Palladium adsorption behaviour from alkaline glycine-cyanide solutions using ion exchange

IF 7.1 Q1 ENGINEERING, CHEMICAL

Chemical Engineering Journal Advances Pub Date : 2025-09-03 DOI:10.1016/j.ceja.2025.100852

C. Rubina Acuna, E.A. Oraby, G.A. Bezuidenhout, C.C. Beh, J.J. Eksteen

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Abstract

The demand for Platinum Group Metals (PGMs) is increasing in new industry applications such as e-waste, auto catalysts, electrical and electronics sectors. Current technologies for separating and purifying metals are generally based on cyanide and acidic chloride systems. The alkaline amino acid leach and recovery method promises a highly selective and more environmentally friendly approach for recovering PGMs, where previous recovery studies have focused on the recovery of precious and base metals from glycine–cyanide solutions. The objective of this study was to assess the feasibility of palladium (Pd) adsorption using ion exchange resin (Amberlite HPR4100 Cl), from synthetic leach solutions containing alkaline glycine–cyanide. 45-minute tests were conducted under different operational conditions (ion exchange resin dosage, temperature, pH, Pd concentration, and concentrations of glycine and cyanide) to analyze the impact on Pd recovery, kinetics and isotherms. The results have shown that Pd can be effectively recovered from glycine-cyanide solutions using ion exchange resin. Pd recovery reached 99.83 ± 3.1 % % within 45 min under standard conditions (Pd = 5 mg/L, [CN] = 300 mg/L, [Gly] = 3000 mg/L, pH = 10.5, resin dosage = 10 g/L, and temperature = 24 °C), with resin dosage and temperature having the largest impact over adsorption results. Kinetic modelling results best fit a pseudo-first-order model (R²>0.80) for all parameters studied. In the isotherm experiments, the Langmuir model provided the best fit (R²>0.87), with the maximum uptake capacity (Q_m) at different initial Pd concentrations ranging from 3.99 ± 0.14 mg/g to 32.36 ± 3.46 mg/g.

The scientific significance of this study lies in confirming the potential of using a more environmentally friendly approach to recover Pd from glycine-cyanide and glycine-only (preliminary) solutions with resin, as opposed to the current cyanide and acidic chloride systems for PGMs.

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离子交换法吸附碱性甘氨酸-氰化物溶液中钯的行为

在电子废物、汽车催化剂、电气和电子行业等新的工业应用中，对铂族金属（PGMs）的需求正在增加。目前的金属分离和提纯技术一般是基于氰化物和酸性氯化物系统。碱性氨基酸浸出和回收方法有望为回收pgm提供高选择性和更环保的方法，此前的回收研究主要集中在从甘氨酸氰化物溶液中回收贵金属和贱金属。本研究的目的是评估离子交换树脂（Amberlite HPR4100 Cl）吸附含碱性甘氨酸氰化物合成浸出液中钯（Pd）的可行性。在不同操作条件（离子交换树脂用量、温度、pH、Pd浓度、甘氨酸和氰化物浓度）下进行45分钟的试验，分析对Pd回收率、动力学和等温线的影响。结果表明，离子交换树脂可以有效地从甘氨酸氰化物溶液中回收钯。在Pd = 5 mg/L, [CN] = 300 mg/L, [Gly] = 3000 mg/L, pH = 10.5，树脂用量= 10 g/L，温度= 24℃的标准条件下，45 min内Pd回收率可达99.83±3.1% %，树脂用量和温度对吸附结果影响最大。动力学建模结果最适合于所有研究参数的伪一阶模型（R2>0.80）。等温线实验中，Langmuir模型拟合最佳（R2>0.87），不同初始Pd浓度下的最大吸收容量（Qm）范围为3.99±0.14 mg/g ~ 32.36±3.46 mg/g。这项研究的科学意义在于证实了使用更环保的方法从甘氨酸氰化物和甘氨酸（初步）树脂溶液中回收Pd的潜力，而不是目前用于PGMs的氰化物和酸性氯化物体系。

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