Silver nanoparticle functionalization of coal fly ash-derived geopolymer

• Main Authors: Nidoy, Andre Leopold S., Quintero, Al Patrick A.
• Format: text
• Language: English
• Published: Animo Repository 2018
• Subjects: Silver nitrate; Environmental degradation; Biology
• Online Access: https://animorepository.dlsu.edu.ph/etd_bachelors/8874
• Institution: De La Salle University

A growing environmental concern is eminent on the disposal of the anthropogenic coal fly ash and economical and sustainable solutions are deemed necessary. This study sought to embed silver nanoparticles (AgNPs) into geopolymer derived from coal fly ash through in situ reduction of AgNO3, producing antibacterial geopolymer spheres. Scanning electron microscopy (SEM) showed that AgNPs were successfully grown inside the geopolymer network and that morphologies of the Ag nanostructures were dependent on reducing agent used. Ascorbic acid produced spherical nanoparticles while sodium borohydride (NaBH4) yielded uneven cubic nanostructures, nanowires, and nanoparticles. The leaching of the AgNPs from the geopolymer and into the surrounding was probed through UV-VIS spectrophotometry, and results showed that the functionalized geopolymer spheres gradually released AgNPs. Preliminary antibacterial tests revealed that AgNP geopolymer spheres synthesized through reduction by NaBH4 were able to inhibit the growth of Escherichia coli (ATCC 25922) and produce a zone of inhibition (ZOI), which significantly differed from the blank, control geopolymer (p < 0.01). This study presents a possible method of producing antibacterial geopolymer spheres, but further improvements to the synthesis of AgNPs and evaluation of the functionalized geopolymer antibacterial activity would be able to optimize more efficient AgNP geopolymers.