Preparation and Adsorption Properties of Corn Straw Amphoteric Adsorbent for Cationic and Anionic Dyes

A highly efficient and environmentally friendly corn straw amphoteric adsorbent (CSAA) was produced using pretreatment, etherification, and graft copolymerization of corn straw (CS) for the purpose of removing methylene blue (MB) and acid red 1 (AR1). The CSAA was subjected to characterize utilizing SEM, FTIR, XRD, Zeta surface potential, and TG. The impacts of pH value, adsorbent dosage, dye concentration, and salt concentration on the adsorption of MB and AR1 by CSAA were examined. The concurrent removal of cationic and anionic dyes under different pH levels has been successfully shown, exhibiting potential utility in dye wastewater. The pseudo-second-order kinetic equation indicated a superior match with the empirical data, suggesting that the principal adsorption mechanism may be attributable to ionic attraction. The equilibrium adsorption isotherm study of the CSAA demonstrated a stronger conformance with the Langmuir isotherm model and the maximum adsorption capacity reached 356.2 and 408.2 mg·g⁻¹ for MB and AR1, respectively. Furthermore, the thermodynamic parameters revealed that adsorption reaction using CSAA was spontaneous and exothermic.