Polyethylenimine Modified Tiger Nut Residue For Removal Of Congo Red From Solution

A surface-modified tiger nut residue (TNR) was achieved by polyethylenimine (PEI) using glutaraldehyde as a cross-linker at room temperature to enhance the adsorption capacity toward anionic dyes. Surface characterizations confirmed the successful loading of PEI onto the surface of TNR. Preliminary batch experiments were performed to explore the adsorption property of PEI-modified TNR (TNR@PEI) toward Congo red (CR, anionic dye) from the solution. The adsorption was favored at solution pH 5 and at 30 degrees C. The kinetic and isotherm curves were described best by the pseudo-second-order kinetic model and Redlich-Peterson model, respectively. The maximum adsorption capacity of the adsorbent towards CR, as revealed by the Langmuir model, was 197, 274, and 240 mg/g at 20 degrees C, 30 degrees C, and 40 degrees C, respectively. The process was endothermic and spontaneous with a signal of entropy decrease, which followed physical adsorption coupled with electrostatic interaction between the surface of the adsorbent (charged -NH3+) and the negatively charged moieties of the anionic CR (-SO3-) under acidic conditions. Besides, TNR@PEI had a good desorption and regeneration performance, hence enhancing its potential to be used as an effective adsorbent to remove the anionic dye.