查看更多>>摘要：In this work, via numerical simulation, we conducted a detailed study on the manner of ion transport, the factors controlling the ion transport, and the effect of ion transport on the desalinating efficiency of the return-flow ion concentration polarization desalination system. An accurate numerical solver was developed to model the ions' transport in the system. Various configurations of applied voltage and fluid flow were enforced to in- vestigate the system response in Ohmic and limiting. Via examining the system in the different operating regimes and various conditions, we report a detailed theoretical understanding of system operation. With the increasing feeding flow rate, the simulation results show that the current and current utilization increases, the salt removal ratio changes inversely, and the energy per ion removed decreases. The system reaches its maximum value of current utilization at a value of porous membrane flow (PM-flow) or 0.04 mm/s in our investigation into the effects of this condition on the performance of the system. The findings are useful in optimizing the design and operation of the return flow -ion concentration polarization (RF-ICP) desalination system, giving firm evidence for the advantage of the ICP-desalination technology.
查看更多>>摘要：Green liquor solution (GLS) is waste pollutant from pulp and paper mills. Causticization process is a common treatment method for GLS, which is energy intensive and environmentally unsafe, because of high operating cost, and solid waste generation, We reported synergetic effect of titanium dioxide nanoparticle (TiO2) incorporated sulfonated PEEK, on the performance cation exchange membrane (CEM), for producing NaOH from industrial GLS by electro-electroldiaysis (EED). Reported composite CEM was studied for morphology, physicochemical, electrochemical properties. The counter-ion transport number, stability and antifouling properties of CEM were significantly improved after the addition of Ti02 nanoparticles in the sulfonated PEEK membrane matrix. Two compartment EED cell (active membrane area: 66 cm~2) was used to perform the experiments for producing NaOH using industrial GLS at 60 mA·cm~(-2) constant current density. The reported results shed light on production of NaOH along with prevention of sulfur scaling in treatment of wood based pulp and paper mills GLS stream. The modified membrane named SPK-T-5 (5 wt% of TiO2) by utilizing containing sulfonated polymer matrix outperforms an increasing trend of NaOH production along with notable sulfur antifouling. The obtained research outcomes are expected to be a valuable source for NaOH production with the aim of zero solid discharge practice for pulp and paper mills.
查看更多>>摘要：Due to the high hydrophilicity of extracellular polymeric substances (EPS) and colloidal property of sludge solids, applying efficient methods has attracted much attention for enhancing sludge dewatering. The oxidation and following flocculation of paper activated sludge is usually used alone or in combined conditioning with other pretreatments for sludge dewatering deeply. However, few studies are reported on the systematic comparison and role positioning of oxidation and flocculation conditioning. The results indicated that the sludge dewaterability of the combined potassium permanganate (KMnO4) and ferric chloride (FeCl3) conditioning was enhanced significantly with FeCl3 dosage decreasing by 75 % compared with individual FeCl3 conditioning. The mechanism is a synergistic effect of oxidation stripping and flocculation re-construction: larger agglomerated sludge flocs formed, and more bound water was released. FeCl3 played a more important role than KMnO4 for sludge dewaterability. The contents of bound water, S-EPS, maximum shear stress, and hysteresis area were the critical factors for sludge dewaterability. These findings provided further understanding of the combined oxidation and flocculation processes for improving dewaterability.
查看更多>>摘要：One of the most common techniques for separating azeotropes and close-boiling mixtures is extractive distillation, where the relative volatility of the components to be separated is altered by adding an entrainer. In recent years, deep eutectic solvents have emerged as a new class of entrainers in extractive distillation. Similar to the related class of ionic liquids, deep eutectic solvents combine the high separation capability of solid salts with the simple handling of liquids, additionally exhibiting low to negligible vapour pressures and non-flammability. Compared to ionic liquids, deep eutectic solvents offer advantages in terms of toxicity issues but also solvent costs. In this review, the current state of research regarding deep eutectic solvents in extractive distillation spanning from vapour-liquid-equilibrium measurements and thermodynamic modelling of the corresponding systems to general entrainer feasibility considerations and process simulations is presented and critically evaluated. Additionally, future prospects and comments on unresolved issues are provided.
Joshua O. IghaloSelvasembian RangabhashiyamKanika Dulta
38页
查看更多>>摘要：Water pollution is one of the major environmental challenges in contemporary times. Biochar from hydrothermal processes (known as hydrochars) has been explored as adsorbents for the removal of pollutants from wastewater. Hydrochars are a special class of biochar that is obtained from hydrothermal processes such as hydrothermal carbonisation (HTC) and hydrothermal liquefaction (HTL). Because of its good pore volume, surface area, high efficiency, and regeneration ability, hydrochar is an appealing choice for the remediation of a wide range of contaminants. This review aimed to focus the uniqueness of hydrochar properties and evaluate their performance on the adsorption of different pollutants from wastewater. It was observed that hydrochars can be effectively applied to a wide variety of pollutants including heavy metals, dyes, Pharmaceutically Active Compounds (PhACs), Endocrine Disruption Chemicals (EDCs), nitrates, phosphates and sulphate. The utilisation of hydrochar in water treatment solves constraints such as lack of regeneration, environmental friendliness, commercial feasibility, and disposal, handling or management concerns.
查看更多>>摘要：Gas-phase polymerization of propylene via 4th generation Ziegler-Natta (ZN) catalysts was studied and optimized using intelligent data-based methods. The effect of co-catalyst (triethylaluminium (TEA)) and external donor (ED) compositions on the activity and PP-isotacticity for two commercial MgCl2/TiCl4/phthalate(ID)/TEA/silane(ED) catalyst systems with different Ti-contents were investigated using design-of-experiment (DOE) combined with response-surface-methodology (RSM). Sobol's sensitivity analysis was employed to determine the quantitative impact of catalyst compositions on the target variables. Both catalysts performance was optimized via multi-objective genetic algorithm (GA) to maximize the activity and PP-isotacticity. Results revealed that the activity and PP-isotacticity for both catalysts will be enhanced at low co-catalyst and high ED amounts, respectively. Increasing the ED improved the activity of low-Ti catalyst, whereas it reduced the activity of high-Ti one. Sensitivity results for both catalysts depicted the comparable influence of co-catalyst and ED on the activity and the strong influence of ED on PP-isotacticity. GA optimization offered the activity of 3.7 - 4.65 gPP/mgCat and PP-isotacticity of 95.8 - 97.5 % for low-Ti catalyst at the optimal TEA/Catalyst = 7-7.2 and TEA/ED = 6.0 - 7.2 and the activity of 3.9 - 4,7 gPP/mgCat and PP-isotacticity of 93 % for the high-Ti one at the optimal TEA/Catalyst = 7 - 11.2 and TEA/ED = 12.
Hugo Fernando Giraldo MejiaJaviera Toledo-AlarconBarbara Rodriguez
15页
查看更多>>摘要：The recycling of discarded membranes (end-of-life) represents a relevant alternative for sustainability of reverse osmosis (RO) desalination plants in the context of circular economy. This work evaluated the feasibility of using discarded commercial RO membranes in the treatment of domestic secondary wastewater to obtain water with a certain standard quality. Crossflow filtration tests were conducted to evaluate desalination and wastewater filtration performance at different operating pressures on RO membranes discarded from desalination plans at different working positions (primary M1; secondary M2). The standard manufacturer desalination tests showed a superior performance on M1 membranes, in terms of rejection (～25 LMH, 97%), compared to M2 (～33 LMH, 50%); both having a lower performance than a standard membrane (38 LMH ± 15%; 99.6%). The failure is sufficient for discarding due to loss of lifespan. Moreover, in wastewater filtration tests using the secondary clarifier outlet effluent from a WWTP at different working pressures, both types of membranes were shown to be effective, with degrees of performance highly dependent on the working pressure. Thus, the operating values of permeate flux/salt rejection were between 56 and 59 LMH/ 96-97% for 600-psi: 33-34 LMH/ 94-96% for 300-psi and in the range of 10-11 LMH/ 90-94% for 80-psi test. Surface characterization of the membrane showed a pressure-related increase in fouling and bacterial adhesion post-filtration. Finally, the operating performance was verified in M1 wastewater filtration at 300 psi over long times (14 h), yielding stable and promising values (～27 LMH; 96%). The permeate obtained has a low concentration of fecal coliforms (< 2 MPN/100 mL, 99.99% removal) and meets local standards for irrigation and drinking water in terms of conductivity, phosphorus and nitrogen concentration in treated water.
查看更多>>摘要：Hydrodynamics of subcritical water (SbW) and particles were simulated using a low density ratio-based kinetic theory of granular flow (KTGF) in pulsed fluidized bed (FB). Five criteria were used to analyze the fluidization state, and results indicated that a transitional state existed in SbW FB, which was characterized by a wavy-like flow near the bottom and large-scale turbulence with chunk-like flow at the upper part. Effects of pulsating inlet fluid velocity frequencies and amplitudes were simulated. The coexistence of the plug-like flow and chunk-like flow occurred along bed height in pulsating SbW FBs. With increasing inlet SbW velocity frequencies, the wavelength increased at first, and then decreased for wave-like flow. The plug-like flow was appeared near the bed bottom with increasing inlet SbW velocity amplitudes. There is an agreement between the measured bed expansion height and computational simulation in an ambient water-particles FB, and the maximum relative error was 1.56 %.
查看更多>>摘要：Gas-liquid fluid dynamics and mass transfer are crucial aspects of aerobic fermentation and robust methodologies for their determination in industrial bioreactors are expected to provide significant improvements in many production processes. In this work, a gas-liquid stirred tank of high aspect ratio, that replicates the geometry of typical industrial aerated fermenters, is investigated. In particular, the liquid phase homogenization dynamics and the gas phase spatial distribution are determined. The selected methodology is based on the analysis of the conductivity measurements obtained by Electrical Resistance Tomography. The gas-liquid flow regimes and the mixing time are identified at various gas flow rates and impeller speeds, thus covering different gas-liquid regimes. Data collected with vertical and horizontal arrangements of the electrodes allow to obtain a detailed picture of the equipment working mode and to gain insight into the gas-liquid flow dynamics under optically inaccessible conditions. Quantitative evaluation of the reliability of the collected data is attempted by comparing the results obtained with the vertical and horizontal arrangements in the same locations.
查看更多>>摘要：Heavy oil reservoirs are much more challenging to be exploited by water flooding than conventional oil reservoirs because of high viscosity. However, gas injection has advantages such as viscosity reduction, oil swelling, extraction, and interracial tension reduction. Furthermore, it is more economical than thermal recovery methods. Previous pressure depletion testing has proved that nitrogen(N2) can form a foamy oil flow in the solution gas drive stage. In addition, crude oil has sufficient mobility under high-temperature conditions in relatively deep, heavy oil reservoirs. In this study, the feasibility of N2 huff-n-puff in heavy oil reservoirs was determined by observing the flow behavior and oil recovery factor through huff-n-puff tests in a two-dimensional planar model and a real-time, high-pressure visual cell. Stable foamy oil flow can be formed, and the overall recovery can reach 35.73 % when the pressure depletion rate was 16 kPa/min. The advantage of nitrogen huff-n-puff is high early production, and the application of nitrogen huff-n-puff in the early stage is not only low in cost but also highly efficient in production. Nitrogen huff-n-puff forms some large-contact-area gas chambers that can enhance the effect of using other high-cost solvents in the later stage. The results of this study can provide some theoretical basis and technical guidance for the application of nitrogen huff-n-puff in relatively deep, heavy oil reservoirs.
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