Use of polyethyleneimine-modified wheat straw for adsorption of Congo red from solution in batch mode

AbstractIt is essential and important to remove dyes from solution and adsorption is considered as a promising technology for removal of dyes from solution. In this study, wheat straw was modified with polyethyleneimine to enhance adsorption capacity for anionic dye, Congo red (CR). The presence of the amine group on modified wheat straw (MWS) was confirmed by FTIR and elemental analysis. The CR adsorption onto the surface of MWS was performed in batch mode. The effects of pH, salt concentration, initial CR concentration, contact time, and solution temperature on adsorption quantity were performed. The results showed that the maximum adsorption capacity was reached at pH 5.0 and inorganic salt had little effect on CR adsorption. Isotherm and kinetic analysis showed that Langmuir and intraparticle model described the adsorption behavior very well, suggesting a monolayer adsorption and the rate-controlling step of intraparticle diffusion, respectively. The adsorption quantity was 89.7 mg g−1 at 303 K from L...