Wastewater Disinfection by Synthesized Copper Oxide Nanoparticles Stabilized with Surfactant

CuO NPs were prepared by a quick precipitation method in the absence and presence of tetraoctylammonium bromide (TOAB) that was used as a stabilizer to control the nanoparticles size. X-Ray Diffraction (XRD) and Scanning electron microscope (SEM) were used to characterize CuO NPs. NPs average size was from 7-12 nm with rod-like shape that was controlled by the change of preparation temperatures and the presence of TOAB surfactant. The antibacterial activity of the prepared CuO NPs were evaluated using total coliform (TC), fecal coliform (FC) and Enterococcus faecalis (E. faecalis) bacteria counts in wastewater. Different parameters were studied to obtain the optimum wastewater disinfection conditions, these parameters are size of nanoparticles with and without TOAB surfactant, nanoparticles concentration, contact time, pH, shaking and temperature of wastewater. CuO-TOAB stabilized NPs showed higher antibacterial activity more than that without TOAB surfactant, where it was less than 100 and 1000 µg/ml for CuO NPs with and without TOAB surfactant, respectively. The effect of NPs size were studied where the sizes for CuO-TOAB stabilized NPs was found to be 11.5, 9.9 and 7.8 nm, while the sizes of CuO non-stabilized NPs was found to be 12.4, 11.4 and 9.1 nm, however, medium size for both CuO-TOAB stabilized NPs (9.9 nm) and CuO non-stabilized NPs (11.4 nm) have the highest antibacterial activity of other sizes. Contact time effect was small as there was slight difference in the antibacterial activity of both CuO NPs with and without TOAB. Noticeable high activity of CuO NPs with and without TOAB surfactant occurred when wastewater samples were treated at 25 ºC and 35 ºC, respectively. The antibacterial activity of CuO NPs with and without TOAB surfactant slightly increased by decreasing wastewater pH values. Antibacterial activity of CuO NPs without shaking showed lower activity of about 70 and 90% for CuO NPs without and with TOAB surfactant in comparison to the antibacterial activity with shaking. In all parameters were studied, the antibacterial activity of both CuO NPs with and without TOAB surfactant were higher against gram positive bacteria (E. faecalis) compared to the activity against gram negative (TC and FC). Flow up test proved the applicability of CuO-TOAB NPs as a novel wastewater disinfection technique.