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光-Fenton技术是高级氧化技术中的一种,常用于难降解废水处理,由于其反应速度快、毒性低、反应条件温和而受到广泛关注.然而,传统的光-Fenton体系具有可见光利用率低、回收困难等缺点.为了解决这些问题,本文采用廉价易得、无污染、吸附能力强的天然矿物海泡石作为催化剂载体,并利用Ag/AgCl能够吸收可见光的表面等离子响应这一光学性质,合成了一种有潜力的非均相等离子体光催化剂Ag/AgCl/铁-海泡石催化剂(Ag/AgCl/Fe-S),并对该催化剂的形貌结构、性能和机理等进行了系统研究.通过XRD,SEM,XPS,BET,UV-vis等表征手段对催化剂形貌、结构和可见光性能进行了分析.其中,XRD和SEM结果显示,Ag/AgCl粒子已经成功负载在Fe-海泡石上;XPS结果显示,铁氧化物的组成主要为FeOOH和Fe_2O_3;UV-vis结果显示,催化剂有较好的可见光吸收性能.以双酚A为目标污染物,分别考察了Ag/AgCl/Fe-S,Ag/AgCl和Fe-海泡石的光-Fenton催化性能.结果显示,Ag/AgCl/Fe-S降解双酚A的效果明显优于另外两种催化剂,在H_2O_2浓度为6 mmol/L,pH为4,光照强度500 W,Ag/AgCl/Fe-S催化剂量为1.0 g/L,双酚A初始浓度为10 mg/L的条件下,1 h时,双酚A基本被完全降解,且3 h时,其矿化率达到61.2%;而Ag/AgCl和Fe-海泡石催化剂在同样的条件下完全降解双酚A至少要3 h,且其矿化率分别只有46.61%和28.85%.另外,还分别探讨了H_2O_2浓度、pH值、光照强度和催化剂剂量对双酚A降解的影响.最后,通过活性物种捕获、ESR、电化学和PL实验对该体系的反应机理进行了探讨.活性物种捕获实验和ESR实验结果表明,羟基自由基(~·OH)和空穴(h+)是该体系中的主要活性物种,且Ag/AgCl/Fe-S+H_2O_2+vis体系产生的~·OH明显多于Fe-S+H_2O_2+vis体系.为了探讨~·OH增多的原因,我们进行了电化学实验和PL实验.电化学实验结果显示,Ag/AgCl/Fe-S催化剂具有更低的阻抗,因此有利于电子-空穴分离.PL结果显示,Ag/AgCl/Fe-S催化剂的电子-空穴复合率更低.结合以上实验,我们提出了Ag/AgCl/Fe-S+H_2O_2+vis体系对双酚A的降解机理,即一方面催化剂能够发生Fenton反应而产生~·OH,另一方面,催化剂中的Ag/AgCl在可见光下由于表面等离子响应而产生电子-空穴,空穴本身可作为活性物种降解双酚A.同时,产生的电子被体系中的Fe~(3+)捕获生成Fe~(2+),从而促进了铁循环,有利于体系中产生更多的~·OH.最后,空穴和羟基自由基发生协同作用共同促进污染物降解.
Light-Fenton technology is a kind of advanced oxidation technology, which is often used in the treatment of refractory waste water, which is widely concerned because of its fast reaction, low toxicity and mild reaction conditions.However, the traditional light-Fenton system has low visible light utilization , Recovery difficulties, etc. In order to solve these problems, this paper uses cheap, easy to get, non-polluting, adsorption of natural mineral sepiolite as a catalyst carrier, and the use of Ag / AgCl can absorb visible light surface plasmon response to the optical properties, A promising heterogeneous plasma photocatalyst Ag / AgCl / iron-sepiolite catalyst (Ag / AgCl / Fe-S) was synthesized and the morphology, properties and mechanism of the catalyst were systematically investigated XRD, SEM, XPS, BET, UV-vis and other characterization methods were used to analyze the morphology, structure and visible light properties of the catalyst.The XRD and SEM results showed that the Ag / AgCl particles have been successfully loaded in the Fe- The results of XPS show that the composition of iron oxides is mainly FeOOH and Fe_2O_3, and the UV-vis results show that the catalyst has better visible light absorption properties.With bisphenol A as the target pollutant, the effects of Ag / AgCl / Fe- S, Ag / AgC l and Fe-sepiolite.The results showed that the degradation of bisphenol A by Ag / AgCl / Fe-S was obviously better than the other two catalysts. Under the condition of H 2 O 2 concentration of 6 mmol / L and pH of 4 , The light intensity was 500 W, the amount of Ag / AgCl / Fe-S catalyst was 1.0 g / L, the initial concentration of bisphenol A was 10 mg / L, the bisphenol A was completely degraded at 1 h, , The mineralization rate reached 61.2%, while the Ag / AgCl and Fe-sepiolite catalysts completely degraded BPA under the same conditions for at least 3 h, with mineralization rates of 46.61% and 28.85% respectively. , And the effects of H 2 O 2 concentration, pH value, light intensity and catalyst dose on the degradation of bisphenol A were also discussed respectively.Finally, the reaction mechanism of the system was discussed through the active species capture, ESR, electrochemistry and PL experiments.The active species The results of capture experiments and ESR experiments showed that the hydroxyl radicals (· · OH) and holes (h +) were the main active species in this system, and ~ · OH of Ag / AgCl / Fe-S + H_2O_2 + vis system was obvious More than that of Fe-S + H 2 O 2 + vis system.In order to investigate the reasons for the increase of OH, we carried out electrochemical experiments and PL experiments.The results of electrochemical experiments showed that Ag / AgCl / Fe-S catalysts have lower Ag / AgCl / Fe-S catalyst has a lower electron-hole recombination rate.According to the above experiments, we proposed the Ag / AgCl / Fe-S + H 2 O 2 + Vis system on the degradation mechanism of bisphenol A, that is, on the one hand the catalyst can produce Fenton reaction to produce · · OH, on the other hand, the catalyst Ag / AgCl in visible light due to surface plasmon response to produce electron - hole, hole Itself can be used as the active species to degrade BPA. At the same time, the generated electrons are trapped by Fe ~ (3+) in the system to generate Fe ~ (2+), which promotes the iron recycling and facilitates the production of more OH. Finally, holes and hydroxyl radicals act synergistically to promote contaminant degradation.