Evaluating the Role of Carboxylic Acid Cross‐linkers in PVA Matrices for Adsorptive Removal of Crystal Violet Dye

Abstract In this work, polyvinyl alcohol (PVA) films cross‐linked with four different carboxylic acids with di‐, tri‐, and tetracarboxyl groups were fabricated, and their utility for the removal of a cationic dye, crystal violet (CV), was investigated. The results show that the adsorption capacity of the films increases with an increase in the number of carboxylic groups of cross‐linkers and surface roughness. A high dye removal efficiency (>90%) and adsorption capacity (38.53 mg/L) were observed for 30 wt% of tetracarboxylic acid cross‐linked film for the dye concentration of 20 ppm with a contact time of 105 min at 30 °C. The equilibrium adsorption data of tetracarboxylic cross‐linked PVA film were analyzed using Langmuir and Freundlich models. The regression results showed that the equilibrium adsorption data were more accurately described by the Langmuir model ( R 2 = 0.98135) rather than the Freundlich adsorption isotherm ( R 2 = 0.86681), suggesting homogeneous adsorption. The kinetic results show that the pseudo‐second‐order model ( R 2 = 0.998) best describes CV adsorption on tetracarboxylic acid‐cross‐linked PVA films, indicating that chemisorption is likely involved. The present study suggests that the tetracarboxylic acid cross‐linked PVA films are potential candidates for the efficient removal of CV from aqueous streams.