Physicochemical and toxicological properties of commercial carbon blacks modified by reaction with ozone.

Ozonation of two commercial carbon blacks (CBs), Printex 90 (P90) and Flammruss 101 (F101), was carried out and changes in their morphology, physical properties, and cytotoxicity were examined. The hypothesis examined was that different methods of manufacture of CBs influence their chemical reactivity and toxicological properties. Structural changes were examined by X-ray photoelectron spectroscopy, infrared spectroscopy, Raman spectroscopy, and electron paramagnetic resonance spectroscopy (EPR). Introduction of surface oxygen functionality upon ozonation led to changes in surface charge, aggregation characteristics, and free radical content of the CBs. However, these changes in surface functionality did not alter the cytotoxicity and release of inflammation markers upon exposure of the CBs to murine macrophages. Interaction of macrophages with F101 resulted in higher levels of inflammatory markers than P90, and the only structural correlation was with the higher persistent radical concentration on the F101.

Investigation of new chelation ion chromatography procedure to determine the surface composition of powdered metal oxide samples in the solid state.

Numerous tests have been conducted on the feasibility of characterizing the surfaces of metal oxide powders using HPLC. An in-line filter housing was modified to serve as a sample chamber to replace the sample loop. A gradient pump was used to gradually increase eluent acidity to find the conditions at which the surface of a metal oxide powder began to dissolve. The theoretical masses of surface monolayers of metal oxide powders were compared with the experimentally determined masses of dissolved material thought to be from the surface to test whether surface and bulk dissolution phenomena in acidic conditions are separable and quantifiable. A set of methods was tested that could first dissolve a metal oxide sample's surface, then separate and detect analyte species by chelation ion chromatography. Surface characterization by ion chromatography could be more cost-effective than existing methods, and reveal chemical properties of the sample where existing methods only give physical composition and properties.