Adsorption behavior of crystal violet on Fe3O4@MoS2 nanocomposite in aqueous media

A magnetic Fe 3 O 4 @MoS 2 nanocomposite was engineered and evaluated as an efficient adsorbent for the removal of crystal violet from aqueous systems. Under optimized conditions (adsorbent dosage of 150 mg/L, initial dye concentration of 30 ppm, and solution pH of 6.02), the composite achieved 99.2 % removal efficiency, corresponding to an adsorption capacity of 193.12 mg/g. Kinetic analysis followed a pseudo-second-order model, indicating a surface-controlled adsorption mechanism. Additional analysis using intraparticle diffusion and Elovich models indicated a multistep adsorption process involving both surface adsorption and diffusion, rather than a single rate-limiting step. Equilibrium data were well described by the Langmuir isotherm with a maximum monolayer capacity of approximately 425 mg/g. Thermodynamic parameters confirmed that the adsorption process is spontaneous (ΔG < 0) and endothermic (ΔH ≈ 18.6 kJ/mol). Selectivity tests revealed a pronounced preference toward cationic dyes, highlighting the role of electrostatic interactions and surface affinity. The material also exhibited stable performance in complex water matrices and maintained efficiency after multiple reuse cycles, indicating strong potential for practical water treatment applications.