Abstract
In the present study, we developed a new adsorbent product with zeolite crosslinked chitosan (ZL–CH hydrogel) to remove acid red 88 (AR88) in an aqueous solution. The effects of several factors, such as the comparison of ZL–CH hydrogel and the absence of chitosan, pH, adsorbent dosage, initial AR88 concentration, contact time, and ion strength, were determined. Obtained results showed that ZL–CH hydrogel improved AR88 removal compared to the absence of chitosan, with an adsorption capacity of 332.48 mg/g in equilibrium time of 1 min, and adding ionic strength had no significant effect. However, with optimal conditions at pH 2.0, dry ZL–CH became hydrogel due to protonation of amino and hydroxyl groups through hydrogen bonds in the AR88 solution. Volume fraction and interaction force decreased with increasing porosity, leading to an increase in adsorption capacity and swelling ratio. Experimental data of the adsorption process showed the Freundlich isotherm model. The equilibrium for adsorption and swelling kinetics studies showed and fitted a pseudo-second-order model. NaOH was successful as a desorbing agent with 93.8%, and it followed the pseudo-second-order kinetics model. The recycling process indicates great potential for AR88 removal.
Highlights
Water contamination is a significant global problem caused by chemical industry effluents such as textiles, printing, food, pharmaceuticals, and paints [1]
Where qe is adsorption capacity, Co is the initial concentration of AR88 concentration in liquid, Ce is the equilibrium of acid red 88 in liquid, W is the weight of the adsorbent (g) of the ZL–CH hydrogel, and V is the volume of AR88 (L)
The decreased band peak before and after adsorption occurred at 1650.65 to 1615.01 cm−1, which corresponded to N–H to –OH groups; the resulting electrostatic repulsion increased between ZL–CH hydrogel and AR88, leading to the color change in the solution
Summary
Water contamination is a significant global problem caused by chemical industry effluents such as textiles, printing, food, pharmaceuticals, and paints [1]. Zeolites have a high surface area [19], which was explored to remove azo dyes [6]. Zeolites are quite effective in removing azo Polymers 2022, 14, 893 which was explored to remove azo dyes [6]. Zeolites are quite effective in removing azo dye from an aqueous solution [18]. Where qe is adsorption capacity (mg/g), Co is the initial concentration of AR88 concentration in liquid (mg/L), Ce is the equilibrium of acid red 88 in liquid (mg/L), W is the weight of the adsorbent (g) of the ZL–CH hydrogel, and V is the volume of AR88 (L)
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