Akademik Veri Yönetim Sistemi
CATALYSIS, CHEMICAL ENGINEERING AND GREEN CHEMISTRY, Tokyo, Japonya, 22 - 23 Mayıs 2023, ss.117-118
It was aimed to couple boron carbide (B4C) and silver ferrite (AgFe2O4) nanoparticles in the composite
heterojunction structure for the CR (VI) photoreduction application. For this purpose, a polymer
precursor, polyvinyl borate (PVB) was synthesized from polyvinyl alcohol and boric acid using the
crosslinking reaction. A heat treatment was applied to the as-prepared polymer precursor to convert
me to B4C nanoparticles using the carbothermal reduction process. Then, B4C/AgFe2O4 composites were
prepared though the synthesis of magnetic AgFe2O4 nanoparticles in the presence of the as-prepared
B4C nanoparticles using an auto-combustion process. B4C and B4C/AgFe2O4 composite nanoparticles
were synthesized successfully, which was proved by Fourier-transform infrared spectroscopy and X-ray
powder diffraction analyses. According to field emission scanning electron microscopy and N2 adsorptiondesorption
studies, all the samples had a mesoporous surface area and the specific surface area of the
prepared samples was close to each other. According to UV-Vis absorption spectroscopy, the composite
samples exhibited high light absorption both in the UV light and in the visible light regions. When
compared with B4C, there was an increase in light absorption within the UV-Vis light region. Combining
B4C with magnetic AgFe2O4 in the composite heterojunction structure provided improvement in the Cr(VI)
photoreduction efficiency. The Cr(VI) photoreduction efficiency increased from 65.1% to 98.0% after
120 min of visible light irradiation. According to photoluminescence spectroscopy, combining B4C with
magnetic AgFe2O4 in the composite structure suppressed the recombination of the photoexcited charge
carriers on both semiconductors, which might be the reason for the enhancement in the Cr (VI) removal
efficiency. Different experiment conditions, like the initial solution pH, the initial solution concentration
and the initial catalyst concentration, were investigated for their effects on the Cr (VI) ratio. Under acidic
conditions, the Cr(VI) removal rate in the presence of B4C/AgFe2O4 increased to almost 99%. The Cr(VI)
photoreduction efficiency decreased to 89.9% when real wastewater spiked with Cr(VI) ions was used
instead of the simulated Cr(VI) solution. Based on the reusability experiments and the magnetic property
analysis, the prepared composites were reusable for the consecutive Cr(VI) photoreduction processes and
could be easily separated from the Cr(VI) solution through the magnetic separation technique.