STUDI KINETIKA DAN TERMODINAMIKA ADSORPSI Co(II) OLEH ASAM HUMAT

IMMANUEL SITOHANG, Sri Sudiono, S.Si., M.Si;Prof. Dr. Triyono, S.U

2017 | Skripsi | S1 KIMIA

Telah dilakukan isolasi asam humat serta aplikasinya untuk studi kinetika dan termodinamika adsorpsi Co(II). Asam humat diisolasi dari tanah gambut yang didapat dari Rawa Pening, Jawa Tengah. Proses isolasi menggunakan larutan alkali pada atmosfer N2 dan pemurnian menggunakan HCl/HF. Asam humat diinteraksikan dengan Co(II) pada variasi pH. Isoterm adsorpsi ditentukan oleh interaksi asam humat dengan larutan Co(II) pada seri konsentrasi dan temperatur. Kinetika adsorpsi ditentukan oleh kontak asam humat asam humat dan Co(II) pada variasi waktu dan temperatur. Filtrat Co(II) dianalisis menggunakan AAS. Asam humat setelah dan sebelum interaksi dikarakterisasi menggunakan spektrofotometer FTIR. Hasil penelitian menunjukkan bahwa pH 4 adsorpsi Co(II) oleh asam humat terjadi secara optimum, didapatkan adsorpsi mengikuti model isoterm Langmuir. Hasil tersebut dapat ditentukan kapasitas adsorpsi maksimum (qm) pada temperatur 30, 40, 50 dan 60 ͦC berturut-turut adalah 14,27, 16,38, 19,00, 12,76 mg/g dan didapatkan parameter termodinamika hasil perhitungan ΔG° adalah -22,85, -26,13, -28,10 dan -29,60 kJ/mol. Didapatkan ΔH° dan ΔS° adalah 44,75 kJ/mol dan 224,57 kJ/mol. Kinetika adsorpsi Co(II) pada asam humat mengikuti model kinetika Ho, didapatkan energi aktivasi reaksi adsorpsi adalah 71,13 kJ/mol. Kata kunci: asam humat, isoterm adsorpsi, kinetika adsorpsi, Co(II)

Isolation of humic acid and the application for adsorption kinetics and thermodinamics study of Co(II) have been done. Humic acid was isolated from peat soil from Rawa Pening, Jawa Tengah. The isolation was carried out by alkali solution under nitrogen atmosphere while the purification was performed using HCl/HF. Humic acid was interacted with Co(II) at various pH. Isotherm adsorption was determined by interaction of humic acid and Co(II) solution at various concentrations and temperatures. Kinetics parameter was determined by the contact between humic acid and Co(II) solution at various time and temperature. Co(II) filtrate was analyzed by using AAS. Humic acid before and after interactions with Co(II) were characterized using FTIR spectrophotometer. The results showed that the adsorption of Co(II) by humic acids was optimum at pH 4, adsorption followed Langmuir isotherm model. The maximum adsorption capacity (qm) at 30, 40, 50 and 60 ͦC were 14.27, 16.38, 19.00 and 12.76 mg/g, respectively. Standard free energy of adsorption (ΔG°) were -22.85, -26.13, -28.10 and -29.60 kJ/mol. The standard enthalpy (ΔH°) and entropy (ΔS°) of adsorption were 44.75 kJ/mol and 224.57 kJ/mol, respectively. The results showed that the adsorption followed Ho kinetics models. The activation energy of Co(II) adsorption by humic acid was 71.13 kJ/mol. Keywords: humic acid, isotherm adsorption, kinetics adsorption, Co(II)

Kata Kunci : asam humat, isoterm adsorpsi, kinetika adsorpsi, Co(II)