nitrophenols and formic-acid

The gamma irradiation-induced degradation of sulfamethazine (SMT) in aqueous solution in the presence of hydrogen peroxide (H2O2) was investigated. The initial SMT concentration was 20mg/L and it was irradiated in the presence of extra H2O2 with initial concentration of 0, 10 and 30 mg/L. The results showed that gamma irradiation was effective for removing SMT in aqueous solution and its degradation conformed to the pseudo first-order kinetics under the applied conditions. When initial H2O2 concentration was in the range of 0-30 mg/L, higher concentration of H2O2 was more effective for the decomposition and mineralization of SMT. However, the removal of total organic carbon (TOC) was not as effective as that of SMT. Total nitrogen (TN) was not removed even at absorbed dose of 5 kGy, which was highest dose applied in this study. Major decomposition products of SMT, including degradation intermediates, organic acids and some inorganic ions were detected by high performance liquid chromatography (HPLC) and ion chromatography (IC). Sulfate (SO4(2-)), formic acid (HCOOH), acetic acid (CH3COOH), 4-aminophenol, 4-nitrophenol were identified in the irradiated solutions. Possible pathways for SMT decomposition by gamma irradiation in aqueous solution were proposed.

Topics: Acetic Acid; Aminophenols; Anti-Bacterial Agents; Carbon; Chromatography; Chromatography, High Pressure Liquid; Dose-Response Relationship, Drug; Formates; Gamma Rays; Hydrogen Peroxide; Kinetics; Nitrophenols; Organic Chemicals; Oxygen; Sulfamethazine; Sulfates; Waste Disposal, Fluid; Water Pollutants, Chemical

Hollow chitosan fibers were reacted with chloropalladate solutions and subsequently reduced by hydrogen produced in situ by reaction of sulfuric acid with zinc powder in order to manufacture palladium supported on catalytic hollow chitosan fibers (C2HF-Pd). This catalytic support was used to degrade 3-nitrophenol (3-NP) using two different hydrogen donors (hydrogen gas and sodium formate). The solution was flowed through the lumen of the fiber, while the sodium formate was recirculated round the outside of the fiber. In the case of hydrogen gas, the gas was maintained under controlled pressure outside the fiber. The influence of the pH, residence time (ca. flow velocity), nitrophenol concentration, and hydrogen-donor concentration (or pressure) was investigated for both systems in order to evaluate the limiting parameters. While the system using sodium formate was the most efficient for nitrophenol conversion, the system using hydrogen gas avoided the production of secondary waste solutions (formate solutions with traces of nitrophenol, which pass through the fiber membrane).

Topics: Catalysis; Chitosan; Formates; Hydrogen; Hydrogen-Ion Concentration; Industrial Waste; Microscopy, Electron, Scanning; Nitrophenols; Palladium; Waste Management

Yariv beta-D-glucosyl (4a) and Yariv alpha-d-galactosyl (4b) reagents are multivalent phenylglycosides. The beta-D-glucosyl reagent is considered diagnostic for arabinogalactan proteins (AGPs) to which it can reversibly bind, stain, and precipitate. The alpha-D-galactosyl reagent does not bind AGPs and is used as a control. In a new strategy, we accomplished the large scale synthesis of the Yariv reagents in one continuous step by a transfer reduction method and without a need for any specialized apparatus. As the starting material, p-nitrophenyl-D-glycosides (1) were reduced to p-aminophenyl-D-glycosides (2) using ammonium formate as the hydrogen donor. The excess formate was converted to formic acid and ammonia, which then were removed from the reaction by simple distillation. Without isolation, p-aminophenyl-D-glycosides were diazotized (3) and coupled to phloroglucinol to give the Yariv reagents in approximately 40% yield. AGPs are a major component of gum arabic, an emulsifying agent widely used in the food and pharmaceutical industries. Increasing interest in AGPs prompted the development of a relatively easy and inexpensive method for the synthesis of these reagents.

Topics: Formates; Glucosides; Glycosides; Nitrophenols; Phloroglucinol