Andesite as an Affordable Natural Desiccant for Dye-Polluted Aqueous Solutions
摘要
The objective of this study is to utilize the powdered Andesie for effective sorption of methylene blue (MB) from simulated wastewater in a batch process. Characterization of Andesite was done using the SBET, SEM imaging, X-ray spectroscopy, and infrared (IR) spectra. Andesite’s specific surface area was found to be 35.12 (m2/g) using Brunauer– Emmett–Teller analysis. Experimental variables including contact time (5–60 min), andesite dosage (0.5–1.3g), temperature (25–55℃) and pH (2 – 11) were investigated. The optimum conditions were 30 min, 1.1 g, 25°C, and pH 8. Using Freundlich isotherm model, which appropriately represents the process (R2 0.981), the maximum capacity for adsorption of MB was determined to be 2.427 (mg/g). Error analysis for isotherm models using the root mean square errors (RMS), average relative error (ARE), Chi-square error (χ2), sum of the squares of the errors (ERRSQ), hybrid fractional error function (HYBRID), sum of the absolute errors (EABS), and Marquardt's percent standard deviation (MPSD). By analyzing the kinetics of MB dye adsorption, it was discovered that the pseudo-2nd -order model, with an R2 of 0.999, best described the adsorptive behavior of the MB. The values of the free energy (ΔG), enthalpy (ΔH), and entropy (ΔS) were -5.19 (kJ/mol), -42.2 (kJ/mol) and -0.13 (kJ/mol K), respectively. The optimal isotherm model served as the basis for the designing of a one-stage batch adsorber for the sorption of MB by andesite.