A Direct Ammonia Microfluidic Fuel Cell using NiCu Nanoparticles Supported on Carbon Nanotubes as an Electrocatalyst.

This work demonstrates the use of a NiCu electrocatalyst prepared by hydrothermal method with different Ni/Cu mass ratios (70:30, 50:50 and 30:70) supported on carbon nanotubes (CNTs), which was studied with regards to its electrochemical behavior in the ammonia oxidation reaction and direct ammonia microfluidic fuel cell (DAMFC) performance. XRD and SEM-EDX showed the formation of NiCu alloy while TEM showed the particles size to be 15-20 nm. Cyclic voltammetry and chronoamperometry showed that NiCu had higher catalytic activity than pure Ni and pure Cu, and that the active species was a NiCu oxyhydroxide. In DAMFC tests, 50 wt % Ni50 Cu50 /CNTs was found to be the most suitable one since it showed a 43 % higher peak power density and 65 % higher maximum current density than Ni electrode. The improved performance was attributed to the NiCu oxyhydroxides formation, which improved the anodic catalytic activity by increasing amounts of active sites and the combined electronic effect of the Ni-Cu bimetallic catalysts.

Retrieval of Au, Ag, Cu precious metals coupled with electric energy production via an unconventional coupled redox fuel cell reactor.

The recovery of heavy metals from aqueous solutions or e-wastes is of upmost importance. Retrieval of Au, Ag, and Cu with electricity generation through building an ethanol-metal coupled redox fuel cells (CRFCs) is demonstrated. The cell was uniquely assembled on PdNi/C anode the electro-oxidation of ethanol takes place to give electrons and then go through the external circuit reducing metal ions to metallic on the cathode, metals are recovered. Taking an example of removal of 100mgL-1 gold in 0.5M HAc-NaAc buffer solution as the catholyte, 2.0M ethanol in 1.0M alkaline solution as the anolyte, an open circuit voltage of 1.4V, more than 96% of gold removal efficiency in 20h, and equivalent energy production of 2.0kWhkg-1 of gold can be readily achieved in this system. When gold and copper ions coexist, it was confirmed that metallic Cu is formed on the cathodic electrode later than metallic Au formation by XPS analysis. Thus, this system can achieve step by step electrodeposition of gold and copper while the two metal ions coexisting. This work develops a new approach to retrieve valuable metals from aqueous solution or e-wastes.

Assembly of coupled redox fuel cells using copper as electron acceptors to generate power and its in-situ retrieval.

Energy extraction from waste has attracted much interest nowadays. Herein, a coupled redox fuel cell (CRFC) device using heavy metals, such as copper, as an electron acceptor is assembled to testify the recoveries of both electricity and the precious metal without energy consumption. In this study, a NaBH4-Cu(II) CRFC was employed as an example to retrieve copper from a dilute solution with self-electricity production. The properties of the CRFC have been characterized, and the open circuit voltage was 1.65 V with a maximum power density of 7.2 W m(-2) at an initial Cu(2+) concentration of 1,600 mg L(-1) in the catholyte. 99.9% of the 400 mg L(-1) copper was harvested after operation for 24 h, and the product formed on the cathode was identified as elemental copper. The CRFC demonstrated that useful chemicals were recovered and the electricity contained in the chemicals was produced in a self-powered retrieval process.

Culture of Spirulina platensis in human urine for biomass production and O(2) evolution.

Attempts were made to culture Spirulina platensis in human urine directly to achieve biomass production and O(2) evolution, for potential application to nutrient regeneration and air revitalization in life support system. The culture results showed that Spirulina platensis grows successfully in diluted human urine, and yields maximal biomass at urine dilution ratios of 140 approximately 240. Accumulation of lipid and decreasing of protein occurred due to N deficiency. O(2) release rate of Spirulina platensis in diluted human urine was higher than that in Zarrouk medium.

[Effect of flue gas conditions on NO oxidation process by DC corona radical shower].

Using an air-H2O DC corona radical shower system, the influences of reside time of flue gas in the reactor, velocity of flue gas and NO concentration on NO oxidation process were studied. The results show that the increasing velocity of flue gas can restrain corona development and the increasing NO concentration can make discharge more easy. The reside time of flue gas in the reactor has less effect on the NO oxidation. The NO oxidation rate increased only from 54.5% to 57.6% at 2 W input power when the reside time of flue gas in the reactor increased from 8.5 s to 34.2 s. However, the velocity of flue gas has important effect on the NO oxidation. At 1.7 W x h/m3 energy density, when the velocity of flue gas increased from 1.4 cm/s to 6.3 cm/s, the NO oxidation rate dropped from 60.0% to 38.6% and the energy yield also falled from 20.8 g/(kW x h) to 13.3 g/(kW x h). Under the certain flux of humid air, NO initial concentration has a best value, which was about 100 x 10(-6) in this experiment.

A new configuration of membrane stack for retrieval of nickel absorbed in resins.

A new configuration integrated ion exchange effect system with both electro-migration and electrochemical reaction in a single cell was developed to effectively retrieve metal ions from simulated wastewater using ion exchange resins without additive chemicals. By simply assembling cation exchange resins and anion exchange resins separated by homogeneous membranes, we found that the system will always be acidic in the concentrate compartment so that ion exchange resins could be in-situ regenerated without hydroxide precipitation. Such a realizable design will be really suitable for wastewater purification.

Dechlorination by combined electrochemical reduction and oxidation.

Chlorophenols are typical priority pollutants listed by USEPA (U.S. Environmental Protection Agency). The removal of chlorophenol could be carried out by a combination of electrochemical reduction and oxidation method. Results showed that it was feasible to degrade contaminants containing chlorine atoms by electrochemical reduction to form phenol, which was further degraded on the anode by electrochemical oxidation. Chlorophenol removal rate was more than 90% by the combined electrochemical reduction and oxidation at current of 6 mA and pH 6. The hydrogen atom is a powerful reducing agent that reductively dechlorinates chlorophenols. The instantaneous current efficiency was calculated and the results indicated that cathodic reduction was the main contributor to the degradation of chlorophenol.

[Utilizing fereducer reaction to enhance DC corona radical shower for benzene treatment].

Fereducer reaction is introduced to enhance DC corona radicals shower for removal of benzene in air. In the presence of nozzle electrode gas containing Fereducer reagent, the enhanced decomposing efficiencies were 21% and 4.2% for benzene concentration of 953 mg/m3 and 63 mg/m3, respectively. The enhancement of benzene removal was remarkable in the presence of nozzle electrode gas (O2, H2O) with the highest removal rate of 89.6%. Lower initial concentration of benzene has higher removal efficiency. However, higher absolute removal rate would be achieved when initial concentration of benzene was higher.

Degradation of chlorophenol by in-situ electrochemically generated oxidant.

A novel in-situ electrochemical oxidation method was applied to the degradation of wastewater containing chlorophenol. Under oxygen sparging, the strong oxidant, hydrogen dioxide, could be in-situ generated through the reduction of oxygen on the surface of the cathode. The removal rate of chlorophenol could be increased 149% when oxygen was induced in the electrochemical cell. The promotion factor was estimated to be about 82.63% according to the pseudo-first-order reaction rate constant (min(-1)). Important operating parameters such as current density, sparged oxygen rate investigated. Higher sparged oxygen rate could improve the degradation of chlorophenol. To make full use of oxygen, however, sparged oxygen rate of 0.05 m(3)/h was adopted in this work. Oxidation-reduction potential could remarkably affect the generation of hydrogen peroxide. It was found that the removal rate of chlorophenol was not in direct proportion to the applied current density. The optimum current density was 3.5 mA/cm(2) when initial chlorophenol concentration was 100 mg/L and sparged oxygen rate was 0.05 m(3)/h.