Namasivayam C, Sureshkumar M V
Environmental Chemistry Division, Department of Environmental Sciences, Bharathiar University, Coimbatore 641046, India.
Bioresour Technol. 2008 May;99(7):2218-25. doi: 10.1016/j.biortech.2007.05.023. Epub 2007 Jun 29.
Coconut coir pith, an agricultural solid waste was used as biosorbent for the removal of chromium(VI) after modification with a cationic surfactant, hexadecyltrimethylammonium bromide. Optimum pH for Cr(VI) adsorption was found to be 2.0. Reduction of Cr(VI) to Cr(III) occurred to a slight extent during the removal. Langmuir, Freundlich and Dubinin Radushkevich (D-R) isotherms were used to model the adsorption equilibrium data and the system followed all the three isotherms. The adsorption capacity of the biosorbent was found to be 76.3 mg g(-1), which is higher or comparable to the adsorption capacity of various adsorbents reported in literature. Kinetic studies showed that the adsorption obeyed second order and Elovich model. Thermodynamic parameters such as delta G0, delta H0 and delta S0 were evaluated, indicating that the overall adsorption process was endothermic and spontaneous. Effects of foreign anions were also examined. The adsorbent was also tested for the removal of Cr(VI) from electroplating effluent.
椰壳纤维髓，一种农业固体废物，在用阳离子表面活性剂十六烷基三甲基溴化铵改性后用作生物吸附剂以去除六价铬。发现六价铬吸附的最佳pH值为2.0。在去除过程中，六价铬有轻微程度的还原为三价铬。使用朗缪尔、弗伦德里希和杜比宁-拉杜舍维奇（D-R）等温线对吸附平衡数据进行建模，该体系符合所有这三种等温线。发现生物吸附剂的吸附容量为76.3 mg g⁻¹，这高于或与文献报道的各种吸附剂的吸附容量相当。动力学研究表明吸附符合二级动力学和埃洛维奇模型。评估了诸如ΔG⁰、ΔH⁰和ΔS⁰等热力学参数，表明总体吸附过程是吸热且自发的。还研究了外来阴离子的影响。该吸附剂还用于测试从电镀废水中去除六价铬。
