Solvay (United Kingdom)

Abstract Recent research progress in catalytic systems for potential use with hydrogen peroxide in industrial chemical synthesis is reviewed, with special focus on work published in the last five years. The main types of chemistry employed are critically appraised regarding their suitability for industrial exploitation. The most significant catalyst types are discussed in terms of the positive features identified to date, and the obstacles yet to be surmounted in order to become more widely adopted. It is believed that fully inorganic systems have more scope for commercialization than those containing organic ligands or supports, however robust. Critical targets are larger-pore analogs of titanium silicalite TS-1, more exploration of smectite-based materials, effective immobilization of activated metal peroxo systems, and improvements in design and manipulation of polyoxometallate compounds. Cooperation between branches of chemistry that have not traditionally worked closely together is advocated.

Covering 1995 to 1998.

The role of intermixed phases in organic solar cell blends is evaluated through manipulation of their number of phases.

Laboratory experiments and full-scale trials in Brazil and Italy are reported that show that peracetic acid is a good disinfectant (better than sodium hypochlorite) of sewage in tropical and warm temperate climates. Its demonstrated effectiveness against V. cholerae suggests it should be a significant element in cholera control efforts.

AIM: To compare the efficacy and safety of eprosartan and enalapril to lower systolic blood pressure in elderly patients with essential hypertension. METHODS: 334 patients >65 years with sitting systolic blood pressure (sitSBP) > or = 160 mmHg and diastolic blood pressure (sitDBP) 90-114 mmHg were randomized to 12 weeks of double-blind treatment with eprosartan, 600-800 mg once daily (o.d.) or enalapril (5-20 mg o.d.), with flexible dose titration to lower systolic blood pressure below 140 mmHg. The primary outcome measure was change in sitSBP at endpoint. RESULTS: Least-squares mean changes from baseline in sitSBP were -18.0 and -17.4 mmHg in the eprosartan and enalapril groups, respectively (difference eprosartan-enalapril -0.6, 95% confidence interval, CI, -4.1 to 3.0, p = 0.76). The corresponding figures for sitDBP were -9.4 and -9.6 mmHg (difference eprosartan-enalapril 0.2, 95% CI -1.7 to 2.0, p = 0.84). Normalization and response rates were also similar in the two groups. Adverse events were recorded in 61 (35.7%) patients on eprosartan (one with dry cough) and 83 (50.9%) patients on enalapril (10 with dry cough). CONCLUSIONS: Eprosartan and enalapril were equally effective in reducing sitSBP and sitDBP in elderly patients with predominantly systolic hypertension. Eprosartan was better tolerated and, in particular, lacked the propensity of enalapril to cause dry cough.

E.P.R. spin trapping has been employed to study radical production during the bactericidal action of three peroxide compounds (peracetic acid, 4-percarboxy-N-isobutyltrimellitimide and magnesium monoperoxyphthalate) upon both Gram negative (Escherichia Coli) and Gram positive (Staphylococcus Aureus) bacteria. Use of the spin trap 5,5-dimethyl-1-pyrroline N-oxide (DMPO) has allowed direct detection of both carbon-centred and hydroxyl radicals, which are produced at varying rates for the different bacteria/peracid systems studied. The inhibition of bactericidal action, by DMPO and two antioxidants, Vitamin C and Trolox C, indicates that radicals are the lethal species and evidence is presented which suggests that radical production is internal to the bacterial cell. Hydroxyl radicals are believed to be the lethal species. The effect of added iron chelators and haem protein inhibitors indicates that iron species and haem proteins in particular are involved. A marked variation is found in observed hydroxyl-radical adduct signals with both the nature and concentration of peracid. A strong inverse correlation is found between the concentration of the observed radical adduct signal and the relative strength of the peroxide as a bactericide; use of a stable nitroxide as a radical scavenger confirms that strong bactericides produce radicals at a much faster rate than weak bactericides. Plots of radical generation versus time are correlated with % bacterial kill, offering further evidence that hydroxyl radicals are the lethal species.

ABSTRACT This work reports the development of a methodology for the measurement of thermal conductivity of thermosetting polymers during their cure. The study addresses the reliability and robustness of the method through FEA modeling and testing using a noncuring material with known thermal conductivity. The thermal conductivity and its evolution during the cure has been measured for three widely used aerospace epoxy resins, namely, RTM6, 890RTM, and the XU3508/XB3473 system as function of cure temperature. A constitutive model expressing the dependence of thermal conductivity on the degree of cure and temperature has been established. The device developed here can measure thermal conductivity of epoxy resin with accuracy up to 3%. © 2018 The Authors. Journal of Applied Polymer Science published by Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136 , 47015.

The paper outlines some developments in ‘clean’ textile technology and discusses opportunities for effluent treatment with peroxy compounds. Particular aspects dealt with are elimination of organohalogen compounds (AOX) from cotton bleaching and wool shrinkproofing, energy and COD reduction in the continuous preparation of cotton and its blends, dye oxidation without chromium compounds, and the removal of colour from dyehouse effluent.

BACKGROUND: Omega-3 fatty acids from fish and fish oils can protect against coronary heart disease (CHD), which is still the most common cause of death in the Western economies. Evidence from epidemiological and case cohort studies indicate that consumpton of fatty fish and omega-3 fatty acids reduces the risk of cardiovascular mortality. OBJECTIVE: This article briefly reviews the evidence regarding omega-3 fatty acids and CHD and outlines the mechanisms through which omega-3 fatty acids might confer cardiac benefits over and above the standard secondary prevention strategies. CONCLUSION: The conclusion reached is that omega-3 fatty acids play a significant role in secondary prevention post-myocardial infarction. The mechanisms through which two of these omega-3 fatty acids, eicosapentaenoic acid and docosahexanoic acid, exert their action appear to be distinct and adjuvant to the available standard secondary prevention therapies. The role to be played by the administration of a newly licensed 90% concentrate EPA + DHA formulation (1 g/day capsule: Omacor) is explored.

Sixteen pathologically confirmed and 14 suspected cases of a new disease entity, fibrosing colonopathy, have been described in the UK and the US in children with cystic fibrosis since 1991. The patterns of use of pancreatic enzyme supplements in cases were compared with use in controls and in the market, in the 2 years prior to surgery for fibrosing colonopathy or the equivalent date in controls. The disease was only found in children with cystic fibrosis who had received brands of pancreatic enzyme supplement coated with methacrylic acid copolymer, for a period of at least 6 months. The risk was dose-related. No cases could be identified in children who had only received other pancreatic enzyme formulations, irrespective of the strength of the formulation or the dose.

Fibrosing colonopathy is a serious bowel disorder which was first seen in 1991 in patients with cystic fibrosis treated with high doses of pancreatic enzyme supplements. Epidemiological evidence from two case-control studies, temporal data and direct experimental evidence support the conclusion that there is a causal relationship between the disease and intake of high doses of the excipient, methacrylic acid copolymer, which is used to coat certain brands of pancreatic enzyme. A high intake of lipase, the active ingredient in pancreatic enzymes, is not a risk factor for fibrosing colonopathy in the absence of methacrylic acid copolymer. Excipients may be toxic if used in new patient populations such as children and in doses exceeding the safe levels predicted by animal toxicology.

The solid acid catalyst SbF3 supported on hexagonal mesoporous silica is an active and reasonably selective catalyst for the oxidation of cyclohexanone to caprolactone using hydrogen peroxide.

Abstract The mechanisms of reinforcement of an epoxy resin by the addition of graphene nanoplatelets (GNPs) has been studied in detail. It is found that the addition of GNPs increases both the stiffness and fracture toughness of the epoxy resin. The dependence of the flexural modulus upon the volume fraction of the GNPs has been modelled using a combination of the rule of mixtures and shear lag analysis and it is shown that the reinforcement is controlled principally by the aspect ratio (length/thickness) of the GNPs. The dependence of the fracture energy upon the GNP volume fraction has been modelled assuming failure takes place through the debonding of the GNP particles followed by their pull-out and it is again shown that the aspect ratio of the GNPs is a vital parameter in controlling the level of toughening. It is found that the behaviour can be modelled using a similar value of GNP aspect ratio to model both the flexural stiffness and fracture behaviour, demonstrating the importance of this parameter in controlling the mechanical properties of GNP/epoxy resin nanocomposites. Graphical abstract

Stainless steel pickling is a major generator of NOx emissions and is also a major producer of nitrate effluents. Hydrogen peroxide technologies have been developed and proven to suppress NOx emissions and also to replace nitric acid in the pickling process and hence remove the problem of nitrate effluent discharge. Presents case histories to illustrate the effectiveness of hydrogen peroxide both for NOx suppression and for nitric acid‐free pickling when pickling stainless steels.

Thermosets are frequently toughened by a high-Tg thermoplastic (TP). Blend morphologies obtained by curing induced phase separation with scales of a few hundreds of nanometers are relevant for high-performance applications, but no quantitative description for obtaining these morphologies exists yet. We propose such a quantitative approach for predicting and controlling the final morphology. The key is the degree of curing and the corresponding Tg of the blend and both phases when phase separation takes place. It is controlled by the Flory interaction parameter χ of the constituents and their respective Tg’s. We show that if phase separation takes place too early during curing, the Tg is too low and the morphologies grow to reach sizes of a few micrometers or more. Our study of different systems allows us to propose the relevant range of Flory interaction parameter χ and temperature window T–Tg for which the sizes of interest may be obtained. Our work opens the way for devising thermoplastics–thermosets couples with the appropriate affinity and Tg’s in order to make blends with tailored morphologies.

Summary Peracetic acid (PAA) has potential as a disinfectant of low environmental impact for glasshouse hydroponic systems and other horticultural applications, but can have phytotoxic effects. This study examined the physiological effects of PAA when applied hydroponically to tomato plants. Plants treated with 0.5–5 μg ml −1 PAA over several weeks exhibited a reduction in size of all vegetative organs. During the first 2 h of PAA treatment, plants also exhibited a transient wilting, with increased stomatal resistance, and reductions in transpiration and CO2 assimilation. The toxicity of PAA to roots was apparent from increased leakage of root electrolytes, reduced oxygen consumption, death of root tips, and collapse of the internal tissues. The shrivelling of PAA‐treated roots resulted from loss of water to the shoot in the transpiration stream, as the effect could be eliminated by removal of the shoot and sealing of the cut stump. HgCl2, a reagent known to reduce the hydraulic conductivity of root systems, caused the same root shrivelling effects as PAA. Long‐term growth of PAA‐treated plants was dependent upon the replacement of taproot systems by adventitious roots, which, initially at least, displayed greater tolerance of PAA. In aqueous solution, PAA exists in equilibrium with H2O2 and acetic acid, both of which were individually toxic, but acetic acid exhibited a syndrome of effects distinct from those of PAA, while the effects of H2O2 paralleled those of PAA more closely, suggesting that oxidative rather than acidic mechanisms were primarily responsible for the phytotoxicity of PAA solutions.

Abstract Thermoset (TS) epoxy resins can be toughened with a thermoplastic (TP) for high‐performance applications. The final structure morphology has to be controlled to achieve high mechanical properties and high impact resistance. Four polyethersulfone‐modified epoxy resins are considered. They consist of different epoxy monomer structure (TGAP, triglycidyl‐ p ‐aminophenol and TGDDM, tetraglycidyl diaminodiphenylmethane) and a fixed amount of thermoplastic, and they are cured with two different amounts of curing agent. A reaction‐induced phase separation occurs for all formulations generating morphologies, different in shapes and scales. The aim is to control the final morphology and in particular its dominant length scale. This morphology depends on the phase separation process, from the initiation to its final stage. The initiation relies on the relative miscibility of the components and on the stoichiometry between epoxy and curing agent. The kinetics depends on the viscosity of the systems. The different morphologies are characterized by electron microscopy or neutron scattering. Dynamic mechanical analysis allows confirming the presence of a phase separation even when it is not observable by electron microscopy. Vermicular morphologies with few hundreds nanometer width are obtained for the systems containing the TGAP as epoxy monomer. Systems formulated with TGDDM presents morphologies on much smaller scale of order a few tens of nanometers. We interpret the different sizes of the morphologies as a consequence of a larger viscosity for the TGDDM systems as compared to the TGAP ones rather than by a latter initiation of phase separation.

The Composites Industry needs to participate in future circular chemical economies. Cooperation, standardisation and increased availability of transparent industry data for life cycle analysis, are seen as critical to a more sustainable future.

A process has been developed for the oxidation of 4-t-butyltoluene to 4-t-butylbenzaldehyde via an indirect route involving the formation of either 4-t-butylbenzyl bromide or 4-t-butylbenzal bromide. The organic bromides were formed using a photolytic HBr/H2O2 route in the absence of solvent. The bromination steps were found to be highly efficient in that all the substrate could be converted, consuming all the hydrogen peroxide at this stage of the reaction. Partial hydrolysis (up to 50%) of the benzyl bromide to the aldehyde was achieved employing the Sommelet route using hexamethylenetetramine. However, up to 58% aldehyde yield could be afforded from the benzal bromide using a suitable phase transfer agent and a small amount of co-solvent. In both cases, the extent of over-oxidation to 4-t-butylbenzoic acid was reduced by careful control of the bromination step and eliminating dioxygen from the reactor. © 1998 SCI.

Abstract A water supply borehole in the Sherwood Sandstone aquifer in Warrington, UK was found to be infested with iron bacteria that resulted in large ochreous deposits and damaged the pump. Before the pump was replaced, the borehole was treated using hydrogen peroxide. Comparison of the borehole condition seen in CCTV surveys carried out before and after treatment shows that previously observed bacterial growths had been removed. A specific capacity curve was constructed from step test data and used to assess the borehole yield under operational conditions. This showed that the iron bacteria had increased drawdown by some 20% and that the treatment had restored the previous yield characteristics. The improvement is thought to be due to a mechanical scrubbing effect caused by the vigorous release of oxygen bubbles during the decay of the peroxide.