Statistically Optimized Synthesis of Silver Nanocubes from Peel Extracts of Citrus limetta and Potential Application in Waste Water Treatment

Abstract

This work reports statistically optimized synthesis of silver nanocubes from cost effective, readily available bioreductant, in the form of peels of Citrus limetta. Effect of six variables viz. temperature, pH, volume of reductant, reaction volume, illumination, concentration of silver nitrate was examined using Placket Burman Design. Temperature, pH and illumination were found to significantly affect the shape and size of silver nanoparticles. Best conditions for the synthesis of silver nanocubes were 0.001 M AgNO 3 with temperature 27°C and pH 6 under dark incubation. Characterization of the synthesized nanocubes was done using UV-Vis spectroscopy, Scanning Electron Microscopy (SEM). SEM analysis showed clear synthesis of nanocubes in the range of 37-59 nm to 163-205 nm. Additionally, an investigation of biologically synthesized nanocubes in wastewater treatment was done. A filter was designed. The colloidal solution of silver nanoparticles was mixed with activated charcoal in ratio of 1:1, 1:2 and 2:1 respectively, to make filter bed. A series of microbiological tests carried out on the filtrates obtained, showed that the microbes were killed to an extent of 97%, especially E. coli. Our work indicates that silver nanoparticle loaded activated charcoal filter can be used as an excellent antibacterial water filter.