Synthesis and characterization of versatile MgO: Synthetic wastewater treatment and anti-bacterial activity against B. subtilus and E. coli

The removal of bromophenol blue dye from textile wastewater effluents using nano-crystalline magnesium oxide (MgO) was studied. Nano MgO was prepared by a co-precipitation method. The parameters that affected the dye uptake, contact time, reagent dosage and pH were examined and optimized. The dye adsorption equilibrium data fit well to the Langmiur isotherm, but not to the Freundlich isotherm. The adsorption isotherm indicates that the adsorption capacity was 124 mg of dye per gram of MgO. The adsorption isotherms, including the Langmuir constant (Q degrees and b) and Freundlich constant (K(F) and n) for the dye, decreased with an increase in temperature. The value of enthalpy change (∆H) for bromophenol blue dye was –56.5 kJ/mol, indicating that the removal process is exothermic. The adsorption of the dye was enhanced by increasing the pH, reaching a maximum at pH 6–11. MgO was also used because of its antibacterial activity against B. subtilus and E. coli, and we found that the best inhibitory parameters for MgO nanoparticles against 10⁸ CFU/ML of B. subtilus and E. coli were 0.5 gm of MgO and 4 h to kill all cells, as shown in the TEM images. MgO was characterized by X-ray diffraction (XRD), atomic force microscopy (AFM) and diffuse reflectance spectroscopy (DR) before and after the removal of bromophenol blue.