The flocculation performance of chitosan can be enhanced by grafting modification to overcome its disadvantages of poor water solubility. In this study, chitosan was modified by dielectric barrier discharge plasma and polymerized with acrylamide and aluminum chloride to synthesize a new chitosan-based flocculant, namely, chitosan-acrylamide-aluminum chloride (CA-PAC). After optimizing the synthesis conditions of CA-PAC, the best conditions were as follows: discharge time of 3 min, discharge power of 50 W, polymerization temperature of 60 degrees C, polymerization time of 3 h, total monomer concentration of 100 g/L, and m(AlCl3):m(CA) ratio of 2:1. Characterization was performed through SEM, XPS, FTIR, XRD, TG and 1H NMR. Results showed that the preparation of CA-PAC was successful. The influences of flocculant dosage, pH, and stirring intensity on flocculation efficiency were investigated. The removal efficiency of turbidity was 94.1 %. The investigation of the flocculation mechanism revealed that CA-PAC mainly relied on charge neutralization or the synergic action of electric neutralization, bridging, and roll-sweep under acidic and neutral conditions, but it depended on the joint action of adsorption bridging and net sweeping under alkaline conditions. This study provides new ideas for the preparation and development of modified chitosan and broadens its application in water treatment.

Molybdenum disulfide (MoS2) was added to the system after being treated with high-voltage pulse discharge plasma to improve the degradation efficiency of pollutants and reduce energy consumption. The discharge plasma-treated solution contains hydrogen peroxide and metal iron ions, and MoS2 addition can cause co-catalytic Fenton reaction. The effects of discharge time, initial pH, phenol concentration, MoS2 dosage, discharge voltage, and gas type on phenol removal and aqueous H2O2 concentration were mainly investigated. Results showed that the addition of MoS2 after plasma treatment can reduce the plasma treatment time by 70% and maintain or even increase the degradation efficiency of phenol from 40% (after 20 min of discharge plasma) to 92% (after turning off the discharge and dosing with MoS2 for 30 min). Acidic conditions (pH = 3-4) and oxygen were beneficial to phenol removal. MoS2 addition greatly improved the catalytic oxidation of discharge plasma. This study provides a promising direction for water treatment based on plasma technology.

Carbon nanotube (CNT) membrane electrochemical filtration has been found to provide effective solutions for water contaminant removal. However, bubble elimination, water flux increase, and CNT membrane robustness enhancement still remain great challenges for CNT electrochemical filtration technologies. To improve the performance of the electrochemical CNT filter, a ceramic flat membrane is used as the CNT electrode support. Aniline (AN) is chosen as the target pollutant to investigate the effects of water quality (initial pH, initial AN concentration, and support electrolyte concentration) and running conditions (anode potential and water flux). In addition, the current efficiencies (CE) of the two different modes (single-pass filtration and recirculated filtration) are also estimated. The results showed that the effects of various impact factors on the AN degradation were generally similar in both modes. Overall, the CEs of the sing-pass filtration mode with the stable influent conditions were higher than those of the recirculation filtration mode. Increasing the flux and applied anode potential did increase the AN degradation rate. The maximum water flux density of the high-flux CNT electrochemical filter reached 83.9 mL/(cm(2).h), 4.0-16.1 fold of that of a typical CNT electrochemical filter, addressing the defects of bubble formation and CNT fragility of the free-standing BUCKYPAPER membrane in a conventional electrochemical filter. The configuration with a ceramic membrane support greatly improved the practicability of CNT-based electrochemical filtration technology for real wastewater treatment.