固定化蟹壳生物炭制备及吸附Pb^(2+)的研究

Preparation of immobilized crab shell biochar and its adsorption of Pb^(2+)

以废弃的蟹壳为原料制备蟹壳生物炭(BC),采用海藻酸钠固定制备复合凝胶球。结合成球形态和对Pb^(2+)的去除率发现,在BC与海藻酸钠质量比为1∶2的条件下制备的蟹壳生物炭-海藻酸钠凝胶球(BC-SA)的性能最佳。探究了影响BC-SA吸附Pb^(2+)的因素及其再生能力,通过扫描电镜和傅里叶红外光谱仪对未添加BC的凝胶球和吸附Pb^(2+)前后的BC-SA进行表征。结果表明,Pb^(2+)溶液初始pH、BC-SA投加量、Pb^(2+)初始浓度和反应时间都会对BC-SA吸附Pb^(2+)产生显著影响。吸附过程符合拟二级动力学模型,表明吸附以化学吸附为主,Langmuir等温线可以更好地拟合实验数据,Pb^(2+)最大去除率为91.06%。再生结果表明,经5次解吸-吸附循环后,BC-SA对Pb^(2+)的去除率为82%,展现出良好的可重复利用性。BC得以成功地固定且BC-SA表面的羟基和羧基与Pb^(2+)之间发生了官能团的络合作用。

The crab shell biochar(BC)was prepared from waste crab shells,and the composite gel ball was prepared by sodium alginate fixation.Combined with the shape of the ball and the removal rate of Pb^(2+),it was found that the performance of the crab shell biochar sodium alginate gel ball(BC-SA)was the best when the mass ratio of crab shell biochar to sodium alginate was 1∶2.The factors affecting the adsorption of Pb^(2+)by BC-SA and its regeneration ability were investigated.The blank rubber ball and BC-SA before and after adsorption of Pb^(2+)was characterized by scanning electron microscopy and Fourier infrared spectroscopy.The results showed that the initial pH of the Pb^(2+)solution,the amount of BC-SA dosage,the initial concentration of Pb^(2+),and the reaction time had significant effects on the adsorption of Pb^(2+)by BC-SA.The adsorption process conformed to the pseudo-second-order kinetic model,indicating that the adsorption was mainly chemical adsorption.Langmuir isotherm could better fit the experimental data,and the maximum removal rate was 91.06%.The regeneration results showed that after five desorption adsorp⁃tion cycles,the removal rate of Pb^(2+)by BC-SA was 82%,showing good reusability.BC was successfully immobilized and the carboxyl group of hydroxyl group on the surface of BC-SA complexed with Pb^(2+).