Reed straw-based activated carbon produced via microwave method-assisted-ZnCl2 for the removal of crystal violet dye: multivariate modeling and optimization

Abstract

In this study, reed straw (RS) was utilized as a promising precursor for producing a mesoporous active carbon (RSAC) with a large surface area of 1141.9 m²/g by using microwave-assisted ZnCl₂ activation method. The RSAC was applied as an efficient adsorbent for the removal of crystal violet (CV) dye from aqueous solutions. Thus, the working range of the adsorption key parameters such as A: RSAC dosage (0.02 to 0.1 g); B: pH (4 to 10); and C: the contact time (2 to 6 min) was statistically optimized using Box–Behnken design (BBD) to achieve the highest possible removal of CV. The adsorption kinetics were found to align with a pseudo-second-order kinetic model while the Temkin model elucidated the equilibrium adsorption data. The adsorption capacity of the RSAC adsorbent for the CV dye was remarkably determined to be 200.7 mg/g. The multifaceted mechanism governing the adsorption of the CV onto the RSAC surface was identified to encompass an array of interactions, including electrostatic forces, π-π stacking, and hydrogen bonding. Thus, this research work introduces RS as a renewable and cost-effective precursor for producing high surface area activated carbon with potential application for removal of toxic cationic dye-contaminated water.