•CaO2 activated by Fe3+ was used as an oxidant for BPA degradation.•With OA, 91.7% of Fe3+ was reduced comparing to CaO2/Fe3+ system.•The ferric sludge was reused and successfully promoted BPA removal in CaO2/OA system.•Acidification and chelation are responsible for the improved BPA removal.The performance of calcium peroxide (CaO2) oxidation catalyzed by Fe3+ for the removal of bisphenol A (BPA) from aqueous solution was investigated. The ability of chelating agents (CAs), such as citric acid (CA), oxalic acid (OA), ethylenediaminetetraacetic (EDTA) and tartaric acid (TA), to accelerate the BPA degradation and to reduce the Fe3+ dosage was assessed. Furthermore, ferric sludge was reused as a source of catalyst to reduce solid waste accumulation. Results showed that the dosage of CaO2 and Fe3+ progressively influenced the BPA degradation and the optimal dosage was 2.0 mM CaO2 and 3.0 mM Fe3+. The addition of CAs effectively enhanced the BPA removal in CaO2/Fe3+ system and remarkably reduced Fe3+ utilization from 3.0 mM to 0.25 mM. BPA degradation increased from 21.3% (without CAs) to 98.3%, 98.9%, 95.5%, 95.0% with 1.0 mM CA, OA, EDTA and TA respectively. When 2.4 g/L ferric sludge was used as catalyst source, a 95.1% removal of BPA was achieved in the presence of OA. This study presents a high-impact contribution to Fenton-based wastewater treatment that can increase treatment efficiency and decrease waste sludge yield.

Recently, the removal of phenolic compounds has attracted great attention in wastewater treatment. In this work, the influences of various cyclodextrins (CDs) on the photodegradations of phenol and bisphenol A (BPA) under UV light were investigated systematically. The results show that the photodegradation of phenol displays no obvious differences in the presence or absence of CDs. In contrast, BPA photodegradation increases considerably in the presence of β-CD and its derivatives. Moreover, the catalytic effects of BPA differed among α-CD, β-CD, carboxymethyl-β-CD (CM-β-CD), and hydroxypropyl-β-CD (HP-β-CD), following the order β-CD ≈ HP-β-CD > CM-β-CD > α-CD. Specifically, over 99% of the BPA was degraded in the HP-β-CD and β-CD systems within 120 min. Additionally, six main intermediates of BPA in the presence of β-CD were confirmed, and the probable degradation pathway was proposed, which provides a useful platform for the application of CDs in the photodegradation of BPA.

Pine sawdust (PS) was modified with citric acid (CA) and β-cyclodextrin (CD) for aniline removal, and its adsorption properties were investigated using a batch and column experiment. On the basis of the Langmuir analysis, the maximum adsorption capacities were determined to be 16.3, 117.0, and 233.6 μmol g–1 of the base-treated PS, CA-modified PS, and CA+CD-modified PS, respectively, which showed that CA+CD-modified PS possesses the strongest adsorption ability for aniline because of the hydrogen bond interaction, hydrophobic interaction, and cyclodextrin inclusion. The adsorption capacities of aniline on modified PS increased with an increase in the ionic strength and changed little with an increase in pH from 5.0 to 10.0. The column experiment results showed that the space velocity strongly influenced the aniline uptake capacity. As modified PS is easily obtained and exhibits high adsorption capacity, it is a promising candidate for use in the removal of aniline from wastewater.

The sorption behaviour of bisphenol A (BPA) from aqueous solutions onto a biosorbent such as peat, rice husk, bagasse, and sawdust was evaluated. The effects of various parameters, including sorbent dose, solution pH, ionic strength, temperature, and competitive adsorption, were determined. The sorption capacity of peat notably increased to a level even higher than that of activated carbon after modification with a quaternary ammonium surfactant. The sorption process fitted the pseudo-second-order model well. The sorption of BPA onto modified peat is preferred in the presence of phenol as a competitor. Hydrophobic interactions play an important role during the sorption process. These observations indicate that the BPA sorption capacity of natural peat can be significantly promoted via surfactant modification and is of great potential for environmental application.

Fibric peat was modified with hexadecyltrimethylammonium bromide (HTAB) and its efficiency as a biosorbent for the removal of endocrine disrupting chemical-bisphenol A (BPA) was investigated. The HTAB-modified peat displayed a faster initial BPA sorption and substantially higher capacity than the unmodified peat over a wide concentration range. Kinetic study showed that the sorption followed the pseudo-second-order kinetic model. The maximum sorption capacity of 31.40 mg g−1 was obtained at initial concentration of 45 mg L−1. The BPA sorption to HTAB-modified peat was better described by Freundlich isotherm, while Langmuir isotherm fits better to the BPA sorption against unmodified peat. Comparing with raw fibric peat, the HTAB-modified peat removed more BPA molecules and the desorption rate was much lower. It shows that the improved hydrophobic interactions are the dominant mechanism and the chemical modification of the peat surface greatly enhanced the sorption capacity toward organic compound dissolved in water.Highlights► Fibric peat was modified with hexadecyltrimethylammonium bromide (HTAB) as a biosorbent for the removal of bisphenol A. ► The HTAB-modified peat displayed a faster initial BPA sorption and substantially higher capacity than the unmodified peat. ► The chemical modification of the peat surface greatly enhanced the sorption capacity toward bisphenol A. ► The improved hydrophobic interactions are the dominant mechanism.

A large amount of waste lye is produced in petroleum refineries during alkali cleaning process, which consists of high concentration of phenols, sulfides, oils and other pollutants. In this study, tributyl phosphate (TBP) was used as extraction agent and the extraction kinetics of phenolic compounds was investigated by the constant interfacial cell method. The effects of stirring speed, temperature and specific area on extraction rate were studied. The experimental results show that the extraction of phenols by TBP is a first-order reaction, and the extraction process may be controlled by diffusion. The effects of stirring speed and specific area on extraction rate are significant.