PDF(Pubmed)
Abstract：
Environmental sustainability has gained acceptance to achieving the goal of a secure ecosystem with a reliable management system. Heavy metal remediation of aqueous streams is of special concern due to the intractability and persistence in the environment. Adsorption is a potential alternative to the existing inefficient conventional technologies for the removal and recovery of metal ions from aqueous solutions and becomes vital to align with the Sustainable Development Goals (SDGs) and mitigate the adverse environmental and social impacts. Calcium Alginate-Graphene oxide (CA-GO) composite has been synthesized for the adsorption of heavy metals including Cr3+, Cu2+, and Cd2+ ions from tannery effluents. Graphene oxide is prepared from commercial graphite powder and reacted with sodium alginate and calcium chloride to form the beads of CA-GO composite. The developed composite was characterized by FTIR, elemental analysis, SEM, XRD analysis, and Raman spectroscopy. Moreover, the effect of pH, adsorbent dosage, contact time, and initial concentration of metal ions on the adsorption capacity were investigated through batch experiments. At a pH>3.0 (pHzpc), the carboxyl group of CA-GO was deprotonated to make the surface negatively charged and facilitate metal adsorption. The optimum pH and maximum adsorption capacity of CA-GO for removal of Cr(III), Cu(II), and Cd(II) were 4.5, 6.0, and 7.0, and 90.58, 108.57, and 134.77 mg g-1, respectively. The kinetics, adsorption isotherms, and thermodynamics were studied to determine the adsorption mechanism. The kinetic of adsorption adopted the second-order model. Thermodynamic parameter were calculated and the adsorption process was determined to be exothermic and spontaneous at room temperature. The developed composite has been efficaciously applied for the removal of metal ions and pollution from real tannery effluents.
摘要：
环境可持续性已被接受，以实现具有可靠管理系统的安全生态系统的目标。由于在环境中的难处理性和持久性,水流的重金属修复受到特别关注。吸附是用于从水溶液中去除和回收金属离子的现有低效常规技术的潜在替代方案，对于与可持续发展目标（SDG）保持一致并减轻不利的环境和社会影响至关重要。已合成了海藻酸钙-氧化石墨烯（CA-GO）复合材料，用于吸附包括Cr3在内的重金属，Cu2+,和来自制革废水的Cd2+离子。由市售石墨粉制备氧化石墨烯,并与海藻酸钠和氯化钙反应以形成CA-GO复合材料的珠粒。通过FTIR对所开发的复合材料进行了表征,元素分析,SEM,XRD分析,和拉曼光谱。此外，pH的影响，吸附剂用量,接触时间,通过批量实验考察了金属离子初始浓度对吸附容量的影响。在pH>3.0（pHzpc）时，将CA-GO的羧基去质子化，使表面带负电荷，促进金属吸附。CA-GO去除Cr(Ⅲ)的最佳pH值和最大吸附量,Cu(II),和Cd（II）分别为4.5、6.0和7.0，以及90.58、108.57和134.77mgg-1。动力学，吸附等温线，和热力学研究确定吸附机理。吸附动力学采用二阶模型。计算了热力学参数，并确定了吸附过程是放热的，并且在室温下是自发的。开发的复合材料已有效地用于去除金属离子和实际制革废水中的污染。
