Microscopic zero valent silver for dye removal in wastewater

In the present study the removal efficiency towards dyes of microscopic metal silver, produced with a sodium borohydride reduction, was tested. In absence of stabilizers the synthesis proved to be fast, with completion in less than 5 minutes and yield of 99.7 %. The product has micrometric dimensions, while when citrate is added in the reactor particle size is reduced to 10-100 nm and stability results highly increased. The removal efficiency was tested on two dyes, Methylene Blue (MB) and Bromophenol Blue (BPB) for the micrometric particles only. Both dyes are removed in less than 1 hour, with 94 % efficiency on MB and 90 % of BPB. The promising performances shown by our material, which are very good removal efficiency and the evidence of removing the dye by degradation rather than its adsorption, suggest the possibility to overcome the health risk posed by nanometric silver particles (AgNPs), obtaining a material which presents both catalytic and antibacterial properties plus an easier removal from the treated effluent.