Behaviour of modified hexadecyltrimethylammonium bromide bentonite toward uranium species

• Published in: Journal of environmental chemical engineering Vol. 4; no. 3; pp. 3459 - 3467
• Main Authors: Houhoune, F., Nibou, D., Chegrouche, S., Menacer, S.
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.09.2016
• Subjects: Adsorption; Bentonite; Reaction mechanism; Surfactant HDTMA; Uranium (VI); Bentonite; Reaction mechanism; Surfactant HDTMA; Adsorption; Uranium (VI)
• ISSN: 2213-3437; 2213-3437
• DOI: 10.1016/j.jece.2016.07.018

•Algerian bentonite was modified by large organic alkylammonium cations (HDTMA).•Modified bentonite was found to be an effective sorbent in removing uranium.•Bt interlamellar distance d001 increases from 12.63 to 19.03Å by increasing surfactant loadings.•HDTMA-Bt enhances the affinity towards anionic and cationic species of uranium.•Bt with 120% CEC exhibits the best cationic adsorption capacity for anionic species. Algerian bentonite from Maghnia, has been modified with cationic alkylammonium surfactant (HDTMA-Br) from 30 to 150% of the CEC. A positively charged bilayer of the surfactant cations of HDTMA is created within the structure of the clay. The organic modification changes the bentonite material behavior towards cationic and anionic pollutant species. The unmodified and modified bentonites were characterized with several techniques: X-ray diffraction XRD, infrared spectroscopy measurements FTIR and thermal analysis TG/DTG. The intercalation of the alkylammonium cations in the interlayer space of the bentonite was confirmed by the increasing of the basal spacing from 1.26 to 1.91nm. Batch adsorption experiments were performed to evaluate the uranium removal efficiency from aqueous solutions on unmodified and modified bentonites in the range pH solution from 3 to 10 for uranium concentration of 10mg/L. The presence of HDTMA in the interlayer space of the bentonite greatly increased the retention capacity from 8.15 for the base material at pH 3 where UO22+ is exclusively present to 17.39mg/L at pH 10 for bentonite exchanged with 120% of the CEC. The modification of the bentonite at 120% by HDTMA enhanced affinity towards anionic species of uranium (UO2(CO3)34− and UO2(CO3)22−) present at pH 10. Equilibrium sorption experiments of unmodified bentonite and modified bentonite loaded with HDTMA less or equal 1 CEC best fitted to Langmuir isotherm and the kinetic data were found to follow the pseudo second order model.