Abstract
Background: To bring new materials with high performance, a large number of composites, among others, such as starch-laminated double hydroxides (starch/ZnCr-LDH), have been produced, which have shown significant adsorption predisposition to remove heavy metals and dyes. These LDHs display great adsorption potential due to their high anion exchange capacity, large surface area, and good thermal stability. Objective: This study aimed to develop starch-ZnCr-hydroxide composite (S/ZnCr-LDH) as a new material and investigate its performance in removing various anionic dyes compared to ZnCr- LDH. Methods: The starch-ZnCr-laminated double hydroxides (S/ZnCr-LDH) and ZnCr-LDH composites were prepared by the co-precipitation method and their structures were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), differential thermogravimetric/ thermal analysis (TG/DTA) Scanning electron microscopy (SEM), and Energy Dispersive Xrays Spectroscopy (EDX). Results: The effects of different operating parameters, such as pH, initial CR concentration, contact time, and adsorbent dose, on CR removal were studied. The results showed that the S/ZnCr- LDH composite is more efficient for CR removal, reaching 99% at pH 3, while ZnCr-LDH presented a removal efficiency of 90%. Isothermal data were processed according to the Langmuir, Freundlich, and Temkin models. According to the results, Langmuir's isothermal model best matched the experimental data, with a maximum adsorption capacity of 252. 92 and 236. 98 mg/g for S/ZnCr-LDH and ZnCr-LDH, respectively. The adsorption kinetics corresponded to the PSO model. CR dye molecules were adsorbed to different sites on the S/ZnCr-LDH composite based on various interactions, such as electrostatic interactions, hydrogen bonds, and Van der Waals forces. Conclusions: S/ZnCr-LDH composite displays the highest capacity to remove CR dye molecules compared to ZnCr-LDH.
Published Version
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