Measurement and relationship between critical tube diameter and critical energy for direct blast initiation of gaseous detonations

For the explosion safety assessment in industrial setting, detonation dynamic parameters provide important information on the sensitivity and conditions whereby detonations can be favorably occurred. In this study, new measurement of the critical tube diameter and the critical energy for direct initiation of a detonation is reported for a number of hydrocarbon–oxygen mixtures. The simultaneous experimental measurement carried out in this work allows the investigation of the direct scaling between these two dynamic parameter quantities of gaseous detonations. Using the new set of data, this paper also assesses the validity of an existing semi-empirical initiation model, namely, the surface energy model by Lee, and a simplified work done model. Both phenomenological models provide a general relationship between the two dynamic detonation parameters and comparison shows a good agreement between the theoretical results and the experimental measurement. The scaling of critical tube diameter with detonation cell size in this study also confirms the results in the previous literature.     

Non-hazardous waste generation characteristics and recycling practices in Saskatchewan and Manitoba,Canada

The paper presents the results on the analysis of non-hazardous waste generation characteristics and recycling practices in Saskatchewan (SK) and Manitoba (MB) using the biennial waste reports published by Statistic Canada. The objectives are to examine the waste generation rates from both residential and non-residential sources from 1998 to 2010, and to evaluate the effectiveness of their recycling programs and regulations. In spite of the many similarities between the provinces, MB on average generated 17.5 % more residential waste than SK, and about 15 % less non-residential waste than SK during the study period. It appears that MB waste generation characteristics were very different from SK and the rest of Canada. The amount of MSW generation in MB was, to a certain degree, independent from the economic factors. Assuming status quos conditions, the linear models predicted that the per capita MSW generations in MB would be about 33 % lower than SK in 2020. Data from this study suggest that (1) curbside recycling programs and (2) pay-as-you-throw collection systems may be important factors for increasing diversion rate in SK. It is also found that the non-residential waste generation in Canada was substantially larger than the residential waste generation during the 13-year period.     

Ashes to ashes,and dust to dust: Is scattering garden the sustainable destination for cremated ashes?

Environmental Science and Pollution Research - Cremation is commonly practiced around the world because it requires small space for the disposal of ashes. Among various options for ash disposal,...     

Nitrous oxide emission by denitrifying phosphorus removal culture using polyhydroxyalkanoates as carbon source

Nitrous oxide (N₂O) emission has been reported to be enhanced during denitrification when internally-stored compounds are used as carbon sources. However, negligible N₂O emissions have been detected in the few studies where polyhydroxyalkanoates (PHA) were specifically used. This study investigated and compared the potential enhancement of N₂O production, based on utilization of an internally-stored polymer and external carbon (acetate) by a denitrifying phosphorus removal culture. Results indicated that at relatively low chemical oxygen demand-to-nitrogen (COD/N) ratios, more nitrite was reduced to N₂O in the presence of an external carbon source as compared to an internal carbon source (PHA). At relatively higher COD/N ratios, similar N₂O reduction rates were obtained in all cases regardless of the type of carbon source available. N₂O reduction rates were, however, generally higher in the presence of an internal carbon source. Results from the study imply that when the presence of an external carbon source is not sufficient to support denitrification, it is likely competitively utilized by different metabolic pathways of denitrifying polyphosphate accumulating organisms (DPAOs) and other ordinary denitrifiers. This study also reveals that the consumption of PHA is potentially the rate-limiting step for N₂O reduction during denitrification.     

Accelerated sunlight photocatalysis through improved electron mobility between g-C3N4 and BiPO4 nanomaterial

Herein, we report a detailed study on creating heterojunction between graphitic carbon nitride (g-C₃N₄) and bismuth phosphate (BiPO₄), enhancing the unpaired free electron mobility. This leads to an accelerated photocatalysis of 2,4-dichlorophenols (2,4-DCPs) under sunlight irradiation. The heterojunction formation was efficaciously conducted via a modest thermal deposition technique. The function of g-C₃N₄ plays a significant role in generating free electrons under sunlight irradiation. Together, the generated electrons at the g-C₃N₄ conduction band (CB) are transferred and trapped by the BiPO₄ to form active superoxide anion radicals (?O₂^?). These active radicals will be accountable for the photodegradation of 2,4-DCPs. The synthesized composite characteristics were methodically examined through several chemical and physical studies. Due to the inimitable features of both g-C₃N₄ and BiPO₄, its heterojunction formation, 2.5wt% BiPO₄/g-C₃N₄ achieved complete 2,4-DCP removal (100%) in 90 min under sunlight irradiation. This is due to the presence of g-C₃N₄ that enhanced electron mobility through the formation of heterojunctions that lengthens the electron-hole pairs’ lifetime and maximizes the entire solar spectrum absorption to generate active electrons at the g-C₃N₄ conduction band. Thus, this formation significantly draws the attention for future environmental remediation, especially in enhancing the entire solar spectrum’s harvesting.

Graphical abstract