Investigating the potential ability of graphene/polydimethylsiloxane coated magnetic Fe3O4 nanoparticles as the adsorbent for the dairy wastewater treatment

In this paper, the graphene/polydimethylsiloxane coated magnetic Fe3O4 adsorbents were fabricated by the chemical co-precipitation method and were used in dairy wastewater treatment. Scanning X-ray diffraction test, and Brunauer-Emmett-Teller were employed to investigate the structure and morphology of the magnetic nanoparticles. The effects of initial chemical oxygen demand (COD) concentration, initial solution pH, temperature, and contact time on wastewater adsorption were systematically studied in batch adsorption experiments. The batch adsorption experiments revealed that increasing adsorbent dosage and contact time, but decreasing temperature and initial COD concentration increased percentage removal. The results indicated that maximum removal was achieved as high as 98.5% using an adsorbent dosage of 25 g/L, pH of 2, and temperature of 45 degrees C. In order to investigate the mechanism and kinetics of the adsorption, experimental data were fitted to some adsorption isotherms and kinetic models. The kinetic data showed that the adsorption processes were associated with the pseudo-second-order mechanism. Also, the equilibrium data were more compatible with the Liu isotherm. The maximum adsorption capacity was measured as 108.7 mg/g at 45 degrees C. The values of thermodynamic parameters (Delta G degrees, Delta S degrees, and Delta H degrees) showed that the adsorption of dairy wastewater molecules onto the adsorbent surfaces was spontaneous, feasible, and endothermic. It is inferred that this magnetic nano-adsorbent can be employed for effective dairy wastewater treatment.