Preparation Of ZnTiFe-LDHs Composite Material And Study On Visible Light Catalytic Performance

Removal of refractory organics is a difficult point in water treatment.Photocatalytic reactions can effectively remove refractory organics.Among them,the research and development of photocatalysts is a hot spot.Hydrotalcite-like materials have high specific surface area,high interlayer anion exchange capacity,adjustable internal structure,low cost and non-toxicity.In addition,they also have excellent characteristics of semiconductors and can be used as efficient photocatalysts.ZnTiFe-LDHs has a stable structure,is easy to prepare,and is low in price,but its photocatalytic performance is poor.In order to improve and promote its application in the field of water treatment photocatalysis,the UV photocatalytic performance of ZnTiFe-LDHs is improved by introducing energy PANI;Explore its visible light catalytic performance,and then add AgBr to improve the visible light absorption of the composite material.Therefore,PANI/ZnTiFe-LDHs and AgBr/PANI-ZnTiFe-LDHs were prepared.The composite materials were characterized by XRD,SEM,FT-IR,XPS,UV-Vis DRS,BET,PL,etc.Using composite materials to remove rhodamine B and tetracycline hydrochloride,the specific research results are as follows:PANI/ZnTiFe-LDHs composite materials were prepared by in-situ polymerization oxidation method and one-step hydrothermal method,and the composite materials were used to remove rhodamine B and tetracycline hydrochloride by UV photocatalysis.The crystallinity of the composites prepared by the in-situ polymerization oxidation method is slightly lower than that prepared by the one-step hydrothermal method,but they all retain the crystalline structure of ZnTiFe-LDHs,and PANI exists in the composite in an amorphous form.The photocatalytic performance of 7-LDHs/PANI prepared by in-situ polymerization oxidation method is the best.Under the conditions of pH=7,dosage of 0.4 g/L,initial concentration of 10 mg/L,adsorption for 60 min and UV catalysis for 180min,the removal rate of Rhodamine B by 7-LDHs/PANI was 80%;In the photocatalytic process,hydroxyl radicals(·OH)dominate.The photocatalytic performance of PANI-LDHs-7 prepared by one-step hydrothermal method is the best.Under the conditions of pH=7,dosage of 0.1 g/L,initial concentration of 10 mg/L,60 min adsorption and 120 min UV catalysis,the removal rate of tetracycline hydrochloride by PANI-LDHs-7 reached 90%;In the photocatalysis process,superoxide radicals(·O2-)and electrons(e")play a major role;repeated experiments show that both catalysts have good stability.By precipitation-deposition method,AgBr was loaded on the surface of PANI-LDHs-7 to prepare AgBr/PANI-LDHs-7 composite material.AgBr particles were distributed on the surface of PANI-LDHs-7,and the Ag element existed in the form of Ag+.The specific surface area and pore volume of the material are slightly reduced,but the pore size is increased,and the band gap energy is reduced,the fluorescence intensity is weakened,the electron-hole recombination rate is lower,and the charge transfer rate is greatly accelerated,and the visible light catalytic performance is good.20%AgBr/PANI-LDHs-7 has the best visible light catalytic performance to degrade Rhodamine B.Under the conditions of pH=9,dosage of 0.3g/L,initial concentration of 10mg/L,adsorption for 60min and visible light catalysis for 150min,the removal rate of Rhodamine B by 20%AgBr/PANI-LDHs-7 was 97%.In the photocatalysis process,superoxide radicals(·O2-)and hydroxyl radicals(·OH)together play a major role.Under the conditions of pH=7,dosage of 0.1g/L,initial concentration of 10 mg/L,60 min adsorption and 60 min visible light catalysis,the removal rate of tetracycline hydrochloride by 20%AgBr/PANI-LDHs-7 was 90%.In the photocatalytic process,superoxide radicals(·O2-)dominate;and the catalyst has good stability.