Metal nanoparticles in flaxseed and orange Waste: Sustainable Applications as Antimicrobial agents in water treatment systems

The generation of agro-industrial waste has become a growing concern due to the high volume generated, which can result in increased environmental pollution. In this respect, the reuse of these materials as adsorbents would contribute to environmental sustainability. Flaxseed and orange waste are co-products that can be given added value when functionalized with metallic nanoparticles that have an antibacterial action, becoming an alternative for water contaminated by pathogenic microorganisms, an increasingly recurring problem in the world due to the quality of the water consumed and distributed to the population. Therefore, the main objective of this study was to develop adsorbents with brown flaxseed and orange peel waste impregnated with copper and silver nanoparticles using green synthesis to evaluate the antibacterial activity of these adsorbents against two bacterial strains, Escherichia coli and Pseudomonas aeruginosa, in contaminated water. For the synthesis of the nanomaterials, copper and silver nitrates were used as precursors, and Moringa oleifera leaf extract as a reducing agent. For the microbiological tests, MIC and MBC were initially evaluated. Subsequently, adsorption, bacterial growth curve, and time-kill tests were carried out for E. coli and P. aeruginosa. The antibacterial and bactericidal activities of the functionalized materials were demonstrated. The proposed adsorption mechanism reported that increasing the mass favored a higher percentage of bacterial reduction. However, the adsorbents functionalized with copper oxide nanoparticles showed better results against the bacteria under study, using the lowest mass of material (0.05 g), achieving a 99 % reduction of bacterial biomass after 24 h of treatment. In addition, the inhibition of E. coli and P. aeruginosa biomass was effectively observed after 2 h of treatment, demonstrating that these materials have a high potential for controlling these microorganisms in water.