Application of magnetic carbon nanocomposites to remove melanoidin from aqueous media: kinetic and isotherm studies

This study examined the removal of melanoidin as a by-product of bioethanol production from aqueous solutions through an adsorption process using a magnetic carbon nanocomposite (MCNC). The magnetic adsorbent was synthesized by the chemical precipitation method and characterized by TEM, BET, and FTIR analysis. The effect of operational factors such as pH, adsorbent dosage, and temperature on the removal efficiency was modeled and optimized by the statistical response surface method. The data were well fitted by a second order polynomial model with R-2 of 0.977. Based on the model, the process optimum conditions were introduced as adsorbent dosage of 413.6 ppm, pH = 3.03, and temperature of 39.9 degrees C that for these conditions the software predicted 90% removal efficiency for 40 ppm of melanoidin. Also, the data obtained from adsorption of melanoidin on the MCNC were fitted by a Langmuir isotherm model and a pseudo-second-order kinetic model. Finally, removal of melanoidin from a real alcohol industries wastewater was assessed such that 80.76% efficiency was obtained in the optimum condition after 30 min of the process.