Temperature-dependent infrared and calorimetric studies on arsenicals adsorption from solution to hematite nanoparticles.

To address the lack of systematic and surface sensitive studies on the adsorption energetics of arsenic compounds on metal (oxyhydr)oxides, we conducted temperature-dependent ATR-FTIR studies for the adsorption of arsenate, monomethylarsonic acid, and dimethylarsinic acid on hematite nanoparticles at pH 7. Spectra were collected as a function of concentration and temperature in the range 5-50 °C (278-323 K). Adsorption isotherms were constructed from spectral features assigned to surface arsenic. Values of K(eq), adsorption enthalpy, and entropy were extracted from fitting the Langmuir model to the data and from custom-built triple-layer surface complexation models derived from our understanding of the adsorption mechanism of each arsenical. These spectroscopic and modeling results were complemented with flow-through calorimetric measurements of molar heats of adsorption. Endothermic adsorption processes were predicted from the application of mathematical models with a net positive change in adsorption entropy. However, experimentally measured heats of adsorption were exothermic for all three arsenicals studied herein, with arsenate releasing 1.6-1.9 times more heat than methylated arsenicals. These results highlight the role of hydration thermodynamics on the adsorption of arsenicals, and are consistent with the spectral interpretation of type of surface complexes each arsenical form in that arsenate is mostly dominated by bidentate, MMA by a mixture of mono- and bidentate, and DMA by mostly outer sphere.

Evaluation of antibacterial efficacy of garlic (Allium sativum) and ginger (Zingiber officinale) crude extract against multidrug-resistant (MDR) poultry pathogen.

Objective: The study is aimed to understand the antibacterial sensitivity of native and Indian varieties of garlic (Allium sativum) and ginger (Zingiber officinale) crude extracts against multidrug-resistant (MDR) poultry pathogen (Escherichia coli and Salmonella sp.). Materials and Methods: Thin layer chromatography (TLC) is used to identify the target spices' bioactive antibacterial compounds. MDR E. coli and Salmonella sp. were isolated from poultry. The TLC-Bioautography technique was applied to explore the antibacterial potentiality of garlic and ginger. Results: Inhibitory activities of garlic were Zone of inhibition (ZI) = 14.03 ± 0.15 mm and 19.70 ± 0.36 mm, Minimum inhibitory concentration (MIC): 0.625 and 0.325 mg/ml, and ginger were ZI = 14.63 ± 0.30 mm and 11.56 ± 0.51mm, MIC: 9.0 mg/ml against E. coli and Salmonella sp., respectively. Two bands of garlic (Rf value = 0.31 and 0.50) and one band of ginger (Rf value = 0.71) showed inhibitory potential in TLC-Bioautography against both MDR isolates. Conclusion: Garlic and ginger were effective against MDR E. coli and Salmonella sp. These spices could be a suitable alternative during the antibiotic void.