Development of a new vacuum impregnation method at room atmosphere to produce silver-copper oxide nanoparticles on activated carbon for antibacterial applications.

A new impregnation method was tested in this study. Without a stabilizing agent, silver and copper metallic compounds were directly impregnated on activated carbon using vacuum impregnation followed by drying at 100°C and vacuum impregnation followed by thermal decomposition at 350°C in an ambient atmosphere. The effect of thermal decomposition on the structural, morphological, and textural characteristics of the modified nanomaterials was analysed by Brunauer-Emmett-Teller, X-ray diffraction, scanning electron microscopy, energy dispersive X-Ray, and transmission electron microscopy. The characteristics of the produced materials were not altered. Silver and CuO nanoparticles were identified in the samples with average diameters ranging from 33.3-36.8 nm and 29.0-33.3 nm, respectively. The materials were tested for their antibacterial capacity and for their potential to leach Ag and Cu into water, thus analysing the effect of the thermal decomposition process on the impregnation process. The vacuum impregnation process followed by thermal decomposition produced the best results, with the resultant material reducing bacterial abundance by 5.31-6.61 log and leaching only low concentrations of metals into the water (Ag - 0.010-0.025 mg L-1 and Cu - 0.270-0.361 mg L-1). Samples produced without the thermal decomposition step reached bacterial reductions of 1.86-1.97 log and yielded higher concentrations of metals in the water (Ag - 0.051-0.086 mg L-1 and Cu - 0.819-0.894 mg L-1).

Water treatment with exceptional virus inactivation using activated carbon modified with silver (Ag) and copper oxide (CuO) nanoparticles.

Continuous flow experiments (450 mL min-1) were performed in household filter in order to investigate the removal and/or inactivation of T4 bacteriophage, using granular activated carbon (GAC) modified with silver and/or copper oxide nanoparticles at different concentrations. GAC and modified GAC were characterized by X-ray diffractometry, specific surface area, pore size and volume, pore average diameter, scanning electron microscopy, transmission electron microscopy, zeta potential and atomic absorption spectroscopy. The antiviral activity of the produced porous media was evaluated by passing suspensions of T4 bacteriophage (∼105 UFP/mL) through filters. The filtered water was analyzed for the presence of the bacteriophage and the release of silver and copper oxide. The porous media containing silver and copper oxide nanoparticles showed high inactivation capacity, even reaching reductions higher than 3 log. GAC6 (GAC/Ag0.5%Cu1.0%) was effective in the bacteriophage inactivation, reaching 5.53 log reduction. The levels of silver and copper released in filtered water were below the recommended limits (100 ppb for silver and 1000 ppb for copper) in drinking water. From this study, it is possible to conclude that activated carbon modified with silver and copper oxide nanoparticles can be used as a filter for virus removal in the treatment of drinking water.