Proses simultan sol gel dan imprinting ionik dalam pembuatan hibrida organo-silika untuk adsorben selektif logam transisi

BUHANI, Promotor Prof. Dr. Narsito

2010 | Disertasi | S3 Ilmu Kimia

Material hibrida organo-silika imprinted ionik Cd(ll) dan Cu(II) telah berbasil disintesis dengan menggunakan senyawa 3-aminopropiltrimetoksisilan (3-A.PTMS) dan 3-merkaptopropiltrimetoksisilan (3-MPTMS) dengan prekursor tetraetil ortosilikat (TEOS) melalui proses simultan sol gel dan imprinting ionik. Beberapa variabel, yaitu media proses sol-gel, konsentrasi dan pengelusi ion logam dievaluasi. Karakterisasi material imprinted ionik dilakukan melalui identifikasi gugus fungsional, analisis morfologi permukaan, komposisi unsur, luas permukaan spesifik, dan analisis kadar logam. Sifat adsorpsi yang dipelajari atas material HAS imprinted ionik Cd(II) (i-CdHAS) dan Cu(IJ) (i-Cu-HAS) serta HMS imprinted iooik Cd(IJ) (i-Cd-HMS) meliputi penentuan keasamao optimum medium, laju dan mekanisme adsorps~ kapasitas dan energi adsorpsi, selektivitas, stabilitas kimia, penggunaan ulang, karakteristik adsorpsidesorpsi multi logam, dan prekonsentrasi tingkat kelumit ion logam. Sintesis hibrida organo-silika imprinted ionik menggunakan media campuran air-etanol dengan perbandingan volume I : 1 dan eluen 0, I M Na2EDTA - 0,5 M HCJ masing-masing menghasilkan pengikatan dan pelepasan ion templat yang optimal. Kontribusi interaksi ion logam (templat) dalam HAS dan HMS imprinted ionik didominasi oleh interaksi elektrostatik dan kovalen, masing-masing sebesar 43,06 :t 0,42 dan 50,91 ± 0,25 % pada Cd-HAS serta 40,96 ± 0,21 dan 54,87 ± 0,20 % pada CuHAS, 35,24 ± 0,33 dan 61 ,57 ± 0,09% pada Cd-HMS. Adsorpsi ion Cd(II) pada i-Cd-HAS optimum pada pH 5, ion Cu(II) pada i-CuHAS dan ion Cd(ll) pada i-Cd-HMS optimum pada pH 6. Kinetika adsorpsi ion Cd(fl) pada i-Cd-HAS dan ion Cu(II) pada i-Cu-HAS mengikuti kinetika orde satu menuju kesetimbangan serta ion Cd(II) pada i-Cd-HMS mengikuti kinetika pseudo orde dua. Isoterm adsorpsi ion Cd(ll) pada i-Cd-HAS, ion Cu(II) pada i-Cu-HAS, dan ion Cd(ll) pada i-Cd-HMS mengikuti isoterm adsorpsi Langmuir dengan harga kapasitas adsorpsi masing-masing sebesar 43,40 - 62,1 0, 50,84 - 71 ,40, dan 65,74 - 83,89 mg g·1 lebih besar dari kapasitas adsorpsi HAS dan HMS tanpa imprinted ionik. Material i-Cd-HAS, i-Cu-HAS, dan i-Cd-HMS stabil pada media asam karena adanya protonasi dan kurang stabil pada media basa. Data selektivitas dan adsorpsi multi logam menunjukkan bahwa HAS dan HMS imprinted ionik lebih selektif dari HAS dan HMS dan dapat digunakan secara berulang sebanyak 4-5 kali pengulangan adsorpsi. Mekanisme adsorpsi ion d(Il) pada i-Cd-HAS, ion Cu(IJ) pada i-Cu-HAS, dan ion Cd(IJ) pada i-Cd-HMS didominasi oleh pembentukan ikatan bidrogen. Material imprinted ionik memiliki kemampuan recovery dengan konsentrasi awal ion logam 10,0 J.tg L"1 pada i-Cd-HAS, iCu- HAS, dan i-Cd-HMS masing-masing sebesar 94,50 ± I ,32; 99,86 ± 0,14 ; 99,90 ± 0, 10%. Kata kunci : imprinted ionik, hibrida organo-silika, sol-geL adsorben selektif

Synthesis of an organo-silica hybrid imprinted with Cd(Il) and Cu(ll) ions using 3-aminopropyltrimethoxysilane (3-APTMS) and 3-mercaptopropyltrimethoxysilane (3- MPTMS) compounds with precursor of tetraethyl orthosilicate (TEOS) as the silica source and metal ion solutions as the imprinting ions was carried out through simultaneous sol gel and ionic imprinting process. Several variables including sol-gel media, metal ion concentrations, and metal ion elution were evaluated. The characterizations of the ionic imprinted materials were performed through identification of functional groups, surface morphologies and elemental compositions, specific surface area, as well as metal concentrations. Adsorption properties studied on ionic imprinted amino-silica hybrid of Cd(ll) (i-Cd-HAS) and Cu(TI) (i-Cu-HAS) as well as ionic imprinted mercapto-silica hybrid of Cd(IT) (i-Cd-HMS) material include medium optimum acidity, rate and adsorption mechanism, capacity and adsorption energy, selectivity, chemical stability, reusability, adsorption mechanism, characteristics of multi-metal adsorption-desorption, and preconcentration of trace level of metal ions. The synthesis of the organo-silica hybrid material used water-ethanol media in a volume ratio of 1 : 1 resulting a bonding and a releasing an optimum template ion by using an eluent of 0.1 M Na2EDTA-0.5 M HCI. The interaction contribution of the metal ions (templates) in the ionic imprinted HAS and HMS material was dominated by a covalent and an electrostatic interaction, with the value of 43.06 ± 0.42 and 50.91 ± 0.25% on Cd-HAS, 40.96 ± 0.21 and 54.87 ± 0.20% on Cu-HAS, and 35.24 ± 0.33 and 61.57 ± 0.09% on Cd-HMS, respectively. The adsorption of Cd(IT) ion on i-Cd-HAS was optimum at pH 5, those of Cu(Il) ion on i-Cu-HAS and Cd(ll) ion on i-Cd-HMS were optimum at pH 6. The adsorption kinetics of Cd(IT) ion on i-Cd-HAS and Cu(ll) ion on i-Cu-HAS followed the first order kinetic up to equilibrium, as well as Cd(ll) ion on i-Cd-HMS followed the pseudo second order kinetic model. The adsorption isotherm of Cd(ll) ion on i-Cd-HAS, Cu(II) ion on i-Cu-HAS, and Cd(II) ion on i-Cd-HMS followed Langmuir adsorption isotherm model with the adsorption capacities of 43.40- 62.10, 50.84- 71.40, and 65.74- 83.89 mg g·1 , respectively, and these were higher than the adsorption capacities of HAS and HMS without ionic imprinting. Materials of i-Cd-HAS, i-Cu-HAS, and i-Cd-HMS were stable in an acid condition because of protonation and lack of stability in a base condition. The data of adsorption selectivity showed that the ionic imprinted material was more selective than HAS and HMS materials and it can be reused for 4-5 times. The adsorption mechanism of Cd(U) ion on i-Cd-HAS, Cu(Il) ion on i-Cu-HAS, and Cd(II) ion on i-Cd-HMS were dominated by the formation of hydrogen bonding. The ionic imprinted material has the metal ion adsorption recovery of 94.50 ± 1.32; 99.86 ± 0.14; 99.90 ± 0.10% for i-Cd-HAS, i-Cu-HAS and i-Cd-HMS respectively, with the metal ion initial concentrations of I 0.0 J.Lg L"1 Key word: ionic imprinted, organo-silica hybrid, sol-gel, selective adsorbent

Kata Kunci : Imprinted ionik,Hibrida organo-silika,Sol-gel,Adsorben selektif