The promising performance of manganese gluconate as a liquid redox sulfur recovery agent against oxidative degradation

This work studied the oxidative degradation performance of manganese gluconate as a liquid redox sulfur recovery (LRSR) agent. The degradation of gluconate in an aerated sulfide containing 0.1 M manganese/0.8 M gluconate/pH 13 solution was 11% in 47 h and 20% in 100 h of reaction time. With the total price of chelates being more or less comparable, these were superior to the degradation resistance of EDTA chelate in a solution of 0.1 M iron/0.2 M EDTA/pH 8 which degraded by about 30% in 47 h, and NTA in Fe-NTA (0.1 M metal/0.2 M chelate/pH 6.5), which was degraded by 40% in 100 h of reaction time. At pH of 13, 0.1 M Metal, and 0.8 M gluconate, manganese degraded gluconate more severely than iron and copper. At a lower chelate to metal molar ratio (RCM) of 2 and as well as at a lower pH of 10, the manganese gluconate degradation, expressed as relative concentration to its initial concentration, was faster than at RCM of 8 and pH of 13. All of these observations can be explained among others by the well-known Fenton reaction hydroxyl radicals mechanism as the main cause of the degradation process.

Carbon-coated Single-phase Ti4O7 Nanoparticles as Electrocatalyst Support

The unique structure of Magnéli phases TiOx renders them effective for the electrochemical applications. This work demonstrates a synthesis of carbon-coated Magnéli phases TiOx (TiOx@C) nanoparticles from 3-aminophenol and rutile titania (TiO2) nanoparticles as a support for platinum (Pt) electrocatalyst. 3-aminophenol was polymerized and carbonized on the surface of TiO2 nanoparticles respectively in a microwave hydrothermal reactor and a tubular furnace. Reduction of the carbon-coated TiO2 (TiO2@C) into TiOx@C was performed in hydrogen atmosphere at 800-1050 °C. The carbon coating effectively prevented TiO2 nanoparticles from sintering, resulted in TiOx@C sizes from 50 to 100 nm. Single-phase Ti4O7 core, which has the highest theoretical electrical conductivity among the Magnéli phases, was obtained from reduction of TiO2@C at 1000 °C. for 10 min C/Ti4O7-supported Pt exhibited an electrochemical surface area of 46 m2 mgPt-1 at 15% Pt loading, slightly higher than that reported for commercial TKK electrocatalyst with 20% Pt loading (44.13 m2 mgPt-1).

Manganese gluconate, A greener and more degradation resistant agent for H2S oxidation using liquid redox sulfur recovery process

Iron chelate liquid redox sulfur recovery (LRSR) has been one of the most frequently recommended technologies for the oxidation of H₂S in natural gas into elemental sulfur, particularly when the acid gas has a high CO₂/H₂S molar ratio. The process is however known to suffer from extensive oxidative ligand degradation that results in high operational costs. Moreover, poor biodegradability or toxicity of the existing ligand has become a concern. In this research, we demonstrated that gluconate, a naturally greener ligand, when coupled with manganese as the metal, has considerable potential to be a better redox agent. Manganese gluconate solution was more resistant against ligand degradation compared with iron NTA. As required, aerated solution was capable of converting dissolved NaHS into elemental sulfur. At sufficiently high pH, manganese gluconate solutions were stable enough from precipitation of manganese hydroxide, carbonate, or sulfides. An equilibrium calculation has been developed to understand the precipitation behavior.

Cationic Defect Engineering for Controlling the Infrared Absorption of Hexagonal Cesium Tungsten Bronze Nanoparticles

Cesium tungsten bronzes (Cs_0.32WO₃) have attracted much attention as a near-infrared absorbing material. We report the successful synthesis of highly crystalline and high purity Cs_0.32WO₃ nanoparticles through a spray pyrolysis route. Careful analyses disclosed the presence of cationic defects, that is, a tungsten deficiency and insufficient Cs doping in the Cs_0.32WO₃ nanoparticles. These cationic defects can be controlled by facile heat treatment in a mildly reducing atmosphere. In particular, we clarify that the tungsten deficiency is a key factor among the cationic defects to obtain high near-infrared absorption properties. Furthermore, this study clearly demonstrates the precise tunability of the optical properties by means of the lattice constants of the Cs_0.32WO₃ crystal. The realized range of lattice constants is significantly wider than those previously reported. These findings should contribute to the engineering of Cs_0.32WO₃ structure and properties.

Electrochemical properties of TiOx/rGO composite as an electrode for supercapacitors

This work investigated the electrochemical characteristics of TiO_x and its composite with reduced graphene oxide.

Correlations between Reduction Degree and Catalytic Properties of WO x Nanoparticles

Degrading organic dyes via catalytic processes for waste water purification is an important research topic from the environmental conservation point of view. Herein, the catalytic performance of tungsten blue oxide (WO _x ) nanoparticles was investigated systematically by varying the reduction temperature. The optimum reduction temperature to obtain the most stable WO _x phase was obtained when plasma-synthesized WO₃ nanoparticles were thermally reduced at 425 °C. The as-synthesized nanoparticles had an average diameter of 10 nm and a calculated band gap of 2.37 eV, which is lower than that of the WO₃ nanoparticles (2.61 eV). The WO _x nanoparticles exhibited an excellent performance in degrading rhodamine B under dark conditions and visible light irradiation, with a reaction rate constant 93 times higher than that of the WO₃ nanoparticles.