Removal of anionic dyes from aqueous solution by modified alginate

In this study, alginate as a low-cost and eco-friendly adsorbent was modified to remove dyes from wastewater. Modification of alginate was done using ethylenediamine. Fourier transform infrared was used to study the characteristic of alginate and modified alginate. The presence of functional groups such as hydroxyl, carboxylate, and amine groups was detected. Modified alginate was used to remove Direct Red 23 (DR 23), Direct Red 31 (DR 31), and Direct Red 80 (DR 80) from aqueous solution. The effect of three parameters such as adsorbent dosage, pH, and inorganic salts on dye removal was investigated at room temperature (26°C). During the dye removal study, the dye adsorption isotherm and kinetic were studied. It was found that DR 23 and DR 80 followed with Tempkin isotherm and DR 31 followed with Langmuir isotherm. In addition, the adsorption kinetic of dyes was found to fit into pseudo-second-order kinetics. Based on the obtained data from the current investigation, it could be concluded that the modified alginate as a biocompatible green material and low-cost adsorbent might be an appropriate alternative to remove anionic dyes from colored wastewater.