Degradation Of Herbicides In Water By Modified TiO₂ Loaded On Soft Material

Due to the development of agriculture and requirement of urban greening in China, the development and application of pesticides has resulted in more and more serious pollution to groundwater and surface water. Herbicide is one kind of pesticides which is used wdely and for a long time. However, as potential carcinogen, most of the herbicide possess high toxicity with their chlorinated intermediate products which can result in water pollution and threat natural environment and human health.Because of excellent weed killing performance and reasonable price, 2,4-dichlorophenoxyacetic acid (2,4-D) and atrazine are applied as the most widely used i herbicides in the world. Half-life of 2,4-D is 20 days in nature and the degradation products can be enriched in soil and water. Atrazine has relatively stable chemical properties and can only be decomposed by acid or alkali only at high temperatures. Half-life of Atrazine is 42 days in water. Both of them belong to endocrine disruptors and potential carcinogens.This paper discusses the modified TiO2 as water environmental remediation materials repair micro polluted water affected by 2,4-D and atrazine under the visible light.Prepared Fe doped TiO2 catalyst based on photodeposition method to degradate 2,4-D and prepared n?Fe co-doped TiO2 catalyst based on sol-gel method to degradate atrazine respectively with good degradation effect.Therefore, the catalytic activity, influencing factors, degradation mechanism and stability of Fe-TiO2 visible light photocatalytic degradation of 2,4-D and N/Fe-TiO2 visible light photocatalytic degradation of 2,4-D were studied in this paper.The stability and loading amount of N/Fe-TiO2 load on suft material were also studied. The these two modified TiO2 photocatalyst were characterized by SEM?XRD?UV-vis. 1?Study on the photocatalytic degradation of 2,4-D with Fe-TiO2 load on soft material(1) Preparation and characterization of Fe-TiO2The experimental results show that when the Fe content is 1.0 wt%, the photocatalytic activity of Fe-TiO2 photocatalyst prepared by the method is the highest;The XRD characterization results show that Fe doped into the TiO2; SEM results show that the Fe doped TiO2 grain size distribution more uniform, UV-vis results show that Fe doping enlarges the TiO2 visible light absorption range.(2) Study on the influencing factors and degradation mechanism of 2,4-D degradation by Fe-TiO2 in soft materials.Study the influence factors of Fe-TiO2 on soft materials photocatalytic degradation of 2,4-D, obtained the optimum experimental conditions:Fe doping amount is 1.0 wtl%, the soft material of Fe-TiO2 photocatalytic load 2 g/L, the initial pH of 4.6, the whole aeration, under the reaction conditions,240 min of reaction time, initial concentration of 10 mg/L 2,4-D solution degradation rate up to 74.2%. The Fe-TiO2 photocatalytic degradation experiment and the experimental results show that the catalyst is loaded on the soft material and has a good performance of reuse 2,4-D. By HPLC-MS and TOC test results, the degradation pathway of 2,4-D was deduced.2?Study on the photocatalytic degradation of atrazine with N/Fe-TiO2 load of soft material(1) Preparation and characterization of Fe-TiO2The experimental results show that when the Fe content is 0.5 (Fe and Ti molar ratio), the content of N is 0.1 (the molar ratio of N and Ti), the N/Fe-TiO2 photocatalyst prepared by the sol gel method is the highest; SEM results show that the N and Fe doped TiO2 grain size distribution more uniform. XRD results show that N, Fe doped to the TiO2 grains:UV Vis results show that N, Fe doped TiO2 greatly widened the the visible light absorption range.(2) Study on the influencing factors and degradation mechanism of atrazine degradation by N/Fe-TiO2 load of soft materialsStudy the influence factors of photocatalytic degradation of atrazine N/Fe-TiO2, optimum experimental conditions were obtained:when the Fe content is 0.1, N doping amount is 0.5, the catalyst N/Fe cast dosage of 1 g/L,the initial solution pH of 5.8, the whole aeration, under the reaction conditions, reaction time is 6 h, initial concentration of 10mg/L solution of atrazine degradation rate reached 90.3%. Soft material catalyst N/Fe-TiO2 optimal loading amount and repetitive studies show that: N/Fe-TiO2 in soft materials optimal loading of 2.25 g/L and catalyst stability better set; By HPLC-MS analysis and TOC test results are used to infer the atrazine degradation process may exist in three ways.The above experimental results suggest that the photocatalytic degradation efficiency to 2,4-D of Fe-TiO2 loaded on soft material(Load amount was 2 g/L)which was prepared by photodeposition method was up to 60% after 4h reaction time. Photocatalytic degradation efficiency to atrazine of N/Fe-TiO2 loaded on soft material(Load amount was 2.25 g/L) which was prepared by sol-gel method was up to 55.1% after 8 h reaction time. Compared to natural half-life of 2,4-D(20d) and atrazine(42d), degradation efficiency of such kinds of pesticides is promoted obviously which suggests that above catalysts have application value on field of water environmental remediation technology.