Synthesis, Adsorption Isotherm and Kinetic Study of Alkaline- Treated Zeolite/Chitosan/Fe3+ Composites for Nitrate Removal from Aqueous Solution—Anion and Dye Effects

Abstract

In the present study, alkaline-treated zeolite/chitosan/Fe3+ (ZLCH-Fe) composites were prepared and analyzed using scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR) and pH of zero point of charge (pHzpc) to remove nitrates from water. The process was carried out using an adsorption method with a varied initial pH, adsorbent dosage, initial nitrate concentration and contact time. The pHzpc demonstrated that the ZLCH-Fe surface had a positive charge between 2 and 10, making it easier to capture the negative charge of nitrate. However, the optimal pH value is 7. After 270 min, the maximum adsorption capacity and percent removal reached 498 mg/g and 99.64%, respectively. Freundlich and pseudo-second-order were fitted to the adsorption isotherm and kinetic models, respectively. An evaluation was conducted on the effects of anions—SO42− and PO43−—and dyes—methylene blue (MB) and acid red 88 (AR88)—upon nitrate removal. The results indicated that the effect of the anion could be inhibited, in contrast to dye effects. However, the optimal pH values were changed to 10 for MB and 2 for AR88, resulting in a hydrogel formation. This might be indicated by the protonation of hydroxyl and amino groups resulting from a chitosan nitrate reaction in the AR88 solution.

A Carbonized Zeolite/Chitosan Composite as an Adsorbent for Copper (II) and Chromium (VI) Removal from Water

“…Figure 4 demonstrates that Cu(II) and Cr(VI) adsorption capacities increased from 47.15 to 85.23 mg/g and 25.53 to 31.93 mg/g, respectively. This is because of the high driving force of metal ions and the increase in the number of molecules, which enhances the amount adsorbed onto C-ZLCH [ 43 , 44 , 45 , 46 , 47 ].…”

“…The equilibrium concentration of each metal ion was calculated, and the corresponding equilibrium adsorption capacities were obtained. To explore the adsorption process, experimental equilibrium data were evaluated using different isotherm models, including the Langmuir (Equation (4)) and Freundlich (Equation (6)) models [ 25 , 40 , 41 , 42 , 43 , 44 , 45 ]. …”

Investigation of Calcination Duration on the Surface Morphology and Specific Surface Area of Zeolite-Chitosan Composite with Oil Palm Ash for Potential Water Contaminant Remediation

“…The fluctuations in the surface area of the Zeolite-Chitosan-Oil Palm Ash composite are closely connected to the dynamic development of its pore network, which is a crucial structural component with a central role in shaping adsorption efficiency [7]. As the calcination duration is prolonged from 1 to 3 hours, the developing pore network within the composite experiences clear modifications, resulting in noticeable shifts in specific surface area.…”

“…Among these methods, the use of composite materials for adsorption has shown promise in terms of efficiency and versatility [5,6]. This study investigates the crucial role of calcination duration in influencing the surface characteristics and specific surface area of a composite material comprising Zeolite, Chitosan, and oil palm ash [7]. The ultimate aim is to contribute to the development of efficient and sustainable adsorbents for addressing water contamination.…”

“…Zeolite-Chitosan composites have gained attention for their exceptional adsorption capabilities and environmental friendliness. Zeolites have well-defined porous structures and active sites for contaminant capture, while Chitosan, a biodegradable biopolymer derived from chitin, complements these properties [7][8][9][10]. The addition of oil palm ash, a waste material rich in silica and minerals, further enhances the composite's adsorption potential [11].…”