Abstract：
Heavy metals (HMs) in water are highly poisonous and carcinogenic agents for human health. To alleviate the toxic impacts of HMs, green remediation technologies are the need of the hour. In this regard, different nanosorbents (CMCG@ORP, ORAC, NiO/NPs, and NiO@ORAC/NCs) were synthesized in the present study, and the percentage removal of heavy metals [chromium(VI) and cadmium(II) ions] was evaluated. The nanosorbents were characterized by using FTIR, SEM, UV-Vis spectroscopy, and XRD. UV-Vis spectroscopy confirmed the synthesis of nanosorbents such as NiO/NPs and NiO@ORAC/NCs at 330.5 nm and 352.55 nm, respectively. The characterization studies show that the surface of synthesized nano-sorbents was highly coarse, uneven, and abrasive. XRD pattern deduced that the sample was of single phase, and no other impurity was detected except the face-centered cubic-phase peak of NiO. The maximum adsorption of Cd (91%) and Cr (92%) was found at initial concentrations of 100 and 60 ppm respectively at contact time = 180 min, temperature 25 °C, and with an adsorbent dose of 0.5 g. Isothermal, kinetic, and thermodynamic studies were also performed to evaluate the adsorption mechanisms and feasibility of the process. Adsorption mostly followed Freundlich isotherm which indicates the multilayer adsorption phenomenon and the negative value of Gibb\'s free energy showed the spontaneous nature and feasibility of the adsorption reaction. Surface complexation, ion exchange, surface precipitation, and the phenomenon of physical adsorption occurred on the sorbent surface which led to the attachment of Cd and Cr to the tested nanosorbents. In conclusion, NiO@ORAC/NCs were the most effective in the alleviation of Cd(II) and Cr(VI) ions in contaminated water.
摘要：
水中的重金属（HMs）是对人体健康具有剧毒和致癌作用的物质。为了减轻HMs的毒性影响，绿色修复技术是时代的需要。在这方面,不同的纳米吸附剂(CMCG@ORP，ORAC,NiO/NPs,和NiO@ORAC/NCs)在本研究中合成，并评估了重金属[铬（VI）和镉（II）离子]的去除百分比。使用FTIR对纳米吸附剂进行了表征,SEM,紫外-可见光谱,和XRD。UV-Vis光谱证实了在330.5nm和352.55nm处合成了诸如NiO/NPs和NiO@ORAC/NCs的纳米吸附剂,分别。表征研究表明,合成的纳米吸附剂的表面高度粗糙,不均匀,和磨料。XRD图谱推断样品为单相，除了NiO的面心立方相峰外，没有检测到其他杂质。在接触时间=180分钟时，分别在100和60ppm的初始浓度下发现Cd（91％）和Cr（92％）的最大吸附。温度25°C,吸附剂剂量为0.5克。等温，动力学,和热力学研究也进行了评估吸附机理和可行性的过程。吸附主要遵循Freundlich等温线，表明多层吸附现象，Gibb自由能的负值表明了吸附反应的自发性质和可行性。表面络合,离子交换,地表降水,并且在吸附剂表面发生物理吸附现象，导致Cd和Cr附着到测试的纳米吸附剂上。总之,NiO@ORAC/NCs对污染水体中Cd(Ⅱ)和Cr(Ⅵ)离子的缓解效果最好。
