Trimethylphenylammonium-modified montmorillonite: efficient hybrid adsorbent for removal of U(VI) from carbonate- and sulfate-containing solutions

Montmorillonite (MMT) clay was modified using the hydrothermal method through the intercalation and adsorption of the trimethylphenylammonium bromide (TMPA) and applied for the removal of U(VI) from the carbonate- and sulfate-containing solutions using batch experiments. The hydrothermal technique provides a simple, fast, and efficient route for the successful preparation of TMPA-MMT. The prepared adsorbent was characterized by FTIR, XRD, SEM, and TGA techniques. The increasing interlayer space of MMT from 1.20 to 2.02 nm occurs as a result of TMPA intercalation. The modification of MMT by a TMPA surfactant enhanced adsorption capacity of U(VI) species from sulfate- and carbonate-containing solutions over a wide range of pH. The highest capacity for adsorption of U(VI)-carbonate and U(VI)-sulfate complexes was around 38 and 26 mg/g, respectively. The outer-sphere surface complexation is probably dominant mechanism in adsorption of anionic uranyl carbonate and sulfate species. These findings proposed that TMPA-MMT can be applied as an efficient and potential adsorbent for the removal of uranyl anionic species from carbonate- and sulfate-containing aqueous solutions.