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An electro‐responsive hydrogel with semi‐interpenetrating polymer networks (semi‐IPN) composed of crosslinked poly(2‐acrylamido‐2‐methyl‐l‐propanesulfonic acid‐co‐acrylamide) (P(AMPS‐AM)) and linear polyelectrolyte polyacrylic acid (PAA) was explored. The semi‐IPN hydrogel was characterized with different methods and then used as advanced draw agent toward high water recovery for forward osmosis (FO) desalination. The swelling kinetics of the semi‐IPN hydrogel was investigated, and the electro‐responsive nature of the hydrogel under electric stimulus (in direct contact with electrodes) was determined. Results indicated that in comparison with pure P(AMPS‐AM) hydrogel, the semi‐IPN hydrogel exhibited a loose network structure with more pores. In addition, a higher equilibrium swelling capacity and more pronounced deswelling under electric stimulus can be observed for the semi‐IPN hydrogel. Furthermore, the semi‐IPN hydrogel displayed a similar initial water flux of 2.20 L m−2 h−1 (LMH) from 2 g/L NaCl solution of a lab‐scale FO process. Importantly, the semi‐IPN hydrogel had a 25% increase in water recovery efficiency under the electric stimulus of 15 V, and showed better recyclability during three cycles of regeneration compared with pure P(AMPS‐AM). The mechanism of enhanced dewatering nature for the semi‐IPN hydrogel under electric stimulus was elucidated. These results indicate this new hydrogel's potential as a promising candidate for improving FO performance. [ABSTRACT FROM AUTHOR]

Amino‐functionalized magnetic zirconium alginate beads with an interpenetrating network (Fe3O4/PAM/SA–Zr) were prepared, characterized, and then tested as a novel biomass adsorbent for phosphate removal and recovery. The hydrogel beads exhibited outstanding thermostability and possessed a magnetic response. The effects of the pH, dosage, initial phosphate concentration, interference ions, and temperature on the removal of phosphate were investigated. The kinetics, isotherms, and thermodynamics of the adsorption were studied. Notably, the adsorption of phosphate was endothermic, feasible, and spontaneous with a maximum uptake capacity of 42.23 mg‐P/g at an optimized pH of 2.0. The phosphate could be desorbed effectively with a 0.2 mol/L NaOH solution, and the adsorbent exhibited a good reusability. The possible adsorption mechanisms were verified by zeta potential, Fourier transform infrared spectroscopy, and X‐ray photoelectron spectroscopy analyses. Continuous phosphate‐adsorption tests were conducted in a fixed‐bed columns packed with Fe3O4/PAM/SA–Zr, and the breakthrough curves were predicted by the Adams–Bohart, Thomas, and Yoon–Nelson models, respectively. The suitability of the hydrogel beads for the treatment of real wastewater was also tested. These hydrogel beads should be a promising adsorbent for phosphate removal and recovery from aqueous solutions, with the advantages of a high uptake capacity, good reusability, and easy magnetic separation. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 46897. [ABSTRACT FROM AUTHOR]

Tetracycline (TC) is a commonly used human and veterinary antibiotic that is mostly discharged into wastewater in the form of the parent compounds. At present, wastewater treatment plants (WWTPs) use activated sludge processes that are not specifically designed to remove such pollutants. Considering the biological toxicity of TC in aquatic environment, the migration and fate of TC in the process of wastewater treatment deserve attention. This paper reviews the influence of TC on the functional bacteria in the sludge matrix and the development of tetracycline-resistant genes, and also discusses their adsorption removal rates, their adsorption kinetics and adsorption isotherm models, and infers their adsorption mechanism. In addition, the biodegradation of TC in the process of biological treatment is reviewed. Co-metabolism and the role of dominant bacteria in the degradation process are described, along with the formation of degradation byproducts and their toxicity. Furthermore, the current popular integrated coupling-system for TC degradation is also introduced. This paper systematically introduces the interaction between TC and activated sludge in WWTPs. The review concludes by providing directions to address research and knowledge gaps in TC removal from wastewater. Unlabelled Image • The activity of function strain recovers after adapting to tetracycline (<5 mg/L). • Sludge protects itself with extracellular polymers which offer adsorption sites. • The biochemical adsorption process is rapid, but involves ion competition. • A lag period is needed before a cometabolism-led biodegradation process. • The integrated coupling system has the higher tetracycline mineralization rate. [ABSTRACT FROM AUTHOR]

Currently, there is a growing trend in employing natural biomaterials (e.g., alginate) to prepare a novel bead adsorbent for phosphorus (P) elimination. However, the utilization of alginate beads to remove and recover P from effluents possesses limitations associated with its physical characteristics such as a dense gel layer, poor mechanical strength and low stability. To overcome the limitations and improve the adsorption performances, we synthesized a novel alginate-derived bead constituted of PNIPAM network interpenetrated in alginate-Zr 4+ network (PNIPAM/SA-Zr) decorated with polyethylene glycol as a pore-forming agent, and then investigated its ability to remove and recover P from effluents. The morphology, functional groups, surface area, and mechanical strength of the beads were evaluated by SEM, FTIR, BET, and swelling analysis. The adsorption of P was investigated by varying various factors. The adsorption kinetics, isotherms, and thermodynamics were studied. Particularly, the P-loaded beads exhibited a faster desorption rate under thermal stimulus, and remained good desorption efficiency and reusability within five consecutive cycles. Zeta-potential and XPS results revealed that the adsorption mechanisms were related to electrostatic interactions, ligand exchange, and the formation of inner-sphere complexes. The beads possessed favorable fixed-bed column operation performances for P removal and recovery from real wastewater., (Copyright © 2018. Published by Elsevier B.V.)