Recovery of palladium from secondary waste using soluble tannins cross‐linked Lagerstroemia speciosa leaves powder

BACKGROUND Naturally available biomass can be explored as a potential sorbent for recovery of precious metals. This work evaluates the sorption potential of a biosorbent developed by host soluble tannins cross‐linked Lagerstroemia speciosa leaves powder ( TLS ) for Pd recovery from secondary waste. RESULTS Batch experiments suggest 95% Pd( II ) sorption by TLS is achieved over a pH range of 1–6 with a maximum of 99% at pH 2. The experimental data for Pd( II ) sorption onto TLS is well explained by pseudo‐second‐order kinetics and the Langmuir isotherm model with a monolayer sorption capacity of 46.3 mg g −1 . Thermodynamic variables indicate that Pd( II ) sorption onto TLS is spontaneous, endothermic, and physical in nature. TLS biosorbent was characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, and X‐ray photoelectron spectroscopy ( XPS ). XPS results reveal the presence of zero‐valent Pd and mono or divalent Pd species on the TLS surface, which conclude that Pd( II ) removal is governed by a sorption‐reduction mechanism. CONCLUSIONS The TLS is effective in Pd( II ) recovery from an acid‐leached solution of monolithic ceramic capacitors (A‐ MLCC ) and simulated spent automobile catalyst (A‐ SSAC ), which suggests that this biosorbent can be used as a promising material in biotechnological processes for recovery of precious metals from secondary waste. © 2016 Society of Chemical Industry