Thermal behaviour of arsenic trioxide adsorbed on activated carbon

Abstract

Problem: Previous research indicated that conversions of intersections into roundabouts appear to increase the number of injury crashes with bicyclists. However, it was assumed that the effectiveness of roundabouts could vary according to some differences in design types of cycle, facilities and other geometrical factors. Method: Regression analyses on effectiveness-indices resulting from a before-and-after study of injury crashes with bicyclists at 90 roundabouts in Flanders, Belgium. Results: Regarding all injury crashes with bicyclists, roundabouts with cycle lanes appear to perform significantly worse compared to three other design types (mixed traffic, separate cycle paths, and grade-separated cycle paths). Nevertheless, an increase of the severest crashes was noticed, regardless of the design type of the cycle facilities. Roundabouts that are replacing signal-controlled intersections seem to have had a worse evolution compared to roundabouts on other types of intersections. Impact on industry: The results might affect design guidelines for roundabouts, particularly for the accommodation of bicyclists.

Pyrolysis of chromated copper arsenate (CCA) treated wood waste at elevated pressure: Influence of particle size, heating rate, residence time, temperature and pressure

“…To explain these findings a two stage mechanism is proposed which agrees with earlier experiments [6,11] using wood model compounds and heavy metal model compounds: arsenic pentoxide, originating from the decomposition of chromium arsenate, part of which has not formed thermally stable compounds with wood minerals (e.g. Cr(III)As(V)Ca(II)), is reduced to arsenic trioxide.…”

“…At temperatures around 400 • C or higher, the desorption of arsenic trioxide is likely to be the most important process leading to arsenic release. Earlier TGA experiments with arsenic trioxide adsorbed on activated carbon showed a broad desorption peak between 290 • C and 500 • C with a peak temperature at 405 • C [6]. Similar behavior of limited amounts of arsenic trioxide originating from the reduction of arsenic pentoxide (which is the product of chromium arsenate decomposition) could result in a reduced arsenic retention at temperatures of 400 • C or higher.…”

“…During pyrolysis CrAsO 4 decomposes to chromium(III) trioxide (Cr 2 O 3 ) and arsenic(V) pentoxide (As 2 O 5 ). Hereafter As 2 O 5 is reduced by reductive pyrolysis vapors to arsenic(III) trioxide (As 2 O 3 ) which sublimates after desorption from the pyrolysis residue matrix [3][4][5][6]. Low temperature pyrolysis aims at controlling or even eliminating this volatilization process by strictly controlling process operating conditions.…”

Inhibitory effects of CaO/Fe2O3 on arsenic emission during sewage sludge pyrolysis

“…And the emission ratio of arsenic accelerated slightly with the temperature increased, which was similar with the arsenic emissions during the coal pyrolysis (Lu et al, 2004). As 2 O 5 and organic arsenic compounds would decompose to As 2 O 3 (Kakitani et al, 2004) which released easily at a low temperature during the pyrolysis (Cuypers et al, 2009;Helsen et al, 2004). In this study, As 2 S 3 whose melting point is 573 K was also one of the origins that caused arsenic to release at a low temperature.…”

Formation of arsenolite crystals at room temperature after very high dose arsenic implantation in silicon

“…This is consistent with the low sublimation temperature of the arsenolite phase. 20 The low temperature sublimation of arsenolite microcrystals suggests that they are not the source for the apparent increase of arsenic dose upon annealing, reported in the literature. 8,9 SIMS measurement of the capped sample (S2) revealed the presence of a very thin As rich layer at the Si interface.…”