Kavitha D, Namasivayam C
Department of Environmental System Engineering, Hallym University, 1 Okchon-dong, Chuncheon, Gangwon-do 200-702, Republic of Korea.
Bioresour Technol. 2007 Jan;98(1):14-21. doi: 10.1016/j.biortech.2005.12.008. Epub 2006 Jan 19.
Varying the parameters such as agitation time, dye concentration, adsorbent dose, pH and temperature carried out the potential feasibility of thermally activated coir pith carbon prepared from coconut husk for removal of methylene blue. Greater percentage of dye was removed with decrease in the initial concentration of dye and increase in amount of adsorbent used. Kinetic study showed that the adsorption of dye on coir pith carbon was a gradual process. Lagergren first-order, second-order, intra particle diffusion model and Bangham were used to fit the experimental data. Equilibrium isotherms were analysed by Langmuir, Freundlich, Dubnin-Radushkevich, and Tempkin isotherm. The adsorption capacity was found to be 5.87 mg/g by Langmuir isotherm for the particle size 250-500 microm. The equilibrium time was found to be 30 and 60 min for 10 and 20 mg/L and 100 min for 30, 40 mg/L dye concentrations, respectively. A maximum removal of 97% was obtained at natural pH 6.9 for an adsorbent dose of 100 mg/50 mL and 100% removal was obtained for an adsorbent dose of 600 mg/50 mL of 10 mg/L dye concentration. The pH effect and desorption studies suggest that chemisorption might be the major mode of the adsorption process. The change in entropy (DeltaS0) and heat of adsorption (DeltaH0) of coir pith carbon was estimated as 117.20 J/mol/K and 30.88 kJ/mol, respectively. The high negative value of change in Gibbs free energy indicates the feasible and spontaneous adsorption of methylene blue on coir pith carbon.
通过改变诸如搅拌时间、染料浓度、吸附剂用量、pH值和温度等参数，研究了由椰壳制备的热活化椰壳髓炭去除亚甲基蓝的潜在可行性。随着染料初始浓度的降低和吸附剂用量的增加，染料的去除率更高。动力学研究表明，染料在椰壳髓炭上的吸附是一个渐进的过程。采用 Lagergren 一级、二级、颗粒内扩散模型和 Bangham 模型拟合实验数据。用朗缪尔、弗伦德利希、杜宾-拉杜舍维奇和坦普金等温线分析平衡等温线。对于粒径为250-500微米的颗粒，朗缪尔等温线得出的吸附容量为5.87毫克/克。对于10和20毫克/升的染料浓度，平衡时间分别为30和60分钟，对于30、40毫克/升的染料浓度，平衡时间为100分钟。在天然pH值6.9下，吸附剂用量为100毫克/50毫升时，最大去除率为97%；对于10毫克/升的染料浓度，吸附剂用量为600毫克/50毫升时，去除率为100%。pH值影响和解吸研究表明，化学吸附可能是吸附过程的主要模式。椰壳髓炭的熵变（ΔS0）和吸附热（ΔH0）分别估计为117.20焦/摩尔/开尔文和30.88千焦/摩尔。吉布斯自由能变化的高负值表明亚甲基蓝在椰壳髓炭上的吸附是可行的且自发的。
