Effect of surfactant and sonication on Pd(II) adsorption from synthetic electroless plating solutions using commercial activated charcoal adsorbent

This work addresses the evaluation of Pd(II) adsorption characteristics on commercial activated charcoal using synthetic electroless plating solutions with and without cationic surfactant. The experimental investigations involved wider Pd (50-500mg/L) and surfactant solution concentrations (1-4CMC). Surface characterization was conducted using Brunauer-Emmett-Teller analysis, Fourier transform infrared spectroscopy, laser particle size analysis, scanning electron microscopy and energy dispersive X-ray spectroscopy techniques. It was observed that the Pd(II) adsorption characteristics from synthetic electroless plating solutions were distinct and referred to lower metal uptake and removal efficiency. The presence of CTAB surfactant significantly altered the adsorption characteristics with higher surfactant concentrations providing higher metal uptake and removal efficiency. Both agitation- and sonication-assisted adsorption were deployed to identify the optimal process parameters. The optimal batch adsorption process parameters have been evaluated to be 300min, 10, 6g/L, 500mg/L and 4CMC for contact time, pH, adsorbent dosage, Pd solution concentration and surfactant solution concentration, respectively. For these conditions, the maximum metal uptake and removal efficiency have been evaluated to be 62.46mg/g and 93.82%, respectively. Further, it was evaluated that the sorption data fit well with Freundlich isotherm model and pseudo-second-order kinetic model. Also, the evaluated thermodynamic model parameters confirm endothermic nature of adsorption.