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Chitosan is interestingly thought to be used as raw material to make membrane for it has functional group of –NH2 and –OH that is easy to modify. Chitosan membrane has weakness like low mechanical properties. To overcome those weaknesses, silica is added on chitosan membrane synthesis to improve chitosan membrane stability. In membrane synthesis process, plasticizer is used to improve mechanical properties, maintain integrality, and avoid holes and crackness. Polyethylene Glycol plasticizer addition is expected to increase physical and mechanical properties and hydrophilic properties on membrane surface significantly therefore metal ion solution can easily diffuse through chitosan-silica-PEG membrane. In this research, it is done chitosan-silica-PEG (Ch/Si/P) membrane synthesis with tetraethyl orthosilicate (TEOS) that is used as silica source then the membrane is used as adsorbent for ion Cu(II), Zn(II) and Cd(II) by batch method. Research shows that adsorption with batch method to all membranes is optimum pH for metal ions Cu(II) and Zn(II) = 6, Cd(II) = 5.5. Adsorption for ions Cu(II), Zn(II) and Cd(II) in membrane tends to follow Langmuir isotherm model. Generally, it can be said that Ch membrane ability on all adsorption metal ions increases with silica or PEG addition. Adsorption capacity value for Ch/Si/P membrane in \(\mu\)mol/g for ion Cu(II), Zn(II) and Cd(II) in order are 262, 183, and 107 \(\mu\)mol/g. Generally, in adsorption kinetic data there is a tendency of coefficient score of R2 linearity that is higher in the second order of pseudo kinetic model.

In this research, chitosan/silica/polyethylene glycol (Ch/Si/P) composites membrane was studied for selective adsorbent of Pb(II) from aqueous solution. This study started by preparation of Ch/Si/P composites membrane. The structure and surface morphology of Ch/Si/P composites membrane was characterized by X-ray diffraction (XRD), Fourier Transform Infra Red (FTIR) spectroscopy, and Scanning Electron Microscopy (SEM). Batch adsorption experiments were conducted with various contact time and Pb(II) concentrations to evaluate the adsorption kinetics and thermodynamics. Results show that adsorption fitted to Langmuir model and followed a kinetic model of pseudo-second-order. The adsorption capacity of Pb(II) onto the Ch/Si/P composites membrane is 0.16 mmol/g. The relative selective factor (αf) value of Pb(II)/Rhodamine B is 2.38. This means that Pb(II) can be determined even in the presence of Rhodamine B interference.

Adsorption of Cr(III) and Cr(VI) in aqueous solution by the zeolite A from coal fly ash modified hexadecyltrimethylammonium bromide (HDTMAB) at various pH conditions has been carried out. Zeolite A was synthesized from fly ash through modified alkaline fusion hydrothermal process in a reactor stainless steel. The surface modification was performed using cationic surfactant HDTMAB twice as much as the cationic exchange capacity of the elite A resulted. The surfactant modified zeolite A was then applied to adsorption the metal ion chromium as Cr(III) and Cr(VI) in aqueous solution. The results showed that the acidity (pH) of adsorption conditions, affect the ability of adsorption surfactant modified zeolite A (SMZA) to Cr(III) and Cr(VI) in aqueous solution. The optimum pH conditions for the adsorption of Cr(III) and Cr(VI) on SMZA exist at pH 6. Surfactant modified zeolite A capable to adsorb either cation Cr(III) or anion Cr(VI). Adsorption of SMZA on Cr(III) increased from 36.30% to 97.04% with the increase the acidity of pH of 2 to 6. Adsorption SMZA to Cr(VI) is lower than the adsorption of the Cr3+, adsorption increasing from 19.63 to 64.07% with increase pH of 2 to 6