落叶松基复合材料SiO2@C的制备及其对染料的吸附行为研究

以落叶松木屑为原料,SiO2为孔结构调控剂,采用一步原位掺杂法制备了落叶松基SiO2@C复合材料,探讨了炭化温度、模板剂SiO 2对复合材料孔结构及吸附性能的影响。利用扫描电镜(SEM)、透射电镜(TEM)、氮气的吸附/脱附、拉曼光谱、X射线衍射仪(XRD)、傅里叶红外光谱(FT-IR)仪和X射线光电子能谱(XPS)对复合材料进行表征,并以乙基紫染料为模型物研究了复合材料的吸附行为。研究表明:随着炭化温度由700℃升高至900℃,SiO2@C复合材料的形貌由交联的球形形貌转变为网状结构,孔隙结构由整体无序向局部有序转变,比表面积由538 m^2/g提高到780 m^2/g;经900℃炭化制备的复合材料SiO2@C-900具有较高的比表面积和有序的孔隙结构,对乙基紫染料的吸附值高达378 mg/g,在温度55℃,pH值7的最佳吸附条件下,对乙基紫染料的脱除率达99%;重复利用5次后,脱除率仍在97%以上,说明复合材料稳定性良好。SiO2@C复合材料对染料的吸附符合Langmuir吸附等温模型,吸附动力学符合准二级动力学,即主要是化学吸附。

Preparation and Adsorption Behavior Study of Larch-based SiO2@C Composites for Dyes

The porous SiO2@C composites were fabricated via a one-step in situ doping approach using biomass waste larch sawdust as raw material and SiO2 as pore structure regulator.The effects of different carbonization temperature and SiO2 as the template on pore structure and adsorption property of composites were investigated.The SEM,TEM,nitrogen adsorption/desorption,Raman spectroscopy,X-ray diffraction(XRD),Fourier infrared spectroscopy(FT-IR)and X-ray photoelectron spectroscopy(XPS)were adopted to characterize the composite material.Meanwhile,the adsorption behavior of the composites was studied by using ethyl violet dye as the model.The results showed that the morphologies of SiO2@C composites obtained from carbonization between 700 to 900℃changed from cross-linked spherical to network-like structure,and the porous structures changed from disorder to order.Moreover,the large specific surface areas increased from 538 m^2/g to 780 m^2/g of the SiO2@C composites.Benefitting from high specific surface area and ordered pore structure,the adsorption value of SiO2@C-900 was as high as 378 mg/g for ethyl violet dye;the removal rate of ethyl violet dye was 99% at the optimal adsorption condition of temperature 55℃ and pH 7,and the removal rate was still above 97% after repeated 5 times,indicating that these composites had good stability.The adsorption isothermal was in line with the Langmuir adsorption isothermal model,and the adsorption kinetics was in line with the second-order kinetic model,namely,which was mainly chemical adsorption.