School of Pharmaceutical and Chemical Engineering, Taizhou University, Dongfang Road No. 605, Linhai 317000, Zhejiang, PR China.
J Hazard Mater. 2011 Feb 28;186(2-3):1320-7. doi: 10.1016/j.jhazmat.2010.12.006. Epub 2010 Dec 9.
In this paper, silkworm exuviae (SE) waste, an agricultural waste available in large quantity in China, was utilized as low-cost adsorbent to remove basic dye (methylene blue, MB) from aqueous solution by adsorption. Kinetic data and sorption equilibrium isotherms were carried out in batch process. The adsorption kinetic experiments revealed that MB adsorption onto SE for different initial dye concentrations all followed pseudo-second order kinetics and were mainly controlled by the film diffusion mechanism. Batch equilibrium results at different temperatures suggest that MB adsorption onto SE can be described perfectly with Freundlich isotherm model compared with Langmuir and D-R isotherm models, and the characteristic parameters for each adsorption isotherm were also determined. Thermodynamic parameters calculated show the adsorption process has been found to be endothermic in nature. The analysis for the values of the mean free energies of adsorption (E(a)), the Gibbs free energy (ΔG(0)) and the effect of ionic strength all demonstrate that the whole adsorption process is mainly dominated by ion-exchange mechanism, which has also been verified by variations in FT-IR spectra and pH value before and after adsorption and desorption studies. The results reveal that SE can be employed as a low-cost alternative to other adsorbents for MB adsorption.
本文以中国大量存在的农业废弃物——蚕蛹壳（SE）为廉价吸附剂，通过吸附作用从水溶液中去除碱性染料（亚甲蓝，MB）。采用间歇法进行动力学数据和吸附平衡等温线实验。吸附动力学实验表明，对于不同初始染料浓度，MB 在 SE 上的吸附均遵循拟二级动力学，主要受膜扩散机制控制。不同温度下的批量平衡结果表明，与 Langmuir 和 D-R 等温模型相比，MB 在 SE 上的吸附可以用 Freundlich 等温模型完美描述，并且还确定了每个吸附等温模型的特征参数。计算得到的热力学参数表明，吸附过程本质上是吸热的。对平均吸附自由能（E(a)）、吉布斯自由能（ΔG(0)）和离子强度效应值的分析表明，整个吸附过程主要受离子交换机制控制，这也通过吸附和解吸前后 FT-IR 光谱和 pH 值的变化得到了验证。结果表明，SE 可作为替代其他吸附剂用于 MB 吸附的廉价选择。
