Study and improvement of the adsorbent capacity of a natural and activated local clay for the removal of methyl blue dye:influential parameters and choice of optimal conditions

Abstract

Water pollution resulting from methylene blue (MB) dyes discharged by the textile industry poses a significant environmental threat. Adsorption is an economical and uncomplicated separation technique for removing colors from wastewater. This study details the extraction of methylene blue (MB) from water utilizing Analcime (Ana) clay treated with HNO3 (1.5M, 3M) and commercial chitosan CTS (25%, 50%) sourced from El Menia (El-Golea), Algeria. The clay was analyzed by XRD, FTIR, BET, and SEM methodologies. SEM and FTIR analyses were employed to identify the structural alterations in clay resulting from chemical and physical treatments, as well as from methylene blue adsorption. To enhance MB adsorption, activated Analcime (Ac/Ana) treated with HNO3 and modified Analcime with chitosan (CTS/Ana) were optimized utilizing the Box–Behnken design approach. The critical parameters (activated concentration (A), adsorbent dosage (B), pH (C), temperature (D), and time (E)) for Ac/Ana, and (CTS loading (A), adsorbent dose (B), pH (C), temperature (D), and time (E)) for CTS/Ana were adjusted. For the Ac/Ana, the maximum MB removal efficiency (99.02%) was achieved under optimal conditions (A: 1.5 M, B: 0.03 g, C: 7, D: 30 °C, and E: 30 min) with significant interactions (AB and BC). In contrast, the CTS/Ana exhibited a highest removal rate of 99.08% under optimal conditions (A: 25%, B: 0.1 g, C: 10, D: 45 °C, and E: 25 min) with significant interactions (AB, AC, AD, BE, CE, DE). The optimal adsorption capabilities of 416.67 mg/g for Ac/Ana and 129.87 mg/g for CTS/Ana were attained at 45 °C under these settings. The Langmuir and pseudo-second-order models demonstrated efficacy for isotherms and kinetics, respectively