Adsorptive removal of oil from water using SPIONs-chitosan nanocomposite: kinetics and process optimization

Marine oil spills and petrochemical discharges occurring either naturally or deliberately can have destructive impacts on environment and economy of a nation. Water bodies contaminated by oil pose challenge to the survival of aquatic biodiversity. Nanotechnology is offering new potential routes to remediate the oil pollution. In the present study, a superparamagnetic nanocomposite of Fe3O4/chitosan was synthesised using co-precipitation method. The prepared material was characterized to determine chemical structure, morphology, shape and size, thermal and magnetic properties. The magnetic adsorbent was employed for the adsorptive removal of petroleum based diesel oil from oil-in-water emulsions. The efficiency of the synthesized nanocomposite was examined by batch adsorption experiments to determine the effect of pH, adsorption time and adsorbent dose on the oil removal process. From the experimental data, it was found that the adsorption process followed the pseudo second order kinetics (R-2 = 0.9962) and Langmuir isotherm (R-2 = 0.9998) indicating towards a monolayer chemisorption process. Thermodynamic parameters showed that the adsorption was spontaneously endothermic (Delta H = + 38.779 kJ/mol) and the nanocomposite was found to be recyclable up to least five cycles of oil-water separation. The optimization of oil removal process was carried out using response surface methodology (RSM) as function of four factors consisting of pH, adsorbent dose, stirring speed and adsorption time. The study provides the basis for development of an eco-friendly and promising material for treatment of oil and hydrocarbon pollution from water bodies in environmental clean-up.