The presence of toxic heavy metals in wastewater is a continuing threat to both the environment and living organisms. The present study investigates the ion-exchange potential of a dual-exchanged (Na⁺/H⁺) chelating resin to remove nickel ions from wastewater in a fixed bed column ion exchanger. The resin contains iminodiacetic acid (IDA) functional groups that can lead to the capture of heavy metal ions, provided that the pH condition and ratio of Na⁺: H⁺ are appropriate. Too much Na⁺ results in precipitation of nickel hydroxide, resulting in clogging of the ion exchange columns, while too much H⁺ in the solution leads to competitive protonation, reducing the uptake of Ni²⁺ ions. The experimental work has been supported by modelling results using a new film-homogeneous surface diffusion model (HSDM) to simulate the fixed bed breakthrough curves for the two exchange processes – assigned 1 and 2. The best fit model simulation curves were obtained by optimizing the overall external diffusion mass transfer coefficient k_f (=5.41 × 10⁻³ cms⁻¹), the surface diffusivity D_s (D_s1 = 224 × 10⁻⁷cm²s⁻¹ for 2Na⁺/Ni²⁺ exchange; and, D_s2 = 3.60 × 10⁻¹⁰ cm²s⁻¹ for 2H⁺/Ni²⁺ exchange) and the equilibrium constant K_RP (K_RP1 = 351 dm³/g for 2Na⁺/Ni²⁺ exchange; and K_RP2 = 781 dm³/g for 2H⁺/Ni²⁺ exchange) until a good fit was obtained between the model and experimental data. Optimisation was achieved by employing the downhill simplex method and performing a multidimensional minimization of the objective function, i.e. minimizing the SSE between the experimental data and the model prediction.

废水中有毒重金属的存在对环境和生物均构成持续威胁。本研究研究了固定床柱离子交换器中双交换（Na ⁺ / H ⁺）螯合树脂从废水中去除镍离子的离子交换潜力。该树脂包含亚氨基二乙酸（IDA）官能团，只要合适的pH条件和Na ⁺：H ^+的比例，就可以导致重金属离子的捕获。Na ⁺过多会导致氢氧化镍沉淀，导致离子交换柱堵塞，而溶液中H ⁺过多会导致竞争性质子化，从而减少Ni的吸收²⁺离子。通过使用新的膜均质表面扩散模型（HSDM）来模拟两个交换过程（分配为1和2）的固定床穿透曲线的模型结果，为实验工作提供了支持。对于2Na ⁺ / Ni ²⁺交换，总的外部扩散传质系数k _f（= 5.41×10 ^-3  cms ^-1），表面扩散率D _s（D _s1  = 224×10 ^-7 cm ² s ^-1）；并且， D _s2  = 3.60×10 ^-10 cm ² s ^-1对于2H ⁺ / Ni ²⁺交换）和平衡常数K _RP（对于2Na ⁺ / Ni ²⁺交换，K _RP1  = 351 dm ³ / g ;对于2H ⁺ / Ni ²⁺交换，K _RP2  = 781 dm ³ / g ），直到模型与实验数据之间获得良好的拟合为止。通过使用下坡单纯形法并执行目标函数的多维最小化（即，将实验数据与模型预测之间的SSE最小化）来实现优化。