ADSORPSI NITRAT DALAM AIR TAWAR DAN AIR LAUT SINTETIK MENGGUNAKAN ZEOLIT ALAM TERLAPIS OKSIDA BESI

Kuntari, Dr. Nurul Hidayat Aprilita, M.Si.

2013 | Tesis | S2 Ilmu Kimia

Telah dilakukan penelitian tentang adsorpsi NO3- menggunakan zeolit alam terlapis oksida besi. Penelitian ini bertujuan untuk mempelajari kemampuan zeolit alam terlapis oksida besi dalam mengadsorpsi NO3-. Beberapa parameter yang dipelajari meliputi massa adsorben, pH awal, medium adsorpsi, kinetika adsorpsi dan isoterm adsorpsi. Karakterisasi zeolit alam terlapis oksida besi dianalisis menggunakan metode X-ray Diffraction (XRD), spektrofotometri Infra Red (IR) dan Gas Sorption Analyzer (GSA). Konsentrasi NO3- ditentukan secara kuantitatif dengan metode natrium salisilat. Hasil penelitian menunjukkan bahwa oksida besi yang melapisi zeolit alam menyebabkan luas permukaan spesifik adsorben meningkat. Luas permukaan spesifik adsorben meningkat dari 26,53 m2/g menjadi 38,87 m2/g. pH optimum adsorpsi NO3- menggunakan zeolit alam terlapis oksida besi sebesar 6,65. Adsorpsi NO3- dalam air tawar mengikuti model kinetika pseudo order satu dengan nilai k1 sebesar 4,90x10-3 /menit, sedangkan adsorpsi NO3- dalam air laut sintetik mengikuti model kinetika pseudo order dua dengan nilai k2 sebesar 1,80x10-1 g/mg menit. Kapasitas dan energi adsorpsi rata-rata diperkirakan menggunakan model isoterm adsorpsi Dubinin-Radushkevich. Kapasitas adsorpsi zeolit alam terlapis oksida besi dalam air tawar dan air laut sintetik secara berurutan sebesar 1,05x10-1 mmol/g dan 9,70x10-2 mmol/g. Energi adsorpsi rata-rata dalam air tawar dan air laut sintetik secara berurutan sebesar 1,89 kJ/mol dan 1,76 kJ/mol, mengindikasikan bahwa proses adsorpsi nitrat menggunakan zeolit alam terlapis oksida besi didominasi oleh fisisorpsi.

A research on adsorption of NO3- using iron oxide coated natural zeolite has been conducted. This research aimed to examine the ability of iron oxide coated natural zeolite in NO3- adsorpstion. Some adsorption parameters i.e. adsorbent mass, initial pH, adsorption medium, adsorption kinetic and adsorption isotherm were examined in the adsorption processes. The characterization of iron oxide coated natural zeolite was analyzed using X-Ray Diffraction (XRD) method, Infra Red (IR) spectrophotometry and Gas Sorption Analyzer (GSA). The concentration of NO3- was measured quantitatively by sodium salicilate method. The results showed that iron oxide coated on natural zeolite contribute to an increase in the spesific surface area. The specific surface area of adsorbent increased from 26.53 m2/g to 38.87 m2/g. The optimum pH of NO3- adsorption using iron oxide coated natural zeolite was 6.65. Nitrate adsorption in freshwater was best described by pseudo first order kinetic model with k1 value of 4.90x10-3 /min, whereas NO3- adsorption in saltwater was pseudo second order kinetic model with k2 value of 1.8x10-2 g/mg min. The adsorption capacity and average adsorption energy were estimated from Dubinin-Radushkevich isotherm model. The adsorption capacity of iron oxide coated natural zeolite in freshwater and saltwater were 1.05x10-1 mmol/g and 9.70x10-2 mmol/g, respectively. The average adsorption energy in freshwater and saltwater were 1.89 kJ/mol and 1.76 kJ/mol, respectively. The results indicated that NO3- adsorption using natural zeolite coated iron oxide was dominated by physisorption.

Kata Kunci : zeolit, oksida besi, nitrat, air laut, dan adsorpsi