Bhattacharyya Krishna G, Sarma Jyotirekha, Sarma Arunima
Department of Chemistry, Gauhati University, Guwahati, Assam, India.
J Hazard Mater. 2009 Jun 15;165(1-3):271-8. doi: 10.1016/j.jhazmat.2008.09.109. Epub 2008 Oct 7.
Azadirachta indica leaves are converted to a fine powder for use as a biosorbent for the removal of metal ions in aqueous solution. In this work, the adsorptive interactions between Ni(II) and the powder were studied under a variety of conditions involving variations in pH, Ni(II) concentration, biosorbent amount, interaction time and temperature, all in single batch processes. The experimental data have been interpreted on the basis of existing mathematical models of equilibrium kinetics and thermodynamics. The biosorption of Ni(II) increased in the pH range of 2.0-5.0 with approximately 92.6% adsorption at pH 5.0 for the highest amount of the biosorbent (4 g/L). The biosorption followed second-order kinetics and intra-particle diffusion was likely to have significant influence in controlling the process. The Langmuir monolayer adsorption capacity varied from 2.4 to 9.1mg/g and the equilibrium coefficient from 1.09 to 2.78 L/g with strong indication that the Ni(II) ions were held on the biosorbent surface by formation of an adsorption complex. The thermodynamic parameters showed the process to be exothermic in nature supported by appropriate ranges of values of enthalpy change, entropy change and Gibbs energy change.
印楝叶被加工成细粉，用作去除水溶液中金属离子的生物吸附剂。在这项工作中，研究了镍（II）与该粉末在多种条件下的吸附相互作用，这些条件包括pH值、镍（II）浓度、生物吸附剂用量、相互作用时间和温度的变化，所有这些均采用单批次工艺。已根据现有的平衡动力学和热力学数学模型对实验数据进行了解释。在pH值为2.0 - 5.0的范围内，镍（II）的生物吸附量增加，对于最高生物吸附剂用量（4 g/L），在pH 5.0时吸附率约为92.6%。生物吸附遵循二级动力学，颗粒内扩散可能对控制该过程有显著影响。朗缪尔单层吸附容量在2.4至9.1 mg/g之间变化，平衡系数在1.09至2.78 L/g之间，有力地表明镍（II）离子通过形成吸附络合物而被固定在生物吸附剂表面。热力学参数表明该过程本质上是放热的，焓变、熵变和吉布斯自由能变的值在适当范围内支持了这一点。
