RESUMO
Water reclamation from lakes needs to be accomplished efficiently and affordably to ensure the availability of clean, disinfected water for society. Previous treatment techniques, such as coagulation, adsorption, photolysis, ultraviolet light, and ozonation, are not economically feasible on a large scale. This study investigated the effectiveness of standalone HC and hybrid HC + H2O2 treatment techniques for treating lake water. The effect of pH (3 to 9), inlet pressure (4 to 6 bar), and H2O2 loading (1 to 5 g/L) were examined. At pH = 3, inlet pressure of 5 bar and H2O2 loadings of 3 g/L, maximum COD and BOD removal were achieved·H2O2 was observed to significantly improve the performance of the HC when used as a chemical oxidant. In an optimal operating condition, a COD removal of 54.5 % and a BOD removal of 51.5 % using HC alone for 1 h is observed. HC combined with H2O2 removed 64 % of both COD and BOD. The hybrid HC + H2O2 treatment technique resulted in a nearly 100% removal of pathogens. The results of this study indicate that the HC-based technique is an effective method for removing contaminants and disinfection of the lake water.
RESUMO
Our current study reports the anti-bacterial activity of the gold nanoparticles (AuNps) synthesized by the green synthesis method using Vitex negundo plant leaves. The aqueous extract of Vitex negundo plant leaves are acting as the capping and stabilizing agent in the synthesis of AuNps. It is already evident from earlier studies that Vitex negundo is an abundant source of polyphenols, flavonoids, terpenoids, and many other biologically active compounds. The present study reveals the potential of biologically active compounds from the plant in the reduction reaction of chloroauric acid (HAuCl4) into gold nanoparticles. The green synthesis method is adapted instead of the chemical method, which is toxic and more expensive. The gold nanoparticles subjected to characterization with the help of UV-visible spectroscopy, FTIR to determine functional groups, light scattering to estimate size and uniformity, scanning emission microscopy with EDX for accurate size and shape of AuNps, and X-ray diffraction to reveal the crystalline structure. The characteristics of AuNps formed are UV reading at 520 nm, FTIR showing the presence of phenols and alkenes, DLS, SEM, and XRD confirming the spherical shape with the size around 70-90 nm. The anti-bacterial activity of the gold nanoparticles is evaluated against four different species of bacteria, each two gram-positive and gram-negative. The gold nanoparticles formed by Vitex negundo show good anti-bacterial activity against Salmonella typhi and M. luteus bacteria with a zone of inhibition of 6 mm and 2 mm respectively. Furthermore, the cytotoxic activities of the gold nanoparticles are yet to be known to their full extent.
