Abstract A dual network Poly(Acrylamide-co-Acrylic Acid)/Xanthan Gum (XG) hydrogel incorporated with graphene oxide (GAMAAX) was synthesized through free radical polymerization method for the removal of heavy metal ions. The GAMAAX hydrogel was characterized by Fourier transform infrared spectrum (FTIR), environmental scanning electron microscope (ESEM), energy dispersive X-ray spectroscopy (EDS) and rheology tests. The adsorption capacity and electrical conductivity of GAMAAX hydrogel was investigated for varying pH range and adsorption dosage by central composite design (CCD) method. The results indicated that the heavy metal ion adsorption followed the pseudo-second-order kinetic model, and conformed Freundlich adsorption model with substantial adsorption capacities of 312.15 mg/g and 185.0 mg/g for Cd2+ and Ni2+, respectively. In addition to a great single-ion affinity for Cd2+ and Ni2+ ions, it also proved a remarkable dual-ion adsorption capability with the adsorption of 259.25 mg/g and 80.75 mg/g Cd2+ and Ni2+, respectively. Moreover, less than 20% reduction in the adsorption capacity after four adsorption–desorption cycles, verified the reusability of the GAMAAX hydrogel for the practical and large-scale wastewater treatment applications.

中文翻译：

---

用于在废水处理应用中有效去除镉和镍离子的坚韧双网络 GAMAAX 水凝胶

摘要 通过自由基聚合法合成了一种双网络聚（丙烯酰胺-共丙烯酸）/黄原胶（XG）水凝胶掺入氧化石墨烯（GAMAAX），用于去除重金属离子。GAMAAX 水凝胶通过傅里叶变换红外光谱 (FTIR)、环境扫描电子显微镜 (ESEM)、能量色散 X 射线光谱 (EDS) 和流变学测试进行表征。通过中心复合设计（CCD）方法研究了 GAMAAX 水凝胶在不同 pH 范围和吸附剂量下的吸附能力和电导率。结果表明，重金属离子吸附遵循拟二级动力学模型，符合Freundlich吸附模型，对Cd2+和Ni2+的吸附容量分别为312.15 mg/g和185.0 mg/g。除了对 Cd2+ 和 Ni2+ 离子具有很好的单离子亲和力外，它还证明了显着的双离子吸附能力，分别为 259.25 mg/g 和 80.75 mg/g Cd2+ 和 Ni2+。此外，经过四次吸附-解吸循环后吸附容量减少不到 20%，验证了 GAMAAX 水凝胶在实际和大规模废水处理应用中的可重复使用性。