Composite of Magnetically Modified Coal Fly Ash for Crystal Violet Removal with Performance and Mechanistic Evaluation

Magnetized coal fly ash (MCFA) was utilized as a low-cost and eco-friendly adsorbent for the removal of crystal violet (CV) dye from aqueous solution. This study aims to investigate the adsorption behavior of CV onto MCFA through kinetic and isotherm evaluations. The magnetic modification was performed using Fe 3 O 4 to enhance the separation efficiency and adsorption performance of raw fly ash. Batch adsorption experiments were conducted to examine the effects of pH, adsorbent dosage, contact time, and initial dye concentration. The kinetic analysis revealed that the adsorption process followed the pseudo-second-order model, suggesting chemisorption as the dominant mechanism. Isotherm modeling showed that the Langmuir model provided the best fit, indicating monolayer adsorption on a homogeneous surface, with a maximum adsorption capacity (q m ) reflecting the strong affinity of CV toward MCFA. The incorporation of magnetic properties significantly improved the adsorbent’s recovery and reusability. Overall, MCFA demonstrated excellent potential as a cost-effective magnetic adsorbent for the remediation of dye-contaminated wastewater.