Ethylene oxide removal by sorption on aluminium oxide

The dynamics of ethylene oxide sorption and desorption on Al2O3 sorbent were investigated. The investigations of ethylene oxide sorption on Al2O3 show that significant sorption appeared above 125°C. The removal of sorbed ethylene oxide from Al2O3 was achieved by continuous increasing of the temperature up to 450°C in air stream. The analysis of desorbed products show that 90% of adsorbed ethylene oxide is converted to CO2 and the rest consists of the three derivatives of ethylene oxide. The exact composition of desorbed organic products will be determined in further investigation. The desorption temperature profiles point out the presence of two exothermic picks, as was confirmed by detection of CO2 and derivates of ethylene oxide at these temperatures. Investigation of textural characteristics and thermal stability of Al2O3 sorbent show that there are no changes of any characteristics of Al2O3 in sorption/desorption operating temperatures regimes. Only at 700°C the specific surface area of Al2O3 decreases of about 10%. This indicates that the investigated Al2O3 is convenient material for removal of ethylene oxide by sorption.U ovom radu prikazana su ispitivanja dinamike sorpcije i desorpcije etilen oksida na Al2O3 kao i sorpcioni kapaciteti, temperaturni režimi desorpcije i sastav produkata desorpcije etilen oksida. Rezultati su ukazali da sferni Al2O3 sorbent poseduje zadovoljavajuće sorpcione karakteristike za uklanjanje etilen oksida. Na temperaturama iznad 125°C ne dolazi do značajnog povećanja kapaciteta sorpcije etilen oksida. Produkti desorpcije etilen oksida sa Al2O3 sorbenta, postepenim povećanjem temperature u vazduhu, sadrže oko 90% CO2, a ostatak čine derivati etilen oksida. Ispitivanja teksturalnih karakteristika i termičke stabilnosti Al2O3 sorbenta pokazala su da u sorpciono/desorpcionom operativnom režimu nema nikakvih teksturalnih promena sorbenta. Ovo ukazuje da je ispitivana alumina pogodan materijal za sorpciono uklanjanje etilen oksida

Synthesis and characterization of biphasic calcium phosphate/poly-(DL-lactide-co-glycolide) biocomposite

In this paper we report the results on synthesis of a composite biomaterial based on biphasic calcium phosphate (BCP) and poly-(DL-lactide-co-glycolide) (DLPLG). Besides, we have investigated the influence of new synthesis method on the structure and characteristics of the composite. The synthesis of biphasic calcium phosphate from Ca(NO3)(2) x 4H(2)O and (NH4)(3) PO4 in alkali environment was performed by means of precipitation technique. Composite material BCP/DLPLG was first prepared from commercial granules using chemical methods. Powdered polymer DLPLG was then homogenized at appropriate ratio with addition of biphasic calcium phosphate into the suspension. All samples were characterized by DSC, IR, X-Ray and SEM techniques.Current Research in Advanced Materials and Processes, 6th Conference of the Yugoslav-Materials-Research-Society, Sep 13-17, 2004, Herceg Novi, Montenegr

TiO2/WO3 photocatalytic composite coatings prepared by spray pyrolysis

TiO2/WO3 composites supported on a stainless steel foil were prepared by the spray pyrolysis technique. Content of WO3 was gradually increased from 1 wt% to 100 wt.%, while the coating thickness was limited to about 1 pm. The coatings were characterized by X-ray diffraction, scanning electron microscopy, atomic force microscopy, X-ray photoelectron spectroscopy, and Raman spectroscopy. The photocatalytic activity of obtained coatings was investigated by degradation of methyl orange, used as model pollutant. The results show that with increasing WO3 content up to 10 wt.% photoactivity increases as result of better charge separation that could effectively prevent the recombination of photogenerated electrons and holes. Further increase of WO3 content led to decrease of photoactivity. (C) 2014 Elsevier B.V. All rights reserved

Low concentration volatile organic pollutants removal in combined adsorber-desorber-catalytic reactor system

The removal of volatile organic compounds (VOCs) from numerous emission sources is of crucial importance due to more rigorous demands on air quality. Different technologies can be used to treat the VOCs from effluent gases: absorption, physical adsorption, open flame combustion, thermal and catalytic incineration. Their appropriateness for the specific process depends on several factors such as efficiency, energy consumption, secondary pollution, capital investments etc. The distinctive features of the catalytic combustion are high efficiency and selectivity toward be­nign products, low energy consumption and absence of secondary polluti­on. The supported noble catalysts are widely used for catalytic incineration due to their low ignition temperatures and high thermal and chemical stability. In our combined system adsorption and desorption are applied in the spouted bed with draft tube (SBDT) unit. The annular zone, loaded with sorbent, was divided in adsorption and desorption section. Draft tube enabled sorbent recirculation between sections. Combustion of desorbed gases to CO2 and water vapor are realized in additive catalytic reactor. This integrated device provided low concentrations VOCs removal with reduced energy consumption. Experiments were conducted on a pilot unit of 220 m3/h nominal capacity. The sorbent was activated carbon, type K81/B - Trayal Corporation, Krusevac. A sphere shaped commercial Pt/Al2O3 catalyst with "egg-shell" macro-distribution was used for the investigation of xylene deep oxidation. Within this paper the investigations of removal of xylene vapors, a typical pollutant in production of liquid pesticides, in combined adsorber/desorber/catalytic reactor system is presented.U okviru ovog rada izvršena su ispitivanja adsorpcije ksilola, kao Predstavnika volatilnih organskih jedinjenja, na aktivnom uglju. Ispitivanja su vršena u cilju dobijanja parametara za određivanje efikasnosti adsorpcije realne smeše polutanata. Takođe, ispitivana je desorpcija ksilola u širokom temperaturnom intervalu u cilju određivanja optimalne temperature desorpcije i efikasnost katalitičkog sagorevanja desorbovanog ksilola na katalizatoru. Ova ispitivanja bila su osnov za razvoj integrisanog sistema adsorber-desorber-katalitički reaktor za uklanjanje malih koncentracija ksilola. Ispitivanja su obuhvatila tretiranje gasne smeše vazduh-ksilol, koja je po svom sastavu slična otpadnim gasovima iz pogona za proizvodnju tečnih pesticida. Eksperimenti su izvršeni na pilot postrojenju nominalnog kapaciteta 220 m3/h smeše vazduha sa ksilolom. U ispitivanjima je korišćen komercijalni adsorbens aktivni ugalj i katalizator sa kontrolisano dispergovanom platinom na spoljnoj površini sfere poroznog AI2O3 nosača

Properties and efficiency of a Pt/Al2O3 catalyst applied in a solid fuel thermo-accumulating furnace

A prototype of a solid fuel thermo-accumulating furnace has been developed. In order to achieve a higher combustion efficiency, a Pt/Al2O3 catalyst in the form of 3 ± 0.3 mm spheres was applied, which enabled further combustion of flue gases within the furnace. Experimental investigation of the influence of the catalyst on the conversion of CO has been done for different operation regimes and positions of the catalyst. Paper presents selected results regarding CO emission during wood and coal combustion. Investigations suggest a considerable effect of the catalyst and a strong influence of the catalyst position to CO emission reduction. The microstructure of the catalyst beads, characterized by selective chemisorption of CO, has shown the decrease of the number of Pt sites as a consequence of blockage by coke deposits formed during the combustion of solid fuel

Reduction of carbon monoxide emission from a solid-fuel thermo-accumulation furnace

Many households in Serbia, using electric thermo-accumulation furnaces for heating, have been forced to find an alternative solution, due to a significant increase in electricity prices during the last decade. A possible solution is replacing electric heating appliances with the solid fuel-fired ones. A prototype of a new concept of thermo-accumulation solid fuel-fired furnace has been developed to meet these growing needs, providing electricity saving together with considerable environmental benefits. Two strategies for reduction of carbon monoxide emission are examined in the paper: application of Pt/Al2O3 catalyst, in the form of 3 ± 0.3 mm spheres, providing further combustion of flue gases within the furnace, as well as an additional emission reduction by means of the air excess control. Experimental investigations of the catalyst influence on the conversion of carbon monoxide have been done for different operation regimes and positions of the catalyst. The paper presents selected results regarding carbon monoxide emission during wood and coal combustion. Investigations suggest a considerable effect of the catalyst and a strong influence of the catalyst position within the furnace to carbon monoxide emission reduction. In addition, experimental tests have been conducted to asses the effect of the air excess control in the furnace on carbon monoxide emission. The amount of combustion air, the flue gas flow rate, and the fuel feeding regime have been adjusted in order to keep the flue gas oxygen content in a relatively narrow range, thus obtaining controlled combustion conditions and lower carbon monoxide emission. In this way, the furnace has been made able to respond to the changes in heating needs, fuel quality and other parameters, which is advantageous in comparison with similar solid-fuel fired furnaces