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

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 approximate to 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 degrees C. The sorption of Cr(VI) followed pseudo-second-order kinetic with rate constant k(2) = 0.013 g mg(-1)min(-1) (R-2 = 0.9982). Furthermore, thermodynamic parameters (Delta H, Delta S and Delta G) of Cr(VI) retention by the sorbent were calculated and assigned. The positive values of Delta H (45.61 J mol(-1)) proved the endothermic nature of Cr(VI) retention on TPPs and Delta S (162.45 Jmol(-1)K(-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 Delta G (-48.6 kJ mol(-1) at 298 K) indicates the spontaneous and chemical sorption nature of Cr(VI) uptake onto TPPs.