Fabrication Of Visible-light Responsed Photocatalytic Fibers For The Degradation Of Antibiotic Contaminants

With the development of human civilization,advanced science and technology and advanced industries have brought convenience to people,at the same time they have also raised a great deal of environmental problems.Water pollution has received significant attention recently.Contaminated water contains a large number of organic pollutants,such as drugs,antibiotics and chlorinated aromatic compounds.These pollutants are characterized by low concentration,high toxicity and difficult to be biodegraded,which have caused serious damage to the water environment.Particularly the abuse of antibiotics on individual treatment and livestock husbandry has made environment pollution severe,such as sulfonamides and tetracycline hydrochloride.Therefore,it is of great social significance to design an effective system for treating organic pollutants in water.Photocatalysis has recently been a hotspot of research as an environmentally benign,low-cost and highly-efficient approach to the decomposition of organic pollutants.Large numbers of photocatalysts have been investigated,such as TiO₂,MoS₂,Bi₂WO₆ and some composite catalysts.Polymeric graphitic carbon nitride?g-C₃N₄?,as a metal-free photocatalyst,is furnished with a narrower band gap in comparison with many catalysts,possessing high photocatalytic activity,which makes it an excellent candidate for the utilization of solar energy as a sustainable source of visible light for photocatalysis.However,powdery g-C₃N₄ is inclined to aggregate and deposit in dilute solutions,restricting its application.This study prepared a kind of visible-light responsed photocatalytic fibers for the degradation of antibiotics.In this paper,g-C₃N₄ powder was prepared by pyrolysis.Low melting point sheath-core composite polyester fiber?LMPET?,possessing a unique low-temperature hot stickiness,was used for the immobilizaiton of g-C₃N₄ powders.The resultant nonwoven catalyst was labeled g-C₃N₄@LMPET.The images of scanning electron microscope?SEM?and three-dimensional microscope showed that g-C₃N₄@LMPET-140 was a three-dimensional?3D?irregular interpenetrating network structure with g-C₃N₄ particles embedded in the surface of fibers uniformly.The load amount of g-C₃N₄ was calculated to be 3.25%according to the results of organic elemental analysis.The efficiency of the as-prepared nonwoven catalyst towards micropollutant removal was determined by the degradation of sulfadiazine?SDZ?under simulated solar irradiation.g-C₃N₄@LMPET-140 showed remarkable reusability and achieved high conversion of antibiotics even in complex background.Furthermore,·O₂^–was identified as the controlling radical,indicating that this photocatalyst was corrosion resistant.The results of ultra-performance liquid chromatography and high-definition mass spectrometry?UPLC-HDMS?analysis showed that SDZ could be degraded effectively in this photocatalytic system and finally formed a series of biodegradable small molecule acids by ring opening.Water impact experiments and tensile strength tests showed that g-C₃N₄@LMPET-140 possessed excellent permeability and tensile strength.In order to accelerate the mass transfer of polluted water on the surface of the catalytic material and solve the problem of poor hydrophilicity of single polyester carrier,viscose fibers were introduced into this catalytic system.g-C₃N₄@LMP/V20 was fabricated in the same way of g-C₃N₄@LMPET.SEM,Fourier infrared spectrum and ultraviolet/visible diffuse reflection spectrum analysis showed that there were LMPET and viscose fibers existed in g-C₃N₄@LMP/V20 and g-C₃N₄ could effectively be embedded in the surface of LMPET.The load amount of g-C₃N₄ was determined to be 1.90%,much smaller than that of g-C₃N₄@LMPET.Tetracycline hydrochloride?TC?was selected as the model pollutant.In comparison with g-C₃N₄@LMPET,the efficiency of TC degradation was significantly increased in the presence of g-C₃N₄@LMP/V20.The degradation rate of TC reached to 100%at p H 7 after irradiation for2 hours.Capture agent and EPR experiments indicated that·O₂^–was the main active species.Furthermore,the degradation pathways of TC in this photocatalytic system were analyzed by UPLC-HDMS.This study offered a new idea for designing a simple and efficient catalyst loading method.The catalytic material prepared by this method has excellent mechanical strength and load stability,providing a new method for photocatalytic degradation of natural water pollution.