Carbon material from polyvinyl chloride as an adsorbent of 2,4-dichlorophenoxyacetic acid

The adsorption of 2,4-dichlorophenoxyacetic acid (2,4-D) as a typical herbicide from aqueous solutions on activated carbons prepared based on polyvinyl chloride by its alkaline dehydrochlorination and the subsequent heat treatment was studied. The structure of the activated carbon surface and the presence of functional groups on it were established. The kinetics of the process of adsorption was studied. The influence of activated carbon preparation conditions on the properties of the adsorbents was demonstrated.     

Effectiveness of active physical training as treatment for long-standing adductor-related groin pain in athletes: randomised trial

BACKGROUND: Groin pain is common among athletes. A major cause of long-standing problems is adductor-related groin pain. The purpose of this randomised clinical trial was to compare an active training programme (AT) with a physiotherapy treatment without active training (PT) in the treatment of adductor-related groin pain in athletes. METHODS: 68 athletes with long-standing (median 40 weeks) adductor-related groin pain--after examination according to a standardised protocol--were randomly assigned to AT or PT. The treatment period was 8-12 weeks. 4 months after the end of treatment a standardised examination was done. The examining physician was unaware of the treatment allocation. The ultimate outcome measure was full return to sports at the same level without groin pain. Analyses were by intention to treat. FINDINGS: 23 patients in the AT group and four in the PT group returned to sports without groin pain (odds ratio, multiple-logistic-regression analysis, 12.7 [95% CI 3.4-47.2]). The subjective global assessments of the effect of the treatments showed a significant (p=0.006) linear trend towards a better effect in the AT group. A per-protocol analysis did not show appreciably different results. INTERPRETATION: AT with a programme aimed at improving strength and coordination of the muscles acting on the pelvis, in particular the adductor muscles, is very effective in the treatment of athletes with long-standing adductor-related groin pain. The potential preventive value of a short programme based upon the principles of AT should be assessed in future, randomised, clinical trials.     

Domain structure and miscibility studies of blends of styrene–butadiene–styrene block copolymers (SBS) and styrene–glycidyl methacrylate statistical copolymers (PS‐GMA) using SAXS and DMTA

The domain structure and miscibility in the solid state of a series of blends of styrene‐butadiene‐styrene (SBS) block copolymers and styrene‐glycidyl methacrylate (PS‐GMA) statistical copolymers with varying molecular weights and compositions were studied using small angle X‐ray scattering and dynamic mechanical thermal analysis. Depending on the molecular characteristics of each component, different types and degrees of solubilization of PS‐GMA in SBS were found which, in addition to the initially SBS phase morphology, lead to materials with multiphase domain morphologies with differences in size and structure. The degree of solubilization of PS‐GMA into the PS domains of SBS was found to be higher for blends containing PS‐GMA with lower molecular weight (M_w = 18 100 g mol^?1) and lower GMA content (1 wt%) and/or for SBS with higher PS content (39 wt%) and longer PS blocks (M_w = 19 600 g mol^?1). Localized solubilization of PS‐GMA in the middle of PS domains of SBS was found to be the most probable to occur for the systems under study, causing swelling of PS domains. However, uniform solubilization was also observed for SBS/PS‐GMA blends containing SBS with composition in the range of a morphological transition (PS block M_w = 19 600 g mol^?1 and 39 wt% of PS) causing a morphological transition in the SBS copolymer (cylinder to lamella). Copyright © 2006 Crown in the right of Canada. Published by John Wiley & Sons, Ltd     

Prediction of stability of cobalt catalysts for hydrocarbon synthesis from CO and H<Subscript>2</Subscript> in terms of resistance of cobalt crystallites against high-temperature agglomeration

The effect of temperature of calcination of Co catalysts reduced at 400°C on their characteristics (the surface area, degree of reduction, particle size, and average crystallite diameter), was investigated. It was found that an increase in the calcination temperature from 400 to 500°C significantly affects the size of cobalt crystallites. Based on these data, a method for predicting the catalyst stability is proposed.     

Highly selective cobalt-based zeolite catalysts for isoparaffin synthesis

Cobalt-based zeolite catalysts prepared via the impregnation technique have been studied in the synthesis of hydrocarbons from CO and H₂ at atmospheric pressure and a temperature of 160–220°C. The liquid hydrocarbons thus prepared contain 96–98% paraffins and olefins of the gasoline fraction. The content of isoparaffins in these products comprises 65–81% and depends on the nature of zeolite. The isomerization ability of the catalysts is linearly dependent on the total acidity of the surface.     

Development of a model for the hydrocracking of normal paraffins

A mathematical model was developed for the hydrocracking of paraffins obtained by the Fischer-Tropsch synthesis. This model takes into account hydrocracking catalyst characteristics such as acidity and the numbers of metallic centers and adsorption centers. The model proposed in this work can be used in studies for improving hydrocracking catalysts.     

Manufacture of C<Subscript>13</Subscript> higher fatty acids from their esters by carbonylation of dodecene-1 in ionic liquid medium

The effect of catalyst nature, temperature, acidity, promoters, and feedstock composition on dodecene-1 carbonylation in the presence of Pd compounds in an ionic liquid medium yielding higher fatty acid and their esters was studied. Palladium salts without phosphine ligands show high activity in tetrabutylammonium bromide. In systems of this kind, the catalyst is suspended in the reaction mass in the form of Pd particles with a size of 4–10 nm. It was shown that the catalytic system can be repeatedly used without loss of activity. It is acceptable to use synthesis gas instead of bare carbon monoxide with the selectivity for tride-canoic acid increasing.     

Ethane aromatization on Ga-Pt/HZSM-5 zeolites prepared by solid-state modification

The results of a comparative study of the catalytic properties of gallium and platinum pentasil (ZSM-5) zeolites, prepared according to the solid-state modification and impregnation techniques, in the ethane aromatization reaction are reported. It has been found that the procedure for the preparation of bimetallic catalysts has no substantial effect on their activity and selectivity for aromatic hydrocarbons. The formation of the active sites of the catalysts obtained by solid-state modification was investigated with the use of X-ray diffraction and X-ray photoelectron spectroscopy, and it has been supposed that Ga-Pt clusters similar to the species revealed earlier in bimetallic pentasil catalysts prepared by impregnation are produced as a result of topochemical reactions involving hydrogen. Based on the catalytic and physicochemical data, a reaction scheme for the ethane aromatization on Ga-Pt/HZSM-5 is proposed, which suggests the involvement of bimetallic clusters in a key step, the dehydrogenation of ethane followed by the formation of ethylene oligomers and their dehydrocyclization.