Chemical and mineralogical comparison of two antibacterial

clays

Amanda Turner

Dr. Lynda Williams, Dr. Shelley Haydel*, Christine Remenih* & Tanya Borchardt*

School of Earth & Space Exploration

Investigating Antibacterial Clay Minerals

Isolating bacteria affected by clay

Isolating the antibacterial clay minerals

ANTIBACTERIAL EFFECTIVENESS

ANTIBACTERIAL MECHANISM

Testing for chemical interaction

ICP-MS, Electron Probe, pH, Eh:

Toxin provided? Nutrient depleted?

Testing for physical interaction

SEM, Mineralogy:

Clay-cell attraction? Physical disruption?

Bulk Mineralogy

NONClays Clays10.4% Qtz 44.9% Smectite6.2% Olig 16.5% Illite5.3% Alb 1.1% Gibbsite

6.7% Others

NONClays Clays39.3% Qtz 21.5% Illite3.2% Pyrite 16.2% Smectite1.2% Barite 4.1% Kaol.1.0% Magnetite 3.3% Pyroph.

Clay Mineralogy

No ONE antibacterial mineral How about the chemistry?

InterlayerSurfaces X

X

X

X

Adsorbed onto surface

20 nm thickclay laths

OR

Antibacterial clay

NV

10-20 nmamorphous

particles

graphiteAntibacterial clay

Leachate Chemistry

x x x

H2O

200C

C H O N S P F Cl Br I Hg

OR07 Kills

NV07 Kills

X X X X X

x

x

AntibacterialClay

Leachate Chemistry

x x x

H2O

200C

C H O N S P F Cl Br I Hg

550C

x x x

OH

Rb Cs Se Cd As

OR07 Kills

NV07 Kills

OR07 doesn’t kill

NV0 partially kills

X X X X X

x

x

AntibacterialClay

Leachate Chemistry

x x x

H2O

200C

C H O N S P F Cl Br I Hg

550C

x x x

OH

Rb Cs Se Cd As

900C

Elements not volatilizedFe Zn Ni Cu V Co W Cr Ag Cd Pb U

All below MICIn oxidized form!

OR Kills

NV Kills

OR doesn’t kill

NV partially killsNeither Kill!

X X X X X

x

x

AntibacterialClay

pH Eh (mV)

NV (<2.0µm) 3.96 +146

OR (<2.0µm) 3.48 +172

French clays HIGH LOW

Non-AB clays Neutral Neutral

2 µm

500 nm

5 µm

Healthy E. coli

2 µm

500 nm

After clay incubation

What We’ve Learned

X X X X X

x

x

AntibacterialClay

PHYSICAL CHEMICAL

Mineralogy

SEM pH, Eh

Leachates

No ONE mineral responsible

No visible disruption of the cell

Extreme pH, Eh values

Heating regimes may volatilize vital elements

Agents soluble at pH ~4

Illite/Smectite

Future Work

• More Imaging!• Model elemental speciation at varying pH

and Eh – similarities?• Cation exchange (xc)

- remove xc’able ions-test xc solution and xc’d clay

• Electron and Ion Microscopy - clay/bacteria interactions

Acknowledgements

Other ColleaguesDr. Dennis Eberl

Dr. Ross Giese

NCCAM

LeRoy Eyring CSSS

Dr. Shelley HaydelTanya BorchardtChristine RemeniAmanda CoteyDr. Renu SharmaDr. Karl WeissDr. Laurence GarvieDr. Gordon MooreZack BowlesDr. Panjai Prapaipong