水滑石与海泡石复合材料对有机染料的光催化降解性能（英文）

Facile preparation of sepiolite@LDH composites for the visible-light degradation of organic dyes

由于ZnCr-LDH纳米粒子具有良好的光催化性能,但极易团聚,在一定程度上制约了它在光催化领域的应用.将水滑石制成核-壳复合材料可以避免粒子团聚,改善其单分散性和稳定性,从而提高光催化活性.本文设计了一种水滑石/海泡石(Sep@LDH)纳米复合材料作为光催化剂,以甲基橙(MO)和亚甲基蓝(MB)混合溶液模拟有机染料废水,进行光催化反应.通过XRD,SEM,UV-Vis DRS,PL,TG-DTG和BET/BJH,证明了水滑石成功的生长在海泡石的表面,通过光催化实验详细研究了Sep@LDH纳米复合材料的光催化性能及光降解反应机理.采用共沉淀制备了不同Zn/Cr摩尔比的水滑石纳米材料,对水滑石进行优化,结合表征分析,发现摩尔比为1的ZnCr-LDH其结晶度、层间规整度高,禁带宽度最窄(2.30 eV)和光致发光性能最佳.因而用作后续复合材料的制备.另一方面,我们以酸活化的海泡石(Sep)为载体,采用原位生长法成功制备了一种新型的水滑石/海泡石(Sep@LDH)光催化剂,研究了海泡石的添加量对复合材料性能的影响.结果表明,Sep含量对复合材料形貌、粒径大小、结构以及光学性质影响较大.其中,样品Sep_4@LDH(海泡石添加量为4 g),比表面积最大,因而光催化效率最高.降解动力学结果表明,染料的光降解过程遵循准一级动力学模型.我们通过对活性物种(·OH,h^+,·O_2^-)的考察,研究了光催化降解机理.结果表明,·OH在光降解过程中起着至关重要的作用.Sep_4@LDH复合材料循环使用5次后,MO和MB的光降解率依然分别可以达到86.2%和84.9%,表现出较高的稳定性.

Sepiolite@LDH(Sep@LDH)composites were designed and prepared based on the assembly of layered double hydroxides(LDH)on acidified sepiolites(Sep)for the simultaneous photocatalytic degradation of methyl orange(MO)and methylene blue(MB).The structure,morphology,texture,optical properties,and photocatalytic performance of the prepared Sep@LDH were studied in detail.Among the Sep@LDH composites,Sep4@LDH(4.0 g Sep)exhibited the highest photocatalytic activity under visible‐light irradiation,which could be attributed to its large surface area,high crystallinity,and plentiful active sites on its surface.The photodegradation of the dyes followed a pseudo first‐order kinetic model(Langmuir‐Hinshelwood model),indicating that the copious and homogeneous active sites on the surface of the composites contributed to the high photocatalytic activity.The photodegradation mechanism was studied by examining the active species(^-OH,h+,and·O2^-anions)using appropriate scavengers.It was found that·OH radicals played a critical role in the photocatalytic process of MO and MB,where the generation of·OH radicals occurred on the electron/hole(e^-/h+)pairs on the surface of the Sep@LDH composites.