Comprehensive UV–Vis analysis of rhodamine B adsorption by Sulfocalix[4]arene thin film: dye removal application

Abstract The utilisation of dyes has escalated drastically in recent years, raising serious environmental and health concerns. In particular, the growing consequences of synthetic dyes in the textile industry have intensified research toward sustainable alternatives. Rhodamine B (RhB), a widely used textile dye, is known for its carcinogenic properties and its persistence and stability in water, posing significant ecological risks. This study investigates the adsorption behaviour of RhB upon 4-Sulfocalix[4]arene (SC[4]) thin films, a material notable for its exceptional water solubility and host–guest properties. The SC[4] thin films in multilayer configurations (5, 10, and 20 number of layers), a derivative from calixarene macrocycles functionalised with the presence of sulfonate groups, exhibit enhanced adsorption capability, offering the potential for the effective removal of deleterious dyes from wastewater. Ultraviolet–Visible Spectroscopy analysis was employed to investigate the adsorption dynamics, providing insights into the interaction between the RhB dye and the SC[4] thin film surface. The results demonstrate that adsorption is the primary mechanism regulating RhB adhesion onto SC[4] thin films, facilitated by physical interactions without inducing colour degradation, rather than being due to photocatalytic degradation. The study has advanced the development of innovative, sustainable materials for dye removal and represents an advancement in addressing the environmental problems associated with textile dyeing processes.