Preparation Of Modified TiO₂?ZnO Photocatalyst And Its Study On Degradation Of Dyes

With the rapid development of economy,industrial water pollution has become an increasingly non-negligible environmental issue because it is directly related to people's health.In the treatment of industrial wastewater,printing and dyeing wastewater is more difficult to treat.Semiconductor materials such as TiO₂ and ZnO are widely used in dyeing wastewater treatment because of their simple preparation,low cost and high catalytic activity.However,the electron hole pairs of TiO₂ and ZnO photocatalysts are easily combined and have low utilization of solar light,which affects their application in practical production.In this paper,the photocatalytic properties were improved by modifying the TiO₂ and ZnO.1.In this paper,anatase Ti O₂ nanoparticles were synthesized by hydrothermal synthesis.TiO₂ was modified by nitrate?magnesium nitrate,calcium nitrate and strontium nitrate?.The photocatalytic degradation of modified catalysts was studied with methylene blue and methyl violet as target pollutants.The results indicated that When the molar ratio of Mg?NO₃?₂ to TiO₂ was 0.75%and the amount of catalyst was 0.05 g,the degradation of the Mg?NO₃?₂ modified TiO₂ catalyst for methylene blue and methyl violet solution could reach 88%and 86%respectively.The degradation rate was increased by 35%and 39%than the pure anatase TiO₂ catalyst.The high degradation could achieved when the initial concentration of 5-20 mg/L methylene blue and methyl violet.The relationship between ln?A_t/A₀?and reaction time t was linear,and the correlation coefficient R² was greater than 0.98.The reaction process followed the first-order reaction kinetics.The degradation of the Ca?NO₃?₂,Sr?NO₃?₂ and Mg?NO₃?₂modified TiO₂ catalyst were similar to Mg?NO₃?₂ modified TiO₂ catalyst for methylene blue and methyl violet solution.Under the optimal molar ratio,the order of photocatalytic degradation of the TiO₂ modified by nitrate was TiO₂?Mg-0.75%?>TiO₂?Ca-0.75%?>TiO₂?Sr-0.75%?.2.Using chloroplatinic acid as the platinum source,Pt-modified TiO₂ was obtained by heat treatment without changing the structure of the anatase TiO₂.The photocatalytic activity of Pt modified TiO₂ catalyst was studied.The results showed that the Pt content of 1.52%TiO₂?Pt-4?and the catalyst dosage of 0.05 g,the degradation of Pt modified TiO₂ catalyst for methylene blue and methyl violet solution could reach86%and 87%respectively.Compared with pure TiO₂,the degradation increased by 32%and 24%,respectively.The TiO₂?Pt-4?catalyst had good degradation effect on the initial concentration of 5-15mg/L methylene blue and methyl violet solution.The reaction process also followed the first-order reaction kinetics.3.The TiO₂ catalysts modified by noble metal Pt and magnesium nitrate were also synthesized and its photocatalytic activity were also investigated using methylene blue and methyl violet as target pollution.The results indicatedthat the noble metal Pt and magnesium nitrate co-modified TiO₂ could effectively reduce the charge recombination.The catalytic performance of TiO₂ modified by bimetal was better than that of any single metal modified TiO₂ catalyst.The photocatalyst TiO₂?Pt-2?/Mg?NO₃?₂ with was the most active.When the Pt content of 0.76%and the molar ratio of 0.75%and the amount of catalyst was 0.05 g,the methylene blue solution and methyl violet were used.The degradation could reach 94%and 95%,respectively.The degradation increased by 45%and 53%compared with pure TiO₂.The catalyst had good degradation effect on the initial concentration of 5-20mg/L of methylene blue and methyl violet solution.4.The ZnO modified by nitrate?magnesium nitrate,calcium nitrate,strontium nitrate?were also produced and its photocatalytic activity were also investigated using methylene blue and methyl violet as target pollution.The results indicated that the modified ZnO photocatalyst could improved the degradation effect of methylene blue obviously.when the molar ratio of Mg?NO₃?₂ to ZnO is 1%?ZnO?Mg-1%??,and the amount of catalyst was 0.05 g,the degradation could reached 78%.The ZnO?Mg-1%?catalyst had a good degradation effect on the methylene blue as its initial concentration was 5-10 mg/L.The relationship between ln(A_t/A₀)and reaction time t was linear,and the correlation coefficient R² was greater than 0.98.This reaction process followed the first-order reaction kinetics.The degradation of Mg?NO₃?₂ and Sr?NO₃?₂ modified ZnO catalysts were similar to Mg?NO₃?₂ modified ZnO catalysts.Under the optimum molar ratio,theorderofdegradationactivityofthecatalystwas ZnO?Mg-1%?>ZnO?Ca-1%?>ZnO?Sr-1%?...