Removal of Carcinogenic Direct Azo Dyes from Aqueous Solution Using a Functional Biopolymer

In this study, a batch system was used to investigate the adsorption methyl violet from aqueous solution onto a β-cyclodextrin polymer synthesized with citric acid as a crosslinking agent. Several operational variables were tested. The results showed that increasing the amount of adsorbent improved the removal efficiency. Higher temperatures also enhanced dye adsorption, while ionic strength had no significant effect on the process. A slight decrease in removal efficiency was observed as pH values increased. FTIR spectra revealed the formation of a complex inclusion, which was identified as the dominant adsorption mechanism; this was further confirmed by the absence of the characteristic peaks of methyl violet in β-cyclodextrin polymer after adsorption.