Panapitiya P H P, Weerakoon Tharindra, Fernando M Shanika, Wimalasiri A K D V K, de Silva K M Nalin, de Silva Rohini M
Centre for Advanced Materials and Devices (CAMD), Department of Chemistry, University of Colombo Colombo 03 Sri Lanka
Department of Life Sciences, Faculty of Science, NSBM Green University Mahenwatta, Pitipana Homagama 10206 Sri Lanka.
RSC Adv. 2025 Aug 5;15(33):27356-27368. doi: 10.1039/d5ra00562k. eCollection 2025 Jul 25.
A new, non-toxic, environmentally friendly nanocomposite, based on graphene oxide and biopolymers was developed as an effective adsorbent for water hardness removal. Graphene oxide was synthesized by a modified Hummers' method, whereas crosslinked carboxymethyl cellulose (CMC) and chitosan were used as biopolymers. Montmorillonite (MMT) was utilized as an additive to enhance the adsorbent's performance. The solubility and adsorption behaviours of the prepared materials were investigated in respect to calcium ions (Ca) and magnesium ions (Mg). Among the prepared materials, a film containing graphene oxide (GO), crosslinked carboxymethyl cellulose (CMC), and montmorillonite (MMT), denoted as GO-CMC-MMT-3, exhibited the highest water softening capacity. The successful synthesis of the materials was confirmed through scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), and ultraviolet-visible spectroscopy (UV-Vis). The optimal pH for the adsorption process was around 6-7. Kinetic studies showed that second-order kinetic model described the adsorption process. The thermodynamic analysis indicated that the process was endothermic in nature and showed a reduced degree of spontaneity at the given conditions. The Langmuir isotherm model was the best fit, and the adsorption capacities were 6.46 mg g for Mg and 7.98 mg g for Ca, which indicated the formation of a monolayer of cations on homogeneous adsorption sites. Further, an investigation on the reusability of gravity filtration was carried out, demonstrating the practical utility of the GO-CMC-MMT-3 membrane in real-life water treatment.
一种基于氧化石墨烯和生物聚合物的新型无毒、环保纳米复合材料被开发出来，作为去除水硬度的有效吸附剂。氧化石墨烯通过改进的Hummers法合成，而交联羧甲基纤维素（CMC）和壳聚糖被用作生物聚合物。蒙脱石（MMT）被用作添加剂以提高吸附剂的性能。研究了所制备材料对钙离子（Ca）和镁离子（Mg）的溶解性和吸附行为。在所制备的材料中，一种包含氧化石墨烯（GO）、交联羧甲基纤维素（CMC）和蒙脱石（MMT）的薄膜，记为GO-CMC-MMT-3，表现出最高的水软化能力。通过扫描电子显微镜（SEM）、傅里叶变换红外光谱（FT-IR）、X射线衍射（XRD）和紫外可见光谱（UV-Vis）证实了材料的成功合成。吸附过程的最佳pH约为6-7。动力学研究表明，二级动力学模型描述了吸附过程。热力学分析表明，该过程本质上是吸热的，并且在给定条件下自发性程度降低。Langmuir等温线模型拟合效果最佳，对Mg的吸附容量为6.46 mg/g，对Ca的吸附容量为7.98 mg/g，这表明在均匀吸附位点上形成了阳离子单层。此外，还对重力过滤的可重复使用性进行了研究，证明了GO-CMC-MMT-3膜在实际水处理中的实用性。
