Preparation of a new hybrid MgAlLDH@Magnetite activated charcoal by hydrothermal method for stability and adsorption mechanism of congo red

The removal of hazardous dyes from water by magnetic adsorbents has received significant interest due to their low cost and ease of separation from the solution phase. This study explores the efficacy of a novel hybrid adsorbent, magnetite and activated charcoal-modified MgAl layered double hydroxide (MgAlLDH@MAC), for removing congo red (CR) from aqueous solutions. MgAlLDH@MAC was successfully prepared via a co-precipitation to hydrothermal method and characterized using FE-SEM, FE-STEM, VSM, BET, XRD, FTIR, and XPS analysis. Through a series of batch adsorption experiments, the performance of the hybrid adsorbent for CR removal was evaluated, with CR concentrations measured via HPLC analysis. The incorporation of magnetite and activated charcoal was successful, resulting in excellent adsorption performance for CR and easy separation from the solution due to its magnetic properties. In an experimental setting with a pH of 5, a dose of 0.02 g of the adsorbent resulted in 100% removal of CR within 60 min. This removal followed a pseudo-second-order kinetic model. The adsorbent achieved a maximum adsorption capacity of 625 mg/g, which is in line with the Langmuir isotherm model. Based on thermodynamic analysis, it was determined that the adsorption process exhibited spontaneity and favorability. Moreover, the adsorbent demonstrated excellent stability and reusability, retaining 91.78% efficiency after five adsorption-desorption. The adsorption mechanism involves electrostatic interaction, π − π interaction, hole filling, ion exchange, and hydrogen bonding. This study offers a fresh viewpoint on creating high-performance LDH adsorbents that remove dyes quickly and effectively using carbon and magnetite materials. • Preparation of MgAlLDH@MAC by co-precipitation followed by the hydrothermal method. • MgAlLDH@MAC has excellent adsorption performance and easy separation. • The Langmuir maximum adsorption capacity for congo red was 625 mg/g. • Excellent stability and reusability, retaining 91.78% after the fifth cycles.