Reza Tajik, Hasan Asilian, Ali Khavanin, Ahmad Jonidi Jafari, Babak Eshrati, Ardalan Soleimanian, Jaber Ghrehdaghi,
Volume 6, Issue 19 (1-2013)
Abstract
Background: Poly chlorinated biphenyls (PCBs) are a class of chlorinated organic chemicals that do not easily degrade in the environment. This study was conducted to determine the effect of microwave rays, hydrogen peroxide, dioxide titanium and ethanol solvent on the degradation of PCBs.
Methods: A 900w domestic MW oven with a fixed frequency of 2450 MHZ was used to provide MW irradiation. Ray powers were used in 540, 720, and 900w. A hole was made on the top portion of the oven and a Pyrex vessel reactor (250ml volume) was connected to condensing system with a Pyrex tube connector. The PCBs were analyzed by GC-ECD.
Results: The degradation of total PCBs was 54.62%, 79.71%, and 95.76% in terms of their ratio to solvent with transformer oil at 1:1, 2:1, and 3:1, respectively. The degradation of total PCBs was 84.27%, 89.18%, and 96.1% when using 540, 720, and 900W microwave radiation, respectively. The degradation of total PCBs was 70.72%, 93.02%, 94.16, 95.23% and 96.1% when not using H2O2/ Tio2 and using 20% H2O2 and 0.05, 0.1, 0.15, and 0.2g Tio2, respectively.
Conclusion: In the present study, the optimum conditions to decompose PCBs efficiently included 50 ml volume of ratio to solvent with transformer oil (3:1), sodium hydroxide solution (0.2N) 1 cc, use of 20% hydrogen peroxide of total volume of samples, dioxide titanium (0.2g), and irradiation for 9 minutes. Under these optimum conditions, efficiency of PCBs decomposition increased.
Mrs. Somayeh Soleymanzadeh Moghadam, Mrs. Maliheh Nobakht, Mrs. Zahra Mohammadi, Mr. Soheil Rahmani Fard, Mrs. Farideh Hajian Hossein Abadi, Mrs. Samaneh Mazar Atabaki, Mr. Pedram Ebrahimnejad,
Volume 17, Issue 4 (10-2023)
Abstract
Background: Nowadays, due to the increasing problems of microbial resistance, scientists are searching for the safest and most effective way to fight them. The colloidal silver (Ag) and titanium dioxide (TiO2) nanoparticles can effectively fight against many bacterial microorganisms. Therefore, the purpose of this study was to investigate the antibacterial and cytotoxic properties of Ag and TiO2 nanoparticles, against Shigella dysenteriae and Staphylococcus aureus.
Methods: In this study, Ag and TiO2 nanoparticles were synthesized, and the minimum inhibitory and bactericidal concentrations (MIC & MBC) were determined. In addition, the cytotoxicity of these agents was evaluated on Hu02 fibroblast cell line.
Results: We found that the MIC and MBC for Ag and TiO2 nanoparticles were similar (12.5 µg/ml) against S. aureus, while the MIC’s for Ag and TiO2 against S. dysenteriae were found to be 12.5 and 25 µg/ml. In addition, the MBC’s for Ag and TiO2 against S. dysenteriae were 25 and 50 µg/ml. Based on the cytotoxicity tests, the cell viability percentage after 48 hours of exposure to TiO2 was higher than that of Ag (0.025 µg/ml).
Conclusion: The Ag and TiO2 nanoparticles demonstrated good antibacterial properties while they had low toxicity against the Hu02 fibroblast cell line.
