The half-wave rectified alternating current electrochemical (HWACE) method is feasible for high-capacity extractions of heavy metal ions (HMI) from low-strength wastewater but exhibits sluggish extraction kinetics. Herein, to expedite Pb extraction, carbon felts (CFs) were modified with well-aligned polyaniline (PANI) actiniae-like nanoarrays and used as cathodes. Consequently, Pb was exclusively extracted (∼99.9%) from binary-component solutions [Pb-Na (50–500 mg/L)] within 12 h with highest extraction rates of 14.35 mg L∙h, better than that of CF (88.4%, 9.7 mg L∙h). Characterizations and COSMOL Multiphysics simulations demonstrated that PANI/CF electrodes enhanced electric fields, promoted Pb mass transfer, and reduced nucleation overpotential, accelerating Pb electrodeposition kinetics and thereby expediting Pb extraction. Moreover, the qualitative discrepancies of Pb diffusion coefficients under Na (0.368)/Ca (0.355) interference caused faster Pb extractions in Na. During extraction, Pb was continuously electrodeposited as lead crystals onto electrodes under Na/Ca interference, achieving high-capacity extractions of >4000 mg/g, ∼70% of them were recovered using a tweezer, and well-maintained 6-cycle-extraction performance. Kinetic analysis and density functional theory demonstrated that stronger leadophilicity of Pb(111) than electrode surfaces caused Pb extraction a self-accelerating process. This work gives fresh insights to expedite HMI extraction in the HWACE method.

中文翻译：

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通过加速铅电沉积动力学，半波整流交流电化学法加速从低浓度废水中提取 Pb2+

半波整流交流电化学 (HWACE) 方法可用于从低浓度废水中高容量萃取重金属离子 (HMI)，但萃取动力学缓慢。在此，为了加快 Pb 的提取，用排列良好的聚苯胺 (PANI) 类海葵纳米阵列对碳毡 (CF) 进行改性，并将其用作阴极。因此，在 12 小时内，Pb 从二元溶液 [Pb-Na (50–500 mg/L)] 中被完全萃取（∼99.9%），最高萃取率为 14.35 mg L∙h，优于 CF（88.4 %, 9.7 毫克·升·小时)。表征和 COSMOL Multiphysics 模拟表明，PANI/CF 电极增强了电场，促进了 Pb 传质，降低了成核过电势，加速了 Pb 电沉积动力学，从而加快了 Pb 萃取。此外，Na (0.368)/Ca (0.355) 干扰下 Pb 扩散系数的定性差异导致 Na 中 Pb 的萃取速度更快。萃取过程中，Pb 在 Na/Ca 干扰下以铅晶体的形式连续电沉积到电极上，实现 >4000 mg/g 的高容量萃取，使用镊子回收约 70%，并且维护良好的 6 循环萃取表现。动力学分析和密度泛函理论表明，Pb(111)的亲铅性比电极表面更强，导致Pb提取成为一个自加速过程。这项工作为加快 HWACE 方法中的 HMI 提取提供了新的见解。