Application of chitosan ionically crosslinked with sodium edetate for reactive dyes removal from aqueous solutions

In this study, we investigated the effect of chitosan crosslinking with sodium edetate (SE) on its sorption capacity of Reactive Black 5 and Reactive Yellow 84 dyes. The first stage of the study allowed establishing conditions of chitosan crosslinking. The process of ionic crosslinking was effective only at pH 4 and at the optimal dose of sodium edetate ranging from 0.046 to 0.462 g/g CHs. Process temperature in the range of 20-60oC had no significant effect on the stability of crosslinked chitosan. Contrary to the non-crosslinked chitosan (CHs), chitosan crosslinked with sodium edetate (CHs-SE) was capable of dyes sorption at pH 3. Sorption of reactive onto both CHs and CHs-SE was the most effective at pH 4. Chitosan crosslinking with SE had a positive effect on the effectiveness of RB5 and RY84 sorption. This effect was especially tangible within the first ten or so hours of sorption. After 24 h of the process, the sorption capacity of CHs-SE against RB5 and RY84 reached 1296.69 mg/g and 1883.62 mg/g, respectively. In the case of CHs, sorption capacity achieved after the same time was lower and accounted for 1025.55 mg RB5/g and 1539.67 mg RY84/g.