Study of the Effect of Acid-base Character of the Lamellar Double Hydroxides "Zn3Al-CO3" and of the "Ghassoul" Clay on Their Redox Potential and Antimicrobial Activities

Our study is to highlight the effect of the acid-base character and the redox potential of two clays, synthetic anionic Layered Double Hydroxides Zn3Al-CO3 (LDH) clay, and natural commercial cationic clay "Ghassoul" on their antioxidant and antibacterial activities. The antibacterial effect was tested on two Gram-positive bacteria: Staphylococcus aureus and Enterococcus faecalis. Then it was tested on a Gram-negative bacterium: Escherichia coli. The determination of the minimum inhibitory concentration of the two materials was carried out using the microplatemicrotitration technique. The antioxidant activities of clays are assessed by the methods 2.2-diphenyl-1-picrylhydrazyl and the reducing power of iron (Fe3+). The redox potential (Eh) was measured and the redox strength (rH2) was evaluated. The results showed that these materials have an antibacterial effect on the three bacteria tested, the measured zero charge point of Ghassoul (pHzpc =8.75) more basic than that of double layer hydroxide (pHzpc =7.5), redox potential of LDH (-27mV) was higher than that of Gh (- 103mV), and the rH2 of Gh (14.04) was higher compared to anionic clay (13.33).
Keywords: LDHs, Ghassoul, Redox Potential, Zero point of Charge, Antibacterial.