Al-Mhyawi Saedah R, Abdel-Tawab Nader Abdel-Hamed, El Nashar Rasha M
Department of Chemistry, College of Science, University of Jeddah, Jeddah 22233, Saudi Arabia.
Chemistry Department, Faculty of Science, Cairo University, Giza 12613, Egypt.
Polymers (Basel). 2023 Jan 5;15(2):277. doi: 10.3390/polym15020277.
In recent years, due to the developments in the textile industry, water contaminated with synthetic dyes such as methylene blue (MB) has become an environmental threat based on the possible impacts in terms of chemical and biochemical demand, which leads to disturbance in aquatic plants photosynthesis, besides their possible toxicity and carcinogenicity for humans. In this work, an adsorbent hydrogel is prepared via free radical polymerization comprising acrylic acid (PAA) as a monomer and orange peel (OP) as a natural modifier rich in OH and COOH present in its cellulose and pectin content. The resulting hydrogels were optimized in terms of the content of OP and the number of cross-linkers and characterized morphologically using Scanning electron microscopy. Furthermore, BET analysis was used to follow the variation in the porosity and in terms of the surface area of the modified hydrogel. The adsorption behavior was found to follow pseudo-second-order as a kinetic model, and Langmuir, Freundlich, and Temkin isotherm models. The combination of OP and PAA has sharply enhanced the adsorption percent of the hydrogel to reach 84% at the first 10 min of incubation with an adsorption capacity of more than 1.93 gm/gm. Due to its low value of pHPZc, the desorption of MB was efficiently performed at pH 2 using HCl, and the desorbed OP-PAA were found to be reusable up to ten times without a decrease in their efficiency. Accordingly, OP-PAA hydrogel represents a promising efficient, cost-effective, and environmentally friendly adsorbent for MB as a model cationic dye that can be applied for the treatment of contaminated waters.
近年来，由于纺织工业的发展，受亚甲基蓝（MB）等合成染料污染的水已成为一种环境威胁，这是基于其在化学需氧量和生化需氧量方面可能产生的影响，除了对人类可能具有毒性和致癌性外，还会导致水生植物光合作用受到干扰。在这项工作中，通过自由基聚合制备了一种吸附性水凝胶，该水凝胶以丙烯酸（PAA）作为单体，以富含纤维素和果胶中所含的OH和COOH的橙皮（OP）作为天然改性剂。所得水凝胶在OP含量和交联剂数量方面进行了优化，并使用扫描电子显微镜进行了形态表征。此外，采用BET分析来跟踪改性水凝胶的孔隙率和表面积的变化。发现吸附行为符合伪二级动力学模型以及朗缪尔、弗伦德利希和坦金等温线模型。OP和PAA的组合显著提高了水凝胶的吸附百分比，在孵育的前10分钟达到84%，吸附容量超过1.93 gm/gm。由于其较低的零电荷点pH值，使用HCl在pH 2时能有效地实现MB的解吸，并且发现解吸后的OP-PAA可重复使用多达十次而效率不降低。因此，OP-PAA水凝胶作为一种用于MB的模型阳离子染料的有前景的高效、经济且环保的吸附剂，可应用于处理受污染的水。
