PREPARASI DAN KARAKTERISASI KARBON AKTIF DARI KULIT KACANG METE (Anacardium occidentale) SERTA UJI AKTIVITAS ADSORPSI MENGGUNAKAN METHYLENE BLUE

ASWIN, S.Pd, Prof. Dra. Wega Trisunaryanti, M.S., Ph.D.Eng.

2011 | Tesis | S2 Ilmu Kimia

Telah dilakukan kajian tentang preparasi dan karakterisasi karbon aktif dari kulit kacang mete untuk mengadsorpsi methylene blue (MB) dalam larutan berair. Preparasi dilakukan dengan metode karbonisasi, aktivasi fisika dengan gas N2 dan aktivasi kimia dengan HNO3 5 M. Karakterisasi karbon aktif meliputi penentuan keasaman dengan metode gravimetri, titrasi asam basa dan spektrofotometer inframerah (IR). Sifat kekristalan dengan difraksi sinar-X (XRD), luas permukaan spesifik, volume total pori dan rerata jejari pori dengan Brunauer-Emmet-Teller (BET). Morfologi karbon aktif dengan scanning electron microscope (SEM). Uji aktivitas karbon aktif untuk mengadsorpsi MB dengan cara menentukan kondisi optimum adsorpsi meliputi pH, waktu kontak, konsentrasi awal, isoterm adsorpsi, kinetika adsorpsi, kapasitas adsorpsi dan energi adsorpsi ditentukan dengan spektrofotometer UV-Vis. Hasil penelitian menunjukkan bahwa pengurangan massa karbon aktif dari kulit kacang mete terbesar 29,49% diperoleh melalui aktivasi fisika pada temperatur 850 o C dan waktu 150 menit. Keasaman karbon aktif tertinggi melalui aktivasi kimia dengan HNO3 5 M dicapai pada waktu optimum 30 menit dengan metode gravimetri sebesar 4,00 mmol/g dan titrasi asam basa sebesar 16,26 mmol/g, kristalinitas meningkat sebesar 69,23%, volume pori 2,736 ï‚´ 10 -3 cm 3 /g dan rerata jejari pori 66,91 Ã…. Kapasitas adsorpsi maksimum karbon aktif terhadap MB sesuai isoterm Langmuir sebesar 4,00 mg/g dan energi adsorpsi 27,07 kJ/mol pada pH 10 dan waktu 60 menit. Kinetika adsorpsi MB oleh karbon aktif pada konsentrasi awal MB 25 dan 50 mg/L mengikuti reaksi order dua semu dengan konstanta laju adsorpsi 0,911 g/mg.min dan 0,545 g/mg.min. Isoterm adsorpsi MB oleh karbon aktif pada konsentrasi awal MB 25 dan 50 mg/L mengikuti model Langmuir dengan kapasitas adsorpsi sebesar 0,985 mg/g dan 2,439 mg/g.

Preparation and characterization of activated carbon from cashew nut shell of methylene blue (MB) adsorption in aqueous solution had been investigated. The preparation performed by the method of carbonization, physical activation by nitrogen gas and chemical activation with 5 M HNO3. Characterization of activated carbon includes determining of aciditity gravimetric method, acid-base titration and infrared spectrophotometric (IR). Crystalinity by X-ray diffraction, specific surface area, total pore volume and pore average radius using Brunauer-Emmett-Teller (BET). Morphology by scanning electron microscope (SEM). Activity of the activated carbon in adsorption of MB was perfomed by determining the optimum adsorption conditions included the optimization of pH, contact time, initial concentration, adsorption isotherm, adsorption kinetics, adsorption capacity and adsorption energy were determined using UV-Vis spectrophotometer. The results showed that the largest cashew nut shell activated carbon mass reduction of 29.49% through of physical activation at temperature of 850 o C and optimum time was 150 min. Aciditity of activated carbon highest through of chemical activation with treatment HNO3 5 M was obtained at the optimum time 30 min. The aciditity of activated carbon by gravimetric method was 4.00 mmol/g and acid-base titration was 16.26 mmol/g, crystalinity increased by 69.23%, pore volume 2.736 ï‚´ 10 -3 cm 3 /g and average pore radius 66.91 Ã…. The maximum adsorption capacity of activated carbon of MB fitted Langmuir isotherm was 4.00 mg/g and adsorption energy 27.07 kJ/mol at pH of 10 and 60 min. Kinetics adsorption of MB on activated carbon by initial concentration MB of 25 and 50 mg/L following the reaction of second pseudo order by rate constant adsorption of 0.911 g/mg.min and 0.545 g/mg.min. Adsorption isotherm of MB on activated carbon by initial concentration MB of 25 and 50 mg/L following the model of Langmuir by adsorption capacity of 0.985 mg/g and 2.439 mg/g.

Kata Kunci : kulit kacang mete, karbon aktif, methylene blue, adsorpsi, kinetika adsorpsi, isoterm adsorpsi