Ajay Krishnamurthy PhD Student Department of Mechanical Engineering. Advisor: Prof. Nikhil Koratkar

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Nikhil Koratkar Collaborators: Prof. Ramana Gadhamshetty, Florida Gulf-Coast University Prof. H-M.

1 A Graphene Based Coating for Protection Against Microbially Induced Corrosion (MIC) Ajay Krishnamurthy PhD Student Department of Mechanical Engineering Rensselaer Polytechnic Institute, Troy, NY, USA Advisor: Prof. Nikhil Koratkar Collaborators: Prof. Ramana Gadhamshetty, Florida Gulf-Coast University Prof. H-M. Cheng, Shenyang National Laboratory for Materials Science, China 2013 Rensselaer Nanotechnology Center Research Symposium Wednesday, November 6, 2013

Microbially Induced Corrosion (MIC) Biofilm An aggregate of microbial cells and extracellular substances which affects the metal surface interface. polymeric Videla, H.

2 Microbially Induced Corrosion (MIC) Biofilm An aggregate of microbial cells and extracellular substances which affects the metal surface interface. polymeric Videla, H. a & Herrera, L. K. Microbiologically influenced corrosion: looking to the future. International microbiology : the official journal of the Spanish Society for Microbiology 8, (2005). 2

3 Effects of Biofilm Removal of passive metallic oxides by detachment of the biofilms Alteration of structure of inorganic passive layers and thereby increasing their dissolution. Decreasing the local ph of the metal surface by creating acidic byproducts. Prevention of MIC Physically flushing the surface Biocides Coatings Silane, polyurethane, thiol based monolayers 3

ACS nano 5, 1321 7 (2011). 20x Prasai, D., Tuberquia, J. C., Harl, R.

4 Corrosion Resistance of Graphene 7x 4x Chen, S. et al. Oxidation resistance of graphene-coated Cu and Cu/Ni alloy. ACS nano 5, (2011). 20x Prasai, D., Tuberquia, J. C., Harl, R. R., Jennings, G. K. & Bolotin, K. I. Graphene: corrosion-inhibiting coating. ACS nano 6, (2012). 4

5 Multilayer Graphene coating on Nickel No Defects 3D porous scaffold 1 layer, 2 layers and 4 layers Krishnamurthy, A. et al. Passivation of microbial corrosion using a graphene coating. Carbon 56, (2013). 5

6 MIC Reactor Ni Ni e -, E a = 0.25V Fe (CN) e - Fe(CN) 6 4- E c = 0.36 V C 6 H 12 O H 2 O 6 CO H e E a = V Krishnamurthy, A. et al. Passivation of microbial corrosion using a graphene coating. Carbon 56, (2013). 6

days). Anode media Glucose supplemented minimal media PBS Buffer, ph 7.

7 Anolyte Microbial Colonization Parent MFC inoculated with mixed culture from primary clarifier of Albany Wastewater Treatment (functional for more than 365 days). Anode media Glucose supplemented minimal media PBS Buffer, ph Minerals Soln + Vitamin Soln 100ml of anolyte transferred to MIC anode compartment. 7

8 Reactors used MFC Anode Compartment Surface Anolyte Anode Area (m 2 ) Volume (ml) Ni (plain) Pure Nickel Foam Ni (parylene) Ni (polyurethane) Nickel + Parylene (33nm) Nickel + Polyurethane (30-70um) Ni (graphene) Nickel+Graphene Cathode Graphite Brush Graphite Brush Graphite Brush Graphite Brush Cathode Compartment Surface Area Catholyte (m 2 ) Volume (ml) 1 inch dia and 2 inches length of 250 brush - panex35 carbon fiber 1 inch dia and 2 inches length of 250 brush - panex35 carbon fiber 1 inch dia and 2 inches length of 250 brush - panex35 carbon fiber 1 inch dia and 2 inches length of 250 brush - panex35 carbon fiber Krishnamurthy, A. et al. Passivation of microbial corrosion using a graphene coating. Carbon 56, (2013). 8

Spectrophotometric Analysis http://tle.tafevc.com.

9 Spectrophotometric Analysis 9

10 Nickel Concentration Analysis Krishnamurthy, A. et al. Passivation of microbial corrosion using a graphene coating. Carbon 56, (2013). 10

11 Cyclic Voltammetry Analysis Krishnamurthy, A. et al. Passivation of microbial corrosion using a graphene coating. Carbon 56, (2013). 11

12 EIS (Bode Plot) Krishnamurthy, A. et al. Passivation of microbial corrosion using a graphene coating. Carbon 56, (2013). 12

13 Equivalent Circuits Ni (plain) R(el) Cdl CPE Rint R (ct) Wo Ni (parylene) R(el) Cdl Rint Ni (polyurethane) Cm Rct Electrode Type Rct (kω.cm 2 ) Ni (plain) 0.86 Ni (parylene) Ni (polyurethane) Ni (graphene) 35.8 R(el) Cdl Cm Rint Rct Wo Ni (graphene) R(el) CPE R (ct) Wo Krishnamurthy, A. et al. Passivation of microbial corrosion using a graphene coating. Carbon 56, (2013). 13

14 Visual Evidence Ni (plain) Ni (polyurethane) Before Degradation Ni (parylene) Ni (graphene) Krishnamurthy, A. et al. Passivation of microbial corrosion using a graphene coating. Carbon 56, (2013). 14

15 Reasons for Coating Failures Low Parylene coating thickness 33nm 15

16 Spray Coated Polyurethane coating (non conformal) 16

17 Conclusions Prevents microbial access to the Ni surface. Graphene Forms a protective barrier between the Ni surface and the anolyte and minimizes (Ni 2+ ) charge transport into the solution. Protects the Ni surface from microbial byproducts (e.g. H + ) that enhance Ni dissolution. Krishnamurthy, A. et al. Passivation of microbial corrosion using a graphene coating. Carbon 56, (2013). 17

18 Acknowledgements & Funding I thank my former and my current labmates for all the support they have provided in making this research successful. Funding: Clark and Crossan endowed chair professorship at the Rensselaer Polytechnic Institute, NSFC ( ). Partial funding from NYSPPI. 18

19 Thank You 19

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