Sorption of Tannin from Aqueous Solutions on Organo-Modified Smectite-illite

An organophilic clay-based adsorbent was prepared by incorporating a cationic surfactant, hexadecyltrimethylammonium (HDTMA) at different levels of CEC in Tunisian smectite-illite clay. The presence of the HDTMA surfactant enhanced the adsorption ability of the clays toward plyphenolic compounds from aqueous systems. Adsorption experiments were carried out using a batch equilibration technique to investigate the removal of tannin by the surfactant modified clay. Adsorbent characterizations were investigated using X-ray diffraction, infrared spectroscopy, surface area analysis, and potentiometric titration. The effects of pH, contact time and initial solute concentration on the adsorption of tannin onto modified clay were investigated. The adsorption process was much dependent on the pH and was found to follow pseudosecond-order kinetics. The optimum pH value was at pH ranging from 4.5 to 6. The maximum removal efficiency of tannin from aqueous solution was 91%. The adsorption isotherms were measured and correlated to Langmuir isotherms. From the results it can be concluded that the surfactant-modified clay could be a good adsorbent for treating tannin-contaminated waters.