Sulfonyl-Functionalized Materials Enable In Situ Purification and Circular Resource Recovery from Chromium Electroplating Aging Solutions

Chromium electroplating is widely used in manufacturing but generates large volumes of highly toxic Cr(VI)-contaminated aging solutions, posing significant environmental and energy challenges. Current treatment methods mainly rely on end-of-pipe processes that consume large amounts of chemicals, generate secondary waste, and fail to recover resources. Here, we report a materials-enabled strategy for sustainable management of electroplating aging solutions through an integrated system for online separation and in situ reuse. A sulfonyl-functionalized resin was engineered to achieve exceptional oxidative stability under strongly acidic, Cr(VI)-rich conditions. Sulfonyl-induced electronic modulation, together with a rigid framework, effectively suppresses polymer backbone degradation while maintaining stable ion-exchange performance. Coupling ion exchange with diffusion dialysis and electro-oxidation enables simultaneous impurity removal, sulfuric acid recovery, and chromium regeneration, establishing a closed-loop resource recovery pathway. Industrial-scale trials demonstrate that the regenerated electrolyte can be directly reused for electroplating, delivering coating performance comparable to fresh baths while reducing energy consumption by 35% and improving corrosion resistance by 28.4% relative to untreated solutions. Life-cycle and techno-economic analyses further confirm substantial environmental and economic benefits, reducing operating costs to 2.1% of conventional treatment. These findings provide a scalable pathway for transforming hazardous electroplating wastes into recyclable resources, advancing circular manufacturing and zero-liquid-discharge electroplating.