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研究论文

摘要：选取木棉为原材料，在不同温度下制备成生物炭.实验考察了溶液初始pH、不同热解温度及生物炭投加量对吸附效果的影响，并利用吸附动力学、吸附等温线及SEM-EDS、FTIR、XPS、Zeta电位等手段研究木棉生物炭对水溶液Cr（Ⅵ）的吸附特性及吸附机理.结果表明，热解温度为400℃，固液比为2∶1，pH=2.0时，木棉生物炭对水溶液中Cr（Ⅵ）的吸附效果最好.吸附动力学和吸附等温线结果显示，颗粒内扩散方程和Langmuir模型更能较好地拟合吸附过程.由Langmuir模型可以看出，400、550、700℃热解温度下制备的木棉生物炭对水溶液中Cr（Ⅵ）的最大吸附量分别为25.325、20.602、19.616 mg·g^-1.FTIR和Zeta结果表明，木棉生物炭主要通过官能团络合和静电吸附作用去除水溶液中Cr（Ⅵ）.XPS分析结果显示，生物炭表面大部分Cr（Ⅵ）被还原为Cr（Ⅲ），其中，Cr（Ⅵ）占比为26.6%，Cr（Ⅲ）占比为73.4%.研究表明，木棉生物炭作为去除水溶液中Cr（Ⅵ）的吸附剂具有较大的应用潜力.

Abstract：The kapok biochar were prepared at different pyrolysis temperature. the influence of pH, pyrolysis temperature and biochar dosage on Cr(Ⅵ) absorption were study. The adsorption kinetics, adsorption isotherm and SEM-EDS, FTIR, XPS and Zeta potential were used to investigate the mechanisms of chromium sorption. At the pyrolysis temperature of 400 ℃, solid-to-liquid ratio of 2:1 and pH=2.0, kapok biochar has the optimal absorption efficiency to the Cr(Ⅵ). The adsorption kinetics and adsorption isotherm demonstrated that the intraparticle diffusion model and Langmuir model can reveal the adsorption process better. The maximum adsorption capacity of Cr (Ⅵ) obtained from the Langmuir model was 25.325 mg·g^-1 (pyrolysis temperature 400 ℃), 20.602 mg·g^-1 (550 ℃) and 19.616 mg·g^-1 (700 ℃), respectively. The results of FTIR and Zeta potential indicated the Cr(Ⅵ) adsorption with kapok biochar based on functional group complexing and electrostatic incorporation. The XPS showed that Cr(Ⅵ) were restored to Cr(Ⅲ) on the surface of biochar, in which Cr(Ⅵ) accounts for 26.6% and Cr(Ⅲ) accounts for 73.4%.The kapok biochar shows potential for application in Cr(Ⅵ) removal.