Rice husk filtrate as a nutrient medium for the growth of Desulfotomaculum nigrificans: characterisation and sulfate reduction studies

The filtrate obtained by interacting a known amount of rice husk with deionised, Milli-Q water was assessed as a carbon source and nutrient medium for the growth of Desulfotomaculum nigrificans, a typical sulfate-reducing bacterium. The filtrate contained essential growth constituents such as magnesium, potassium, phosphorous apart from calcium, sodium, chloride and sulfate ions. Based on the 1H and 13C NMR characterization studies, the organic composition of the components dissolved from the rice husk, was found to be: (i) 66% lignocellulosic material, (ii) 24% xylose + arabinose and (iii) 10% galactose. The growth studies indicated a 15-fold increase in the bacterial cell number in about 20 days. Nearly 81% and 66% reduction in sulfate concentration could be achieved in about 28 days, from the solutions containing initial sulfate concentrations of 550 mg/l and 1200 mg/l respectively. In both the cases studied, the iron concentration could be reduced by over 85%.

Electrochemical reduction of hydrogen peroxide on stainless steel

Electrochemical reduction of hydrogen peroxide is studied on a sand-blasted stainless steel (SSS)electrode in an aqueous solution of NaClO4.The cyclic voltammetric reduction of H2O2 at low concentrations is characterized by a cathodic peak at -0 center dot 40 V versus standard calomel electrode(SCE).Cyclic voltammetry is studied by varying the concentration of H2O2 in the range from 0 center dot 2 mM to 20 mM and the sweep rate in the range from 2 to 100 mV s(-1)Voltammograms at concentrations of H2O2 higher than 2 mM or at high sweep rates consist of an additional current peak, which may be due to the reduction of adsorbed species formed during the reduction of H2O2. Amperometric determination of H2O2 at -0 center dot 50 V vs SCEprovides the detection limit of 5 A mu M H2O2. A plot of current density versus concentration has two segments suggesting a change in the mechanism of H2O2 reduction at concentrations of H2O2 a parts per thousand yen 2 mM. From the rotating disc electrode study, diffusion co-efficient of H2O2 and rate constant for reduction of H2O2 are evaluated.

Chemoselective reduction of azides catalyzed by molybdenum xanthate by using phenylsilane as the hydride source

A chemoselective, neutral, and efficient strategy for the reduction of azides to corresponding amines catalyzed by dioxobis(N,N,-diethyldithiocarbamato) molybdenum complex (1, MoO2[S2CNEt2](2)) in the presence of phenylsilane is discovered. This chemoselective reduction strategy tolerates a variety of reducible functional groups.

A direct borohydride fuel cell employing Prussian Blue as mediated electron-transfer hydrogen peroxide reduction catalyst

A direct borohydride-hydrogen peroxide fuel cell employing carbon-supported Prussian Blue (PB) as mediated electron-transfer cathode catalyst is reported. While operating at 30 °C, the direct borohydride-hydrogen peroxide fuel cell employing carbon-supported PB cathode catalyst shows superior performance with the maximum output power density of 68 mW cm−2 at an operating voltage of 1.1 V compared to direct borohydride-hydrogen peroxide fuel cell employing the conventional gold-based cathode with the maximum output power density of 47 mW cm−2 at an operating voltage of 0.7 V. X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), and Energy Dispersive X-ray Analysis (EDAX) suggest that anchoring of Cetyl-Trimethyl Ammonium Bromide (CTAB) as a surfactant moiety on carbon-supported PB affects the catalyst morphology. Polarization studies on direct borohydride-hydrogen peroxide fuel cell with carbon-supported CTAB-anchored PB cathode exhibit better performance with the maximum output power density of 50 mW cm−2 at an operating voltage of 1 V than the direct borohydride-hydrogen peroxide fuel cell with carbon-supported Prussian Blue without CTAB with the maximum output power density of 29 mW cm−2 at an operating voltage of 1 V.

Kinetics of photocatalytic reduction of NO by CO with Pd2+-Ion-Substituted Nano-TiO2

The objective of the present study is to develop the reaction mechanism and kinetics of photoreduction of NO by CO. For this purpose, the reactions were conducted in the presence of Pd-ion-substituted nano-TiO2, Ti1-xPdxO2-delta, which was synthesized via a solution combustion method. The photocatalytic activity was investigated with unsubstituted TiO2, 1% Pd/TiO2(imp), and Ti1-xPdxO2-delta (where x = 0.05-0.3). No appreciable NO conversion was observed over unsubstituted TiO2, although, despite competitive adsorption of NO and CO on the Pd2+ sites, there was a significant reduction of NO over Ti1-xPdxO2-delta. The kinetic model showed that the enhanced catalytic activity is due to the NO photodissociation at the oxide-ion vacancy.

Single atom (Pd/Pt) supported on graphitic carbon nitride as efficient photocatalyst for visible-light reduction of carbon dioxide

Reducing carbon dioxide (CO2) to hydrocarbon fuel with solar energy is significant for high-density solar energy storage and carbon balance. In this work, single palladium/platinum (Pd/Pt) atoms supported on graphitic carbon nitride (g-C3N4), i.e. Pd/g-C3N4 and Pt/g-C3N4, acting as photocatalysts for CO2 reduction were investigated by density function theory (DFT) calcu-lations for the first time. During CO2 reduction, the individual metal atoms function as the active sites, while g-C3N4 provides the source of hydrogen (H*) from hydrogen evolution reaction. The complete, as-designed photocatalysts exhibit excellent activity in CO2 reduction. HCOOH is the preferred product of CO2 reduction on the Pd/g-C3N4 catalyst with a rate-determining barrier of 0.66 eV, while the Pt/g-C3N4 catalyst prefers to reduce CO2 to CH4 with a rate-determining barrier of 1.16 eV. In addition, depositing atom catalysts on g-C3N4 significantly enhances the visible light absorption, rendering them ideal for visible light reduction of CO2. Our findings open a new avenue of CO2 reduction for renewable energy supply.

Formation of an oxo-radical of peroxovanadate during reduction of diperoxovanadate with vanadyl sulfate or ferrous sulfate

Formation of oxygen radicals during reduction of H2O2 or diperoxovanadate with vanadyl sulfate or ferrous sulfate was indicated by the 1:2:2:1 electron spin resonance (ESR) signals of the DMPO adduct typical of standard radical dotOH radical. Signals derived from diperoxovanadate remained unchanged in the presence of ethanol in contrast to those from H2O2. This gave the clue that they represent a different radical, possibly radical dotOV(O2)2+, formed on breaking a peroxo-bridge of diperoxovanadate complex. The above reaction mixtures evolved dioxygen or, when NADH was present, oxidized it rapidly which was accompanied by consumption of dioxygen. Operation of a cycle of peroxovanadates including this new radical is suggested to explain these redox activities both with vanadyl and ferrous sulfates. It can be triggered by ferrous ions released from cellular stores in the presence of catalytic amounts of peroxovanadates.

Reactions with disulphur monoxide solutions obtained by the reduction of cupric oxide by elemental sulphur

When the products of reaction between elemental sulphur and copper oxide at elevated temperature in vacuum are bubbled through chilled inert organic solvents like carbontetrachloride, orange-yellow solutions were obtained indicating the presence of lower oxide of sulphur. This lower oxide has been found to be disulphur monoxide as shown by three different types of reactions; (1) Mercury decomposition, (2) Reaction with hydrogen iodide and hydrolytic reaction in an alkaline homogeneous medium.

Steroids and related natural products. VII. Boron trifluoride etherate-lithium aluminum hydride reduction of smilagenin acetate

Reduction of smilagenin acetate (Va) using a boron trifluoride etherate-lithium aluminum hydride reagent, followed by hydrogen peroxide oxidation and acetylation, was found to yield: 3β-ethoxysmilagenin (Vb), 3β-ethoxydihydrosmilagenin acetate (VIa), dihydrosmilagenin diacetate (VIb), and a complex mixture of partially acetylated products. Similar reaction conditions were employed to convert dihydrodiosgenin (II) to dihydrochlorogenin (III). Boron trifluoride etherate-lithium aluminum hydride reduction of 3β-acetoxy-5α-cholestane and 3β-acetoxy-5α-lanostane (VIIIa) was shown to yield the corresponding 3β-ethoxy (e.g., VIIIb) derivatives.

Colorimetric determination of 2,4-dinitrophenylamino groups by sodium borohydride reduction

When sodium borohydride is added to aqueous solutions of 2,4-dinitrophenylamino acids and related derivatives, an intense red color is formed. Measurement of the red color, with a 420 filter, permits the determination of such compounds in concentrations of 0.01 to 0.06 μmole per ml. with a precision to 2%. The reaction is highly specific-while 2,4-dinitroaniline will react to the test, o-, m-, and p-nitroanilines, 2,4-dinitrophenyl aryl or alkyl ethers, and 2,4-dinitrophenyl-imidazole and pyrrolidine derivatives will not. Heretofore aromatic nitro groups have been considered resistant to attack by sodium borohydride. The method, as developed, is applicable to the evaluation of the degree of substitution of protein amino groups by fluorodinitrobenzene.

Polarographic and redox potential studies on copper(I) and copper(II) and their complexes. Part III. Copper (I and II)-ethylene diamine and edta complexes and theory of formation of step reduction waves in cupric copper systems

Polarographic and redox potential measurements on the cupric and cuprous complexes of ethylenediamine and EDTA have been carried out. From the ratio of the stability constants of the cupric and cuprous complexes, and the stability constant of the cupric complex, the stability constant of the cuprous-ethylenediamine complex is obtained. In the case of the EDTA complex it has been possible to obtain only βic/β2ous from the equilibrium concentrations of the cuprous and cupric complexes and the disproportionation constant. The inequalities for the appearance of step reduction waves have been given. The values of the stability constants of the cupric and cuprous complexes determined by the polarographic-redox potential method have been used to explain the appearance of step reduction waves in some systems and the non-appearance in other systems.

Quinone Studies—II : Reduction potentials of some 3-substituted phenanthrene quinones

Polarographic reduction potentials of seven 3-substituted phenanthrenequinones have been determined in aqueous dioxan and aqueous ethanol under different pH conditions. The substituent effects on the reduction potentials could be correlated with the Hammett σ- constants (correlation coefficients> 0·995). The possibility of using reduction potentials as an accurate measure of resonance energy has been pointed out.