Silver-Derived Antimicrobial Coatings for the Prevention of Microbial Biofilms in Metal Pipes

Biodeterioration is one of the most important processes in metal pipeline corrosion, and it can be due to physical, chemical, and biological factors. Coatings rich in silver have been used to inhibit this undesirable phenomenon. In this study, the antimicrobial properties of several silver-containing products used as a coating in pipelines were determined on a pilot scale in order to evaluate the ability of silver to inhibit biofilm formation. The results showed that the coating with silver zeolite at a concentration of 2000 mg L–1 inhibited the formation of a microbial biofilm and prevented the biodeterioration process. Therefore, from our study, it can be concluded that silver zeolite shows greater protection capacity than other silver preparations and presents advantages in relation to other silver coatings that are currently available

In vitro evaluation of antimicrobial efficacy of silver zeolite against common oral pathogens

Objectives. Antimicrobial efficacy and toxicity analysis of 5 different concentrations of silver zeolite (SZ) compound against 5 common oral pathogens Streptococcus mutans, Streptococcus pyogenes, Lactobacillus sp., Staphylococcus aureus, Candida albicans. Material and methods. The antimicrobial efficacy of 5 different concentrations of SZ was tested against 5 common oral pathogens using the agar well diffusion method and the MIC and MBC values were determined using the micro broth dilution method. The toxicity of all 5 different concentrations was evaluated using brine shrimp assay and lethal concentration (Lc50) value was determined. Results. At 10 μg/mL the antimicrobial activity of SZ was almost negligible. The antimicrobial activity was observed in an increasing trend against all the test microorganisms as the concentration increased. At 75 & 100 μg/mL the zone of inhibitions was more than the control. Furthermore, MIC and MBC values of SZ with concentrations 25, 50, 75, and 100 μg/mL were determined and recorded. SZ was equally effective against all the test organisms. The LC25 (lethal concentration25) value was 1.6 μg/mL, whereas the LC50 value was 1.77 μg/mL and the LC75 value was 1.90 μg/mL, calculated from the probit computational method. Conclusion. SZ has the potential to change the ongoing system and bring about a revolution as an antimicrobial drug. However, the dose must be regulated as it can be toxic in higher concentrations. SZ compounds with the correct study of physicochemical properties and toxicity analysis can increase their pharmacological use and market value.

Development of New Organic Iodine Filter for FCVS

All of the boiling water reactors in Japan were required to install filtered containment venting system (FCVS) for restart after the accident of Fukushima Daiichi Nuclear Power Plant. FCVS is composed of alkaline water and a metal fiber filter (MFF). Alkaline water has the function of reducing aerosol and inorganic iodine (I2). MFF is constituted for the purpose of removing the aerosol which was not able to be removed with alkaline water. With the above system, the released aerosol can be removed with DF1000 and inorganic iodine DF100. On the other hand, organic iodine that cannot be removed by alkaline water and MFF is removed by silver zeolite added downstream of the FCVS because of its high scattering property. Silver zeolite has particle of silver in the pores of the zeolite. Organic iodine is removed by chemical bonding with the silver. In the current system, the silver zeolite is DF50. Hitachi has developed the organic iodine removal system focusing on removing liquid chemicals for the purpose of improving the performance andmaintain ability, and reducing the price. In this presentation, we report the ionic liquid (IL) that has high heat resistance, high radiation resistance and high gas adsorption among liquid chemicals. In the small-scale tests, we found that IL has a higher performance than DF250, and improved maintainability by liquid property that is able to discharge with scrubber water at the same time, and have got the prospect of reducing manufacturing costs.

Research about the Hydrogen Removal Verification Method through Porous Medium of Silver Zeolite in Nuclear Power Station

After severe accident in the nuclear power station, it is necessary to remove the hydrogen timely for the purpose of preventing the containment integrity from breach. This report has investigated and studied the role of silver zeolite in the reaction of hydrogen and oxygen. According to the catalyst role, the principle test device for hydrogen removal with silver zeolite is provided. The force of natural circulation for principle test device is created by the Chimney Effect, which is the result of different density between the internal and external of the device. Also, this report suggests the flowing capability calculation method of up-thrust about the mixture gas passing through the catalyst layer of silver zeolite. The evaluation method of hydrogen removal efficiency with silver zeolite is described. Finally, this report gives the method of CFX numeric analog and the specific simulating steps for the layer of silver zeolite using for catalytic role.

Fabrication of Poly(Butylene Succinate) Composite Films with Silver Doped ZSM-5: Effect of Silver ZSM-5 on Antibacterial Activity and Biodegradable Behavior

This work was focused on the effects of filler concentration on the antibacterial activity and biodegradable behavior of poly (butylene succinate) (PBS) composite films containing silver exchanged zeolite ZSM-5 (SZSM-5). The composite films were prepared by chill roll cast film extrusion, by varying the silver zeolite content from 0.5 to 4 %wt. The silver content in zeolite was examined by energy dispersive X-ray spectroscopy (EDX). The morphology and crystal structure of silver zeolite were analyzed by scanning electron microscopy (SEM) and X-ray diffraction (XRD) technique, respectively. The incorporation of silver did not influence the zeolite morphology and its crystal structure. The antibacterial action of composite films was investigated against gram-negative Escherichia coli and gram-positive Staphylococcus aureus. The results revealed that the PBS composite films containing SZSM-5 showed 99.9% of bacterial reduction. The optimal SZSM-5 content in PBS composite films was 0.5%wt because it was the lowest concentration that showed high efficiency of antibacterial behavior. In case of biodegradable ability, PBS composite films incorporated with 0.5%wt of SZSM-5 exhibited the degradation after three-month of soil burial test, although they exhibited slower rate than neat PBS films. The SEM micrographs of the films after soil burial test displayed the cavity on film surface, indicating the biodegradable properties of the films. PBS composite films incorporated with 0.5%wt of SZSM-5 showed the potential to be used as the food packaging.