Single entity electrochemistry and the electron transfer kinetics of hydrazine oxidation

The mechanism and kinetics of the electro-catalytic oxidation of hydrazine by graphene oxide platelets randomly decorated with palladium nanoparticles are deduced using single particle impact electrochemical measurements in buffered aqueous solutions across the pH range 2–11. Both hydrazine, N2H4, and protonated hydrazine N2H5+ are shown to be electroactive following Butler-Volmer kinetics, of which the relative contribution is strongly pH-dependent. The negligible interconversion between N2H4 and N2H5+ due to the sufficiently short timescale of the impact voltammetry, allows the analysis of the two electron transfer rates from impact signals thus reflecting the composition of the bulk solution at the pH in question. In this way the rate determining step in the oxidation of each specie is deduced to be a one electron step in which no protons are released and so likely corresponds to the initial formation of a very short-lived radical cation either in solution or adsorbed on the platelet. Overall the work establishes a generic method for the elucidation of the rate determining electron transfer in a multistep process free from any complexity imposed by preceding or following chemical reactions which occur on the timescale of conventional voltammetry.

Development of a cost-effective wastewater treatment process: combination of different process

Caprolactam wastewater produced by the production process of caprolactam is characterized by a very high toxicity and chemical oxygen demand (COD) values, having potential harm to the environment if treated improperly. However, these characteristics make caprolactam wastewaters difficult to treat using traditional methods. So the aim of this work was to develop a cost-effective caprolactam wastewater treatment process. Fenton oxidation, sequencing batch reactor activated sludge process (SBR) and electro-catalytic oxidation were proposed to treat caprolactam wastewater in the laboratory scale, and the treatment effects were investigated. Compared with Fenton oxidation, SBR and electro-catalytic oxidation can treat caprolactam wastewater at a lower cost and more efficiently. The pilot test results indicate that the COD can be decreased to less than 1000 mg/L by the combination process, and when the COD removal rates maintain 90%, the cost of caprolactam wastewater treatment is below 6 yuan/m3. The combination process showed better economic benefit.

Electrocatalytic Effect of Al2O3 Supported on Clay in Oxidizing of Ibuprofen at Graphite Electrode

In this work, the electro-catalytic oxidation of ibuprofen was studied using aluminum oxide supported on clay (Clay/Al2O3). The latter has been successfully prepared by impregnating aluminum particles in the clay by heat treatment. The electro-catalytic performances of Clay/Al2O3 for the oxidation of ibuprofen were studied using cyclic voltammetry (CV), chronoamperometry, and differential pulse voltammetry (DPV) in 0.1 mol L-1 of the phosphate buffer (pH = 7). It has been shown that the proposed catalyst exhibits remarkably an electro-catalytic effect performance vis-a-vis the oxidation of ibuprofen. In addition, the peak oxidation currents depend linearly on the ibuprofen concentration in the wide ranges from 1.0·10-3 mol L-1 to 1.0·10-6 mol L-1 with a detection limit of 1.95·10-8 mol L-1 and response time of 30 second. Possible interferences were evaluated in 1.0·10-5 mol L-1 ibuprofen. The proposed catalyst also indicated suitable repeatability and stability. Besides, the proposed CPE-Clay/Al2O3 has been successfully applied for ibuprofen analysis in human blood with good recoveries.

The performance of three typical single and two coupled electrochemical processes for drilling wastewater treatment：comparison and implication

Electrochemical process especially for anode and cathode coupling process is promising and energy efficient for wastewater treatment. In this study, three single processes (Electrocoagulation (EC), Electro-catalytic oxidation (ECO) and E-peroxone)...