Thiazine dye sorption onto (NH4)2S2O8 treated bio-adsorbent: Implications for batch and fixed-bed column applications

Abstract

In an era of increasing environmental concern, this study pioneers the synthesis of Ap@BC, a carbonized material produced from biochar derived from waste biomass and activated with (NH₄)₂S₂O₈. Sodium alginate was utilized to prepare adsorbent beads from this material, which were investigated for their remarkable potential as an efficient adsorbent for MB dye, employing both batch and fixed-bed column systems. Various characterization techniques, including TGA, FTIR, Raman spectroscopy, and SEM, provided valuable insights into the surface properties of Ap@BC, significantly enhancing its dye-binding capabilities. Kinetic analyses revealed that MB removal adheres to the Pseudo-second-order kinetic model, indicative of a chemisorption mechanism, while adsorption equilibrium data exhibited a robust correlation with the Freundlich isotherm model, highlighting the heterogeneous adsorption characteristics of Ap@BC. The monolayer adsorption capacity of 52.6 mg/g, as determined by the Langmuir isotherm model. The fixed-bed column experiment showed that the efficiency of the column enhanced significantly with increased bed depth and reduced flow rates, emphasizing the operational advantages of Ap@BC in real-world applications. The robust fit of the kinetic data with Thomas and Yoon Nelson models highlights its feasibility for large-scale deployment. Furthermore, potential mechanisms of MB adsorption encompassing n-π interaction, hydrogen bonding, and electrostatic interactions illustrate the multifaceted approach of Ap@BC in addressing dye pollution. Altogether, these findings position Ap@BC as a promising and effective adsorbent in wastewater purification and environmental remediation.