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Novel Heat-Conducting “Metallic” Coatings Against Biofouling And Biocorrosion

Novel antimicrobial heat-conducting “metallic” coatings against biofouling and biocorrosion
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Seawater biofouling is a major threat in heat exchanger operations. It decreases the heat transfer efficiency and service life of heat exchangers1,2. The formation of deposits caused by biofouling on the heat exchanger metal surfaces increases surface roughness and decreases cross-sectional flow area, which leads to higher friction loss in fluid flow3,4. Mitigation methods, including surface scrubbing, fluidizing bed heat exchangers, cleaning-in-place and dosing anti-fouling chemicals, are the main ways to tackle biofouling5. Conventional approaches to treat biofouled components by periodic electrochlorination or acid flushes are costly and environmentally hazardous. Huge costs are associated with heat exchanger biofouling losses, but there is still a lack of research to develop heat-conducting antifouling coatings to heat exchangers3.

Product Number: 51322-18178-SG
Author: Di Wang, Timothy D. Hall, Tingyue Gu
Publication Date: 2022
Industries: Science of Corrosion , Corrosion Monitoring and Control , Coatings
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$20.00
$20.00

NiMo and NiMo with embedded CeO2 nanoparticles (100 nm) were tested as antimicrobial coatings (~15 µm thickness) on Ti (titanium) surfaces using an electrochemical process for heat exchanger applications onboard marine vessels. Preliminary static biofouling and biocorrosion (also known as microbiologically influenced corrosion) assessments were carried out in glass bottles using pure-strain Desulfovibrio vulgaris, a sulfate reducing bacterium (SRB), in deoxygenated ATCC 1249 medium at 37oC, and using an alga (Chlorella vulgaris) mixed with general heterotrophic bacteria (GHB) in enriched artificial seawater at 28oC. It was found that NiMo/CeO2 was much more effective than NiMo in preventing SRB biofilm formation with an efficacy of 99% reduction in D. vulgaris sessile cells after 21-day incubation. The NiMo/CeO2 coating also exhibited a 50% lower corrosion current density compared to the uncoated Ti against SRB corrosion. Both NiMo and NiMo/CeO2 coatings achieved 99% reduction in sessile algal cells. Confocal laser scanning microscopy (CLSM) biofilm images indicated a large reduction of sessile GHB cells. The CLSM images also confirmed the biocidal kill effects of the two coatings. Unlike polymer coatings, the “metallic” costings are heat conductive. Thus, the corrosion resistant antifouling coatings are suitable for heat exchanger applications. 

NiMo and NiMo with embedded CeO2 nanoparticles (100 nm) were tested as antimicrobial coatings (~15 µm thickness) on Ti (titanium) surfaces using an electrochemical process for heat exchanger applications onboard marine vessels. Preliminary static biofouling and biocorrosion (also known as microbiologically influenced corrosion) assessments were carried out in glass bottles using pure-strain Desulfovibrio vulgaris, a sulfate reducing bacterium (SRB), in deoxygenated ATCC 1249 medium at 37oC, and using an alga (Chlorella vulgaris) mixed with general heterotrophic bacteria (GHB) in enriched artificial seawater at 28oC. It was found that NiMo/CeO2 was much more effective than NiMo in preventing SRB biofilm formation with an efficacy of 99% reduction in D. vulgaris sessile cells after 21-day incubation. The NiMo/CeO2 coating also exhibited a 50% lower corrosion current density compared to the uncoated Ti against SRB corrosion. Both NiMo and NiMo/CeO2 coatings achieved 99% reduction in sessile algal cells. Confocal laser scanning microscopy (CLSM) biofilm images indicated a large reduction of sessile GHB cells. The CLSM images also confirmed the biocidal kill effects of the two coatings. Unlike polymer coatings, the “metallic” costings are heat conductive. Thus, the corrosion resistant antifouling coatings are suitable for heat exchanger applications. 

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