Study On Photocatalytic Treatment Of Trace Antibiotics In Wastewater

Antibiotics are used to prevent and treat bacterial infections.Due to its massive abuse,it has seriously polluted environment,threatened human and biological health.Photocatalytic treatment technology has the advantages of low pollution,low cost and thorough degradation.It is considered to be an effective way to degrade organic pollutants.In order to resolve environmental pollution caused by the abuse of antibiotics,the photocatalytic technology is combined with neural networks in this work.A series of composites are prepared based on bismuth oxide（Bi₂O₃）.Titanium silicon molecular sieve（TS-1）and graphite phase carbon nitride（g-C₃N₄）are adopted as carriers to enhance the photocatalytic activity.Taking the typical antibiotics（erythromycin and tetracycline）in wastewater as the research objects,the photocatalytic treatment of antibiotic wastewater was carried out under different experimental conditions.An artificial neural network（ANN）was established based on the experimental data and used as the fitness function.The optimal experimental parameters corresponding to the highest degradation efficiency were obtain by the genetic algorithm（GA）method.The influence of environmental factors（p H,antibiotic concentration,wastewater composition,etc.）on the photocatalytic degradation efficiency is measured under the optimal experimental conditions.The relative importance of environmental factors on the photocatalytic degradation efficiency is obtained through the combination of ANN and Garson.This research can provide theoretical basis and technical support for the selection of catalysts and the practical application of photocatalytic treatment of antibiotic wastewater.The main research contents of this paper include the following two aspects:（1）TS-1 was synthesized by hydrothermal method and used to synthesize Bi₂O₃/TS-1composite by photodeposition method.The morphology,structure and photoelectric properties were characterized.The photocatalytic degradation efficiencies of ERM with were measured under differents experimental conditions（different Bi content and varied catalyst concentration）.The Bi content and catalyst concentration were used as the input layer,and the degradation efficiency was used as the output layer,an ANN model is established based on the experimental data.The optimal experimental conditions corresponding to the highest degradation efficiency were obtained by the GA optimation method.The highest degradation efficiency of erythromycin（98.02%）was measured under the optimal experimental conditions.In addition,the effect of environmental factors（p H and antibiotic concentration）on the photocatalytic degradation efficiency was carried out under the optimal experimental conditions,and the results showed that environmental factors had little effect on the degradation efficiency.The results indicated that the composite material has good chemical stability and is expected to realize photocatalytic treatment of trace erythromycin wastewater.（2）Melamine was used as the precursor and prepare flaky carbon nitride（g-C₃N₄）.A series of Bi₂O₃/g-C₃N₄ composites with different Bi contents were prepared by light deposition method.The morphologystructure and photoelectric properties were characterized by various instruments.The photocatalytic degradation experiments of tetracycline were carried out under different experimental conditions（p H,catalyst concentration,Bi content and TC concentration）.The experimental variables as the output layer and the degradation efficiency as the output factor,an ANN model was established based on the experimental data.and the optimal experimental conditions were predicted by GA optimization method.Moreover,the effect of wastewater components(NH₄⁺,Ca²⁺,PO₄^3-,HPO₄^2-,Mg²⁺and COD)on degradation efficiency were measured with different experimental conditions.The wastewater composition is used as the input layer,and the degradation efficiency is used as the output layer.An ANN model was proposed based on experimental data and the results indicated that the relative importance of components is in order of PO₄^3-,HPO₄^2-,Mg²⁺,NH₄⁺,COD and Ca²⁺.This work provided theoretical guidance for the synergistic effect of wastewater components on the degradation efficiency of antibiotics.