Jingzhen Zhang;Chao Xia;Qinyan Yue
Water, Air, & Soil Pollution 2017 Volume 228( Issue 6) pp:196
Publication Date(Web):06 May 2017
DOI:10.1007/s11270-017-3377-6
The urban sewage-dewatered sludge (UDSS) containing cationic polyacrylamide is difficult to dewater. FeCl3 was used as conditioner to adjust the UDSS. To investigate the effect and principle, the physicochemical properties of UDSS were evaluated in terms of dewatering equipment, micro electrophoresis, Malvern laser particle size analyzer, nuclear magnetic resonance analyzer, and scanning electron microscopy. Results showed that the network structure of UDSS produced by CPAM still had high negative charge, which locked much water in the flocs and resulted in the poor dewaterability of UDSS. When Fe3+ was added into the UDSS, the inner structure of sludge was destroyed by the charge neutralism and releasing more water. At the same time, because the function of precipitate produced by the hydrolytic action, the inner structure of the sludge was solidified; therefore, the compressibility of UDSS decreased. Finally, the dewaterability of UDSS was improved and the moisture content of filter cakes can be decreased to 55%.
Co-reporter:Wen Song, Baoyu Gao, Hailan Wang, Xing Xu, Moxi Xue, Minchao Zha, Bo Gong
Bioresource Technology 2017 Volume 240(Volume 240) pp:
Publication Date(Web):1 September 2017
DOI:10.1016/j.biortech.2017.03.064
•Amine-crosslinked magnetic biopolymer resin was prepared for perchlorate uptake.•This study provides a rapid adsorption-microbial reduction for perchlorate.•Perchlorate removal by resin mainly includes ion exchange and physical absorption.•This novel bio-adsorbent could achieve rapid separation from effluents.•Reduction time, pH and biomass affect efficiency of microbial regeneration obviously.The aim of this work was to study the adsorption characters of resin, microbial reduction of perchlorate and combined process of perchlorate removal in aqueous solution. Study demonstrated the adsorption equilibrium was achieved in 120 min, which based on ion exchange reaction. Dissolved perchlorate (100 mg/L) can be completely removed by acclimated anaerobic sludge in 15 h, and the concentrated perchlorate (∼200 mg/g) on the surface of resin would be effectively microbial reduced after 3 days. Neutral environment (pH = 7.4), higher biomass and additional electron donor can apparently improve the biological reduction efficiency of concentrated perchlorate. Addition of many co-anions showed the competition adsorption towards perchlorate, especially in the presence of NO3−. This study provides an effective method for perchlorate reduction by the adsorption-microbial process.Download high-res image (165KB)Download full-size image
Co-reporter:Ruihua Li, Baoyu Gao, Kangying Guo, Qinyan Yue, Huaili Zheng, Yan Wang
Bioresource Technology 2017 Volume 240(Volume 240) pp:
Publication Date(Web):1 September 2017
DOI:10.1016/j.biortech.2017.02.088
•Lignin-based flocculant (LBF) was prepared from papermaking sludge.•Primary mechanism affecting floc properties under different conditions was studied.•Addition of LBF improved the floc properties significantly at pH 9–10.•Bridging effect of LBF played a more important role in the increase of floc size.•Flocs in dual-coagulation were hard to be broken under the strong force condition.In this study, papermaking sludge was used as the raw biomass material to produce the lignin-based flocculant (LBF) by grafting quaternary ammonium groups and acrylamide. LBF was used as a coagulant aid with polyaluminum chloride (PAC) to treat reactive and disperse dyes wastewater. Effects of dosing method, pH, hardness and stirring speed on the coagulation behavior and floc properties were studied. Results showed that the superior coagulation efficiency and recovery factor were achieved by PAC + LBF compared with PAC and LBF + PAC. The primary mechanisms of LBF in the treatment of disperse and reactive dye solutions were charge neutralization and bridging effect, respectively. In the dual-coagulation, the impact of pH on the coagulation efficiency was weak during pH range of 5–9. Moderate hardness could enhance the floc properties due to the decrease of electrostatic repulsion and the chelation of Ca(II) and LBF. Besides, flocs coagulated by PAC + LBF had a stronger anti-crush ability.
Co-reporter:Xiuzhen Zhu, Yuan Gao, Qinyan Yue, Yujiao Kan, Wenjia Kong, Baoyu Gao
Ecotoxicology and Environmental Safety 2017 Volume 145(Volume 145) pp:
Publication Date(Web):1 November 2017
DOI:10.1016/j.ecoenv.2017.07.053
•Potassium tartrate was a novel activating agent to prepare activated carbon.•Optimum activated carbon (AC-PT) owned high specific surface area of 1692 m2/g.•AC-PT was prepared by less activating agent and activation time.•AC-PT had high adsorption capacity of 709.2 mg/g towards chloramphenicol.Potassium tartrate (C4H6K2O7) was utilized as a novel activating agent to prepare activated carbon with relatively high specific surface area by using less activating agent and activation time from marine waste–green alga (Enteromorpha prolifera) for the first time. The influences of activation temperature, impregnation ratio and activation time on the pore structure were investigated to obtain the optimum conditions (activation temperature: 700 °C, impregnation ratio: 1:1, and activation time: 30 min). Meanwhile, the activation temperature was evaluated to be the essential factor that dominated the form of pore structure in activated carbon. The green alga-based activated carbon that was prepared under optimum conditions has shown the high surface area of 1692 m2/g and total pore volume of 1.22 cm3/g, which could be used as an effective adsorbent to remove chloramphenicol. The thermodynamic data of chloramphenicol were well fitted by Langmuir isotherm model and the green alga-based activated carbon has showed high adsorption capacity of 709.2 mg/g towards chloramphenicol.
Co-reporter:Ruihua Li, Baoyu Gao, Shenglei Sun, Qinyan Yue, Meng Li, Xudan Yang, Wuchang Song, and Ruibao Jia
ACS Sustainable Chemistry & Engineering 2015 Volume 3(Issue 12) pp:3253
Publication Date(Web):October 19, 2015
DOI:10.1021/acssuschemeng.5b00844
In this study, a lignin-based flocculant (LNF) was synthesized by grafting amine groups into alkali lignin containing papermaking sludge. Characterization of LNF, such as FTIR, zeta potential, cationic degree, viscosity, and molecular weight, showed that the product was a cationic polymer with high solubility. LNF was used with aluminum sulfate (AS) and polyaluminum chloride (PAC) in humic acid coagulation to demonstrate its efficiency. Coagulation behavior and floc properties of LNF+PAC and LNF+AS dual-coagulant were comparatively evaluated. Results showed that the coagulation aid effect of LNF was independent of aluminum species. Addition of LNF could enhance humic acid removal efficiency and floc properties including size, strength, and fractal dimension significantly. The effect of solution pH on coagulation processes was also studied. Dual-coagulants showed the same variation trend as that of aluminum-based coagulants but enhanced coagulation performance during the investigative pH range. Flocs formed at pH 9 and pH 5 achieved maximum floc size in AS and PAC coagulation systems, respectively. Fractal dimension was relatively high at pH 7–9 due to the sweeping effect of aluminum hydrolysates. Overall, LNF brought in charge neutralization and absorption bridging effect and played a positive role in coagulation processes.Keywords: Flocculating efficiency; Flocculating mechanism; Fractal dimension; Lignin-based polymer; Papermaking sludge
Co-reporter:Wen Song, Xing Xu, Xin Tan, Yan Wang, Jianya Ling, Baoyu Gao, Qinyan Yue
Carbohydrate Polymers 2015 Volume 115() pp:432-438
Publication Date(Web):22 January 2015
DOI:10.1016/j.carbpol.2014.09.010
•We prepared the efficient amine-crosslinked biopolymer based resin from wheat stalk for perchlorate uptake.•Perchlorate was column adsorbed by the amine-crosslinked biopolymer based resin.•Chemical regeneration of the saturated amine-crosslinked biopolymer based resin in column was conducted.•We applied the mixed bacteria for bio-regenerating the perchlorate loaded on amine-crosslinked biopolymer based resin.Column adsorption of perchlorate by amine-crosslinked biopolymer based resin was investigated by considering the bed depth, stream flow rate and influent pH. The empty bed contact time (EBCT) increased with the growth of bed depths, meanwhile rising flow rate at constant bed depth (3.4 cm) decreased the breakthrough time. It was observed that perchlorate adsorption capacity was optimum at neutral condition (pH: 6.0, 170.4 mg/g), and decreased at acidic (pH: 3.0, 96.4 mg/g) or alkalic (pH: 12.0, 72.8 mg/g) influents. The predominant strains of the acclimated sludge for resin biological regeneration were the β-subclass of Proteobacteria. Biological regeneration of the saturated amine-crosslinked biopolymer based resin with mixed bacteria have shown its merit with regeneration and biological perchlorate destruction simultaneously, although its regeneration efficiency was only 61.2–84.1% by contrast to chemical regeneration with efficiency more than 95%.
Co-reporter:Ruihua Li, Baoyu Gao, Shenglei Sun, Hui Wang, Yingxue Liu, Qinyan Yue and Yan Wang
RSC Advances 2015 vol. 5(Issue 121) pp:100030-100038
Publication Date(Web):09 Nov 2015
DOI:10.1039/C5RA22637F
To recycle papermaking sludge, a novel lignin-based flocculant with high cationic degree and molecular weight was introduced. The product, lignin–diallyl dimethyl ammonium chloride–acrylamide (LDA) was combined with polyferric chloride (PFC) to treat simulated humic acid (HA) solution. To identify its flocculation mechanisms, coagulation efficiencies and floc properties under different dosing methods and pH conditions were studied. Results showed that LDA was superior to polyacrylamide, poly diallyldimethylammonium chloride as well as lignin–acrylamide with regards to dissolved organic carbon (DOC) and turbidity removal efficiencies, which demonstrated its significant flocculating efficiency. Compared with single PFC, the addition of LDA enhanced the coagulation performance and floc properties, including floc size, growth rate and the recovery ability within the investigated pH range. The dosing sequence also had an effect on the coagulation mechanism and performance. When PFC was dosed first, negatively charged Fe(III) hydrolysates-colloids were neutralized and bridged by LDA. On the contrary, colloids–LDA complexes with slight negative charge were destabilized by the entrapment and sweeping effect of Fe(III) hydrolysates. As a result, coagulation efficiencies were in the following order: PFC dosed firstly (PFC + LDA) > LDA dosed firstly (LDA + PFC) > PFC. PFC + LDA achieved the maximum floc size and growth rate, whereas flocs with the most open structure was formed by LDA + PFC. Moreover, the effect of solution pH on coagulation behavior was noteworthy due to the variance of hydrolyzed Fe species. PFC was more sensitive to pH with regards to coagulation efficiencies and flocs structure. The variations caused by different pH values decreased after the addition of LDA. Regardless of the coagulant types, the optimal coagulation performance and floc characteristics were achieved under acidic conditions, especially at pH 6. Overall, LDA could introduce strong charge neutralization and adsorption bridging effect within a relatively wider pH range and offer a positive effect on coagulation behavior and flocs properties.
Co-reporter:Xing Xu, Wen Song, Deguo Huang, Baoyu Gao, Yuanyuan Sun, Qinyan Yue, Kaifang Fu
Colloids and Surfaces A: Physicochemical and Engineering Aspects 2015 Volume 476() pp:68-75
Publication Date(Web):5 July 2015
DOI:10.1016/j.colsurfa.2015.03.014
•Novel biopolymer activated carbon and resin were prepared from Arundo donax Linn.•Adsorption capacity of stratified column for phosphate was evaluated.•Adsorption and desorption isotherm of phosphate by the biosorbents were determined.•Raman spectra were used to evaluate the phosphate-laden samples.Arundo donax Linn-based resin (ADI-resin) and Arundo donax Linn-based activated carbon (ADI-AC) were prepared for phosphate elimination from stream. Characteristics (BET surface area, Zeta potential, SEM, FTIR, and Raman spectra) of the biosorbents indicated that some required functional groups have been grafted onto the ADI-resin. The regenerated ADI-resin achieved 92–94% of adsorption capacity even after seven cycles of adsorption and desorption. However, only about 15–25% of phosphate could be desorbed from the ADI-AC at the same desorption conditions. A stratification-packed column with different particles sizes of ADI-resin/ADI-AC was also designed. When the stratified resins with different particle sizes were introduced, the bed utilization of ADI-resin was greatly enhanced. In contrast, the stratified ADI-AC packed in column was not effective as the performance of stratified ADI-resin.
Co-reporter:Bao-dong Ma;Bao-yu Gao;Lei Zhang;Qing-tao Gong;Zhi-qiang Jin;Lu Zhang;Sui Zhao
Journal of Applied Polymer Science 2014 Volume 131( Issue 15) pp:
Publication Date(Web):
DOI:10.1002/app.40562
ABSTRACT
The effects of different types of polymers, partially hydrolyzed polyacrylamide (HPAM) and hydrophobically modified polyacrylamide (HMPAM), on dynamic interfacial tensions (IFTs) of surfactant/model oil systems have been investigated by the spinning drop method in this article. Two anionic surfactants, 1,2-dihexyl-4-propylbenzene sulfonate (366), 1,4-dibutyl-2-nonylbenzene sulfonate (494) and an anionic–nonionic surfactant octyl-[ω-alkyloxy-poly(oxyethylene)]yl-benzene sulfonates (828) with high purity were selected as model surfactants. The influences of polymer concentration on IFT were expounded. It was found that the addition of polymer mostly results in increasing IFT because the interfacial molecular arrangement is modified owing to the interaction between polymer and surfactants. For HPAM, the polymer chains will enter the surfactant adsorption layer to form mixed-adsorption layer. Therefore, HPAM shows strong effect on surfactant molecules with large size, such as 366. Conversely, surfactants can interact with the hydrophobic blocks of HMPAM and form mixed micelle-like associations at interface. As a result, HMPAM shows more impact on IFT of 494 due to small steric hindrance for the formation of interfacial associations. This mechanism has been ensured by 828 molecules with two long alkyl chains. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40562.
Co-reporter:Xing Xu, Baoyu Gao, Xin Tan, Xiaoxiao Zhang, DongTing Yue, Qinyan Yue
Carbohydrate Polymers 2013 Volume 98(Issue 1) pp:132-138
Publication Date(Web):15 October 2013
DOI:10.1016/j.carbpol.2013.05.058
•We prepared the amine crosslinked biosorbent from cotton stalk for ClO4− uptake.•The interaction between ClO4− and biosorbent was measured by XPS, Raman and FTIR.•The mechanism relied on electrostatic attraction between ClO4− and biosorbent.•Thomas model was applied for analyzing the column data.Virgin cotton stalk was produced into an effective biosorbent for perchlorate adsorption. Surface analysis including BET surface area and SEM illustrated the reduction of porous structure in amine-crosslinked cotton stalk (AC-CS). Elemental and zeta potential analysis validated the graft of some positively charged amine groups on surface of AC-CS. Spectra analysis (XPS, FTIR and Raman spectra) suggested that interaction between AC-CS and ClO4− should be based on electrostatic attraction. The maximum adsorption capacity (qmax) of AC-CS for perchlorate at different pHs (3.0, 6.0, 9.0 and 11.0) were calculated as 29.6, 42.6, 41.0 and 33.0 mg/g, respectively. The saturated perchlorate uptakes in column were in range of 25.0–38.1 mg/g at different pHs. In addition, the exhausted AC-CS column was regenerated by 0.5 mol/L of NaCl solution, which was adequate for almost complete desorption of the perchlorate.
Co-reporter:Zhonglian Yang, Baoyu Gao, Yan Wang, Xiaoxiao Zhang, Qinyan Yue
Separation and Purification Technology 2013 Volume 102() pp:147-156
Publication Date(Web):4 January 2013
DOI:10.1016/j.seppur.2012.09.032
This study investigated the relationship between removal efficiency, floc operational parameters and residual Al species when polyaluminum chloride–polydiallyl dimethyl ammonium-chloride (PAC–PDMDAAC) was applied in coagulation of a reservoir water. Various residual Al fractions (total Al, dissolved Al, dissolved monomeric Al, dissolved organically-bound Al and dissolved organic monomeric Al, suspended/particulate Al) were separated and measured in purified water samples. The fundamental floc operational parameters were characterized via floc size, growth rate, and strength factor in this study. Turbidity and organic matter removal were also determined as supporting data. Experimental results demonstrated that the mass ratio of Al to PDMDAAC (MR) and solution pH manifested a significant influence on residual Al speciation distribution. Residual Al content and floc operational parameters exhibited a linear correlation. In addition, moderate floc size, strength factor, growth rate and removal efficiency were favorable to the reduction of residual Al concentration for one coagulant under various pH conditions. For different coagulation system under the same pH condition, the higher the values of floc operational parameters and removal performance, the lower the residual Al content. The Al speciation was altered before and after coagulation. A majority of total Al in treated water was in the dissolved form. In dissolved Al form, the monomeric Al and organically bound Al were presented at a higher proportion under conditions of 4 < pH < 6 and pH > 7, respectively.
Co-reporter:Chunhua Xu;Dandan Cheng
Frontiers of Environmental Science & Engineering 2012 Volume 6( Issue 4) pp:455-462
Publication Date(Web):2012 August
DOI:10.1007/s11783-010-0275-1
Batch adsorption experiments were conducted to explore the adsorption of Cr(VI) in aqueous solutions by β-FeOOH-coated sand. We investigated the key factors which affected the adsorption process such as adsorbent dosage, initial pH, initial Cr(VI) ion concentration, contact time and temperature. The uptake of Cr(VI) was very rapid and 44.3%, 51.6%, 58.9% of the adsorption happened during the first 180 minutes at 293K, 303K and 313K, respectively. The pseudo-second-order rate equation successfully described the adsorption kinetics. To study the adsorption isotherm, two equilibrium models, the Langmuir and Freundlich isotherms, were adopted. At 293K, 303K and 313K, the adsorption capacities obtained from the Langmuir isotherm were 0.060, 0.070 and 0.076 mg Cr(VI) per gram of the adsorbent, respectively. Thermodynamic parameters such as the change of energy, enthalpy and entropy were calculated using the equilibrium constants. The negative value of ΔG0 and the positive value of ΔH0 showed that the adsorption of Cr(VI) in aqueous solutions by β-FeOOH-coated sand was spontaneous, endothermic and occurred by physisorption.
Co-reporter:Wenfeng Sun;Ruibao Jia
Frontiers of Environmental Science & Engineering 2012 Volume 6( Issue 1) pp:66-74
Publication Date(Web):2012 February
DOI:10.1007/s11783-010-0257-3
In this paper, a method using solid-phase extraction (SPE) and gas chromatography-mass spectrometry (GC-MS) was developed to simultaneously analyze five taste and odor compounds in surface water, i.e., 2-methylisoborneol (2-MIB), 2,4,6-trichloroanisole (TCA), 2-isopropyl-3-methoxy pyrazine (IPMP), 2-isobutyl-3-methoxy pyrazine (IBMP), and trans-1,10-dimethyl-trans-9-decalol (geosmin, GSM). The mass spectrometry was operated in selective ion monitoring (SIM) mode. Three kinds of SPE columns and three eluting solvents were compared, the C18 column was chosen as optimum SPE column, and methanol was chosen as the optimum eluting solvent. It was found that the method showed good linearity in the range of 1–200 ng·L−1 and gave detection limits of 0.5–1.5 ng·L−1 for individual compounds. Good recoveries (93.5%–108%) and relative standard deviations (1.58%–7.31%) were also obtained. Additionally, concentrations of these taste and odor compounds in Jinan’s surface and drinking water were analyzed by applying this method, and the results showed that GSM and 2-MIB were the dominant taste and odor compounds in Jinan’s raw water.
Co-reporter:Xing Xu, Bao-Yu Gao, Xin Tan, Qin-Yan Yue, Qian-Qian Zhong, Qian Li
Carbohydrate Polymers 2011 Volume 84(Issue 3) pp:1054-1060
Publication Date(Web):17 March 2011
DOI:10.1016/j.carbpol.2010.12.069
A new adsorbent was prepared from wheat straw (WS) after the crosslinking of amine groups. Its adsorption characteristics and operating parameters for phosphate and chromium (VI) removal were studied. BET surface area, elemental content and zeta potential analysis illustrated the physicochemical change between amine-crosslinked wheat straw (AC-WS) and WS. Significant variation in Raman shift of phosphate/chromium (VI)-loaded AC-WS was observed, and the results suggested the differential adsorption mechanisms for phosphate and chromate (VI) removal by AC-WS. The adverse effect of ionic strength on phosphate and chromate (VI) uptake suggests the possibility of ion exchange mechanisms being active in the adsorption process. The regeneration capacities for phosphate-loaded AC-WS and chromium (VI)-loaded AC-WS were 98.1% and 74.8%, respectively, which validated a potential chemical bonding between chromium (VI) and AC-WS. In addition, the adsorption capacities of AC-WS for phosphate and chromate (VI) were 1.71 and 5.68 mmol/g, respectively, providing a potential application of AC-WS for toxic heavy metals and nutrient substances removal from aqueous solutions.
Co-reporter:Zhonglian Yang, Baoyu Gao, Baichuan Cao, Weiying Xu, Qinyan Yue
Separation and Purification Technology 2011 Volume 80(Issue 1) pp:59-66
Publication Date(Web):12 July 2011
DOI:10.1016/j.seppur.2011.04.007
The coagulation behavior, residual aluminum ratio of three PAC coagulants as well as content and proportion of different residual Al speciation during the treatment of a specific surface water were investigated in this paper. Experimental results suggested that surface adsorption and entrapment effect worked effectively in turbidity removal regarding this specific water. PAC20 was appropriate to remove hydrophilic natural organic matter (NOM), while PAC15 and PAC23 were appropriate to remove hydrophobic fraction NOM. PAC, especially PAC20, could reduce the content of total dissolved Al and dissolved monomeric Al with comparatively higher toxicity. PAC20 showed lower concentration for every residual Al species. The majority of total residual Al existed in the form of unsoluble particulate Al (about 62–93% for PAC15, 65–92% for PAC20 and 54–78% for PAC23). Among total dissolved Al in the effluent treated with PAC15 and PAC23, dissolved organically-bound Al was almost the major speciation (about 40–92% for PAC15 and 37–86% for PAC23). There existed no dissolved organically-bound monomeric Al in purified water treated with three PAC samples. Residual Al ratio of PAC varied in the following order: PAC15 > PAC23 > PAC20. Besides, Al speciation in coagulants likely remained in treated water at lower dosage.Graphical abstractHighlights► Al separation was conducted in PAC (with various B value) coagulated surface water. ► Five Al species were separated and measured in purified water by PAC coagulation. ► Other Al speciation could be achieved through substraction. ► OH/Al and PAC dosage effect on coagulation performance and Al species were studied. ► Others were conducted in terms of Al speciation proportion and residual Al ratio.
Co-reporter:Qian Wang, Baoyu Gao, Yan Wang, Zhonglian Yang, Weiying Xu, Qinyan Yue
Separation and Purification Technology 2011 80(3) pp: 549-555
Publication Date(Web):
DOI:10.1016/j.seppur.2011.06.010
Co-reporter:Xing Xu, Bao-Yu Gao, Qin-Yan Yue, Qian-Qian Zhong, Xiao Zhan
Carbohydrate Polymers 2010 Volume 82(Issue 4) pp:1212-1218
Publication Date(Web):11 November 2010
DOI:10.1016/j.carbpol.2010.06.053
Wheat residue based anion exchanger (WR-AE) was prepared by ETM (epichlorohydrin–triethylamine method), which is the reaction of wheat residue (WR) with epichlorohydrin and triethylamine in the presence of ethylenediamine and N,N-dimethylformamide. Characterization of WR-AE was measured, including BET surface area, SEM, zeta potential, nitrogen content and FTIR analysis. Batch experiments and statistical analysis were conducted to study its ion-exchange property for phosphate from aqueous solutions. Filter bed experiment was conducted for the regeneration test. The characteristic results validated the increased amine groups in WR-AE and its maximum sorption capacity (Qmax, mmol g−1) of phosphate was 1.80 ± 0.06 mmol g−1. More over, the WR-AE regenerated in both NaCl and HCl solutions can be repeatedly used in several sorption–desorption cycles without any significant loss of the sorption capacities.
Co-reporter:Xiao Zhan, Baoyu Gao, Qinyan Yue, Yan Wang, Baichuan Cao
Separation and Purification Technology 2010 Volume 75(Issue 1) pp:61-68
Publication Date(Web):24 September 2010
DOI:10.1016/j.seppur.2010.07.012
Polyferric chloride (PFC) was used to remove natural organic matter (NOM) from the surface water with low concentration of organic matter to evaluate coagulation behavior and floc parameters. The relationship between PFC dosages and chlorine decay was also investigated and the chlorine demand for reacting with organic compounds was estimated by a chlorine model. Under the raw water conditions, the NOM removal efficiency increased within the dosage investigated. The lower specific UV absorbance (SUVA) values were achieved in the dosage range 10–16 mg/L of PFC. Adsorption, entrapment, and complexation played important roles for PFC in removing NOM besides charge neutralization in the coagulation process. Large flocs formed with a PFC dosage of 22 mg/L were better resistant to increasing shear but showed poor recoverability. Small flocs at a PFC dosage of 3 mg/L were little influenced by the increasing shear and showed full reversibility. Coagulation treatment with 22 mg/L of PFC resulted in higher chlorine decay rate, more free chlorine residuals and less total chlorine demand in the effluent when compared to coagulation with dosages of 14 and 3 mg/L. Furthermore, minimal amount of disinfection by-products (DBPs) would be possibly produced after treatment with 22 mg/L of PFC.Research highlightsRemoval of natural organic matter (NOM) has become an increasingly important issue in drinking water treatment because of the formation of disinfection by-products (DBPs) which are caused by the incompletely removed NOM. In this study, PFC was used to treat the surface water with low concentration of OM. The coagulation efficiency was studied as well as the floc properties in terms of floc strength and regrowth in the coagulation process.Additionally, delivery of safe and potable water throughout a distribution system requires free chlorine residuals to be maintained at acceptable levels. In order to comply with DBPs regulations, higher levels of NOM removal should be achieved which can change the water quality and in turn affect the chlorine decay kinetics. In this paper, the relationship between dosage and chlorine decay process was also discussed. The values of chlorine demand for organic compounds were calculated through a chlorine model to estimate the formation of DBPs.
Co-reporter:BaiChuan Cao;ChunHua Xu;Ying Fu;Xin Liu
Science Bulletin 2010 Volume 55( Issue 14) pp:1382-1387
Publication Date(Web):2010 May
DOI:10.1007/s11434-010-0087-5
Enhanced coagulation is one of the major methods to control disinfection by-products (DBPs) in water treatment process. Coagulation pH is an important factor that affects the enhanced coagulation. Recently, many studies focus on the coagulation effects and mechanisms, and few researchers studied the properties of flocs formed under different coagulation pH. Two inorganic polymer coagulants, polyferric silicate sulphate (PFSS) and polyferric sulphate (PFS), were used in Yellow River water treatment. The influence of pH on coagulation effect was investigated under the optimum dosage, and the results show that both coagulants gave excellent organism removal efficiency when pH was 5.50. According to the variation of zeta potential in coagulation process, coagulation mechanisms of the coagulants were analyzed. An on-line laser scatter instrument was used to record the development of floc sizes during the coagulation period. For PFSS, pH exerted great influence on floc growth rates but little influence on formed floc sizes. In PFS coagulation process, when pH was 4.00, PFS flocs did not reach the steady-state during the whole coagulation period, while little difference was observed in floc formation when pH was 5.50 and above. The preformed flocs were exposed to strong shear force, and the variation of floc sizes was determined to evaluate the influence of pH on floc strength and re-growth capability. In comparison of the two coagulants, PFS flocs had higher floc strength and better recovery capability when pH was 4.00, while PFSS flocs had higher floc strength but weaker recovery capability when pH was 5.50 and above.
Co-reporter:Xing Xu, Baoyu Gao, Wenyi Wang, Qinyan Yue, Yu Wang, Shouqing Ni
Colloids and Surfaces B: Biointerfaces 2009 Volume 70(Issue 1) pp:46-52
Publication Date(Web):1 April 2009
DOI:10.1016/j.colsurfb.2008.12.006
Kinetic and column adsorption of phosphate from aqueous solution using modified wheat residue (MWS) as an adsorbent were studied in a batch reactor. The respective characteristic rate constants and activation energy were presented after linear and non-linear fitting. In addition, the effects of influent concentration of phosphate and flow rates on the column adsorption were also investigated. The results showed that the adsorption process could reach equilibrium in 10–15 min, and the pseudo-second-order equation generated the best agreement with experimental data for adsorption systems. The activation energy was 3.39 kJ mol−1 indicating that the synthesis process was a physical adsorption. In the column tests, the increase of influent concentration and flow rate both decreased the breakthrough time, and the MWS-packed column exhibited excellent phosphate removal from aqueous solution. These results provide strong evidence of the potential of MWS for the technological applications of phosphate removal from aqueous solutions.
Co-reporter:Yan Wang, Wei-Zhi Zhou, Bao-Yu Gao, Xiu-Ming Xu, Gui-Ying Xu
Separation and Purification Technology 2009 66(3) pp: 457-462
Publication Date(Web):
DOI:10.1016/j.seppur.2009.02.011
Co-reporter:Baoyu Gao;Xiaobiao Zhu;Chunhua Xu;Qinyan Yue;Weiwei Li ;Jincheng Wei
Journal of Chemical Technology and Biotechnology 2008 Volume 83( Issue 3) pp:227-232
Publication Date(Web):
DOI:10.1002/jctb.1792
Abstract
BACKGROUND: Over the last few decades, the emphasis in studies on extracellular polymeric substances (EPS) has been on the extraction and quantitative analysis methods relating to activated sludge. However, little is currently known about the relationship between EPS and microbial activity and cell hydrophobicity in heterogeneous biofilms. This paper aims to reveal the relationship between them.
RESULTS: Experimental results indicated that EPS content and components varied with depth in the aerobic biofilter. Protein was the main component of EPS at all depths within the biofilter, and the ratio of protein to polysaccharide was higher in the upper media than that in the lower media. Most active biomass was present in the bottom 25% of the biofilter near the inlet. By means of repeatedly washing intact cells, a sharp decline of EPS content of washed cells was obtained, while active biomass rarely decreased. Microbial activity as well as cell hydrophobicity at different filter depths decreased with the decline of EPS.
CONCLUSION: Results indicated that EPS on cell surfaces are essential for microbial metabolism as well as for the formation and stability of biofilm, and it is possible to take EPS into consideration for biofilter control and microbial activity assessment. Copyright © 2007 Society of Chemical Industry
Co-reporter:YongBao Chu;QinYan Yue;Yan Wang
Science China Chemistry 2008 Volume 51( Issue 4) pp:386-392
Publication Date(Web):2008 April
DOI:10.1007/s11426-007-0129-2
The floc formation and re-aggregation potential and the effects of sulfate on coagulation by AlCl3, polyaluminum chloride (PAC), and Al13 species using a photometric dispersion analyzer (PDA) are investigated. It is found that the recovery level from shearing is the highest for the Al13 species. This is likely a result of increased collision efficiency due to more effective charge neutralization. The experimental results show that sulfate has a significant effect on coagulation and promoting aggregation of hydrolyzed species for the Al13 species. It results in significant improvement of the coagulation efficiency through an electrostatic patch effect. The results further indicate that zeta potential of the particle suspension is not the only indicator for the coagulant efficiency when precipitate formation significantly improves coagulation.
Co-reporter:Yujiang Li, Baoyu Gao, Tao Wu, Weisuo Chen, Xia Li, Biao Wang
Colloids and Surfaces A: Physicochemical and Engineering Aspects 2008 Volume 325(1–2) pp:38-43
Publication Date(Web):15 July 2008
DOI:10.1016/j.colsurfa.2008.04.046
Calcined hydrotalcite is a potential ion exchanger/adsorbent which can be used to remove toxic anions from contaminated water. The adsorptive removal of thiocyanate from aqueous solutions by calcined hydrotalcite was investigated in a batch mode. The influence of initial thiocyanate concentration, adsorbent concentration and temperature on the kinetics of thiocyanate removal was tested in kinetic runs. Three kinetic models were used to fit the experimental data, and it was found that the pseudo-second-order kinetics model is most appropriate to describe the adsorption kinetics. A Langmuir isotherm was used to fit the equilibrium experiments, and the saturated adsorption capacity was approximately 96.7 mg/g, under the experimental conditions. The calculated activation energy for the process was 48.9 kJ/mol.
Co-reporter:Bao-Yu Gao, Qin-Yan Yue, Yan Wang
Separation and Purification Technology 2007 Volume 56(Issue 2) pp:225-230
Publication Date(Web):15 August 2007
DOI:10.1016/j.seppur.2007.02.003
A series of polyaluminum silicate chloride (PASiC) composite coagulants were prepared by two approaches: (1) hydroxylation of the mixture of AlCl3 and fresh polysilicate (PASiCc); (2) hydroxylated polyaluminum chloride (PAC) combined with fresh polysilicate (PASiCm). Laboratory experiments were conducted to evaluate PASiC in comparison with PAC for the coagulation of water and wastewater and to investigate the effects of preparation technique, [OH]/[Al] ratio (i.e. γ value), pH, Al/Si ratio, and temperature on the coagulation performance of PASiC. The experimental results showed that PASiC performed more efficiently than PAC did in removing algae, turbidity, oil, chemical oxygen demand (COD) and total phosphate (TP). At the same Al/Si ratios, PASiCc achieved slightly greater removal of turbidity than PASiCm did. However, the difference became less significant at higher dosages. The results also demonstrated that the coagulation efficiency of PASiC was better at greater γ values and that PASiC became unstable during aging at very high γ values. The optimum coagulation pH range of PASiCc at a γ value of 2.0 and an Al/Si ratio of 10 was found to be 6.0–8.5, slightly wider than that of PAC (6.0–8.0).
Co-reporter:Qin-Yan Yue, Qian Li, Bao-Yu Gao, Yan Wang
Separation and Purification Technology 2007 Volume 54(Issue 3) pp:279-290
Publication Date(Web):1 May 2007
DOI:10.1016/j.seppur.2006.10.024
The characterization of polyepicholorohydrin-dimethylamine/bentonite and the kinetics of adsorption of four disperse dyes, namely, Disperse Yellow Brown S-2RFL (DYB S-2RFL), Disperse Red S-R (DR S-R), Disperse Blue SBL (DB SBL) and Disperse Yellow (DY SE-6GFL) onto organophilic bentonite (polyepicholorohydrin-dimethylamine/bentonite) have been studied at various solution concentrations and temperatures. The adsorption kinetics was studied in terms of a two-step first-order kinetic rate equation and intra-particle diffusion model. The adsorption process has been found to follow with two different rate constants (k1 and k2) for two-step first-order kinetic rate equation and also two different intra-particle diffusion rate constants (kint1 and kint2) for intra-particle diffusion model. For both the kinetic steps, the energies of activation of adsorption (Ea1 and Ea2) and other thermodynamic parameters (ΔH1* and ΔH2*, ΔS1* and ΔS2*, ΔG1* and ΔG2*) have been calculated using Arrhenius's and Eyring's equation, respectively. It has been found that for both the adsorption kinetic steps, Ea1 and Ea2 are corresponding to the values of k1 and k2 and ΔH1*<−Tav ΔS1*, ΔH2*<−Tav ΔS2* and ΔG* > 0, which means that the influence of entropy is more remarkable than enthalpy in activation reaction and the adsorption process is not spontaneous.
Co-reporter:Bao-Yu Gao, Yan Wang, Qin-Yan Yue, Jin-Cheng Wei, Qian Li
Separation and Purification Technology 2007 Volume 54(Issue 2) pp:157-163
Publication Date(Web):1 April 2007
DOI:10.1016/j.seppur.2006.08.026
In this study, a new composite coagulant, which was prepared by ployferric chloride (PFC) premixed with polydimethyldiallylammonium chloride (PDMDAAC), was adopted to treat the simulated dye water and the actual textile wastewater. The effect of coagulant dosage and pH of dye water on the color removal was examined. And the color removal results treated by the composite coagulant (PFC–PDMDAAC) were compared with those treated by PFC, PDMDAAC and PFC followed by PDMDAAC (PFC/PDMDAAC), respectively. The following results are discovered. Synergy between PFC and PDMDAAC increases zeta potential of PFC–PDMDAAC and reduces the effect of pH on zeta potential and Fe(III) species of PFC–PDMDAAC. Treatment with PFC–PDMDAAC is very effective in removing disperse blue HGL (98%) and reactive blue STE (86%). And small changes in the color removal efficiency of PFC–PDMDAAC are observed in all pH range. The color removal efficiency for disperse blue HGL and reactive blue STE is higher than 96% and 98% in the pH range 7.5–10.5, respectively. Furthermore, PFC–PDMDAAC is shown to be more effective in removing dye than that of PFC/PDMDAAC. Finally, the treatment of the actual textile wastewater has shown that PFC–PDMDAAC is a more effective coagulant.
Co-reporter:Baoyu Gao;Yongbao Chu;Qinyan Yue
Frontiers of Environmental Science & Engineering 2007 Volume 1( Issue 3) pp:368-373
Publication Date(Web):2007 July
DOI:10.1007/s11783-007-0063-8
In order to investigate the characteristics of pure Nano-Al13, Nano-Al13 was separated and purified from a series of poly-aluminum chloride (PAC) solutions which had the same Al13 percentage but different total Al concentrations, by using column chromatography, ethanol-acetone resolving and SO2−4/Ba2+ displacement. The Al13 species yield was characterized by Al-ferron timed complexation spectrophotometry and 27Al-NMR (nuclear magnetic resonance). The coagulation efficiency of Nano-Al13, PAC and AlCl3 in synthetic water was also investigated by Jar tests. The dynamic process and aggregation state of kaolin suspensions coagulating with Nano-Al13, PAC and AlCl3 were similarly investigated using a photometric dispersion analyzer 2000 (PDA2000). The experimental results indicated that the ethanol-acetone resolving method was simple and could separate the PAC solution at different concentrations, while column chromatography could separate PAC solutions at low concentrations. The SO42−/Ba2+ displacement method could separate PAC solutions at high concentrations. However, extra inorganic cation and anion could be added in the solution during separation. The coagulation efficiency and dynamic experimental results showed that Nano-Al13 with high positive-charged species was effective in removing turbidity and color. The dynamic process results showed that Nano-Al13 also had the best recovery capability after shearing compared with PAC and AlCl3 because the Nano-Al13 conformation is more effective in charge neutralization.
Co-reporter:B.Y Gao, Q.Y Yue, B.J Wang, Y.B Chu
Colloids and Surfaces A: Physicochemical and Engineering Aspects 2003 Volume 229(1–3) pp:121-127
Publication Date(Web):24 November 2003
DOI:10.1016/j.colsurfa.2003.07.005
A new inorganic polymer coagulant, poly-aluminum-silicate-chloride (PASiC), was prepared by two approaches: (1) hydroxylation of the mixture of AlCl3 and fresh polysilicic acid in Al/Si ratios ≥5, (PASiCc); (2) hydroxylated poly-aluminum-chloride (PAC) combined with polysilicic acid aged 2 h in Al/Si ratios ≥5, (PASiCm). The hydrolysis-polymerization process of Al(III) in PASiC solution was examined with pH titration method. The performances of PASiC in comparison with PAC were characterized by various experimental methods. The results have shown that there exist some interactions between aluminum species and polysilicic acid, especially at low basicity (B) value, which can play a part in the chemical structure, the molecular weight distribution, the electrokinetic characteristics and the coagulating properties of PASiC. The complexes formed when different charged aluminum species and polysilicic acid are combined have a less positive charge but a larger molecular weight than the corresponding aluminum hydrolysis products at the same pH value. Therefore, it is necessary to consider the aggregating efficiency and charge effectiveness when developing PASiC coagulant. In general, PASiC has shown a high coagulation effect, superior to that of PAC for both turbidity and color removal.
Co-reporter:Yuanfang Wang, Baoyu Gao, Qinyan Yue, Xiao Zhan, Xiaohui Si, Chunxiao Li
Journal of Environmental Management (November–December 2009) Volume 91(Issue 2) pp:423-431
Publication Date(Web):1 November 2009
DOI:10.1016/j.jenvman.2009.09.012
Epichlorohydrin-dimethylamine polymers with different intrinsic viscosity (η) and cationicity (τ) were synthesized. The flocculation performance and mechanism of these polymers in the removal of the reactive and disperse dyes from synthetic wastewater was investigated in terms of flocculation dynamics and color removal efficiency. The polymer flocculation efficiency was compared with that of polyaluminum chloride (PAC) and a composite flocculant based on polyaluminum chloride-epichlorohydrin-dimethylamine polyamine. The results showed that epichlorohydrin-dimethylamine polymer was effective over a pH range of 2–10 for the reactive and disperse dye removal (Reactive Brilliant Red and Disperse Yellow dyes). Epichlorohydrin-dimethylamine polymer with the highest η and τ gave the best reactive dye removal efficiency, and its adsorption-bridging and electric neutralization ability played important roles in the flocculation process. The higher the η viscosity of the epichlorohydrin-dimethylamine polymer, the better the flocculation performance of epichlorohydrin-dimethylamine polyamine, and stronger adsorption-bridging ability was obtained for removing the disperse dye from dyeing wastewaters. Epichlorohydrin-dimethylamine polymer achieved better decolorization performance when used together with PAC.
Co-reporter:Bo Guo, Huan Yu, Baoyu Gao, Sen Zhang, ... Xing Xu
Journal of Environmental Sciences (January 2017) Volume 51() pp:305-314
Publication Date(Web):1 January 2017
DOI:10.1016/j.jes.2016.08.002
In this study, a new and facile route was employed for synthesis of polyamidine with abundant cations and attractive five-membered ringlike structural unit. N-vinylformamide and acrylonitrile copolymerized firstly to form intermediates, and the intermediates were processed with hydrochloric acid to produce polyamidine. A series of polymerization conditions (e.g. polymerization time, temperature and dosage of initiator) were optimized through productivity, viscosity and cationic degree as evaluation. SEM analysis illustrated that the amidinization process could reduce the size of spaces between molecular and created compact structure, which would contribute to good flocculation performance and high viscosity. FT-IR, XPS and NMR spectra presented a rather clear structure of polyamidine. 34.3% of sludge was sedimentated through the flocculation of polyamidine in the early stages. In contrast, only 6.8% of sludge was sedimentated by polyacrylamide. The moisture content in dehydrated floc could be reduced to 77.7% when 60 mg/L polyamidine was added. These results demonstrated that the polyamidine showed a great potential in the practical application of sludge dewatering.Download high-res image (103KB)Download full-size image
Co-reporter:Qin-Yan Yue, Qian Li, Bao-Yu Gao, Ai-Juan Yuan, Yan Wang
Applied Clay Science (February 2007) Volume 35(Issues 3–4) pp:268-275
Publication Date(Web):February 2007
DOI:10.1016/j.clay.2006.09.008
Co-reporter:Yan Wang, Wei-Zhi Zhou, Bao-Yu Gao, Xiu-Ming Xu, Gui-Ying Xu
Separation and Purification Technology (7 May 2009) Volume 66(Issue 3) pp:457-462
Publication Date(Web):7 May 2009
DOI:10.1016/j.seppur.2009.02.011
In order to investigate the effect of total hardness on coagulation efficiencies of Al species, different Al coagulants – conventional Al salt (AlCl3), polyaluminum chloride (PAC-1) and the purified polyaluminum chloride (PAC-2) – were used to treat humic acid (HA) and kaoline clay in this study. The coagulation efficiency and coagulation kinetics were investigated by treating synthetic water with different total hardness. The results suggest that total hardness can influence the coagulation efficiencies of aluminum salts. The coagulation efficiency of AlCl3, PAC-1 and PAC-2 increased when total hardness increased. The investigations on coagulation kinetics showed that total hardness influences the flocs aggregation in the coagulation process of aluminum salts. Higher total hardness results in longer reaction time in all cases. The maximum floc size of AlCl3, PAC-1 and PAC-2 occurs when total hardness reaches 8, 4, and 1 mmol L−1, respectively.
Co-reporter:Ruihua Li, Baoyu Gao, Defang Ma, Hongyan Rong, Shenglei Sun, Fang Wang, Qinyan Yue, Yan Wang
Journal of Hazardous Materials (21 March 2015) Volume 285() pp:103-108
Publication Date(Web):21 March 2015
DOI:10.1016/j.jhazmat.2014.11.048
•The proportion of trihalomethanes (THMs) species did not change with time.•Mass ratio of CHCl3 to total trihalomethane (TTHM) rose as chlorine dose increased.•TTHM concentration and mass ratio of CHCl3 rose with pH increasing.•Dual-coagulant had higher THMs precursors removal ratio than polyaluminum chloride.•Unfiltered water had higher THMs formation potential than filtered water.In this study, coagulation performance of polyaluminum chloride (PAC) and PAC-lignin acrylamide (PAC + LAM) in reservoir water treatment was contrastively analyzed. Effects of operating conditions including chlorine dose, contact time and pH on the formation potential of trihalomethanes (THMs) during chlorination in coagulated effluent were also investigated. Comparing with PAC, PAC + LAM achieved higher efficiency in the removal of THMs precursors. TTHM yield in unfiltered water samples (UW) was greater than that of filtered water (FW) due to the residual dissolved organic matter (DOM) in the suspended particles or micro flocs. Meanwhile, operating conditions during chlorination had a significant influence on THMs formation potential. With chlorine dose rising, mass ratio of CHCl3 to TTHM increased, whereas that of CHBr2Cl decreased due to higher Cl2/Br− molar ratio. TTHM and CHCl3 levels rose with the increase of pH. Under a given chlorination condition, there was a minor effect of contact time on THM speciation.
Co-reporter:Xing Xu, Baoyu Gao, Bo Jin, Hu Zhen, Xiaoyi Wang, Ming Dai
Journal of Hazardous Materials (21 March 2015) Volume 285() pp:228-235
Publication Date(Web):21 March 2015
DOI:10.1016/j.jhazmat.2014.10.061
•We created a multiple electron acceptor/donor system for ClO4− reduction.•Nitrate reduction was inhibited when using perchlorate-grown Azospira sp. KJ.•Reduction proceeded as an order of ClO3−, ClO4−and NO3−.•Oxidation of acetate was inhibited by succinate in acetate–succinate series.Bioremediation of perchlorate-cotaminated water by a heterotrophic perchlorate reducing bacterium creates a multiple electron acceptor-donor system. We experimentally determined the perchlorate reduction by Azospira sp. KJ at multiple pH, electron acceptors and donors systems; this was the aim of this study. Perchlorate reduction was drastically inhibited at the pH 6.0, and the maximum reduction of perchlorate by Azospira sp. KJ was observed at pH value of 8.0. Perchlorate reduction was retarded in ClO4−–ClO3−, ClO4−–ClO3−–NO3−,and ClO4−–NO3− acceptor systems, while being completely inhibited by the additional O2 in the ClO4−–O2 acceptor system. The reduction proceeded as an order of ClO3−, ClO4−, and NO3− in the ClO4−–ClO3−–NO3− system. KS, vmax, and qmax obtained at different e− acceptor and donor conditions are calculated as 140.5–190.6 mg/L, 8.7–13.2 mg-perchlorate/L-h, and 0.094–0.16 mg-perchlorate/mg-DW-h, respectively.Schemes of perchlorate reduction in ClO4−/ClO3−–NO3− e−acceptor systemsDownload full-size image
Co-reporter:Yu WANG, Bao-yu GAO, Wen-wen YUE, Qin-yan YUE
Journal of Environmental Sciences (2007) Volume 19(Issue 11) pp:1305-1310
Publication Date(Web):1 January 2007
DOI:10.1016/S1001-0742(07)60213-7
In order to reduce the impact of eutrophication caused by agricultural residues (i.e., excess nitrate) in aqueous solution, economic and effective anionic sorbents are required. In this article, we prepared anionic sorbent using wheat straw. Its structural characteristics and adsorption properties for nitrate removal from aqueous solution were investigated. The results indicate that the yield of the prepared anionic sorbent, the total exchange capacity, and the maximum adsorption capacity were 350%, 2.57 mEq/g, and 2.08 mmol/g, respectively. The Freundlich isotherm mode is more suitable than the Langmuir mode and the adsorption process accords with the first order reaction kinetic rate equation. When multiple anions (SO42−, H2PO4−, NO3−, and NO2−) were present, the isotherm mode of prepared anionic sorbent for nitrate was consistent with Freundlich mode; however, the capacity of nitrate adsorption was reduced by 50%. In alkaline solutions, about 90% of adsorbed nitrate ions could be desorbed from prepared anionic sorbent. The results of this study confirmed that the wheat straw anionic sorbent can be used as an excellent nitrate sorbent that removes nitrate from aqueous solutions.
Co-reporter:Shenglei Sun, Zhonglian Yang, Xin Huang, Fan Bu, Defang Ma, Hongyu Dong, Baoyu Gao, Qinyan Yue, Yan Wang, Qian Li
Desalination (2 February 2015) Volume 357() pp:163-170
Publication Date(Web):2 February 2015
DOI:10.1016/j.desal.2014.11.031
•Coagulation performance of PFC/DAM–ECH was better than PFC at proper dosage.•Adding sequence of coagulants was critical for HA removal and floc properties.•Better removal efficiencies of HA by PFC/DAM–ECH achieved at acidic condition.•DAM–ECH improved the floc properties by enhancing charge neutralization mechanism.•Effects of DAM–ECH on floc properties reduced membrane fouling.Polyferric chloride (PFC) and epichlorohydrin–dimethylamine (DAM–ECH) with different PFC (as Fe3 +)/DAM–ECH mass ratios (MR) and dose methods were used in the treatment of humic acid–kaolin (HA–kaolin) simulated water under different pH conditions. Coagulation performance, floc characteristics and membrane fouling of PFC/DAM–ECH in coagulation–ultrafiltration (C–UF) process were investigated in this study. Results showed that the optimum coagulation performance was achieved when PFC dose was 15 mg/L with PFC/DAM–ECH MR of 2:1 under pH 6.0. Opposite adding sequence (DAM–ECH/PFC) would reduce UV254 (ultraviolet adsorption at 254 nm) and DOC (dissolved organic carbon) removal efficiency. Addition of DAM–ECH on the basis of PFC produced larger and stronger flocs with better regrowth ability. Proper dosage of DAM–ECH under certain coagulation condition could achieve the best coagulation performance and keep the UF membrane operating under a preferable status. Results of this study would be beneficial for application of composite coagulant PFC–DAM–ECH and DAM–ECH as coagulant aid in water treatment processes.
Co-reporter:Bao-Yu Gao, Qin-Yan Yue, Yan Wang
Separation and Purification Technology (15 August 2007) Volume 56(Issue 2) pp:225-230
Publication Date(Web):15 August 2007
DOI:10.1016/j.seppur.2007.02.003
A series of polyaluminum silicate chloride (PASiC) composite coagulants were prepared by two approaches: (1) hydroxylation of the mixture of AlCl3 and fresh polysilicate (PASiCc); (2) hydroxylated polyaluminum chloride (PAC) combined with fresh polysilicate (PASiCm). Laboratory experiments were conducted to evaluate PASiC in comparison with PAC for the coagulation of water and wastewater and to investigate the effects of preparation technique, [OH]/[Al] ratio (i.e. γ value), pH, Al/Si ratio, and temperature on the coagulation performance of PASiC. The experimental results showed that PASiC performed more efficiently than PAC did in removing algae, turbidity, oil, chemical oxygen demand (COD) and total phosphate (TP). At the same Al/Si ratios, PASiCc achieved slightly greater removal of turbidity than PASiCm did. However, the difference became less significant at higher dosages. The results also demonstrated that the coagulation efficiency of PASiC was better at greater γ values and that PASiC became unstable during aging at very high γ values. The optimum coagulation pH range of PASiCc at a γ value of 2.0 and an Al/Si ratio of 10 was found to be 6.0–8.5, slightly wider than that of PAC (6.0–8.0).
