Activated carbon derived from finger citron residue (FAC) was tested as a new type of adsorbent for the removal of harmful dyes, namely, the anionic dye methyl orange (MO) and the cationic dye methylene blue (MB), from contaminated water. Liquid-phase adsorption experiments were conducted, and the maximum adsorption capacity was determined. Various conditions were evaluated, including initial dye concentration, adsorbent dosage, contact time, solution pH, and temperature. The Langmuir and Freundlich adsorption models were used to describe the equilibrium isotherm and to calculate the isotherm constants. It was found that the adsorption capacity of FAC is much higher than those of other types of activated carbons. Maximum equilibrium adsorption capacities of 934.58 and 581.40 mg/g for MO and MB, respectively, were achieved. Three simplified kinetic models, namely, pseudo-first-order, pseudo-second-order, and intraparticle diffusion equations, were used to investigate the adsorption process. The pseudo-second-order equation was followed for the adsorption of MO and MB on FAC. The temperature-dependent adsorption behaviors of MO and MB indicated that the adsorption is a spontaneous and endothermic process accompanying an entropy increases (the driving force for adsorption). This work demonstrates that FAC could be employed as a low-cost alternative to commercially available activated carbons in the removal of dyes from wastewater.

A new type of composite adsorbent, MOF-5/Cu(I), was prepared by MOF-5 doped with different amount of CuCl using a spontaneous monolayer dispersion technique. These new composite adsorbents were characterized by X-ray diffraction, thermogravimetric analysis, electrondispersion X-ray scope, and N2 adsorption, respectively. The desulfurizaion performance of the prepared adsorbents was evaluated by the selective adsorption of dibenzothiophene from the simulated oils in a fixed-bed breakthrough column at room temperature. From the obtained breakthrough curves, both the breakthrough capacity and the saturation capacity of the adsorbents for sulfur element were determined. The results show that MOF-5/Cu(I) exhibited high desulfurization capacities, which are superior to those reported previously in the literature. In addition, these novel composite adsorbents possessed good durability and affinities for the adsorption of dibenzothiophene in the presence of aromatic components and moisture. The saturated composite adsorbent MOF-5/Cu(I) can be regenerated with nitrogen atmosphere sweeping at 623 K for 4 h. About 97% of the desulfurization capacity was recovered after regeneration.

A novel electrochemical biosensing strategy based on a three-dimensional fishnet of DNA-linked nanoparticle supramolecular structure triggered by the analyst for detection of Hg2+ has been designed. The detection limit is 7.38 pM and the sensor's selectivity and facility have been significantly improved.

Cytosolic fumarase, a key enzyme for the accumulation of fumaric acid in Rhizopus oryzae, catalyzes the dehydration of l-malic acid to fumaric acid. The effects of carbon–nitrogen ratio on the acid production and activity of cytosolic fumarase were investigated. Under nitrogen limitation stress, the cytosolic fumarase could keep high activity. With the urea concentration decreased from 2.0 to 0.1 g l−1, the cytosolic fumarase activity increased by 300% and the production of fumaric acid increased from 14.4 to 40.3 g l−1 and l-malic acid decreased from 2.1 to 0.3 g l−1. Cytosolic fumarase could be inhibited by substrate analog 3-hydroxybutyric acid. With the addition of 3-hydroxybutyric acid (50 mM) in the fermentation culture, fumaric acid production decreased from 40.3 to 14.1 g l−1 and l-malic acid increased from 0.3 to 5.4 g l−1.

A promising catalyst, KNaY was prepared by an ion exchange method with aqueous potassium chloride solution. Compared with NaY, KNaY was an effective catalyst for the dehydration of methyl lactate to methyl acrylate. Under the optimized conditions, an improved yield of 37.9 mol% was achieved.