Hashem A, Fletcher A J, Younis H, Mauof H, Abou-Okeil A
National Research Center, Textile Research Division, Dokki, Cairo, Egypt.
Department of Chemical and Process Engineering, University of Strathclyde, 75 Montrose Street, Glasgow G1 1XJ, UK.
Int J Biol Macromol. 2020 Dec 1;164:3193-3203. doi: 10.1016/j.ijbiomac.2020.08.159. Epub 2020 Aug 24.
Microcrystalline cellulose (MCC) has been utilized as an adsorbent material for the removal of Pb(II) ions from aqueous solution after treatment with 1,2,3,4-butanetetracarboxylic acid (BTCA) at elevated temperature to obtain MMCC. The resulting adsorbent was characterized for point of zero point charge (pHZPC), estimation of carboxyl content, Fourier transform infrared spectroscopy (FT-IR), scan electron microscopy (SEM), and textural properties, including surface area, and subsequently utilized for the removal of Pb(II) ions from aqueous solution. The adsorption process was probed by investigating the effect of adsorbent dose, pH of solution, temperature, agitation time, and Pb(II) ion concentration. The results showed successful functionalization of MCC using BTCA, significantly improved the binding properties of the adsorbent towards Pb(II) ions. Isothermal adsorption data was analyzed using Langmuir, Freundlich and Temkin models, evaluated via nonlinear regression analysis. The maximum adsorption capacity was found to be 1155 mg/g (at pH 5 and 30 °C) from Langmuir theory, and appears independent of surface area. The Freundlich model was found to provide the best fit and the constant n was determined to be 2.69, indicating that adsorption of Pb(II) ions onto MMCC is favorable. Kinetic modelling showed good agreement for the pseudo-second order kinetic model, supporting the theory that chemisorption is involved in the adsorption process, which is promoted by a high density of active sites. Thermodynamic analysis showed that the adsorption of Pb(II) ions onto MMCC was endothermic and nonspontaneous; hence, MMCC offers an effective method of Pb(II) ion removal from aqueous solutions, with potential for water remediation processes.
微晶纤维素（MCC）已被用作吸附材料，在高温下用1,2,3,4-丁烷四羧酸（BTCA）处理后从水溶液中去除Pb(II)离子，从而得到MMCC。对所得吸附剂进行了零电荷点（pHZPC）、羧基含量估算、傅里叶变换红外光谱（FT-IR）、扫描电子显微镜（SEM）以及包括表面积在内的纹理特性表征，随后用于从水溶液中去除Pb(II)离子。通过研究吸附剂剂量、溶液pH值、温度、搅拌时间和Pb(II)离子浓度的影响来探究吸附过程。结果表明，使用BTCA成功实现了MCC的功能化，显著提高了吸附剂对Pb(II)离子的结合性能。使用Langmuir、Freundlich和Temkin模型对等温吸附数据进行分析，并通过非线性回归分析进行评估。根据Langmuir理论，最大吸附容量为1155 mg/g（在pH 5和30°C下），且似乎与表面积无关。发现Freundlich模型拟合效果最佳，常数n确定为2.69，表明Pb(II)离子在MMCC上的吸附是有利的。动力学建模表明与伪二级动力学模型吻合良好，支持了吸附过程涉及化学吸附的理论，这是由高密度的活性位点促进的。热力学分析表明，Pb(II)离子在MMCC上的吸附是吸热且非自发的；因此，MMCC提供了一种从水溶液中有效去除Pb(II)离子的方法，具有水修复过程应用潜力。
