BACKGROUNDNaturally 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. RESULTSBatch 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. CONCLUSIONSThe 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. (c) 2016 Society of Chemical Industry