Preparation Of TiO₂ And ZnO-TiO₂ Based Polymer Photocatalyst Microspheres And Their Degradation Properties For Tetracycline Hydrochloride

In recent years,with the continuous progress of industrialization in the world,the content of residual antibiotics in wastewater is getting higher and higher,and the pollution situation of tetracycline antibiotics among antibiotics is the most serious,and this contaminant can cause irreversible harm to the food chain and human health.Traditional treatment methods are generally based on biological treatment technology methods,but the removal efficiency of antibiotics is low,the high energy consumption of electrochemical and ultrasonic degradation leads to high operating costs,and the adsorption method is inefficient and does not completely remove tetracyclines.Compared with these methods,photocatalytic oxidation technology has potential application prospects in the treatment of antibiotics in the aqueous environment,and the development of new photocatalyst materials is a research hotspot in recent years,and semiconductor photocatalysts have the advantages of strong photocatalytic performance and good photocatalytic stability.However,there is still a need to solve the problems of their low recycling rate,high raw material and operation cost in the future.In response to the above problems,geopolymer,as a new green inorganic gelling material with three-dimensional mesh structure,can be used as a binder-curing agent to prepare photocatalyst microspheres.Its preparation process is simple and efficient,which can reduce the preparation cost,improve the catalytic efficiency and economic benefits.In this thesis,the preparation conditions and processes of different geopolymer oxide microspheres were investigated,and the preparation of Ti O₂and Zn O-Ti O₂base polymers photocatalyst microspheres and their degradation of tetracycline-based wastewater were carried out respectively.The main research results are as follows.（1）Process study on the preparation of oxide matrix microspheres using geopolymers as bonding agents,using water glass as alkaline exciter,metakaolin and different oxides（titanium oxide,alumina,silicon oxide and zinc oxide）as raw materials.It was observed that oxide matrix microspheres were successfully prepared with good sphericity,specific surface area and pore size,providing the preparation process for subsequent experiments.（2）The TiO₂@GMs photocatalysts were prepared by the geopolymer technique,and single-factor analysis and orthogonal experiments were conducted to determine the optimal preparation process of Ti O₂@GMs photocatalysts with the addition of 6 g Ti O₂,water glass modulus of 1.9 M,water volume of 3 g,and blender speed of 1000 rpm.the obtained Ti O₂@GMs photocatalysts had good sphericity Ti O₂@GMs showed excellent degradation performance against tetracycline hydrochloride in aqueous environment in the Fenton system under UV irradiation.The degradation rate of Ti O₂@GMs on tetracycline hydrochloride reached 98.6%in 30 min under the conditions of setting the concentration of tetracycline hydrochloride at 20 mg/L,the liquid-solid ratio at 0.3 g/L,the addition of H₂O₂（30 wt%）at 10 m M,and p H=4.47.Moreover,Ti O₂@GMs has excellent recycling performance,and the degradation efficiency still reached 90.6%after 5 cycles.Finally,this paper found that the photocatalytic process of Ti O₂@GMs mainly relies on（·O₂^-）and（·OH）to degrade TCs.The composite material has good application prospects for the degradation of tetracycline antibiotic pollutants in aqueous environment.（3）ZnO-TiO₂precursor powders were prepared by the hybrid,solid-phase reaction and sol-gel methods,and then different Zn O-Ti O₂-based geopolymer photocatalyst microspheres were prepared.Preliminarily,the degradation rates of tetracycline hydrochloride by the hybrid,solid-phase reaction and sol-gel precursor geopolymer photocatalyst microspheres were 30.8%,70.9%and98.5%,respectively.Among them,the sol-gel precursor geopolymer microspheres have good photocatalytic stability,and the degradation rate of tetracycline hydrochloride was 99.7%when the concentration of tetracycline hydrochloride was 10 mg/L,the liquid-to-solid ratio was 0.8 g/L,p H=5,and the xenon lamp simulated visible light was irradiated for 150 min,and it has excellent recycling performance.The degradation rate can reach more than 90%.The photocatalytic mechanism study found that·OH is the main reactive radical in the photocatalytic reaction process.