Metal Ion Adsorption Ability of Activated Carbons Surface-Modified by a Molten KNO₃

Abstract

Activated carbon surfaces were modified using molten KNO₃ to introduce functional groups and form microtextures. Their surface treatment temperatures were 250—300 °C; the melting point of KNO₃ is 337 °C. Microtextures formed on the surfaces of the activated carbons during the molten KNO₃ treatment. Furthermore, various functional groups such as -COOH, -COO, and -CO, were observed clearly in XPS spectra of the surface-modified activated carbons. Their metal-ion adsorption ability increased in the order of activated carbon modified at 300 °C > activated carbon modified at 250 °C > original activated carbon.