High-performance of muscovite clay for toxic dyes’ removal: Adsorption mechanism, response surface approach, regeneration, and phytotoxicity assessment

Abstract

Industrial textile discharges are widespread causes of water pollution that threaten the ecosystem and health. This research paper focuses on the removal of the two toxic dyes methylene blue (MB) and crystal violet (CV) by muscovite clay (Mus-C) while studying the selectivity, sensitivity, and different possible interactions to understand the adsorption mechanism. The Mus-C material was characterized by several instrumental techniques including XRD, FTIR, SEM-EDX, TGA/DTA, pHpzc, and Boehm surface functions. The high efficiency of muscovite clay is reflected by the high adsorption rates of MB and CV dyes which are about 98.25% and 99.7% respectively, under 25 °C, pH = 6, dye concentration 70 mg L−1, and adsorbent dose 1.5 g L−1. The kinetics and isotherm of adsorption of MB and CV on Mus-C follow pseudo-second-order and Langmuir models with monolayer adsorption capacities of 66.95 mg g−1 and 69.54 mg g−1 respectively. The thermodynamic characteristics demonstrate that the process is spontaneous, physical, and endothermic. The MB and CV adsorption rate values predicted by the response surface approach were consistent with the experimental values which are in the order of 99.98% and 99.89% respectively. The performance of the Mus-C material according to the tomato bean germination test and its high regeneration capacity in several cycles shows that the adsorption process is a promising and effective technology in the treatment of complex wastewater.

Keywords

• Germination test
• Muscovite clay
• Regeneration
• Response surface approach
• Surface functions