Performance of Biopolymer in Relation to Removal of Reactive Azo-Dyes

Chitosan was used for the removal of water soluble reactive azo-dyes (Procion Orange MX-2R and Procion Red MX-5B) from synthetic textile wastewater. The removal of color was found to be 99.7% for Procion Orange MX-2R at pH 4.8 and 99.5% for Procion Red MX-5B at pH 5.5 at a chitosan dose of 1g/L with significant reduction (75–85 %) of chemical oxygen demand (COD) and total organic carbon (TOC). In contrast, a decline in the percentage removal of dyes above pH 7.0 was also observed. Presence of inorganic salts improved the dye removal efficiency. The plausible chitosan-dye interaction and adsorption mechanism has been explored. It was concluded that chitosan could be effectively used for the removal of color and organic matter at pH less than 6 from the textile wastewater containing reactive dyes.