Effect of SiO <sub>2</sub> aerogels loading on photocatalytic degradation of nitrobenzene using composites with tetrapod-like ZnO
Zhigang Yi, Tao Jiang, Ying Cheng, Qiong Tang
Abstract
Abstract To study the effect of improved adsorption property of tetrapod-like ZnO (T-ZnO) on its photocatalytic performance, a new composite was prepared by loading silica aerogels (SiO 2 (AG)) on the surface of T-ZnO via the sol–gel method. Various characterization methods showed that SiO 2 (AG) was uniformly loaded on the surface of T-ZnO, and the morphology as well as structural characteristics of SiO 2 (AG) and T-ZnO were not changed. Nitrobenzene (NB) was selected as the model pollutant, and the adsorption and photocatalytic properties of T-ZnO and SiO 2 (AG)/T-ZnO for NB were studied. The photocatalytic degradation processes of NB using T-ZnO and SiO 2 (AG)/T-ZnO followed the first-order reaction. Considering the initial moment reaction kinetic, the photocatalytic kinetic of SiO 2 (AG)/T-ZnO and T-ZnO was consistent with the Langmuir–Hinshelwood kinetic model, and reaction rate constant <m:math xmlns:m="http://www.w3.org/1998/Math/MathML"> <m:msubsup> <m:mrow> <m:mi>k</m:mi> </m:mrow> <m:mrow> <m:msub> <m:mrow> <m:mtext>SiO</m:mtext> </m:mrow> <m:mrow> <m:mn>2</m:mn> </m:mrow> </m:msub> <m:mrow> <m:mfenced open="(" close=")"> <m:mrow> <m:mtext>AG</m:mtext> </m:mrow> </m:mfenced> </m:mrow> <m:mo>/</m:mo> <m:mtext>T-ZnO</m:mtext> </m:mrow> <m:mrow> <m:mo accent="true">′</m:mo> </m:mrow> </m:msubsup> <m:mo>></m:mo> <m:msubsup> <m:mrow> <m:mi>k</m:mi> </m:mrow> <m:mrow> <m:mtext>T-ZnO</m:mtext> </m:mrow> <m:mrow> <m:mo accent="true">′</m:mo> </m:mrow> </m:msubsup> </m:math> {k}_{{\text{SiO}}_{2}\left(\text{AG}\right)/\text{T-ZnO}}^{^{\prime} }\gt {k}_{\text{T-ZnO}}^{^{\prime} } , adsorption rate constant <m:math xmlns:m="http://www.w3.org/1998/Math/MathML"> <m:msub> <m:mrow> <m:mi>K</m:mi> </m:mrow> <m:mrow> <m:mtext>ad</m:mtext> <m:mspace width=".5em"/> <m:msub> <m:mrow> <m:mtext>SiO</m:mtext> </m:mrow> <m:mrow> <m:mn>2</m:mn> </m:mrow> </m:msub> <m:mo stretchy="false">(</m:mo> <m:mtext>AG</m:mtext> <m:mo stretchy="false">)</m:mo> <m:mo>/</m:mo> <m:mtext>T-ZnO</m:mtext> </m:mrow> </m:msub> </m:math> {K}_{\text{ad}{\text{SiO}}_{2}(\text{AG})/\text{T-ZnO}} > K ad T-ZnO , which demonstrated that SiO 2 (AG) loading could increase T-ZnO adsorption to NB, then promoted its photocatalytic performance.