Surfactant-modified clinoptilolite-rich tuff to remove barium (Ba2+) and fulvic acid from mono- and bi-component aqueous media

The kinetics of the removal of Ba2+ and fulvic acid by a surfactant-modified Mexican clinoptilolite-rich tuff was investigated. The effect of fulvic acid in a bi-component aqueous medium (Ba2+-fulvic acid) on the sorption of Ba2+ was also considered, and an unmodified zeolitic material was included for comparison. The Ba2+, fulvic acid and fulvic acid-Ba2+ solutions were placed in contact with a Mexican clinoptilolite-rich tuff in a batch system. Atomic absorption and UV–Vis spectroscopy were used to measure the remaining aqueous barium and fulvic acid, respectively. The Ba2+ and fulvic acid sorption kinetic experimental data were best fitted by a pseudo-second-order model. The amount of surfactant covering the surface of the zeolitic material and the fulvic acid influenced the sorption kinetics of Ba2+ from aqueous media by sodium and surfactant-modified Mexican clinoptilolite-rich tuffs. The presence of Ba2+ in the aqueous medium increased the sorption of fulvic acid by the sodium-modified zeolite from Oaxaca (NaZO), but the time to reach equilibrium was greater. The Ba2+ was removed from aqueous media by ion exchange or complexation with fulvic acid, and fulvic acid was adsorbed by the surfactant-modified zeolites through a partitioning mechanism.

Proposed mechanism to explain the interactions between Ba2+ and fulvic acid with the surfactant-modified natural zeolite from mono- and bi-component aqueous media.Figure optionsDownload as PowerPoint slideResearch highlights
► The surfactant on the clinoptilolite-rich tuff influences the maximum sorption of the barium (Ba2+) and fulvic acid (FA) from aqueous solutions.
► The pseudo-second order kinetic model describes the sorption processes for both mono- and bi-component aqueous media (Ba2+and Ba2+-FA).
► The barium pseudo-second order kinetic parameter (k) is affected by both the surfactant on the surface of the natural zeolite and the FA from aqueous solution.
► The k of the FA adsorption by SMZO is affected by the presence of Ba2+ in the solution.
► The ion exchange, complexation and partition mechanisms can explain the sorption of barium (Ba2+) and FA by SMZO.