Yousry Rania, Sayed Asmaa, Behalo Mohamed S, Abdel-Raouf Manar E, Feteha Amr
Chemistry Department, Faculty of Science, Benha University, P.O. Box 13518, Egypt.
Polymer Chemistry Department, National Center for Radiation Research and Technology, Egyptian Atomic Energy Authority, Cairo, Egypt.
Int J Biol Macromol. 2025 Jan;284(Pt 1):137867. doi: 10.1016/j.ijbiomac.2024.137867. Epub 2024 Nov 24.
Green hydrogels were synthesized from carboxymethyl guar gum (CMGG)-polyacrylic acid (PAAc) via gamma irradiation at doses of 10-40 kGy, they were codes as (CMGG/PAAc). FTIR spectroscopy was applied to confirm the chemical transformation of GG into the hydrogel formulations while the HNMR was employed to confirm the successful preparation of CMGG. TGA, XRD, and AFM were used to compare the improved formulation to native and CMGG. The investigated hydrogels were then applied comparatively to remove methylene blue (MB) and methyl orange (MO) dyes from aqueous solution under various operating parameters. In addition, the AFM was used comprehensively to address the adsorption process by comparing the surface topographies, height and roughness measurements between the dry and dye-loaded hydrogel. Four adsorption isotherms were investigated in order to go deep through the adsorption mechanism. These are Langmuir Freundlich, Redlich-Peterson and Jovanovich isotherms. Based on the values of R for all the models, it can be assumed that the Langmuir model is best appropriate for the adsorption process and that the dyes were adsorbed onto a homogenous surface. Kinetic tests showed that the pseudo-second-order model best fitted the adsorption process, with R values of 0.9999 for both dyes, confirming chemisorption as the rate-limiting step. The thermodynamic data indicates spontaneous, exothermic adsorption processes, with Gibbs free energy changes (∆G) for MB ranging from -11.265 to -10.82 kJ/mol and MO from -3.221 to -3.323 kJ/mol. Negative enthalpy changes (∆H) of -17.892 kJ/mol for MB and - 17.005 for MO show the exothermic nature of adsorption. The data proved effective removal of MB and MO dyes onto CMGG/PAAc hydrogels with better affinity for MB dye, making them excellent wastewater treatment adsorbents.
通过10 - 40 kGy剂量的γ辐射由羧甲基瓜尔胶（CMGG）-聚丙烯酸（PAAc）合成绿色水凝胶，它们被编码为（CMGG/PAAc）。采用傅里叶变换红外光谱（FTIR）来确认瓜尔胶向水凝胶配方的化学转变，同时利用核磁共振氢谱（HNMR）来确认CMGG的成功制备。热重分析（TGA）、X射线衍射（XRD）和原子力显微镜（AFM）用于将改进后的配方与天然瓜尔胶和CMGG进行比较。然后在各种操作参数下，将所研究的水凝胶用于从水溶液中比较去除亚甲基蓝（MB）和甲基橙（MO）染料。此外，通过比较干燥和负载染料的水凝胶之间的表面形貌、高度和粗糙度测量，全面利用AFM来研究吸附过程。研究了四种吸附等温线，以便深入了解吸附机理。这些等温线分别是朗缪尔等温线、弗伦德利希等温线、雷德利希-彼得森等温线和约万诺维奇等温线。基于所有模型的R值，可以认为朗缪尔模型最适合吸附过程，并且染料被吸附到均匀表面上。动力学测试表明，准二级模型最适合吸附过程，两种染料的R值均为0.9999，证实化学吸附是限速步骤。热力学数据表明吸附过程是自发的、放热的，亚甲基蓝的吉布斯自由能变化（∆G）范围为-11.265至-10.82 kJ/mol，甲基橙的吉布斯自由能变化范围为-3.221至-3.323 kJ/mol。亚甲基蓝的负焓变（∆H）为-17.892 kJ/mol，甲基橙的负焓变为-17.005 kJ/mol，表明吸附具有放热性质。数据证明CMGG/PAAc水凝胶对MB和MO染料具有有效的去除效果，并且对MB染料具有更好的亲和力，使其成为出色的废水处理吸附剂。
