Chemical state

About: Chemical state is a research topic. Over the lifetime, 2378 publications have been published within this topic receiving 78183 citations.

Chemical Composition of Sewage Sludges and Analysis of Their Potential Use as Fertilizers

Abstract: Electron Spectroscopy for Chemical Analysis (ESCA) was used to provide information concerning the chemical bonding of zinc and copper present in the sludge obtained from the Dayton, Ohio sewage treatment plant. The binding energy of the Zn 2P/sub 3/2/ electron in sludge when placed under a vacuum of 10/sup -7/ Torr was 1023.8 +- 0.2 eV and the binding energy of the Cu 2p/sub 3/2/ electron in the sludge under similar conditions was 937.2 +- 0.3 eV. These energies are characteristic of both Zn and Cu being in the positive two oxidation state. The electronegativity of the ligand attached to either of these metals was found to be 3.5 +- 0.1 on the Pauling scale. This indicates that Zn and Cu exist in similar compounds, that the ligand binding site is oxygen, and that the possible compounds include carbonate, carboxylate, phosphate, nitrate, silicate, and/or oxide. ESCA, when used in conjunction with other methods, offers excellent potential for more specifically identifying the chemical form of metal in sludge or sludge mixtures.

Visible Light-Sensitive Cu(II)-Grafted TiO2 Photocatalysts: Activities and X-ray Absorption Fine Structure Analyses

Abstract: We investigated the role of Cu(II) ions and their associated structural features, such as chemical state and environment, in the Cu(II)-grafted TiO2 photocatalyst by means of 2-propanol oxidative decomposition under visible light and X-ray absorption fine structure (XAFS) measurements. The 2-propanol decomposition activity under visible light (1 mW cm−2, 450−580 nm) was highly reproducible (three repetitions). The XAFS results indicated that the Cu(II) is incorporated in a distorted amorphous CuO-like structure, having a five-coordinated square pyramidal form. The distorted CuO formed clusters and attached to the TiO2 surface. The chemical state and environment of the Cu(II) ions were not changed, even after the photocatalytic oxidative reaction. Thus, Cu(II)-grafted TiO2 can be regarded as a stable photocatalyst. In addition, in situ XAFS measurements were performed under visible light in the presence of 2-propanol and absence of oxygen. Under these conditions, Cu(I) was generated. However, the latter co...

Reduction of oxides of iron, cobalt, titanium and niobium by low-energy ion bombardment

Abstract: Ion-beam bombardment of solid surfaces with rare gas ions is used extensively in conjunction with XPS and AES for surface cleaning and depth profiling. It is sometimes not appreciated that the process can give rise to extensive chemical changes in the surface to be examined. The purpose of this investigation is to study this ion-induced chemical damage. As a vehicle for this, changes in the elemental chemical states associated with some transition metal oxides have been examined using XPS, when the oxides were subjected to progressive periods of argon ion bombardment. Chemical reduction of all oxides investigated has been observed and the data have been compared with theoretical predictions from a current model for preferential oxygen removal. Measurements of the core electron energy levels in oxides and some hydroxides of iron, cobalt, titanium and niobium have been made and the results are tabulated.