Selective separation of Chromium (VI) from aqueous solutions by adsorption onto truffle peels as novel biomass

Abstract

ABSTRACT The current quest develops a simple and highly selective spectrophotometric method for trace determination of Cr(VI) in water using truffle peels powder (TPPs) as solid-phase extractor. Adsorption of Cr(VI) onto TPPs from aqueous media reached equilibrium at pH ≈1.7 in 20 min and was independent of the initial concentration of Cr(VI). The results showed that the maximum Cr(VI) adsorption capacity was found as 0.2776 mg g−1 from the Langmuir model at 25°C. The sorption of Cr(VI) followed pseudo-second-order kinetic with rate constant k2 = 0.013 g mg−1min−1 (R2 = 0.9982). Furthermore, thermodynamic parameters (ΔH, ΔS and ΔG) of Cr(VI) retention by the sorbent were calculated and assigned. The positive values of ΔH (45.61 J mol−1) proved the endothermic nature of Cr(VI) retention on TPPs and ΔS (162.45 Jmol−1K−1) reflected good absorption and/or adsorption of the chromate [(CrO3Cl)]− as an ion associate with the bulky cations and the surface area available on TPPs. The negative value of ΔG (−48.6 kJ mol−1 at 298 K) indicates the spontaneous and chemical sorption nature of Cr(VI) uptake onto TPPs.