Metal-containing wastes in aquatic environments lead to public health hazards and valuable resource lose. Metal-bearing wastewater must be treated to remove heavy metals or recover precious metals. To achieve these, target-tunable adsorbents that bind cationic and anionic metal species were developed through facile polyelectrolyte complexation using polyethylenimine (PEI) and polyacrylic acid (PAA). Utilizing the properties of the two polyelectrolytes and pK_a variabilities, stable tunable adsorbents were fabricated in water without additional solvents. The homogenous complex adsorbents were strategically synthesized via dissolution in 0.1 M NaOH and drop-wise addition of 1 M HCl, followed by crosslinking with glutaraldehyde. Consequently, the adsorbents in alternating weight ratios of 4:1 and 1:4 (PEI:PAA) exhibited good tunability and adsorption properties. The maximum single metal adsorption capacities were 1609.7 ± 49.6 and 558.6 ± 9.67 mg/g for gold and cadmium, respectively. The pseudo-second-order model fitted the kinetics data more appropriately and was recognized as the rate controlling step. In a binary mixture, gold selectivity was observed to be influenced by adsorption-reduction mechanism, which was elucidated by XRD and XPS. Moreover, the adsorbents demonstrated NO₃– sequestration properties, a feat deemed important for environmental remediation of nitrate ions. Finally, sequential separation was achieved with ethylenediaminetetraacetic acid (EDTA) and acidified thiourea.

水生环境中的含金属废物会危害公共健康，并浪费宝贵的资源。必须对含金属废水进行处理，以去除重金属或回收贵金属。为了达到这些目的，通过使用聚乙烯亚胺（PEI）和聚丙烯酸（PAA）的聚电解质络合，开发了可调节阳离子和阴离子金属种类的目标可调吸附剂。利用两种聚电解质和p K _a的性质可变性，稳定的可调吸附剂是在没有其他溶剂的水中制备的。通过溶解在0.1 M NaOH中并滴加1 M HCl，然后与戊二醛交联，策略性地合成了均匀的复合吸附剂。因此，重量比为4：1和1：4（PEI：PAA）的吸附剂表现出良好的可调性和吸附性能。金和镉的最大单金属吸附容量分别为1609.7±49.6和558.6±9.67 mg / g。拟二阶模型更适合动力学数据，并被认为是速率控制步骤。在二元混合物中，观察到金的选择性受吸附-还原机理的影响，该机理已通过XRD和XPS阐明。此外，吸附剂显示NO₃ –螯合特性，对环保修复硝酸根离子很重要。最后，用乙二胺四乙酸（EDTA）和酸化的硫脲实现了顺序分离。