The Synthesis Of Ag₂S-TiO₂ Composite Catalyst And The Photocatalytic Degradation Of TC Under Visible Light

Pharmaceutical and Personal Care Products?PPCPs?with pseudo-persistence,poor biodegradability,ecological toxicity,and low concentration are increasingly a problem in the water environment.Among them,the antibiotics represented by tetracycline are cheap because of their low cost.Broad spectrum,widely used.However,traditional biological methods,physical methods,and chemical methods cannot effectively remove them.In contrast,photocatalytic technology,as a kind of advanced oxidation technology,has a better application prospect in refractory organic wastewater.Ti O₂semiconductor-based photocatalytic technology has achieved a lot of research results in aquatic hydrogen production,solar cells,and environmental governance,but its shortcomings and low photocatalytic utilization efficiency limit its industrial application.How to improve the economic benefits,recycling rate,and photocatalytic efficiency of their applications has become a scientific problem to be solved urgently.Based on the above problems,this paper uses Ag₂S modified narrow band gap semiconductor functional materials,composite Ti O₂and other methods to synthesize highly active Ag₂S-Ti O₂with different molar ratios?n?Ag₂S?:n?Ti O₂??by hydrothermal method combined with continuous ion layer reaction.Composite catalyst.Scanning electron microscopy?SEM?,energy dispersive analysis?EDS?,X-ray diffraction?XRD?,Uv-visible-near-infrared diffuse reflection?UV-vis NIR DRS?,and isoelectric point?Zeta?were used to prepare the prepared composite materials.The micro-morphological features,elemental composition,optical characteristics,stability under acidic conditions were systematically analyzed,and tetracycline was used as the target pollutant degradation efficiency.The feasibility analysis of the prepared composite catalyst was performed through photocatalytic activity and stability experiments.,Evaluation.The results show that the prepared Ag₂S-Ti O₂composite catalysts with different molar ratios have a red-shift phenomenon with respect to the spectral absorption bands of pure Ti O₂,indicating that the prepared catalysts have better photon utilization efficiency in the UV-visible range;EDS and XRD show that the Ag₂S-Ti O₂composite catalyst with a molar ratio of 1:6 has the best dispersibility,the highest crystallinity,and no other impurities appear;Zeta shows that the Ag₂S-Ti O₂composite catalyst with a molar ratio of 1:6has acidic conditions.Strong stability;photocatalytic activity and stability experiments show that the Ag₂S-Ti O₂composite catalyst with a molar ratio of 1:6 has good degradation efficiency for tetracycline and the removal rate of tetracycline can reach a higher level after five repeated experiments Level,indicating that it has better stable performance.With tetracycline as the target pollutant,the degradation efficiency of the prepared Ag₂S-Ti O₂composite catalyst was studied.The effects of the reaction conditions such as the amount of composite catalyst,the initial concentration of pollutants,the initial p H of the solution,and the common ion concentration of the solution on the degradation efficiency were discussed.The results show that the degradation efficiency of tetracycline decreases first and then increases with the increase of the dosage.With the increase of the initial concentration of tetracycline,the degradation rate of tetracycline by the photocatalytic system gradually decreases;tetracycline has a higher Degradation efficiency;the degradation rate of tetracycline increases first and then decreases with the increase of humic acid concentration;the degradation rate of tetracycline gradually increases with the increase of the concentration of calcium ions(Ca²⁺)in the solution,but the effect is not significant.In the reaction system of photocatalytic Ag₂S-Ti O₂composite catalyst for the degradation of tetracycline,the main methods include tetracycline self-degradation,direct photolysis,and free radical catalytic oxidation.Study on the mechanism of photocatalytic degradation of tetracycline by Ag₂S-Ti O₂composite catalyst found that h⁺,·OH,·O₂^-are the main active species involved in photocatalysis,and·O₂^-contributed the most to the degradation of tetracycline;Analysis by high performance liquid chromatography?HPLC-MS?,tetracycline is mainly mineralized into small molecule compounds such as H₂O,CO₂,NH₄⁺through deamination,dehydroxylation,deamination,oxyalkylene type and other oxidation reactions.