Surface modification of natural zeolite with silane agent as effective materials for removal of ammonium

The modified zeolite with silane agent, aminopropyltrimethoxyxilane (APTMS), has been successfully evaluated. Ammonium ions are one of pollutants found in groundwater produced from agricultural residues. These compounds in water are very difficult to be degraded by microorganisms and have high-level toxicity at higher concentrations. Therefore, in this study, zeolite-APTMS material has been developed as an effective material for removing ammonium in water. The modified materials were characterized by x-ray diffraction (XRD), fourier transform infrared (FTIR), surface area analyzer (SAA), and transmission electron microscope (TEM). The results indicated that the prepared materials have a low crystallinity with decreasing ratio of Si/Al with the surface area of 17.34 m²/g and excellent attached APTMS on the zeolite surface. The effect of contact time, pH of NH₄⁺ solution, and zeolite-APTMS dosage were investigated with batch experiments. The adsorption equilibrium of NH₄⁺ can be achieved within 20 min with the adsorption capacity of 61.7 mg g^–1. The adsorption kinetic studies showed that the experiment followed the pseudo-second-order kinetics model and Freundlich model for adsorption isotherm. The results revealed that the presence of the amino-functional group on the zeolite surface could improve the binding analyte target not only as physical interaction but also through the hydrogen bonding as chemical interaction.