Adsorpsi dan desorpsi ion kromium(VI) pada bentonit yang dimodifikasi Heksadesiltrimetilamonium bromida

Abstract

Bentonite is abundant mineral in Indonesia and potentially as adsorbent. Bentonite has negatively charge, so bentonite has high capability to adsorp cations, while the capability of bentonite to adsorp anion was very low. This research was modified bentonite from Leuwiliang with hexadecyltrimethylammonium bromide (HDTMABr). The result of bentonite modification was changes bentonite surface character from hidrofilic become hidrofobic or organofilic, so that can adsorp anion, like Cr(VI). This research made organobentonite 25, 50, and 100 % CEC. Some methodes were done in this research, they were determination of CEC, acidity, and adsorption optimum condition of Cr(VI) that covered determination of adsorption pH, contact time, isotherm, and desorption of Cr(VI) from organobentonite. Capacity Exchange Cation of bentonite, organobentonite 25 %, organobentonite 50 %, and organobentonite 100 % were 54.53, 45.14, 37.37, and 20.72 me/100 g, respectively. Acidity of bentonite, organobentonite 25 %, organobentonite 50 %, and organobentonite 100 % were 4.95, 3.62, 0.90, and 0.60 mmol/g, respectively. Optimum adsorption condition of Cr(VI) onto bentonite, organobentonite 25 %, organobentonite 50 %, and organobentonite 100 % were consist of pH 2 until 4, contact time 3 until 4 hours, on concentration 200 until 500 ppm. Adsorbtion capacity of bentonite, organobentonite 25 %, organobentonite 50 %, and organobentonite 100 %, respectively were 4.44, 11.96, 22.09, and 20.53 mg/g. Ability of HCl, aquadest, and CaCl2 to desorbed Cr(VI) from organobentonite was low, this matter showed that Cr(VI) was trapped strongly on organobentonite.