查看更多>>摘要：Red mud produced in the Bayer process is an ultrafine solid waste containing various metallic elements, which is hazardous to the environment because of its high alkalinity caused by the soluble sodium (Na). In this study, a green method for efficiently solidification and recovery of soluble sodium to eliminate high alkalinity of red mud via super-gravity was developed. Iron-slag melting separation from red mud was firstly conducted at 1523 K, where the Fe was fully recovered into metallic iron and almost all the Na was enriched into the Na-rich slag. Subsequently, the Na was selectively solidified into a stable phase of anorthite at 1373-1323 K, all of which were efficiently separated from the Na-rich slag at 1323 K via supergravity, where the recovery ratio of Na in anorthite was up to 97.09%. Compared to the red mud, the leaching rates of Na+ in the anorthite and residue were significantly decreased to 0.01% and 0.05%, and the pH of both products was decreased to 8.1-8.4. It was confirmed that the high soluble sodium in red mud was efficiently solidified and recovered into a stable phase of anorthite, and the high alkalinity was fully eliminated in both products which are environmentally friendly. (c) 2022 Institution of Chemical Engineers. Published by Elsevier Ltd. All rights reserved.
查看更多>>摘要：Point-of-use (POU) water treatment technology in developing countries and rural regions is more feasible than a centralized water treatment system due to the high cost of pipe distribution. The water filtration system can provide quick and easy access to water with low maintenance and higher pathogen removal among POU technologies. However, non-biodegradable polymeric materials for water filtration membranes raise environmental concerns due to their problematic disposal. There is increasing research on biode-gradable membrane material, but the validation of biodegradability is still lacking as measuring weight loss does not guarantee the complete mineralization of biodegradable membrane. This review aims to discuss various abiotic and biotic factors affecting polymer degradability in soil or compost, gather and evaluate existing studies on biodegradable filtration membrane and identify existing methods used to validate membrane biodegradability. Different kinetic models used to understand the biodegradation mechanism at different stages were studied. Factors affecting morphology and surface properties affect biodegradability. Membrane biodegradation follows a first-order model followed by a lag phase. Finally, future studies of biodegradable filtration membrane could include CO2 quantification and phytotoxicity studies, exploring different additives and membrane formulations to balance membrane performance and degradation ability, and lastly, conducting LCA and TEA to assess overall sustainability. (C) 2022 Institution of Chemical Engineers. Published by Elsevier Ltd. All rights reserved.
查看更多>>摘要：This study investigates the relationship between pressure change, velocity change, and temperature of crude oil through a pipeline and presents a method of using a regression supervised machine learning (ML) algorithm to detect faults. A representative dataset of crude oil flow is generated by computational fluid dynamics (CFD) and used to train the algorithm to develop a model of fluid behavior under normal pipeline operations over a range of typical flow rates and temperatures. CFD data are then collected under several simulated fault conditions: leaks of 10% and 20%, and a 50% restriction to flow, by nominal pipe crosssectional area. This study demonstrates that the ML algorithm can be trained to model the system under normal conditions, thereby successfully recognizing a fault condition as non-conforming and indicative of a statistically significant change in pipeline operation. It is further able to identify the fault type based on the pattern observed in the new data. It is shown that ML may be a safe, low-cost, and accurate method of monitoring a subsea pipeline for optimal performance and fault detection without the need to introduce special equipment to a subsea pipeline network, providing an avenue for enhanced process safety and protection of ocean environments. This paper demonstrates that the application of ML to the monitoring of pipeline networks could provide valuable contributions to the industry in terms of safety, cost, and environmental protection. (c) 2022 Institution of Chemical Engineers. Published by Elsevier Ltd. All rights reserved.
查看更多>>摘要：The current practice in predicting the Boiling Liquid Expanding Vapour Explosion (BLEVE) pressure for structural response analysis and design is based mainly on some semi-empirical energy equivalency methods. These methods are relatively easy to use but may not give accurate BLEVE pressure predictions. Using numerical simulations can yield better BLEVE pressure predictions, but it requires profound modelling knowledge and is time-consuming, which may not be viable to many design and consulting offices. This study generates empirical formulae and charts for easy and accurate predictions of BLEVE pressure using in the analysis and design of structures against BLEVE loads. The empirical relations of critical parameters, namely the side-on peak pressure, peak pressure rise time, duration, arrival time and impulse that are needed to fully define the pressure-time history, as functions of BLEVE parameters are established. The performances of the proposed empirical formulae and charts are evaluated by comparing the prediction results with experimental data. It is proven that the developed BLEVE pressure prediction equations and charts are easy to use and yield more accurate BLEVE pressure predictions than other commonly used empirical methods. (c) 2022 Institution of Chemical Engineers. Published by Elsevier Ltd. All rights reserved.
查看更多>>摘要：Hydrogen fuel cells have been installed in more than 100 facilities and numerous homes in Ulsan hydrogen town in the Republic of Korea. Despite the advantages of hydrogen, accidents can still occur near residential areas. Thus, appropriate risk mitigation plans should be established. In this study, a computational fluid dynamics (CFD) model of natural and forced ventilation is presented as an emergency response to hydrogen leakages in pressure regulator equipment housing. The CFD model is developed and investigated using three vent configurations: UP, CROSS, and UP-DOWN. The simulation results indicate that the UP-DOWN configuration achieves the lowest internal hydrogen concentration out of the three. In addition, the relationship between the total vent size and internal hydrogen concentration is determined. A vent size of 12% of the floor area has the lowest hydrogen concentration. The use of nitrogen for forced ventilation during emergencies is proposed to ensure that the hydrogen concentration of the released gas is less than one-fourth of the lower flammability limit of hydrogen. Compared to natural ventilation, the time required to reach safe conditions is decreased when nitrogen forced ventilation is used.(c) 2022 The Author(s). Published by Elsevier Ltd on behalf of Institution of Chemical Engineers. CC_BY_4.0
查看更多>>摘要：In the work, both elevated thermal and isothermal experiments of azobenzene were carried out by using SENSYS Evolution DSC. Kinetic parameters and decomposition mechanism were figured out by using Kinetic Calculation (KC) method and Molecular Dynamics Simulation (MDS) method. The results show that a first endothermic and following exothermic behavior appears distinctly in the thermal decomposition process of azobenzene; the apparent activation energy keeps approximately constant at the stage of 0.1 <_ alpha <_ 0.4, and then reduces gradually as the reaction goes on; the thermal decomposition behavior of azobenzene can be described by Sestak-Berggren mechanism on here; The step without adequate free radicals and the step with exponential growth of free radicals dominate respectively the stable decomposition process at initial stage and the self-accelerating decomposition process at autocatalytic stage; Based on Semenov model, the calculated SADT of azobenzene is 380.5 celcius, when packed in 25 kg standard package. (c) 2022 Institution of Chemical Engineers. Published by Elsevier Ltd. All rights reserved.
查看更多>>摘要：A gaseous hydrogen sulfide (H2S) oxidative removal technology by a dual ions-dual oxidants coupling activation system (i.e., Cu2+/Fe2+/persulfate(PS)/H2O2 coactivation system) was put forward. The fundamental issues, mainly including H2S removal performance, process parameters optimization, products, free radicals, synergy mechanism and desulfurization mechanism were studied systematically in a bubble column reactor. The study indicates that compared with Fenton system and non-coupling activation systems, the new dual ions-dual oxidants coupling coactivation system shows much higher free radical yield and H2S removal efficiency owing to significant synergistic activation effect. Higher concentrations of Cu2+ or Fe2+ greatly increase the H2S removal efficiency. With the increase of PS concentration, H2O2 concentration or reagent pH value, the H2S removal efficiency is first enhanced, and afterwards slightly declined. The H2S removal efficiency is declined via increasing operating temperature, gas flow rate and contents of H2S, SO2, NO and CO, and is almost not affected by content of Hg0. Sulfate, CuS and elemental sulfur are determined to be the products of H2S removal, and no by-products are produced after the reaction. Oxidation via center dot OH and SO4 -center dot plays a crucial role in H2S removal, which is proved to be the primary pathways of H2S removal. Finally, the recovery strategy of the products is discussed preliminarily. (c) 2022 Institution of Chemical Engineers. Published by Elsevier Ltd. All rights reserved.
查看更多>>摘要：Increasing usage and emission of neonicotinoid insecticides have caused severe risks to ecological en-vironment and human health. The study aimed to explore a Fe2+/UV/ peroxydisulfate (PDS) system for effective degradation of thiacloprid (TCP). The effects of various parameters involving the degradation ef-ficiency including initial solution pH, PDS concentration, Fe2+ concentration, and UV power were in-vestigated. Under the optimized conditions (pH 3.0, PDS concentration of 1 mmol L-1, Fe2+ concentration of 0.36 mmol L-1, and UV power of 45 W), it was observed that 97.5% of TCP was degraded with a pseudo-first-order kinetics reaction constant of 5.63 x 10(-2) min(-1). The Fe2+/UV/PDS system demonstrated excellent performance on reaction stoichiometry efficiency (RSE) (31.25%, 60 min). Meanwhile, the effects of in-organic anions (Cl-, NO3- and HCO3-) and natural organic matter (humic acid) on the removal of TCP were also investigated. In addition, the free radical scavenging experiments indicated that SO4 center dot- was dominant in the Fe2+/UV/PDS system. The intermediates were identified and their toxicity was notably lower than that of TCP. Therefore, the Fe2+/UV/PDS system is efficient and ecologically safe for TCP removal from wastewater.(C) 2022 Institution of Chemical Engineers. Published by Elsevier Ltd. All rights reserved.
查看更多>>摘要：In this work, a new type of compound additive and water mist compatible fire extinguishing method was designed, and the effects of its suppression on a 18650 LiMn2O4/Li(Ni0.5Co0.2Mn0.3)O-2 lithium-ion battery fire was investigated. To do so, a self-designed experimental platform was used to study the fire extinguishing capabilities and influence of the composite additives containing water mist on a lithium-ion battery fire. Several cell parameters were measured to evaluate the suppression effect of the fire extinguishing method, such as extinguishing time, maximum temperature, and heat release rate. The results show that both physical and chemical additives can play significant physicochemical roles in extinguishing fires and are more effective than pure water mist. The physical additives enhance the heat absorption and cooling as well as radiation heat barrier and oxygen asphyxiation mechanisms by reducing the surface tension and droplet size in the fog field. Furthermore, the chemical additives enhance the fire extinguishing efficiency by decomposing the active gases CO2 and H2O in the fire field and capturing the free radicals of the flame in the battery combustion reaction. (C) 2022 Institution of Chemical Engineers. Published by Elsevier Ltd. All rights reserved.
查看更多>>摘要：Reducing carbon emissions has been the consensus among countries worldwide. As an important an-thropogenic source of greenhouse gas (GHG), however, the GHG emission pattern from the waste sector in China's cities and counties is unclear which hinders the development of an effective strategy for GHG reduction. In this study, the GHG emissions from the waste sector of China during 2006-2019 were studied based on the Intergovernmental Panel on Climate Change (IPCC) inventory models. The total GHG emissions from the waste sector increased from less than 55.38 million metric tons (Mt) in 2006-178.06 Mt in 2019, with landfills accounting for the majority of GHG emissions. The proportion of GHG emissions from mu-nicipal solid waste (MSW) incineration increased rapidly from 7.8% in 2006 to 22.4% in 2019. The GHG emissions increased rapidly from less than 2.67 Tg in 2006-55.64 Mt in 2019, with the contribution in-creasing from 4.8% to 31.2%, as more MSW was landfilled. Among the seven regions of China, Eastern China contributed the most to GHG emissions. Therefore, there is a significant GHG mitigation potential in the MSW disposal sector. These findings indicate that GHG mitigation strategies should be based on the MSW generation and disposal situation, economic level, and operational management level of each region and province.(c) 2022 Institution of Chemical Engineers. Published by Elsevier Ltd. All rights reserved.
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