查看更多>>摘要： Low-temperature selective catalytic reduction (SCR) is effective and promising for converting NO_x in flue gas into N2, with wide application prospects. However, low-temperature denitration (DeNO_x) catalysts are susceptible to SO2 and H2O poisoning. Here, we prepared a monolithic Mn-Fe-Ce/Al2O3 catalyst that exhibited excellent DeNO_x performances at low temperatures. At 110 °C, the NO conversion rate of the catalyst was > 90%, exhibiting excellent resistances to H2O and SO2-H2O and SO2 are introduced at the same time, the efficiency is as high as 73%. Furthermore, The catalyst has a porous structure with abundant chemi-sorbed oxygen spices and exposed active, the reaction pathway on the catalyst proved to be the L-H mechanism based on in situ DRIFTS. This study also explored the mechanisms of low-temperature SCR catalyst poisoning by SO2 and H2O, providing insights into the effects of SO2 and H2O and theoretical support for the development of poisoning-resistant low-temperature SCR catalysts.
查看更多>>摘要： Environmental pollution owing to plastic waste is a growing global issue. Packaging materials generate the maximum plastic waste, weighing 141 million tonnes/year. Driven in part by pressure from progressively environmental-conscious consumers, many industries are shifting their means of packing food products to more sustainable options. To promote sustainability, the present work investigates the potential of mussel-inspired polydopamine (pDA) chemistry to develop biodegradable antimicrobial food packaging materials. The food packaging films are designed using unique material combinations including polyvinyl alcohol (PVA), pDA, glycerol, and epsilon-polylysine (ePL). Along with exceptional biodegradability (46% in 1 week), these films demonstrate superb antibacterial activity against both gram-positive and gram-negative bacteria, as well as good thermal and mechanical properties. Additionally, these packaging films display excellent UV shielding properties that can protect the food from UV-induced photodegradation. Overall, this study uncovers numerous novel phenomena of mussel-inspired polydopamine chemistry to address major issues with plastic-based food packaging, such as biodegradability, microbial contamination of food, light-induced food spoilage, and so on.
查看更多>>摘要： An emphasis on sustainable growth helps decrease the initial capital and reduce the impact of industry on an ecologically sensitive environment through resource conservation. Pinch Analysis serves as a valuable tool to identify the potential for resource conservation, waste minimization, and resource costs. However, there are inherent uncertainties associated with these resource conservation networks. The concept of Pinch Analysis is broadened to multi-objective resource conservation problems incorporating parametric uncertainties in this paper. The objective functions are combined to form a single compound objective function using the weighted sum approach. For the compound objective function, prioritized sequences (or resource combinations) are generated through multi-objective prioritized costs to accommodate parametric uncertainties. The multi-objective prioritized cost vs. weights curve helps determine the unique prioritized sequences for different range of weights to achieve optimal solutions. An exact analytical expression for the maximum number of prioritized sequences is also derived. Furthermore, a method is presented to construct the complete Pareto-optimal front to represent all optimal solutions graphically. Two illustrative examples, the hydrogen conservation problem with two objectives (cost and emission) and the water conservation problem with three objectives (cost, land requirement, and emission), demonstrate the proposed method's utility and efficacy.
查看更多>>摘要： Removal of styrene vapors was investigated using a fungi-cultured biotrickling filter (BTF) in the presence of rhamnolipid. Evaluations at empty bed residence times (EBRTs) of 90, 60, and 30 s and inlet loading rates (LRs) ranging from 25.5 to 186.1 g m~(-3) h~(-1) were conducted. The maximum elimination capacity (EC) of 173.7 g m~(-3) h~(-1) was obtained at an inlet LR of 186.1 g m~(-3) h~(-1) at 90s EBRT. Reducing the EBRT to 60 and 30 s resulted in decline of removal efficiency (RE). The performance of BTF was modeled using artificial neural network (ANN) to predict styrene RE using measurable inputs, inlet LR, EBRT, and pressure drop. The model performance was assessed by mean square error and overall coefficient of correlation. The influence of different input parameters on the output was analyzed using casual index. Styrene removal was positively influenced by the increase in EBRTs, negatively impacted by its inlet LRs, while pressure drop had a negligible effect. The BTF was then exposed to intermittent loading phases by varying operational conditions during the non-loading periods. The results from this study confirmed that rhamnolipids could enhance the BTF performance for handling transient load variations at unsteady-state conditions.
查看更多>>摘要： Solar-powered desalination is a cost-effective technology to produce drinkable, potable water using energy from the sun. However, its use in domestic and industrial applications is minimal because of its low daily production. This study produced a novel nanoporous Cr-Mn-Fe oxide nanocoating by modulable chemical oxidation at a temperature of around 90 °C in an acidic mixture of 21-34 wt% conc.H2SO4, 37.5-53 wt% distilled water & 15-30 wt% sodium dichromate salt on a mirror-polished SS202 sheet to act as a basin liner for the nanocoated solar still (NCSS). The optical characterization of nanostructure coating was done using Cary 5000 spectrophotometer and FT1R spectrophotometer for absorptivity (90%) and emissivity (14.4% at 300 °C), respectively. It was found that the nanocoated solar still (NCSS) produced 36.36%, 28.62%, and 26.27% more distillate yield when compared with conventional solar still (CSS) for 1 cm, 2 cm, and 3 cm depth of water, respectively. Enviro-economic studies, energy matrices evaluation, and water quality analysis were performed to compute greenhouse gases emissions, carbon dioxide mitigation, carbon credit gained, energy-payback time (EPT), energy production factor (EPF), life cycle conversion efficiency (LCCE), and suitability of distilled water for drinking. The cost per liter (CPL) of desalinated water for NCSS was inferred to be 15.6% more economical than for a CSS and 81% more economical than packaged drinking water in India.
查看更多>>摘要： Photocatalysts can be effectively recovered and reused by compounding with magnetic nanostructures. How to further improve the photocatalytic performance of magnetic heterojunction photocatalysts remains a great challenge. In this work, g-C3N4/ZnFe2O4 (CN/ZFO) magnetic heterojunction photocatalyst was first prepared and then modified with ultrathin MoS2 (CN/ZFO/MoS2) by simple ball-milling method. Then the photocatalytic removal of Cr(VI) performance of the prepared series photocatalysts was evaluated in detail. The optimum CN/ZFO/MoS2 can achieve 99.3% Cr(VI) removal under 200-min simulated sunlight illumination, which is much higher than CN/ZFO (54.0%). The enhanced photocatalytic performance benefits from the modification of MoS2, which improves the light absorption performance, facilitates the transfer of photogenerated carriers, increases the concentration of photogenerated carriers and promotes the effective separation of photogenerated carriers. This work provides a theoretical basis for further preparation of magnetic recyclable photocatalysts with high photocatalytic performance.
查看更多>>摘要： Biofiltration has grown worldwide, as an inexpensive and consistent air pollution control technology for the elimination of numerous organic compounds. In this work, the biofiltration of methyl ethyl ketone (MEK) has been studied. The agro-wastes namely pressmud and cornstack are mixed and used as packing materials for the removal of MEK. The performance of the biofilter has been explored over 200 days. Experiments are carried out in four periods. In every period, the biofiltration of pollutants is performed for various inlet concentrations (IC) of MEK (0.2-1.2 g m~(-3)) and gas flow rates (GFR) (0.03 m~3 h~(-1) to 0.12 m~3 h~(-1)). The biofilter performances are investigated by their removal rates, elimination capacity, temperature, pressure drop, carbon dioxide production, and variation of bed height at the time of operations. For the IC of 0.2 ± 10% g m~(-3) and GFR of 0.03 m~3 h~(-1), the removal efficiency (RE) of MEK is 97% using the mixture of cornstack (80%) and pressmud (20%). The MEK removal efficiency decreases, when the cornstack ratio increases. The maximum RE is obtained at the IC of 1.2 g m~(-3) and GFR of 0.12 m~3 h~(-1) for all the tested conditions. The pressure drop (PD) is also measured for all the operating conditions. It is found that the PD rises with an increase in height. The temperature is monitored throughout the biofiltration process. It is observed that an increase in RE leads to a rise in temperature in the biofiiter. SEM images confirm the growth of microbes on the packing material. The kinetics of removal of MEK is investigated by using Ottengraf-van den Oever model.
查看更多>>摘要： It is necessary to evaluate the released gases distribution (especially hydrogen) to avoid hydrogen accumulation and maintain containment integrity against the pressure loads due to its deflagration or detonation. For this purpose, this work uses coupling of the FLUENT and MELCOR to evaluate the produced gases distribution in the WWER1000/V446 during in-vessel and ex-vessel phases of the Station Black Out (SBO) along with Large Break Loss of Coolant Accident (LBLOCA). The results indicate that 30 cm mesh size is sufficiently fine to evaluate the gases behavior in the containment. Also, driving force of the hydrogen/carbon monoxide (CO) and steam are mainly in the form of the plume due to buoyancy effects and jet flow caused by momentum, respectively. Furthermore, hydrogen accumulates in the upper compartments more than in other areas and its average volume fraction reaches to 12.7% at the end of the calculations. In addition, it can be concluded that steam condensation on the walls increases the hydrogen volume fraction up to 2%.
查看更多>>摘要： As well known, the solar distiller is one of the introduced solutions to the freshwater shortage problem, but it is demerited by the low freshwater output. In this paper, a design modification that includes the use of a convex dish absorber instead of a flat absorber liner was proposed. Also, a circular stepped surface was used instead of the flat absorber surface. The modified solar distiller is nominated by dish solar distiller and abbreviated by DSD. In addition, a cotton wick was used as a wetting material for facilitating the evaporation process inside the distiller. Besides, the effect of different water heights in the steps was investigated for 0.50, 1, 1.50, 2, and 3 cm. Finally, the space under the dish absorber is filled with a phase change material (PCM) of paraffin wax mixed with CuO nanoparticles. Experimental results revealed that the best water depth over the steps absorber of DSD that provided the highest freshwater productivity was 1.50 cm, where the average daily yields of DSD (at 1.50 cm) and conventional distillers were reported as 6525 and 2800 mL/m~2.day, respectively. Then, the productivity of DSD was improved by around 133% over that of the conventional distiller. In addition, when using the phase change material, the average daily distillate of stepped DSD was improved by approximately 178% compared to that of the conventional solar still, where the distillate of conventional still and DSD with PCM at 1.50 cm water depth over the steps absorber of DSD was 2950 and 8200 mL/m~2.day, respectively. The water productivity of the three established solar distillers has been predicted using machine learning algorithms. Besides, the maximum thermal efficiency of DSD was obtained when using PCM at 1.5 cm water depth over the steps absorber of DSD, where it was 67.62% compared to 31.71% for the conventional distiller. The proposed machine learning algorithms succeeded in predicting water productivity with a high correlation coefficient of 0.99.
查看更多>>摘要： The current study evaluates the potential measures for enhancing energy efficiency in a commercial building application. It is directed towards addressing Northern climate conditions that are scarce in literature. To highlight the recommended measures, a case study involving a two-storey office building that was built in the late 1970s in Ottawa, Canada is presented. As typical for commercial buildings in Northern climates, building heat is provided by natural gas. Cooling, lighting, and other building needs are supplied by electricity. The building current operational condition deviates from what is recommended by the building code. The authors were consulted to propose energy efficiency measures for the building. The building was simulated using the eQuest software. Verification of the simulation results was performed against historic site data. The model highlighted several parameters that can reduce energy consumption and greenhouse gas emission. Major influencers on energy consumption were: building envelope, water heating system, and building air tightness. Amongst them, increasing building air tightness is the cheapest to implement. On the other hand, the parameters that are functions of occupancy had minor effect on the reduction of energy consumption. A detailed economic analysis has been conducted to evaluate the feasibility of the proposed retrofit strategies. The analysis quantified that the wall, roof insulation, boiler upgrade and building air tightness have a high impact on reducing energy consumption by more than 52%. The improvements have the potential to reduce the emissions by around 82 tons of CO2 per year. The return on investment was found to be 5 years. The incorporation of renewable energy to the building was also investigated. Solar energy is not commonly integrated in cold climates in most of the reported research. For the current study, a solar heating system was installed to supply needed hot water and a PV system is used for electricity generation. This causes the payback period to increase to 5.6 years if solar water heating is added and to 9.1 years with solar water heating and photovoltaic integration. Debt ratio and interest rate have detrimental effect on return on investment for the project. The results of the current study are valuable recommendations for people interested in retrofitting commercial applications in Northern climates.
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