Response surface methodology mediated process optimization of Celestine blue B uptake by novel custard apple seeds activated carbon/FeMoO4 nanocomposite

The present study deals with the evaluation of performance and efficacy of a novel nanocomposite based on custard apple seeds derived activated carbon (CAS-AC), prepared by microwave-assisted technique, and FeMoO4 nanoparticles (NPs) synthesized through green route for Celestine blue B (CB) removal from simulated wastewater. The physico-chemical characterization of the nanocomposite was achieved by means of FTIR, XRD, SEM-EDX, TEM and BET techniques. The operational factors such as contact time, initial CB concentration, nanocomposite dosage, and initial solution pH were optimized by Response Surface Methodology. The equilibrium data, modeled with various isotherm and kinetic models, conformed well to Freundlich model and pseudo-second order rate equation, respectively with both intraparticle and film diffusion controlling the overall adsorption process. The considerably higher Langmuir saturation capacity of the nanocomposite towards CB adsorption at 298 K (112 mg/g) than other previously reported adsorbents together with good recyclability depicts its superior adsorptive performance. The spontaneity, feasibility and endothermic nature of the CB removal process were established from the thermodynamic parameters. The hydrogen bonding and π–π interactions primarily governed the overall adsorption mechanism. The spent NC was regenerated using 0.1 mol/l HCl solution. The CAS-AC/FeMoO4 NC showed good reusability maintaining its adsorption efficiency of 86.25% up to fourth consecutive cycles. The results obtained from the present study reflected that the nanocomposite is a promising adsorbent for the liquid phase amputation of CB in effective and efficient manner.