SINTESIS DAN MODIFIKASI SILIKA GEL DARI ABU LAYANG AMPAS TEBU DENGAN CETILTRIMETILAMMONIUM BROMIDA (CTAB) DAN APLIKASINYA SEBAGAI ADSORBEN Cr(VI)

RIHASTIWI SETIYA M, Dr.rer.nat.Nurul Hidayat Aprilita, M.Si; Dr.Suyanta, M.Si

2016 | Tesis | S2 Ilmu Kimia

Telah dilakukan sintesis silika gel (SG) dan modifikasi silika gel dengan CTAB (SG-CTAB) dan aplikasinya untuk adsorpsi anion Cr(VI). Silika gel disintesis dengan cara menambahkan larutan HCl 1 M ke dalam larutan natrium silikat (Na2SiO3) dari abu layang ampas tebu sebagai prekursor. SG-CTAB disintesis menggunakan larutan cetiltrimetilammonium bromida (CTAB) dan SG hasil sintesis melalui metode impregnasi. SG dan SG-CTAB dikarakterisasi menggunakan spektofotometer FTIR, SEM dan BET. Silika gel dikarakterisasi menggunakan difraktometer sinar-X (XRD) dan X-ray Fluoresence (XRF). Kajian adsorpsi dilakukan dengan menggunakan sistem batch dengan variasi berat adsorben, pH, waktu kontak dan konsentrasi awal ion Cr(VI). Ion Cr(VI) yang teradsorpsi dianalisis secara kuantitatif dengan menggunakan spektrofotometer UV-Vis dengan pengompleks 1,5-difenil karbazida. Isoterm adsorpsi dikaji menggunakan model isoterm Langmuir dan Freundlich. Kinetika adsorpsi juga dikaji menggunakan model kinetika orde satu, orde dua, pseudo orde satu dan pseudo orde dua. Aplikasi adsorben dilakukan dalam limbah penyamakan kulit. Adsorpsi ion Cr(VI) oleh adsorben SG-CTAB optimum pada konsentrasi CTAB 20 mmol L-1, massa adsorben 0,05 g , pH 4 dan waktu 60 menit. Studi isoterm adsorpsi menunjukkan adsorpsi Cr(VI) mengikuti model isoterm Langmuir dengan kapasitas adsorpsi maksimum 14,66 mg g-1 dan energi adsorpsi 25,04 kJ mol-1. Studi kinetika adsorpsi menunjukkan bahwa adsorpsi Cr(VI) mengikuti model kinetika pseudo orde dua. Adsorpsi Cr(VI) dalam limbah penyamakan kulit menggunakan adsorben SG-CTAB menunjukkan kapasitas adsorpsi sebesar 9,86 mg g-1 .

Silica gel (SG) and modified silica gel using CTAB (SG-CTAB) had been prepared and their capability for the adsorption of Cr(VI) ion had been studied. The SG was synthesized by adding 1 M HCl into sodium silicate solution (Na2SiO3) prepared from bagasse fly ash (BFA) as a precursor. The SG-CTAB was prepared using CTAB solution and SG via impregnation method. The SG and SG-CTAB were characterized using Fourier Transform Infra Red (FTIR), SEM and BET. The SG was also characterized using X-ray diffractometer (XRD) and X-ray Fluoresence (XRF). Adsorption studies were carried out using a batch system with variation of adsorben dose, pH, time and initial Cr(VI) concentration. The Cr(VI) ion adsorbed was quantitatively analyzed by UV-Vis spectrophotometer using 1,5-diphenyl carbazide as a complex. Adsorption isotherm was investigated using Langmuir and Freundlich isotherm models. Adsorption kinetics were also studied using first order, second order, pseudo first order and pseudo second order kinetics models. The adsorben were used to adsorb Cr(VI) ion in tannery wastewater. Adsorption of Cr(VI) on the SG-CTAB were optimum at at 20 mmol L-1 CTAB, adsorben dose 0.05 g and pH 4. Adsorption of Cr(VI) on the SG-CTAB reached equilibrium after 60 minutes. Isotherm adsorption studies showed that the adsorption of Cr(VI) ion followed the Langmuir isotherm model with adsorption capacity was 14.66 mg g-1 and the adsorption energy was 25.04 kJ mol-1. Adsorption kinetics studies showed that the adsorption of Cr(VI) was followed pseudo second order kinetics model. Adsorption on tannery wastewater using the the SG-CTAB showed an adsorption capacity of 9.86 mg g-1.

Kata Kunci : adsorpsi, Cr(VI), CTAB, silika, abu layang ampas tebu