Toxic Reduction And Deep Removal Of Florfenicol And Arsenic In Water By Electrocatalysis

The uneven distribution of global water resources,huge development and survival needs,and serious pollution have caused many countries and regions to face the problem of shortage of fresh water resources.Sewage reuse can reduce discharge and pollution.It is technically feasible and low-cost,which has become the main way to solve the problem of shortage of fresh water resources.Residues of refractory pollutants such as antibiotics and heavy metals in the water environment severely restrict the deep purification and recycling of water resources.Therefore,the development and research of high-efficiency water pollution repair and prevention technologies are imminent.In this research,a series of novel electrocatalysts have been developed.Driven by an electric field,the conversion and migration of antibiotics and acutely toxic heavy metal arsenic on the electrode surface can be achieved,thereby achieving detoxification or complete removal of target pollutants.The specific research content are as follows:(1)Efficient elimination of antibacterial activity of halogenated antibiotics by dehalogenation pretreatment is desired for a biochemical treatment process.In this study,crystalline cobalt phosphide nanosheet arrays on a Ti plate(C-Co P/Ti)are fabricated by a simple electrodeposition and phosphorization process.The crystalline structure greatly promotes atomic hydrogen(H*)generation.Moreover,the nanosheet arrays can provide abundant active sites and accelerate electron transfer and mass transport.As a result,the dehalogenation rate of florfenicol(FLO,an emerging organic pollutant)on C-Co P/Ti is 11.1,2.97,and 13.6 times higher than that on amorphous Co P/Ti,Pd/Ti,and bare Ti,respectively.The C-Co P/Ti electrode achieves 97.4%dehalogenation of FLO(20 mg L^–1)within 30 min at-1.2 V(vs Ag/Ag Cl).Nearly 100%of Cl and 20%of F are broken away within 120 min,showing the outstanding electrocatalytic defluorination efficiency reported so far.Both experimental results and theoretical calculations reveal that the dehalogenation of FLO on C-Co P/Ti is synergistically accomplished via direct reduction of electron transfer and indirect reduction of H*.This study develops a highly efficient non-noble metal electrode material for dehalogenation of halogenated organic compounds.(2)How to improve the efficiency of antibiotic d etoxification/degradation and effectively block the spread of ARGs is a major scientific and technological issue in the environmental field.Although electrocatalytic dehalogenation can detoxify halogenated antibiotics,the effect of dehalogenation treatment on resistance gene expression and microbial inhibition is poorly understood.Herein,a novel electrocatalyst of Fe-doped Co P nanotubes array on nickel foam(Fe-Co P NTs/Ni F)is prepared through a simple ultrasonication of Fe-doped Co P nanowires hydrothermally grown on Ni F.The transformation from nanowires to nanotubes improves the crystallinity of Co P and fully exposes active sites,producing energetic atomic hydrogen for dehalogenation.Fe-Co P NTs/Ni F exhibits a superior dehalogenation performance towards refractory florfenicol(FLO),achieving 100%removal within 20min(?1.2V vs Ag/Ag Cl,C₀=20 mg L^?1).The dechlorination rate reaches nearly 100%,and the defluorination rate achieves 36.8%within 50 min,showing the best electrocatalytic dehalogenation performance reported so far.Electrocatalytic reductive dehalogenation pretreatment of FLO can maintain microbial richness and diversity in the subsequent biochemical treatment unit,reducing the microbial inhibition caused by antibiotic.Specially,the electrocatalytic reductive dehalogenation treatment can significantly reduce the relative abundance of FLO resistance gene expression.The developed electrocatalytic reductive dehalogenation process is a reliable way for safe treatment of halogenated antibiotic wastewater.(3)The limitation of the mass transfer process of the traditional continuous flow electrocatalytic system resulting in low efficiency in the treatment of refractory pollutant.In addition,the material cost of the filled three-dimensional electrode is relatively,and the space required is large,which limits the wide application of electrochemical technology in the actual water treatment process.Membrane filtration exhibits the advantages of fast separation of pollutants and low environmental impact.However,membrane fouling and concentration polarization phenomena lead to poor performance and increased energy consumption.This work developed a new type of MXene electrocatalytic reduction membrane reaction system to treat antibiotic wastewater.MXene electrocatalytic reductive membrane can not only retain antibiotics to solve the problem of the continuous flow electrocatalytic system that is difficult to remove antibiotics deeply,but also can be used as an electrode to in situ degradation of antibiotics on the membrane surface to solve the problem of difficult treatment of concentrated water.Under the best operating conditions,the removal rate of FLO reaches 100%.In addition,this system can effectively remove five typical antibiotics and reduce their antibacterial activity.This research provides a new insight for the treatment of antibiotic wastewater.(4)Since the previous work used the cathode to achieve the conversion of antibiotics and the reduction of resistance,in order to maximize the utilization value of the electrochemical treatment system,we chose the trivalent arsenic As(III)as the target pollutant of the anode treatment process,which were high toxicity and environmental mobility.Herein,we rationally designed a highly efficient porous Fe-doped Co₃O₄ nano brush-like array in situ grow on nickel foam(Fe-Co₃O₄ NBs/Ni F)anode for simultaneous detoxification and capture of As(III).As(III)levels rapidly reduced to below 10?g L^-1 within 10 min using Fe-Co₃O₄ NBs/Ni F anode and completely converted into less toxic As(V)(+2.0V vs Ag/Ag Cl,C₀=1000?g L^-1).The experimental and density functional theory calculation results verified that As(III)oxidation and adsorption process was enhanced by the electrical field.This single-chamber electrochemical oxidation system can work at broad p H range(3-11),the presence of NO₃^—,CO₃^2—and PO₄^3—negligibly inhibited As(III)removal at+2.0V.After five times of recycling,the As(III)level can be reduced to less than 10?g L^-1within 10-20 minutes not require regeneration.This system could be prepared into a portable device to remediation low-concentration arsenic polluted water.This application affords a green and effective alternative to decontamination of arsenic in natural water.