改性纤维素负载纳米CdS的制备及其性能研究

Study on Preparation and Properties of Nano CdS Supported by Modified Cellulose

为开发可见光响应型的纤维素载体复合材料,以改性纤维素为基底,构筑复合光催化剂,达到高效利用太阳光降解有机污染物的目的。用硝酸-氢氧化钠法制备出改性小麦秸秆纤维素(WSC);以硫化钠(Na_(2)S)和乙酸镉[Cd(CH_(3)COO)_(2)·2H_(2)O]作为原料,利用水热法将二者合成不同粒径大小的纳米硫化镉(CdS);将上述不同粒径大小的纳米CdS通过共沉淀法负载于WSC上,制备出改性小麦秸秆纤维素负载硫化镉复合材料(CdS/WSC)。通过傅立叶红外光谱(FITR)、X射线衍射(XRD)、扫描电子显微镜(SEM)以及紫外-可见光谱(UV-vis)对制备出的复合材料进行表征分析,对亚甲基蓝(MB)溶液催化降解实验表明,不同原料配比所制备的复合材料的催化效率均超过了TiO_(2),在静态吸附60 min后,光照20 min,配比为n(Na_(2)S)∶n[Cd(CH_(3)COO)_(2)·2H_(2)O]=1∶1.5的CdS/WSC,具有最高的去除效果,达到94.9%,显著高于TiO_(2)的73.7%,并且随着反应时间增加,去除率达到99.9%,表明复合材料在制备过程中,改善了CdS的团聚问题,提高了对光能的利用率。对其进行6次的重复实验后,去除率仍为96.5%,说明其光催化效果稳定,具有良好的可重复性。另外,自由基淬灭实验结果表明,CdS/WSC对光催化MB起主导作用的是·OH。研究结果表明,所制备的复合材料具有良好的光催化性能,为半导体复合材料的构建方法以及提高可见光响应能力提供了新的思路。

In order to develop visible light responsive cellulose carrier composites,modified cellulose was used as the substrate to construct composite photocatalysts,so as to efficiently use sunlight to degrade organic pollutants.In this paper,modified wheat straw cellulose(WSC)was prepared by HNO 3-NaOH method.Nano CdS with different particle sizes were synthesized from Na_(2)S and Cd(CH_(3)COO)2·2H_(2)O by hydrothermal method.The nano CdS with different particle sizes were loaded on WSC by coprecipitation method to prepare modified wheat straw cellulose loaded cadmium sulfide composites(CdS/WSC).Fourier transform infrared spectroscopy(FITR),X-ray diffraction(XRD),scanning electron microscopy(SEM)and ultraviolet visible spectroscopy(UV vis)were used to characterize and analyze the prepared composite materials.The catalytic degradation test of methylene blue(MB)solution showed that the catalytic efficiency of the composite materials prepared with different raw material ratios exceeded that of TiO_(2).After 60 min of static adsorption,the composite materials were exposed to light for 20 min.The CdS/WSC with the ratio of n(Na_(2)S)∶n[Cd(CH_(3)COO)_(2)·2H_(2)O]=1∶1.5 performed the highest removal effect,reaching 94.9%,which was significantly higher than 73.7%of TiO_(2).Moreover,the removal rate reached 99.9%with the increase of reaction time.The result indicated that the composite material improved the agglomeration of CdS during the preparation process,thus improved the utilization of light energy.After six times of repeated experiments,the removal rate was still 96.5%,indicating that its photocatalytic effect was stable and had good repeatability.In addition,the results of free radical quenching experiment showed that the dominant role of CdS/WSC in photocatalytic MB was·OH.In a word,the composite materials prepared have good photocatalytic performance,which provide a new idea for the construction of semiconductor composite materials and the improvement of visible light response.