CNC负载ZnO纳米复合材料的吸附-光催化性能

Adsorption photocatalytic properties of cellulose nanocrystal supported ZnO nanocomposites

以醋酸锌为原料、硫酸水解的纤维素纳米晶(CNC)为模板,通过沉淀法制备CNC负载ZnO纳米复合材料(CNC/ZnO),并进一步经550℃处理,得到CNC/ZnO的碳化产物(C CNC/ZnO)。采用透射电子显微镜(TEM)、X射线衍射仪(XRD)、傅里叶红外光谱仪(FT IR)、紫外可见漫反射吸收光谱(UV Vis DRS)对其形貌结构、晶体结构、化学结构和光吸收性能进行表征,并测试其对亚甲基蓝(MB)染料的吸附 光催化性能。结果表明:CNC/ZnO纳米复合材料中,ZnO通过静电作用附着于CNC上,呈棒状及纵横交错排列,分散性得到显著提高;经550℃碳化后,ZnO仍以棒状排列方式沉积于碳化CNC上,排列方式未发生变化。引入CNC模板及碳化处理对ZnO晶体结构及光吸收性能产生重要影响,CNC/ZnO复合材料中,ZnO晶粒尺寸为8.4 nm,高于纯纳米ZnO(6.3 nm),其带隙能(Eg)为3.18 eV;C CNC/ZnO复合材料中,ZnO晶粒尺寸为7.8 nm,Eg值减小至1.75 eV。吸附 光催化性能测试表明:CNC/ZnO纳米复合材料对MB具有良好的吸附性能,黑暗条件下搅拌60 min,对MB的吸附去除率可达58%,开启光照60 min后,其对MB的吸附 光催化去除率增至88%;C CNC/ZnO复合材料对MB具有良好的吸附 光催化协同作用,黑暗下吸附60 min,对MB的吸附去除率为49%,光照60 min后,其对MB的吸附 光催化去除率可达99%。

Cellulose nanocrystal(CNC)supported nano-ZnO(CNC/ZnO)was prepared using zinc acetate[Zn(CH 3 COO)2·2H 2O]as raw materials and CNC as a template with a procedure of precipitation method.With the further high temperature treatment at 550℃,the carbonized CNC/ZnO nanocomposite(C-CNC/ZnO)was fabricated.The morphology structure,crystal structure,chemical structure and optical property of CNC supported ZnO nanocomposites were characterized by the transmission electron microscope(TEM),X-ray diffraction(XRD),Fourier transform infrared spectrometer(FT-IR),and UV-Vis diffuse reflectance spectroscopy(UV-Vis DRS),respectively.The adsorption-photocatalytic properties of CNC supported ZnO nanocomposites were investigated by removing dye methylene blue(MB).The results showed that CNC of the obtained CNC/ZnO nanocomposite acted as a supporting agent to anchor ZnO by the electrostatic interaction.Nano-ZnOs were arranged in short rod shape,which significantly improved the dispersion.After the high temperature treatment at 550℃,nano-ZnO remained the same arrangement and uniformly deposited on the surface of carbonized CNC.The introduction of CNC as the template and the high temperature treatment had an important impact on the crystal structure and optical properties of nano-ZnO.Compared with the crystal size of the pure nano-ZnO(6.3 nm),the crystal size of ZnO of the CNC/ZnO composites was 8.4 nm,and its band gap energy(E g)was 3.18 eV.The crystal size of the ZnO of C-CNC/ZnO composites was 7.8 nm,and its E g value decreased to 1.75 eV.The results of adsorption-photocatalytic properties showed that the obtained CNC/ZnO composite had good adsorption performance with the MB removal rate of 58%under darkness condition for 60 min.Its MB adsorption-photocatalytic removal rate was 88%under the continuous irradiation of light for 60 min.The obtained C-CNC/ZnO composite had the optimum removal efficiency to MB,corresponding to 49%MB adsorption removal rate with the darkness condition,and 99%MB adsorption-photocatalytic removal rate after the light irradiation for 60 min at room temperature.