ABSTRACT
In this study, the specific activities of 226Ra, 232Th and 40K in the unfired construction materials (solid card bricks, 4-hole bricks, pavement bricks) containing fly ash and bottom ash from a coal-fired thermal power plant in Vietnam were measured using the low-level gamma-ray spectrometer with HPGe detector. Also, the 222Rn concentrations in these materials were analyzed using RAD7 radon monitor and then radon mass exhalation rate and emanation fraction of these materials were calculated. The potential radiological hazards for residents living in the model room made of these materials were evaluated. The average specific activity of 226Ra, 232Th and 40K were found as 67.7, 79.3 and 703.5 Bq kg-1, respectively. The total annual effective dose (due to external gamma exposure and internal radon exposure for resident living in the CEN model room made of the unfired brick samples) was found as 0.9 mSv y-1 which is lower than the worldwide average dose of 2.4 mSv y-1. Calculations from ResRad-Build code showed that the doses due to radon exposure account for from 62.3% (at the first year) to 98.8% (at the next 30 years) of the total gamma and radon dose. Under low air exchange to the outside environment, from the 6th year onwards, the total dose may exceed the average dose value from natural radiation exposure sources.
Subject(s)
Radiation Monitoring , Radon , Coal Ash/analysis , Vietnam , Radon/analysis , Construction MaterialsABSTRACT
The sustainable production of hydrogen peroxide (H2O2) from oxygen and water has become an exciting research hotspot in the scientific community due to the importance of this fine chemical in various fields. Besides, piezo-photocatalysis is an emerging star for generating H2O2 from these green reagents. For developing catalysts for this specific application, doping heteroatoms into carbon-based materials such as graphitic carbon nitrides (g-C3N4) is a growing fascination among worldwide scientists. However, systematic study on the effects of doping precursors on the catalytic results is still rare. Herein, we fabricated sulfur (S) and selenium (Se) doped g-C3N4 with various doping precursors to evaluate the effects of these agents on the production of H2O2 under light and ultrasound irradiation. Based on the results, Se-doped g-C3N4 gave an outstanding catalytic performance compared to S-doped g-C3N4, even in a significantly low quantity of Se. In order to fully understand the chemical, physical, optical, and electronic properties of pristine g-C3N4 and its derivatives, the as-prepared materials were thoroughly analyzed with various tools. Thus, this study would give more profound insights into doping techniques for carbon-based materials and encourage further research on the design and development of piezo-photocatalysts for practical applications.
