Preparation of ion-exchange resin via in-situ polymerization for highly selective separation and continuous removal of palladium from electroplating wastewater

To separate palladium (Pd) from electroplating wastewater, a novel mesoporous ion-exchange resin (SiAcyl) was prepared with the loading rate of 27.3 wt% and the cross-linking degree of 10 wt%. It was synthesized by using macroporous silica as inorganic carrier, acrylic acid, and allyl acetoacetate as monomers, EGDMA as cross linking agent, AIBN as chemical initiator, dimethyl sulfoxide as diluent. The as-prepared SiAcyl resin was characterized by SEM-EDS, TG-DSC, N-2-adsorption-desorption isotherm analysis, which revealed its characterization of high loading rate, mesoporous structure, and large specific surface area. It exhibited significant advantages in Pd separation and recovery, such as significant selectivity (SFPd/M > 124 in pH = 1.95 nitric acid solution), remarkable adsorption capacity (92.6 mg.g(-1) Pd), and excellent reusability (n > 5). Moreover, the column separation technique was employed to better evaluate the feasibility of separation of Pd from actual electroplating wastewater by SiAcyl resin that a recovery yield about 100% of Pd and complete separation of Pd from other metal ions were obtained. Compared with several traditional commercial resins, SiAcyl resin exhibited great advantages and potential in industrial applications. Furtherly, XPS and FT-IR analysis demonstrated the ion-exchange between H+ (from -COOH) and Pd(II) is the mechanism during the whole adsorption process.

Automated summary

The novel mesoporous ion-exchange resin SiAcyl demonstrated high loading rate, mesoporous structure, and large specific surface area for effective separation and recovery of palladium (Pd) from electroplating wastewater. It showed remarkable selectivity, adsorption capacity, and reusability, making it a promising option for industrial applications. XPS and FT-IR analysis revealed the ion-exchange mechanism between H+ and Pd(II) during the adsorption process.