Evaluasi penggunaan silika gel untuk imobilisasi Sacharomyces cereviceae dan aplikasinya sebagai adsorben Na(I) dan Cd(II)
ALAM, Rifkah Tajul, Prof.Dr. Narsito
2007 | Tesis | S2 Ilmu KimiaTelah dilakukan sintesis adsoben Sacharomyces cereviceae imobil dan adsorben silika gel sebagai pembanding melalui proses sol-gel menggunakan larutan natrium silikat dengan dua cara yang berbeda. Adsorben yang dihasilkan kemudian diaplikasikan untuk adsorpsi ion logam Na(I) dan Cd(II) dalam medium air. Imobilisasi Sacharomyces cereviceae dilakukan melalui dua cara yang berbeda yaitu pengasaman campuran biomassa-Na2SiO3 (SCI) dan penambahan campuran biomassa-H2SO4 ke dalam larutan alkalis Na2SiO3 (SCI*). Karakterisasi adsoben dilakukan dengan difraksi sinar-X, analisis luas permukaan (SAA) dan spektrofotometer inframerah. Selanjutnya dipelajari sifat-sifat adsorpsi yang mencakup beberapa parameter yaitu pH sistem, laju adsorpsi, kapasitas adsorpsi, selektivitas adsorpsi dan mekanisme adsorpsi. Mekanisme adsorpsi dipelajari melalui desorpsi fraksinasi sekuensial. Berdasarkan karakterisasi adsorben, didapatkan bahwa struktur adsorben bersifat amorf dengan luas permukaan spesifik, distribusi ukuran pori dan volume pori total paling tinggi dimiliki oleh SCI. Melalui proses imobilisasi dapat diketahui bahwa ada interaksi antara gugus C=O dengan Si-OH dari silika gel. Hasil penelitian menunjukkan bahwa pH 6 merupakan kondisi optimum adsorpsi Na(I) dan Cd(II) oleh adsorben SCI dan SCI*. Energi adsorpsi Na(I) dan Cd(II) berturut-turut sebesar 18,76 kJ/mol dan 17,79 kJ/mol dengan kapasitas adsorpsinya sebesar 5,81.10-5 mol/g dan 3,52.10-5 mol/g. Adsorpsi Na(I) berlangsung lebih cepat dibandingkan dengan Cd(II) dengan konstanta laju adsorpsi Na(I) untuk SCI dan SCI* mempunyai harga yang sama yaitu 1.10-4 menit-1 sedangkan konstanta laju adsorpsi Cd(II) untuk SCI dan SCI* juga mempunyai harga yang sama yaitu 4.10-5 menit-1. Adapun mekanisme adsorpsi Na(I) terjadi melalui pertukaran ion dan Cd(II) terjadi melalui pembentukan ikatan hidrogen. Imobilisasi terhadap Sacharomyces cereviceae mengakibatkan adanya peningkatan efektivitas gugus C=O dalam proses adsorpsi
Synthesis of immobile Sacharomyces cereviceae adsorbent and silica gel adsorbent as comparative materials via sol-gel process has been carried out using natrium silicate with two different ways. The resulted adsorbent were then applied to adsorb Na(I) and Cd(II) ions in water. Immobilization of Sacharomyces cereviceae was done through two different ways: acidifying a mixture of biomass-Na2SiO3 (SCI) and addition of a biomass-H2SO4 mixture into alkaline solution of Na2SiO3 (SCI*). Characterization was performed by using X-ray diffraction, surface area analysis (SAA) and infrared spectroscopy. Then, some adsorption characteristics were including pH, adsorption rate, adsorption capacity, adsorbent selectivity and adsorption mechanism were investigated. The adsorption mechanism was studied by sequential fractionation desorption. Based on the adsorbent characteristic, structure of adsorbent was amorphous, with highest specific surface area, pore distribution and total pore volume was found in SCI. Through immobilization process, it was detected that there is interaction between C=O group and Si-OH in silica gel. Results of the research indicated that pH 6 was an optimum condition for adsorption of Na(I) and Cd(II) for both adsorbent SCI and SCI*. Adsorption energy of Na(I) and Cd(II) were 18.76 kJ/mole and 17.79 kJ/mole, respectively with respective adsorption capacity of 5.81x10-5 mole/g and 3.52x10-5 mole/g. Adsorption of Na(I) on SCI and SCI* proceed faster than that of Cd(II). Adsorption rate constants of Na(I) on SCI has a same value as that on SCI* (1.10-4 min-1). Rate constants of adsorption of Cd(II) for SCI was also similar to that for SCI* (4.10-5 min-1). Adsorption mechanism of Na(I) occurred through ion exchange while that of Cd(II) was through hydrogen bonding. Immobilization of Sacharomyces cereviceae resulted in improvement of the effectiveness of C=O group on adsorption process.
Kata Kunci : Adsorpsi,Na(I) dan Cd(II), Sacharomyces cereviceae, silica, immobilization, adsorption, Na(I), Cd(II)
