VOLUME 13 NUMBER 1 (January to June 2020)

by Francis Eric P. Almaquer*, Fredeve John P. Pacatang, Joshua Emmanuel H. Pagulong, and Almie Jane P. Catulay

¹School of Technology, University of the Philippines Visayas,
      Miagao 5023, Philippines

This study investigated the decolorization of methylene blue (MB) dye in both distilled and river water samples using citrate-stabilized silver nanoparticles (cit-AgNP). Cit-AgNP was successfully synthesized using chemical reduction method with sodium borohydride and trisodium citrate as reducing and stabilizing agents, respectively. The resulting cit-AgNP solution was yellow in color with UV Vis absorbance peak at 393 nm, typical of AgNPs. TEM analysis confirmed the presence of spherical nanoparticles with average diameter 9.19 ± 4.91 nm. The calculated full width at half maximum (FWHM) of 59.42 ± 4.59 nm indicate good monodispersity. In the study, an initially prepared 20 ppm MB solution was added with NaBH4 and cit-AgNP that acted as reducing agent and catalyst, respectively. This resulted in the decolorization of the blue MB solution in 10 minutes. The result is consistent with UV Vis analysis showing reduction of MB peak at 663 nm. The percent decolorization at 10 minutes is 94.45%. This is significantly higher than the 57.69% decolorization of MB solution with only NaBH4 present and without cit-AgNP. To further examine its applicability, river water samples were used. Tests showed that at 10 minutes, 20 ppm MB solution using river water exhibited high percent decolorization at 94.33%. Statistical tests revealed the MB decolorization behavior in distilled water is not significantly different with its behavior in river water samples. Overall, the study showed successful synthesis and characterization of cit-AgNP and its potential as catalyst in the decolorization of MB in aqueous solutions.