Abstract:
The purpose of this research was to prepare poly (methyl methacrylate-acrylic acid-divinylbenzene) (P(MMA-AA-DVB) microcapsules encapsulating both bismuth vanadate (BiVO4) and magnetite (Fe3O4) nanoparticles by microsuspension iodine transfer polymerization (ms ITP) for dye treatment in wastewater.
The experiment was divided into 3 parts. In the first part, BiVO4 and Fe3O4 nanoparticles were produced by using BiVO4 nanoparticles (m-BiVO4) modified by 3- (Trimethoxy-silyl) propyl methacrylate (MPS) that increased %loading (%LE) and %encapsulation (%EE), which were higher than those of pristine BiVO4 nanoparticles. The second part was the preparation of P (MMA-methyl acrylate(MA)-DVB) microcapsules the optimum condition of which was prepared by using m-BiVO4 nanoparticles with the ratios of monomer: m-BiVO4: Fe3O4 at 65: 30: 5, and MMA: MA: DVB at 55 : 25 : 20, giving the highest %LE and %EE. Before the dye treatment, the obtained P(MMA-MA-DVB) was hydrolyzed to be pH-responsive P(MMA-AA-DVB) microcapsules. In the final part, the optimum microcapsules were used for the
treatment of methylene blue (MB) as a dye model. It was found that P(MMA-AADVB)/ m-BiVO4/Fe3O4 microcapsules had a higher dye treatment efficiency than that of
P(MMA-MA-DVB) microcapsules in alkaline conditions. However, the dye treatment efficiency was still lower than that of pristine BiVO4 nanoparticles. To increase the treatment efficiency, the porosity of microcapsules was increased by adding various surfactants and extraction of the PMMA segment in the microcapsule shells. P(MMA-AADVB) microcapsules added with 20wt% Span80 showed the highest MB removal efficiency, which was equal to that of pristine BiVO4 nanoparticles. In the case of solvent extraction, polymer microcapsules extracted with 0.5wt% acetone for 3 hours showed the highest MB removal efficiency, which was equal to that of pristine BiVO4 nanoparticles. This was because the prepared microcapsules incorporated Fe3O4 nanoparticles; as a result, the microcapsules were reused for at least 5 treatment times. Although the MB removal efficacy was gradually reduced by the number of treatment times, the treatment efficiency was still higher than 50%.
As a consequence, P(MMA-AA-DVB) microcapsules encapsulating both BiVO4 and Fe3O4 nanoparticles by microsuspension iodine transfer polymerization (ms ITP) were successfully prepared. The microcapsules showed a high performance for the MB treatment in synthetic wastewater, which was equal to that of pristine BiVO4 nanoparticles with reusability.