Nickel (Ni) is an economically important metal characterized by its mechanical strength and anticorrosion properties. With the increasing industrial demand for Ni and the depleting accessible Ni primary ores, sustainable technologies are required for the recovery of this metal from alternative resources. In this study, adsorption using chitosan was investigated as a sustainable technique to recover Ni from sulfate (SO₄²⁻) and calcium (Ca) rich secondary resources. The effects of pH, contact time, and the presence of SO₄²⁻ and Ca on Ni adsorption were investigated in batch experiments. Chemical speciation modeling was performed to analyze how the predominant Ni species present under different conditions may affect the efficiency of the adsorption process. The comparison of chitosan’s maximum Ni adsorption capacities in the absence (1.00 mmol/g) and presence (1.49 mmol/g) of 500 mM SO₄²⁻ and 10 mM Ca indicated the positive effect of these ions on Ni adsorption. The predominance of the neutrally charged NiSO₄⁰ species in Ni/SO₄²⁻ system has contributed to the enhanced Ni adsorption on chitosan as verified by X-ray photoelectron spectroscopy (XPS) analysis. However, kinetic studies confirmed that the Ni adsorption rate decreased by 4.5 times when SO₄²⁻ was present. The subsequent continuous Ni adsorption from a real SO₄²⁻-rich leachate in a column setup revealed that chitosan is selective for Ni over Ca and Cr with selectivity quotients of 9.6 (K_Ni/Ca) and 3.0 (K_Ni/Cr). Overall, this study indicated that Ni complexation with SO₄²⁻ enhances the Ni adsorption capacity of chitosan, but slows down the adsorption process.

镍 (Ni) 是一种经济上重要的金属，其特点是其机械强度和防腐蚀特性。随着工业对镍的需求不断增加以及可获取的镍原矿的枯竭，需要可持续的技术来从替代资源中回收这种金属。在这项研究中，研究了使用壳聚糖的吸附作为从硫酸盐 (SO ₄ ^2- ) 和钙 (Ca) 丰富的二次资源中回收镍的可持续技术。pH 值、接触时间和 SO ₄ ^2-存在的影响和Ca对Ni的吸附进行了批量实验研究。进行化学形态建模以分析在不同条件下存在的主要 Ni 物种如何影响吸附过程的效率。在不存在 (1.00 mmol/g) 和存在 (1.49 mmol/g) 500 mM SO ₄ ^2-和 10 mM Ca的情况下，壳聚糖的最大 Ni 吸附容量的比较表明这些离子对 Ni 吸附的积极影响。Ni/SO ₄ ^{2− 中}带中性电荷的 NiSO ₄ ⁰物种的优势X 射线光电子能谱 (XPS) 分析证实，该系统有助于增强镍在壳聚糖上的吸附。然而，动力学研究证实，当存在 SO ₄ ^2-时，Ni 吸附率降低了 4.5 倍。随后在柱设置中从真正的富含SO ₄ ^{2- 的}渗滤液中连续吸附 Ni，表明壳聚糖对 Ni 的选择性高于 Ca 和 Cr，选择性商为 9.6 ( K _Ni/Ca ) 和 3.0 ( K _Ni/Cr )。总体而言，该研究表明，Ni 与 SO ₄ ^{2− 的}络合增强了壳聚糖的 Ni 吸附能力，但减慢了吸附过程。