查看更多>>摘要：A development of coagulation-flocculation is to improve flocculation performance of organic polymer flocculants. It is hopefully achieved via optimizing molecular structure of flocculants. Herein, molecular structure of cationic organic polymer flocculants, P(AM-DAC), was regulated through adjusting the length of cationic block on the molecular chain of P(AM-DAC). The effect of block length of P(AM-DAC) on its characteristics, flocculation performances and flocculation mechanisms in water treatment was rarely considered. The moderate template contributed to P(AM-DAC)_(10_4:1) possessing the longest cationic block structure, largest molecular weight and best thermal stability compared with other P (AM-DAC). Molecular dynamics (MD) simulation and the flocculation experiments predicted and confirmed that P(AM-DAC)_(10_4:1) performed the best in the treatment of colloidal particles and dyes in terms of removal efficiencies and floc characteristics since the centralized cationic block structure enhanced the interaction among P(AM-DAC)_(10_4:1) and pollutants and further improved charge neutralization and bridging of P(AM-DAC)_(10_4:1).
查看更多>>摘要：The recovery of levulinic acid (LA) and formic acid (FA) from aqueous solutions and actual biomass hydrolysates by using the stepwise adsorption method was investigated for the first time. The carbon molecular sieve was used as the adsorbent for FA and microporous activated carbon was used as the adsorbent for LA according to the steric hindrance effect of the pore channels and the difference in molecular diameter of FA and LA. The adsorption data of LA and FA onto their respective adsorbents were measured and numerically analyzed by adopting batch adsorption experiment and fixed-bed column methods. In the study of static adsorption equilibrium experiment, the Langmuir equation fitted the data of LA adsorption on activated carbon, while the Freundlich equation fitted well the adsorption data of FA adsorption on carbon molecular sieve. In the kinetic study, the LA adsorption on activated carbon and FA adsorption on carbon molecular sieve confirmed the PSO model. Moreover, the effect of various conditions on fixed-bed column adsorption progress was investigated, which indicated that the adsorption property improved with feed flow rate, column length, temperature decreasing and initial concentration increasing. The Yoon-Nelson model was adopted to predict and analyze the whole process of adsorption breakthrough and consistent well with the experimental data. The separation of LA and FA was realized by continuous fractional adsorption.
查看更多>>摘要：In this paper, a novel identification method of piecewise affine (PWA) model for batch processes based on constrained clustering technique is proposed. In traditional clustering-based identification approaches, data classification and region partition are performed individually so that inseparable problem usually occurs in the partition phase. The proposed method uses a constrained K-means clustering algorithm to simultaneously perform both data classification and region partition, which is accomplished by imposing the complete and non-overlapping partition constraints into the clustering optimization problem. We employ a greedy iterative approach combined with the golden section search to efficiently solve the constrained clustering problem. This method can greatly improve the accuracy of the identified PWA model. Finally, we demonstrate the effectiveness of the proposed identification method.
查看更多>>摘要：This study aims to reveal the complex thermal decomposition processes in a pilot-scale pyrolysis furnace for recycling solid waste Mg(NO3)2.2H2O produced in nitric acid leaching process of laterite nickel ore, by using CFD method. Specifically, an integrated mathematical model combining the gas-particle flow and the thermal decomposition reaction as well as the heat, mass transfer between gas and particle was developed based on the Euler-Lagrange method. And then, the developed model was used to study the flow characteristics of the gas and particle and the thermal decomposition processes for Mg (NO3)2.2H2O in the pyrolysis furnace. Furthermore, the effect of operating parameters (gas inlet temperature, mass flow rate and particle size of Mg(NO3)2.2H2O) on the performance of pyrolysis furnace (decomposition rate of Mg(NO3)2.2H2O) was studied. The results show that the developed model is reasonable. Increasing gas inlet temperature, decreasing mass flow rate and particle size of Mg(NO3)2.2H2O can effectively promote the decomposition rate of Mg(NO3)2.2H2O. Under the conditions of gas inlet temperature 1123 K, mass flow rate of Mg(NO3)2.2H2O 200 kg/h, and average particle size of Mg(NO3)2.2H2O 75 μm, the dehydration reaction mainly occurs in the furnace height of 11-8 m, while the denitration reaction mainly occurs in the furnace height of 10.5-1 m. The total decomposition rate of Mg(NO3)2.2H2O is 99.75%.
查看更多>>摘要：Fluid catalytic cracking (FCC) is a key unit in the petrochemical production process with frequently encountered abnormal conditions and great safety challenge due to its complex and harsh production environment. The prediction and early warning of abnormal conditions in FCC process is able to improve the safety and stability of production process and avoid the occurrence of severe accidents. In this paper, a data-driven and knowledge-based fusion approach (DL-SDG) is proposed for prediction and early warning of abnormal conditions in FCC process. Firstly, the key variable is identified as prediction target of the process through the calculation of centrality in complex network. Secondly, Spearman ranking correlation coefficient is used for the selection of feature variables to reduce the input data dimension and improve the prediction accuracy of the deep learning (DL) model. Then, the long short-term memory network with attention mechanism and convolution layer is applied to predict the future trend of the key variable. Finally, the signed directed graph (SDG) model deduces the propagation path of abnormal conditions based on the predicted results of key variable to facilitate handling the anomaly in time. The proposed method was successfully applied to a typical FCC unit in a petrochemical enterprise with an excellent performance.
查看更多>>摘要：Sodium borohydride (NaBH4) is regarded as the most viable chemical for hydrogen production via hydrolysis thanks to its high theoretical hydrogen content, possible hydrogen evolution even at a low operation temperature, and producing environmentally-friendly products. However, the engineering of a high-performance catalyst is still needed to boost the kinetics of hydrolysis. Herein, nickel and cobalt decorated three-dimensional graphene (Ni-Co@3DG) nanostructure was fabricated via facile production pathway and successfully employed as the catalyst in the NaBH4 hydrolysis reaction for the first time. The influence of the different parameters, including reaction temperature, NaBH4 concentration, and catalyst loading, were examined to determine the optimum operating conditions for efficient hydrogen production. Additionally, this work differed from other works since the performance of the different artificial neural network (ANN) models were evaluated to find out the optimal ANN architecture to forecast the H2 production rate. The physicochemical characterizations offered the fabricated nanocatalyst had a large specific surface area (885 m~2.g~(-1)), and uniformly distributed Ni-Co bimetallic alloys, thereby enhancing the electrochemically active surface area for hydrolysis of NaBH4. The findings proved the superior catalytic activity of Ni-Co@ 3DG towards NaBH4 hydrolysis (initial concentration of 0.5 M) with the hydrogen production rate of 82.65 mmol. min~(-1) .g_(cat) at 25 °C, and catalyst loading of 0.05 g. The reusability evaluations revealed that the Ni-Co@3DG catalyst could retain 95.96% of its initial activity after five successive utilizations. The computational results demonstrated that the best performance metrics were obtained for the single-layer ANN model consisting of 15 neurons in the hidden layer trained using the Bayesian Regulation backpropagation algorithm with the tansig-purelin transfer function combination in the hidden and output layers, respectively. The results demonstrated the ANN forecasted data and experimental results were in accordance, implying the optimized ANN architecture could be utilized for the prediction of the H2 production rate of the catalyst.
查看更多>>摘要：The transition towards more sustainable industrial processes implies proposing alternative technologies to help resolving the environmental issues attributed to the industrial sector. This paper presents some aspects of the microwave-assisted technology which, if correctly applied from the R&D phase and up to the industrial scale, may lead to significant savings in energy consumption, process time and environmental remediation connected with industrial processing and process intensification. This article is intended to the development of a more detailed knowledge of the specific elements of the microwave technology and of the practical issues associated with processing using microwaves as to enable a better understanding of microwave-assisted processes and what it takes to scale them up.
查看更多>>摘要：To find a method for efficient removal and conversion of inorganic nitrogen compounds in three reduction systems, which are the sponge iron (s-Fe~0) , the sponge iron + biochar (s-Fe~0/BC) micro-electrolysis system and the sponge iron + biochar + manganese sand (s-Fe~0/ BC/MS)-enhanced micro-electrolysis system, the studies have been completed on the conditions of different material ratios and initial pH. When the initial pH is 7, the nitrate removals reached to 7.6%, 61.5% and 80.3%, the nitrogen ratio of products reached to 5.8%, 22.4% and 38.3% respectively in s-Fe~0, s-Fe~0/BC (3:1) and s-Fe~0/BC/MS (6:2:1) systems. The s-Fe~0/BC/MS system was the best at nitrate removal over a wide pH range (2-12). At the same time, the nitrogen selectivity in the s-Fe~0/BC/MS system was always better than that in other two systems. The X-ray photoelectron spectroscopy (XPS) results showed that the addition of manganese sand could enhance the ratio of Fe3O4 in the sponge iron surface oxide, reduce the passivation of the sponge iron surface and accelerate the electron transfer rate. As a catalyst for the corrosion of sponge iron, manganese sand can increase the corrosion of sponge iron and enhance the micro-electrolysis role between iron and carbon.
查看更多>>摘要：Conjugating peptides with alkyl tails and/or polymer chains to form peptide amphiphiles (PAs) allows self-assembly of PA together with other amphiphilic molecules to nanos-tructures for better peptide stability, longer blood circulation time, and facilitated cell uptake. The morphological transformation of the nanostructures significantly affects the pharmacokinetics and efficacy of the bioactive peptide. We report here the systematical study of the micelle morphological transformation in a ternary system consisting of a phospholipid, a PEGylated lipid, and a model PA (Myr-M3mP6, formed by attaching the novel anti-platelet peptide M3mP6 with the myristoyl group). The size and morphology of the self-assembled nanostructures were characterized by using dynamic light scattering and liquid cell - scanning transmission electron microscopy (LC-STEM). The morphologies of the self-assembled structures are mapped to a phase diagram with three coordinates denoted as the molar percentages of the PEGylated lipid, phospholipid, and Myr-M3mP6. The results provide a guidance for PA lipid formulation design and optimization. In addition, the effect of mixing kinetics is evaluated and a scalable process is developed for the potential of continuous, mass production of the stable micelles with the targeted morphology, size, and peptide loading.
查看更多>>摘要：This paper presents a computational study of the motion of inertia-less particles in the vicinity of freely rising bubbles of carbon dioxide that dissolve into the suspension. The purpose is to assess the extent of particle motion due to diffusiophoresis that is caused by ion concentration gradients, in this case protons and bicarbonate ions. Calculations are reported for spherical bubbles with diameters from 10 to 100 μm. Particle trajectories are computed for bubbles with slip and no slip surfaces, which (respectively) represent the extremes of a high purity system and a contaminated system in which surfactants fully immobilise the surface. The extent of particle motion towards or away from the bubbles (depending on the sign of the diffusiophoretic mobility) is quantified. Particle motion due to removal of dissolved carbon dioxide from a suspension into air bubbles is also considered. In the cases where particles are attracted to the bubbles, some particle trajectories reach the surface of the bubble. The results suggest that this mechanism could therefore be exploited to extend the use of flotation to separate smaller particles.
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