PREPARASI MEMBRAN KITOSAN-SILIKA-POLIETILEN GLIKOL UNTUK ADSORPSI ION Mg(II), Ca(II), Cu(II), Zn(II), DAN Cd(II) DALAM AIR; PREPARATION OF CHITOSAN-SILICA-POLYETHYLENE GLYCOL MEMBRANE FOR ADSORPTION OF Mg(II), Ca(II), Cu(II), Zn(II), AND Cd(II) IONS IN AQUEOUS SOLUTION

Mahatmanti, F. Widhi, Nuryono

2015 | Tesis | FMIPA

Chitosan membrane (Ch) has low mechanical, physical and chemical stability, limiting its application to a variety of purposes. Therefore, this study examined the effect of adding silica and polyethylene glycol (PEG) on the mechanical, physical and chemical properties of chitosan based membrane. As silica precusors tetraethyl orthosilicate silica (TEOS), sodium silicate commercially and sodium silicate isolated from rice husk ash were used. Chitosan-silica-PEG membrane (Ch/Si/P) is prepared using sol-gel process and is used for adsorption of Mg(II), Ca(II), Cu(II), Zn(II), and Cd(II) ions in a batch system and ions transport systems. Membrane's morphology, crystallinity, stability against temperature, changes in functional group and hydrophilicity were analyzed. Adsorption properties, including thermodynamics, were evaluated based on adsorption data on the variation of the initial concentration of metal ions in solution, while the kinetics were determined based on data of contact time. Ion transport properties were evaluated for a mixture of metal ion selectivity by calculating the rejection coefficient (R). Membrane with mass ratio of chitosan/silica 1:0.8 has maximum tensile strength, mass ratio of chitosan/silica/PEG 1:0.8:0.5 has maximum percent elongation and minimum Young's modulus. The adsorption process with batch systems for all membranes give optimum pH Mg(II), Cu(II) and Zn(II) = 6, Ca(II) = 9, Cd(II) = 5.5. There is a tendency for linearity coefficient R2 higher in the pseudo second order kinetic model. Adsorption of Cu(II), Zn(II), and Cd(II) ions on all membranes followed Langmuir isotherm models, while the adsorption Mg(II) and Ca(II) ions better follow Freundlich isotherm models. Adsorption capacity membrane Ch, Ch/Si and Ch/Si/P (?mol g-1) for Cu(II) was 247; 289 and 298 respectively, for Zn(II) was 156; 173 and 182 respectively, and for Cd(II) was 95; 99 and 106 respectively. Freundlich affinity (nF) membrane Ch, Ch/Si, and Ch/Si/P for Mg(II) was 1.15; 1.33 and 1.10 respectively and for Ca(II) was 1.36; 1.25 and 1.27 respectively. Study of ions transport properties of the membranes can be concluded that mixed Mg(II), Ca(II), Cu(II), Zn(II), and Cd(II) ions on H2O, HCl and Na2EDTA showed that the most of the ions (> 80%) are not able to penetrate the membrane as a result of the reaching of equilibrium and partially ion bound by active site –NH2 on the membrane.

Kata Kunci : chitosan-silica-polyethylene glycol membrane; adsorption, ions transport