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 k
2
= 0.013 g mg
−1
min
−1
(R
2
= 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
−1
K
−1
) reflected good absorption and/or adsorption of the chromate [(CrO
3
Cl)]
−
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.