Aktivasi dan Karakterisasi Lempung Alam Besito-Kudus untuk Adsorben Zat Warna Congo Red
MIFTAHURROHMAH, Prof. Dr. Triyono, SU
2012 | Tesis | S2 Ilmu KimiaTelah dilakukan penelitian tentang kemampuan lempung yang berasal dari desa Besito, Gebog, Kudus untuk mengadsorpsi congo red (CR) dari larutan. Lempung alam diaktivasi secara fisis dan kimia. Hasil aktivasi lempung dianalisis dengan XRD dan FTIR. Telah dipelajari beberapa parameter seperti waktu kontak, konsentrasi awal zat warna, ukuran lempung, suhu adsorpsi, dan parameter termodinamika seperti ΔHo, ΔSo dan ΔGo Hasil penelitian menunjukkan bahwa aktivasi kimia dengan H2SO4 1,2 M lebih baik dibanding aktivasi fisis. Analisis XRD menunjukkan bahwa lempung Besito-Kudus kemungkinan mengandung feldspar, cristobalite, dickite, muscovite, anatase, aegirine-augite, illite, quartz, dan ferrosillite. Kesetimbangan adsorpsi zat warna tercapai dengan cepat setelah 10 menit dari waktu kontak. Data kesetimbangan model isoterm adsorpsi dari lempung Besito-Kudus teraktivasi kimia memperlihatkan bahwa model isoterm Langmuir lebih baik daripada model isoterm Freundlich. Kapasitas adsorpsi maksimum lempung Besito-Kudus teraktivasi kimia diperoleh dari model isotherm Langmuir sebesar 250,00 mg/g. Studi kinetik menunjukkan bahwa adsorpsi CR dalam lempung Besito-Kudus mengikuti persamaan laju orde dua semu. Konstanta laju adsorpsi diperoleh sebesar 0,025 g.mg-1.min-1 pada 100 mg/L konsentrasi zat warna. Konsentrasi awal zat warna, ukuran lempung, dan suhu adsorpsi memberikan pengaruh yang signifikan terhadap adsorpsi CR. Hasil eksperimen diperoleh nilai ΔHo sebesar +3,127 kJ.mol-1, ΔSo sebesar +64,717 J.mol-1.K-1, dan ΔGo pada suhu 30, 35, 40 dan 50 oC berturut-turut -16,483; -16,806; -17,130; dan -17,777 kJ.mol-1. Nilai ΔHo positif dan ΔGo negatif untuk adsorpsi CR dalam lempung Besito-Kudus teraktivasi kimia mengindikasikan bahwa proses terjadi secara endotermis dan spontan.
The ability of clay from Besito, Gebog, Kudus to adsorb congo red from aqueous solution was investigated. Prior to the investigation, the Besito-Kudus natural clay was physically and chemically activated. The activated clay was then analyzed by X-ray diffractometry (XRD) and Fourier transform infrared (FTIR) spectroscopy methods. Various parameters such as contact time, initial dye concentration, grain size of clay, and temperature of adsorption were studied. The adsorption data were then fitted with the Langmuir and Freundlich isotherm equations. The thermodynamic parameters ΔHo, ΔSo and ΔGo were also determined. The result showed that the chemical activation using H2SO4 1.2 M gave a better result than physical activation. The XRD analysis showed that Besito-Kudus clay may contain feldspar, cristobalite, dickite, muscovite, anatase, aegirineaugite, illite, quartz, dan ferrosillite. The dye adsorption equilibrium was rapidly reached after 10 minutes contact time. Equilibrium adsorption isotherm data of chemical activated Besito-Kudus clay exhibited better fitting to the Langmuir isotherm model than to Freundlich isotherm model. The maximum adsorption capacity of chemical activated Besito-Kudus clay obtained from Langmuir model was 250.00 mg/g. Kinetic studies showed that adsorption of congo red on chemical activated Besito-Kudus clay followed pseudo-second-order kinetics. The adsorption rate constant was found to be 0.025 g.mg-1.min-1 at 100 mg/L dye concentration. The initial dye concentration, grain size of clay, and temperature of adsorption had significant effect to adsorption of congo red. The experiment result of ΔHo was +3.127 kJ.mol-1, ΔSo was +64.717 J.mol-1.K-1, and ΔGo at 30, 35, 40 and 50 oC were -16.483; -16.806; -17.130; and -17.777 kJ.mol-1, respectively. Positive ΔHo and negative ΔGo values indicated that the adsorption of CR on chemical activated Besito-Kudus clay was endothermic and spontaneous.
Kata Kunci : aktivasi, karakterisasi, lempung Besito-Kudus, adsorben, zat warna congo red
