Effect of polyelectrolytes on the synthesis of cerium oxide for photo-catalytic application

Abstract

Photo-catalysis is a method to treat wastewater drained from apparel industries. Cerium oxide (CeO₂) or Ceria is a photo-catalyst which could be used to treat dyes in Wastewaters. Ag nanoparticles were synthesized by chemical reduction using Poly(styrene sulfonate-co-maleic acid) (COPSS) and Sodium borohydride (NaBH₄) as a capping agent and a reducing agent, respectively. Furthermore, CeO₂ nanoparticles were synthesized at the surface of Ag nanoparticles by precipitation technique using Cerium (III) nitrate hexahydrate (Ce(NO₃)₃.6H₂O), and Sodium carbonate (Na₂ NO₃) as precursors and undergoes calcination at 550℃ in order to increase the photo-catalytic activity. In this study, many factors were varied i.e. effect of CeO₂ on Ag nanoparticle for photo-catalytic activity, effect of dosage of Silver nitrate (AgNO₃) and COPSS on photo-catalytic activity, and effect of concentrations and types of polyelectrolyte on synthesis of CeO₂. This work consists of two parts which are the synthesis of CeO₂ using polyelectrolytes and the synthesis of CeO₂ at the surface of Ag nanoparticles. Firstly, polyelectrolytes can control the size of CeO₂ and showed better photo-catalytic activity than pure CeO₂ due to the smaller particles size. The best to least polyelectrolytes used in this work is Poly(acrylic acid) (PAA), COPSS, Poly(PDADMAC). Secondly, CeO₂ with Ag nanoparticles were successfully synthesized and the particles are smaller and finer than pure CeO₂ Additionally, it also improves the photo-catalytic activity of CeO₂ under UV irradiation because Ag nanoparticles can prevent the recombination reaction and enhanced photon harvest.