Quaternary Ammonium Compounds Modified Carbon Composites For Capacitive Deionization Disinfection

Insufficient clean water is one of the crucial challenges that threaten human life andhealth.Although many disinfection technologies(chlorine,ozone,ultraviolet,etc.)are effective for killing pathogenic microorganisms in drinking water,they may produce disinfection by-products which are harmful to human health.Therefore,new disinfection technologies with low disinfection by-products,low toxicity,low power consumption,and high disinfection efficiency should be developed.Capacitive deionization(CDI)has attracted significant attention as an emerging technique for brackish water desalination because of its high energy efficiency and environmental friendliness.Capacitive deionization disinfection(CDID)combines water disinfection with CDI,and its key issue is surface modification of electrode with antibacterial materials.Quaternary ammonium compound(QAC)has been widely used due to its contact-active,broad-spectrum and high-efficiency antibacterial properties.In this dissertation,carbon materials are modified with QAC and used as anode material for CDID.The main contents are as follows:(1)Quaternized poly(4-vinylpyridine)modified activated carbon(AC-QPVP)electrode was used as anode for CDID.AC-QPVP with QAC coated density of 17.07% and 22.02%were prepared respectively by adjusting the addition of monomer and quaternization reagent,and the disinfection efficiency increased when the QAC coated density increased.Antibacterial mechanism of the material was proved to have physical damage on bacterial cell membranes by studies of bacterial morphology.The electrode could kill 99.54% of Escherichia coli or Pseudomonas aeruginosa at a voltage of 1.2 V,and exhibited high cyclic stability.Cell voltage was proved that it had huge effect on CDID performance,while flow rate and ion concentration were little.(2)Dimethyloctadecyl[3-(trimethoxysilyl)-propyl]ammonium chloride modified graphene oxide(GO/QAC)was prepared by one-step covalent modification.The effect of precursor ratio and reaction time on the QAC coated density was studied.The QAC coated density was optimal(61.58%)and GO/QAC exhibited excellent broad-spectrum antibacterial property,when GO/QAC precursor ratio and reaction time were 10:1 and 24 h respectively.The killing rates of Escherichia coli,Pseudomonas aeruginosa or Staphylococcus aureus are above 97.69% after CDID tests.Although salt ions had a little effect on bacteria adsorption,the killing rate could still reach 97.18% in 120 min.