Clean Baeyer–Villiger Oxidation Using Hydrogen Peroxide as Oxidant Catalyzed by Aluminium Trichloride in Ethanol

Baeyer–Villiger oxidation of ketones was carried out using AlCl₃ as catalyst, H₂O₂ (30%) as oxidant in innocuity and environmentally friendly ethanol conditions. Cyclic ketones and acyclic ketones were transformed into the corresponding lactones or esters in 5–24 h at 40–70 °C with very high conversion and selectivity. A possible reaction mechanism was also given.     

Centrifugal Polyelectrolyte Enhanced Ultrafiltration for Removal of Copper‐Citrate Complexes from Aqueous Solutions

Abstract

To replace the conventional dead‐end polyelectrolyte enhanced filtration (PEUF), which is a time consuming process in the optimization of process variables, centrifugal polyelectrolyte enhanced ultrafiltration was investigated to remove copper‐citrate complex in aqueous phase with a cationic polyelectrolyte, poly(diallydimethylammonium chloride) (PDADMAC). Effects of concentration ratios between polyelectrolyte, copper, and citrate and pH were observed. Below pH 3, copper was not removed by centrifugal PEUF. At the same concentration (1 mM) of citrate and copper, removal of copper at pH 5 was the highest value of 54%, 90%, and 98% with 5, 10, and 20 mM PDADMAC, respectively. Removal of copper decreased with the logarithmic ionic strength. Since the centrifugal PEUF is very economical in time compared with conventional dead‐end PEUF, the present method should be a valuable tool in the optimization of process variables.     

Electrocatalytic Oxidation of Hydrogen Peroxide by Poly(NiIIteta) modified Electrodes§

[Ni^II(teta)]²⁺ (teta=C-meso-(5,5,7,12,12,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane) was electropolymerized on glassy carbon (GC) and Nafion^® coated GC electrodes (GC/Nf). These poly(Ni^IIteta) modified electrodes showed 70 mV shift per pH unit and electrocatalysed the oxidation of H₂O₂. The thickness of the Nafion^® film was found to influence the rate of the electrocatalytic reaction. A rate constant of 1.77 × 10³ dm³ mol^–1 s^–1 was observed at 1.0 × 10^–5 cm thick Nafion^® film, whereas a rate constant of 0.08 × 10³ dm³ mol^–1 s^–1 was observed at 3.6 × 10^–5 cm thick film. At a plain GC electrode, a rate constant of 1.29 × 10³ dm³ mol^–1 s^–1 was observed. The poly(Ni^IIteta) is stabilized in the Nafion^® film when compared to the poly(Ni^IIteta) coated on plain electrode.     

Spherical Resorcinol‐Formaldehyde Resin Testing for Cesium Removal from Hanford Tank Waste Simulant

Abstract

A new spherical form of resorcinol‐formaldehyde (RF) resin was tested for efficacy of cesium removal from Hanford tank waste. Two spherical RF formulations, prepared by varying curing temperature, were tested. Both resins had a tight particle size distribution and a high degree of sphericity. Small‐scale column testing (on ～20‐mL resin beds) was conducted evaluating the cesium load profile with AZ‐102 simulated tank waste and the cesium elution profile using 0.5 M HNO₃ eluant. The load and elution profiles were compared in side‐by‐side testing with ground‐gel RF resin and SuperLig® 644, the Waste Treatment Plant baseline ion exchanger. Although breakthrough capacity was not as high as the other resins tested, the spherical RF resin met plant cesium loading requirements with the AZ‐102 simulant matrix. Excellent reproducibility of cesium load and elution was demonstrated over three process cycles with no evidence of degraded performance. Residual cesium on the resin beds after elution was nearly a factor of 10 lower than that of the ground‐gel RF and SuperLig^® 644.     

UV-induced Decomposition of Ozone and Hydrogen Peroxide in the Aqueous Phase at pH 2–7

The photolysis of ozone and formation of hydrogen peroxide were investigated in solution of pH 2–7, in a 200 cm³ photoreactor in the incident photon flow range 9.6 x 10^?8 - 4.2 x 10^?7 einstein s^?1. The quantum yield of the primary photochemical reactions was measured in a direct way by suppressing the secondary radical reactions. The determined quantum yields of the photo-decompositions of ozone and hydrogen peroxide were 0.42 ± 0.042 ± 0.04 and 0.49 ± 0.04, respectively.

A correct mathematical treatment is given for calculation of the light absorption of the individual components of a multi-absorbent reaction mixture.

On the basis of the literature data and die present results, a probable chemical and reaction kinetic model was proposed to characterize the investigated reaction systems. Reaction kinetic simulations demonstrated that the model predicts a good fit to the measured data with the preferred literature rate constants, except that for the HO₃ radical decomposition reaction. A reasonable reduction of this rate coefficient value is in accordance with the latest published results.     

Oxidation of 1,3,5‐trichlorobenzene using advanced oxidation processes

The oxidation of 1,3,5‐trichlorobenzene (TCB) by ozone, ozone/UV, ozone/H₂O₂ and ozone/UV/H₂O₂ was studied. All studies were conducted in a continuously‐flowing completely mixed reactor (CFCMR), operated at steady‐state conditions using a hydraulic retention time of 10 minutes. The greatest removal of TCB using ozone/H₂O₂ treatment was achieved using a H₂O₂ concentration of 60 μM. At low pH values (approx. 2) ozone/UV performed significantly better than either ozone alone or ozone/H₂O₂. However, at circumneutral pH, the removal efficiencies of TCB by ozone/UV and ozone/H₂O₂ and ozone/UV/H₂O₂ were essentially equal (～ 97% for TCB). The removal efficiency of ozone alone was ～93% for TCB. At high pH (> 9) there was no advantage in supplementing ozone with either UV or H₂O₂ as the removal efficiencies for all processes studied were essentially equal.

The effect of humic acid and bicarbonate on the removal of TCB was studied. At 1.6 mg/L humic acid, 92–95% of the TCB was oxidized by the processes studied. The removal of TCB by ozone alone was significantly affected by the presence of bicarbonate ion. For the other processes at 10 mM bicarbonate, approximately 80% of the TCB was oxidized.     

Selective Oxidation of Cyclohexane to Cyclohexanone Catalyzed by Phenanthroline–CuCl2 Complex

A highly efficient oxidation of cyclohexane to cyclohexanone is accomplished over phenanthroline–CuCl₂ catalyst in relatively mild conditions. This study realized nearly 100% selectivity for cyclohexanone at 24.4% conversion of cyclohexane. The reaction has been studied by various parameters like performance of copper(II) salts, effect of solvents, influence of bases, the ratio of o-phenanthroline: CuCl₂, and reaction time. In order to further study this reaction system, the possible mechanism was proposed.     

Spherical Resorcinol‐Formaldehyde Performance Testing with Hanford Tank Waste

The efficacy of a new spherically engineered form of resorcinol‐formaldehyde (RF) resin was tested for cesium removal on two actual Hanford tank wastes. Small‐scale processing was conducted according to the River Protection Project‐Waste Treatment and Immobilization Plant flowsheet in a lead‐lag column format. The RF resin processed 95 bed volumes (BVs) of high potassium‐bearing waste (AP‐101) and >200 BVs of a high complexant‐bearing waste (AN‐102) before reaching 50% cesium breakthrough. Elution with 0.5 M nitric acid was effective and complete after processing 16 BVs. Cesium and other analyte fractionations to the process stream effluent and eluate were evaluated. The RF resin resulted in very little metal and radionuclide fractionation, other than cesium, to the eluate. The spent resins were measured for most analytes relevant to land‐disposal requirements. The actinide concentrations on the spent resins were <3% of the transuranic waste limit; the residual cesium concentrations were <4 mCi/kg; chromium was the only metal, regulated by the Resource Conservation Recovery Act, that was measured in quantities significant to land‐disposal regulations.     

Periclase-Chromite Refractory Decomposition by a Coal – Gas Medium During Copper Sulfide Raw Material Processing

Refractories and Industrial Ceramics - The composition and structure of periclase-chromite refractories contacting the coal–gas atmosphere of copper-sulfide-ore smelting furnaces were...     

The Adhesion of Evaporated Copper to Dow Cyclotene 3022®, Determined by Microscratch Testing

The mechanical integrity, stability, and strong interfacial adhesion between Cu, a high conductivity metal, and Dow Cyclotene 3022^®, a low permittivity polymer, are important for their application in future high-speed microelectronic devices. In the present study, Cu was deposited by both evaporation and sputtering, and various Cyclotene surface modifications were carried out. These modifications included low pressure N₂ plasma and Ar⁺ treatments and the use of a Ti interlayer. The adhesion was evaluated by use of the microscratch test, and complemented by an adhesive tape peel test and XPS. The N₂ plasma treatment was found to lead to a dramatic increase in adhesion, which was influenced to a minor extent by the adhesion promoter that was used at the Cyclotene/Si substrate interface. This significant Cu/Cyclotene adhesion enhancement is interpreted in terms of the chemical groups present at the Cyclotene surface and the bonds formed on Cu deposition.     

Propagation of the Chain Explosive‐Decomposition Reaction in Silver Azide Crystals

The velocity of the chain explosivedecomposition reaction in silver azide whiskes has been measured (1500 m/sec). The measured velocity is identified as the propagation velocity of the diffusion front of holes generated in the course of explosive decomposition.     

Interaction of a High‐Velocity Steel Projectile with a High‐Porous Copper–Duralumin Two‐Layer Bumper

The impact of a steel sphere 2 mm in diameter flying with a velocity of 2–7.3 km/sec on a twolayer bumper is considered. The first layer of the bumper is made of finely disperse copper powder with a density of 2.8 g/cm³, and the second layer is made of Duralumin. For identical impact velocities of 3–5 km/sec and identical thicknesses and areal densities of the bumpers, the twolayer bumper leads to better failure of the steel projectile than the Duralumin bumper. In the case of the twolayer bumper used, the maximum penetration depth of fragments into the witness plate and the number of the largest craters are smaller. The order of the bumper layers does not exert any noticeable effect on projectile failure. With the impact velocity increased to 7 km/sec, the difference in shielding properties of the bumpers almost vanishes.     

The Impact of Metastable Intermolrecular Nanocomposite Particles on Kinetic Decomposition of Heterocyclic Nitramines Using Advanced Solid‐Phase Decomposition Models

Journal of Inorganic and Organometallic Polymers and Materials - Surface oxygen of oxide catalyst has low coordination number; they are negatively charged. Surface oxygen can act active site for...     

The Impact of Traces of Hydrogen Peroxide and Phosphate on the Ozone Decomposition Rate in “Pure Water”

To obtain an idea of the magnitudes of the ozone loss rates r_O3 in practical applications of ozone, an overall determination of the ozone decay profiles and rate constants was carried out in four different systems. These systems resemble different conditions for industrial application of ozone and the peroxone process, such as in the field of micro electronics, drinking water purification, disinfection, etc. Therefore, the behavior of ozone was monitored in the pH range from 4.5 to 9.0, in pure water and phosphate buffered systems in absence and presence of small amounts of hydrogen peroxide (10^?7 M to 10^?5 M H₂O₂). First the reproducibility of the ozone decay profiles was checked and from the various kinetic formalism tests, the reaction order 1.5 for the ozone decay rate has been selected. As expected, hydrogen peroxide increases the decay rates. In pure systems, added concentrations of 10^?7M H₂O₂ already cause a remarkable acceleration of the ozone decay in the acidic and neutral pH range compared to the pure systems. However for alkaline pH conditions almost no effect of the low hydrogen peroxide concentrations was noticed. Contradictory to literature data, in the absence of hydrogen peroxide, ozone displays faster decays in the buffered systems of low ionic strength of 0.02 compared to pure water. This acceleration is more pronounced for acidic pH conditions. Low concentrations of phosphate may indeed accelerate the ozone decay in the presence of organic matter. Adding H₂O₂ concentrations below 10^?5M to phosphate buffered solutions has a negligible effect on the ozone decay rate compared with pure water systems, except for pH 7. It appears that phosphate masks the effect of hydrogen peroxide below 10^?5 M as tested here. Thus the application of AOP's by adding low concentrations of hydrogen peroxide is not well feasible in the presence of phosphate buffers in pure water systems.