ADSORPSI Cr(VI) PADA HIBRIDA AMONIUM KUATERNER SILIKA BERBAHAN DASAR ABU SEKAM PADI ADSORPTION OF Cr(VI) ON QUATERNARY AMMONIUM SILICA HYBRID FROM RICE HULL ASH

Rofi'ati, Syukri, Eko Sugiharto

2015 | Skripsi | FMIPA

Adsorption of Cr(VI) on quaternary ammonium silica hybrid (QASH) material in a batch system has been studied. QASH was synthesized using sodium silicate (Na2SiO3) prepared from rice hull ash as precursor and trimethyl-[(3-trimethoxysilyl)propyl]ammonium iodide via sol-gel method. Quaternary ammonium was synthesized by reacting (3-aminopropyl)trimethoxysilane with excess of methyl iodide in methanol solvent and sodium methoxide (NaOCH3) base. QASH was characterized by FTIR spectrophotometer and X-ray diffractometer (XRD), while the adsorbed Cr(VI) ion was quantitatively analyzed using UV-Vis spectrophotometer. Adsorption was carried out with variation of time, pH, and initial Cr(VI) concentration. Adsorption isotherm was investigated using Langmuir and Freundlich isotherm models. The influence of coexisting anions found in metal plating industrial waste, i.e. Cl-, SO42-, and PO43-, toward Cr(VI) adsorption was also studied. The FTIR spectrophotometry characterization showed that QASH was successfully synthesized, indicated by the presence of specific absorption of functional groups, i.e. methyl (–CH3), methylene (–CH2–), silanol (?Si–OH), and siloxane (?Si–O–Si?). Based on the XRD data, it could be concluded that the structure of QASH was amorphous. The adsorption of Cr(VI) was optimum at 30 minutes and pH 3. Isotherm adsorption studies showed that the adsorption of Cr(VI) followed the Langmuir isotherm model with the adsorption capacity was 25.995 mg.g-1 and the adsorption energy was 25.170 kJ.mol-1. The presence of anion Cl-, SO42-, and PO43- influenced the adsorption of Cr(VI), with the largest decreasing concentration was caused by PO43- anion.

Kata Kunci : adsorption; Cr(VI); quaternary ammonium; silica; rice hull ash