Industrial Chemistry Centre, Royal Scientific Society, P.O. Box 1438, Amman, Jordan.
J Hazard Mater. 2010 Apr 15;176(1-3):510-20. doi: 10.1016/j.jhazmat.2009.11.059. Epub 2009 Nov 13.
A potential usefulness of raw date pits as an inexpensive solid adsorbent for methylene blue (MB), copper ion (Cu(2+)), and cadmium ion (Cd(2+)) has been demonstrated in this work. This work was conducted to provide fundamental information from the study of equilibrium adsorption isotherms and to investigate the adsorption mechanisms in the adsorption of MB, Cu(2+), and Cd(2+) onto raw date pits. The fit of two models, namely Langmuir and Freundlich models, to experimental data obtained from the adsorption isotherms was checked. The adsorption capacities of the raw date pits towards MB and both Cu(2+) and Cd(2+) ions obtained from Langmuir and Freundlich models were found to be 277.8, 35.9, and 39.5 mg g(-1), respectively. Surface functional groups on the raw date pits surface substantially influence the adsorption characteristics of MB, Cu(2+), and Cd(2+) onto the raw date pits. The Fourier transform infrared spectroscopy (FTIR) studies show clear differences in both absorbances and shapes of the bands and in their locations before and after solute adsorption. Two mechanisms were observed for MB adsorption, hydrogen bonding and electrostatic attraction, while other mechanisms were observed for Cu(2+) and Cd(2+). For Cu(2+), binding two cellulose/lignin units together is the predominant mechanism. For Cd(2+), the predominant mechanism is by binding itself using two hydroxyl groups in the cellulose/lignin unit.
本研究旨在提供从吸附平衡等温线研究中获得的基本信息，并探讨在利用原状椰壳对亚甲基蓝（MB）、铜离子（Cu(2+)）和镉离子（Cd(2+)）进行吸附时的吸附机理。通过检查两种模型（即 Langmuir 和 Freundlich 模型）对吸附等温线实验数据的拟合情况，对这两种模型进行了评估。从 Langmuir 和 Freundlich 模型获得的原状椰壳对 MB 以及 Cu(2+)和 Cd(2+)离子的吸附容量分别为 277.8、35.9 和 39.5mg/g。原状椰壳表面的官能团对 MB、Cu(2+)和 Cd(2+)在原状椰壳上的吸附特性有很大的影响。傅里叶变换红外光谱（FTIR）研究表明，在溶质吸附前后，吸收峰的吸光度、形状及其位置都有明显的差异。观察到两种机制可以用于 MB 的吸附，即氢键和静电吸引，而其他机制则可以用于 Cu(2+)和 Cd(2+)。对于 Cu(2+)，结合两个纤维素/木质素单元是主要的机制。对于 Cd(2+)，主要的机制是利用纤维素/木质素单元中的两个羟基来结合自身。
