A rancieite (K2Mn4O9), nanomaterial was synthesized and studied for the removal of both trivalent and hexavalent chromium from solution under light conditions. The effects of pH on chromium (III) and chromium (VI) were studied to determine the optimal binding pH, which were both found to be at 2. Isotherm studies were performed at temperatures of 20 C, 40 C, and 60 C for chromium (III) and chromium (VI) with binding capacities of 4.629, 1.827, and 0.79 mg/g for Cr(III) and 3.95, 2.26, and 1.08 mg/g for Cr(VI) at the respective temperatures. The thermodynamic parameters showed that the binding processes for the reactions were spontaneous and exothermic in which the enthalpy was -26.12 kJ/mol for chromium (VI) and -34.45 kJ/mol for chromium (III). The free energy of adsorption for the chromium (III) were determined to be -3.57 kJ/mol, -1.56 kJ/mol and 0.64 kJ/mol at the afore mentioned temperatures, and chromium (VI) -3.35 kJ/mol, -2.08 kJ/mol, and -0.22 kJ/mol at the respective temperature. The free energy data indicate that the reaction was spontaneous or at equilibrium at all temperatures. Furthermore, the enthalpy values were determined to be -77.42 kJ/mol for chromium (VI) and -105.28 kJ/mol for chromium (III) indicating that the reaction occurred through chemisorption.

Removal of chromium(III) and chromium(VI) from aqueous solution using K2Mn4O9 under light conditions

255th National Meeting (2018)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.