Ethylenediamine/glutaraldehyde-modified starch: A bioplatform for removal of anionic dyes from wastewater

The worth of this work lies in giving the surface of starch a positive charge for removal of azo dyes. A novel ethylenediamine/glutaraldehyde-modified starch (SEG) bioadsorbent was developed here, characterized by Fourier infrared spectroscopy and scanning electron microscopy analyses, and then applied in removal of Direct Red 23 (DR23) and Acid Blue 92 (AB92) anionic dyes from aqueous solutions. The efficacy of the SEG as bio-based adsorbent was studied in terms of adsorption characteristics, including dye removal percent, adsorption capacity, adsorption kinetic and adsorption isotherm, taking the initial dye concentration, adsorption time and SEG dosage as changing variables. Overall, it was found that the SEG is an efficient bio-based adsorbent in removal of anionic dyes. Experimental analyses (Temperature=25 °C & pH=2) revealed that either a pseudo-second-order kinetic or Langmuir isotherm model can properly express the behavior of adsorption based on chemisorption phenomenon. For structural change characterization, FT-IR analysis was performed. The highest adsorption efficiency belonged to the solution in which 0.035 g SEG was added to 30 mg/L water.