The single and binary adsorption of Cd(II) and Ni(II) from aqueous solution on lignin of sugarcane bagasse, a secondary product of sugarcane industry, has been demonstrated in this work. Experimental parameters affecting the adsorption are studied, such as the lignin dose, pH, contact time and temperature. The optimal values found for these parameters, both binary and single adsorption, are the followings: lignin dose (7g / L), pH (6), contact time (12 hours) and temperature (40°C). Different empirical adsorption models are used for the evaluation of sorption equilibrium data. Experimental results were interpreted considering speciation curves of ions present in the solution. In single and binary system adsorption data are analyzed using the following adsorption isotherms: single, non-modified, extended and modified Langmuir; single, non-modified and modified Redlich–Peterson; single and extended Freundlich; single and multicomponent Langmuir-Freundlich; and Sheindorf–Rebuhn–Sheintuch. The experimental adsorption isotherms are better adjusted to the extended Langmuir model. This study indicates that the lignin is an adsorbent able to remove Ni (II) and Cd (II) in binary systems, having a greater affinity for cadmium.

中文翻译：

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镍和镉离子从二元溶液中生物吸附到甘蔗渣木质素上：动力学和热力学研究

这项工作已经证明了水溶液中 Cd(II) 和 Ni(II) 在甘蔗工业的副产品甘蔗渣的木质素上的单一和二元吸附。研究了影响吸附的实验参数，例如木质素剂量、p H、接触时间和温度。为这些参数（二元吸附和单吸附）找到的最佳值如下：木质素剂量 (7g/L)，pH (6)、接触时间（12 小时）和温度（40°C）。不同的经验吸附模型用于评估吸附平衡数据。考虑到溶液中存在的离子的形态曲线来解释实验结果。在单一和二元系统中，使用以下吸附等温线分析吸附数据：单一、未改性、扩展和改性朗缪尔；单一的、未修改的和修改的 Redlich-Peterson；单一和扩展 Freundlich；单组分和多组分 Langmuir-Freundlich；和 Sheindorf-Rebuhn-Sheintuch。实验吸附等温线更好地调整到扩展的朗缪尔模型。该研究表明，木质素是一种能够去除二元系统中的 Ni (II) 和 Cd (II) 的吸附剂，对镉具有更大的亲和力。