Department of Chemistry, Indian Institute of Technology, Rookree 247667, India.
Environ Sci Pollut Res Int. 2013 Apr;20(4):2632-44. doi: 10.1007/s11356-012-1176-6. Epub 2012 Sep 15.
The utilization of sustainable and biodegradable lignocellulosic fiber to detoxify the noxious Cr(VI) from wastewater is considered a versatile approach to clean up a contaminated aquatic environment. The aim of the present research is to assess the proficiency and mechanism of biosorption on Ficus carica bast fiber via isotherm models (Langmuir, Freundlich, Temkin, Harkin's-Jura, and Dubinin-Radushkevich), kinetic models, and thermodynamic parameters. The biomass extracted from fig plant was characterized by scanning electron microscopy and Fourier-transform infrared spectroscopy. To optimize the maximum removal efficiency, different parameters like effect of initial concentration, effect of temperature, pH, and contact time were studied by batch method. The equilibrium data were best represented by the Langmuir isotherm model, and the maximum adsorption capacity of Cr(VI) onto biosorbent was found to be 19.68 mg/g. The pseudo-second-order kinetic model adequately described the kinetic data. The calculated values of thermodynamic parameters such as enthalpy change (∆H(0)), entropy change (∆S(0)), and free energy change (∆G(0)) were 21.55 kJ/mol, 76.24 J/mol K, and -1.55 kJ/mol, respectively, at 30 °C which accounted for spontaneous and endothermic processes. The study of adsorbent capacity for Cr(VI) removal in the presence of Na(+), Mg(2+), Ca(2+), SO 4 (2-) , HCO 3 (-) and Cl(-) illustrated that the removal of Cr(VI) increased in the presence of HCO(3-) ions; the presence of Na(+), SO 4 (2-) or Cl(-) showed no significant influence on Cr(VI) adsorption, while Ca(2+) and Mg(2+) ions led to an insignificant decrease in Cr(VI) adsorption. Further, the desorption studies illustrated that 31.10% of metal ions can be removed from an aqueous system, out of which 26.63% of metal ions can be recovered by desorption in first cycle and the adsorbent can be reused. The results of the scale-up study show that the ecofriendly detoxification of Cr(VI) from aqueous systems was technologically feasible.
利用可持续和可生物降解的木质纤维素纤维来解毒废水中的有毒 Cr(VI)，被认为是一种清理受污染水生态环境的多功能方法。本研究旨在通过等温模型（朗缪尔、弗伦德利希、特金、哈金-朱拉和杜比宁-拉德乌舍夫斯基）、动力学模型和热力学参数来评估生物吸附在榕属植物纤维上的效率和机制。从榕属植物中提取的生物质通过扫描电子显微镜和傅里叶变换红外光谱进行了表征。通过批量法研究了初始浓度、温度、pH 和接触时间等不同参数对最大去除效率的影响，以优化最大去除效率。平衡数据最好由朗缪尔等温模型表示，生物吸附剂对 Cr(VI)的最大吸附容量为 19.68mg/g。准二级动力学模型很好地描述了动力学数据。计算得出的热力学参数值，如焓变(∆H(0))、熵变(∆S(0))和自由能变(∆G(0))分别为 21.55kJ/mol、76.24J/molK 和-1.55kJ/mol，这表明该过程是自发的和吸热的。在存在 Na(+)、Mg(2+)、Ca(2+)、SO 4 (2-)、HCO 3 (-)和 Cl(-)的情况下，研究了吸附剂对 Cr(VI)去除的容量，结果表明，HCO 3 (-)离子的存在增加了 Cr(VI)的去除；Na(+)、SO 4 (2-)或 Cl(-)的存在对 Cr(VI)吸附没有显著影响，而 Ca(2+)和 Mg(2+)离子导致 Cr(VI)吸附略有下降。此外，解吸研究表明，可从水溶液中去除 31.10%的金属离子，其中 26.63%的金属离子可通过第一循环的解吸去除，且可重复使用吸附剂。扩大规模研究的结果表明，从水溶液中去除 Cr(VI)是一种具有生态效益的技术。
