Humic acid sorption properties of calcium-rich derivatives of Neapolitan Yellow Tuff

Abstract

With the objective of developing new agents for the removal of humic substances from water, the sorption properties of Ca-enriched Neapolitan Yellow Tuff (NYT), obtained by cation exchange at room temperature or by treatment with CaCl2 at high temperature, were tested. Sorption of humic acids onto NYT samples was evaluated at neutral pH and room temperature by batch sorption tests and dynamic experiments on small columns. The salt-thermal treatment gives rise to samples with higher calcium content and superior sorption ability. For all the samples tested the sorption capacity increased with the contact time between the solid phase and the humic acids solution. The Langmuir parameters of the sorption isotherms and the breakthrough curves recorded by dynamic experiments indicate that high-temperature Ca-enriched NYT exhibits sorption properties higher than that recorded for commercial activated carbon and at least comparable to those of other materials recently investigated.