The use of response surface methodology to determine governing factors driving a nanodiamond-based wastewater treatment method

Abstract

The purpose of this study was to determine and characterize the factors involved in the treatment of wastewater containing an azo dye, Congo red, using nanodiamond (ND). A Box Behnken study was developed by the authors that considered the dye wastewater dilution, catalyst dose, and light source. Statistical analysis, XRD, and SEM analysis confirmed that ND loses its effectiveness when the concentration is below 0.025 g/100 mL of Congo red. It was also determined that at these catalyst doses ND is primarily driven by adsorption, confirmed by observing high treatment efficiency within 30 min of each experimental run. While one cannot absolutely confirm this is the case at much higher doses of ND, it was clear that adsorption plays a major role in color removal by the carbon allotrope. An additional EDS analysis shows that ND specifically adsorbs of sodium, lead, chlorine, and sulfur from Congo red. © 2018 American Institute of Chemical Engineers Environ Prog, 38: 246–253, 2019.