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The produced water-containing polymer brings new challenges to oil-water separation in oilfield production, yet separators with coalescing plates to remove free water have been playing an active role. In this paper, the flow-field characteristics of polymer-laden produced water in a separator with coalescing plates are analyzed using computerized mathematical methods to investigate the effects with a water content of 55%, 70%, and 85%, flow rate of 3500 m3/d, 4800 m3/d, and 6000 m3/d, and duration time of 20 min, 40 min, and 60 min on flow-field properties and separating efficiency are studied. The results show that the separating efficiency is positively correlated with water content and duration time, and duration time has the greatest improvement to the separating efficiency, but the enhancement of flow rate may reduce the separating efficiency. It is also observed that the separation efficiency of free-water reached 70.9% and the water content at the oil outlet of the separator reached 20.4% at a duration time of 60 min, when the contained polymer concentration and water content in the oil-water mixture are 500 mg/L and 70%, respectively.

Mussel-inspired surface chemistry is recognized as a simple, efficient, and mild surface modification method and has become a research hotspot in many fields. In this study, polyethylenimine/dopamine was coated on the surface of SBA-15 using a co-deposition method, making it possible to immobilize naringinase with high activity and operation stability. The optimal modification and immobilization conditions as well as enzyme properties were investigated. The naringinase activity can reach up to 753.78 U/g carrier, which was much higher than those of the previous works. Besides, the residual naringinase activity still kept 78.91% of the initial activity after one month of storage and maintained 60.79% after 8 cycles. Therefore, the strategy of mussel-inspired enzyme immobilization could be recognized as a promising and universal enzyme immobilization method, with the advantages of high relative enzyme activity, enzyme carrying rate, enzyme activity recovery rate, and good reusability and storage stability.

Integrated methods are used in the modification of trajectory, including improved perturbation impact point deviation prediction, adaptive proportional guidance and adaptive proportional differential guidance, thus improving the firing accuracy of guided mortar shell. The six degrees of freedom of both the trajectory model and the control model were established, and their guidance laws were designed based on the three guidance schemes. Firstly, the perturbation impact point deviation prediction method is improved by setting up a discrimination factor in the rising phase of trajectory based on the principle of traditional perturbation impact point deviation prediction method and in combination with the trajectory characteristics of guided mortar, which further improves the correction efficiency. The adaptive proportional guidance law is designed in the longitudinal plane, while the adaptive proportional differential guidance law is designed in the transverse plane due to the fact that the constant proportional coefficient in the proportional guidance law does not conform to the requirements of actual trajectory. In this paper, Monte Carlo simulation method and ammunition flight test are used to verify the designed guidance law, and the simulation results illustrate that the integrated guidance method is both reasonable and effective. As for the error of the guidance tool and actuator, the method is available for the reduction of impact point deviation and the improvement of accuracy. The circular error probability (CEP) not under control decreases from 126.317m to 10.1284m when control is applied. Besides, the feasibility of the designed guidance law is verified by the flight tests of guided mortar projectile in large, medium and small range respectively from the perspective of engineering application. It can be seen from the test trajectory impact point data that the guidance law is available for the effective correction of trajectory deviation in the actual hardware operation and site environment with reliable guidance. As the outcome, the CEP reaches 10.86m, and the impact point deviation of some guided missiles is within 2m.

The hydrogenation of carbon dioxide (CO2) is one of important processes to effectively convert and utilize CO2, which is also regarded as the key step at the industrial methanol synthesis. Water is likely to play an important role in this process, but it still remains elusive. To systematically understand its influence, here we computationally compare the reaction mechanisms of CO2 hydrogenation over the stepped Cu(211) surface between in the absence and presence of water based on microkinetic simulations upon density functional theory (DFT) calculations. The effects of water on each hydrogenation step and the whole activity and selectivity are checked and its physical origin is discussed. It is found that the water could kinetically accelerate the hydrogenation on CO2 to COOH, promoting the reverse water gas shift reaction to produce carbon monoxide (CO). It hardly influences the CO2 hydrogenation to methanol kinetically. In addition, the too high initial partial pressure of water will thermodynamically inhibit the CO2 conversion.

Alkali/surfactant/polymer (ASP) flooding process is proven to be vitally effective for enhancing oil recovery (EOR) in the oil industry. However, foaming behavior is generated by the breakthrough of chemical agents in the produced liquid and is increasingly concerned as a terrible problem during production. A set of experiments were recently performed to investigate the effects of foaming properties of ASP flooding produced liquid. The factors affecting foaming capacity and foam stabilization were discussed, and the differences in foaming properties of produced liquid between the strong base and weak base ASP flooding were first compared. The results indicated that in addition to temperature and pressure, the concentrations of chemical agents in the produced liquid were responsible for the foaming properties and foam stabilization. The foaming capacity could enhance 3–7% at 45 °C compared with a lower temperature of 35 °C. The average comprehensive index of the foam could increase from 2.2 × 105 at 29 psi to 2.5× 105 at 73 psi. The regularity of Plateau borders was highlighted at higher pH and surfactant concentration and thus facilitated the foam stabilization. The liquid film thickened and its shape expanded to the state of maintaining foam stabilization with the increase of polymer concentration. Furthermore, the foaming behavior of produced liquid in strong base ASP flooding production is much-more troublesome than that in weak base ASP flooding production. This study is significant in that it further supports the development of efficient treatment technology for produced liquid in the oilfield.

The specific scheme of two-loop attitude control system was formulated based on the design principle of attitude control system with the damping circuit as the inner loop and the overload control loop as the outer one. As required by the formulated scheme, the damping loop is designed firstly, of which the stability and the dynamic response quality are improved by adjusting the damping coefficient and the addition of the correction network. After that, the design and optimization of the overload control loop are implemented. With the same design method, gain coefficient and correction network are introduced to reduce overshoot of overload response curve, shorten response time and improve efficiency. Besides, the validity of the overload control loop is tested with square wave as input to reflect the real overload command signal.

Polyethyleneimine-modified Fe

A bioadsorbent composed of magnetic silica nanoparticles encapsulated by chitosan microspheres was prepared by the emulsion cross-linking method, and it was then modified with quaternary ammonium groups by reaction with ethylenediamine and glycidyl trimethylammonium chloride. Characterization of the bioadsorbent indicated that it was highly acid resistant and magnetically responsive. The bioadsorbent was then used to remove Cr(VI) from acidic aqueous solution. The results of batch experiments indicated that the optimal pH value was 2.5, and the adsorbent exhibited low pH dependence. The maximum adsorption capacity was 233.1 mg/g at pH 2.5 and 25 degrees C, and the equilibrium time was determined to be 40-120 min depending on the initial Cr(VI) concentration. The adsorbent could be effectively regenerated using a mixture of 0.3 mol/L NaOH and 0.3 mol/L NaCl with a desorption efficiency of 95.6%, indicating high reusability. In conclusion, the bioadsorbent shows potential for Cr(Vl) removal from acidic wastewater. (C) 2016 Chinese Society of Particuology and Institute of Process Engineering, Chinese Academy of Sciences. Published by Elsevier B.V. All rights reserved.

The modification of the surface of silica gel to prepare hydrophilic chromatographic fillers has recently become a research interest. Most researchers have grafted natural sugar-containing polymers onto chromatographic surfaces. The disadvantage of this approach is that the packing structure is singular and the application scope is limited. In this paper, we explore the innovative technique of grafting a sugar-containing polymer, 2-gluconamidoethyl methacrylamide (GAEMA), onto the surface of silica gel by atom transfer radical polymerization (ATRP). The SiO2-g-GAEMA with ATRP reaction time was characterized by Fourier infrared analysis, Thermogravimetric analysis (TGA), and elemental analysis. As the reaction time lengthened, the amount of GAEMA grafted on the surface of the silica gel gradually increased. The GAEMA is rich in amide bonds and hydroxyl groups and is a typical hydrophilic chromatography filler. Finally, SiO2-g-GAEMA (reaction time = 24 h) was chosen as the stationary phase of the chromatographic packing and evaluated with four polar compounds (uracil, cytosine, guanosine, and cytidine). Compared with unmodified silica gel, modified silica gel produces sharper peaks and better separation efficiency. This novel packing material may have a potential for application with highly isomerized sugar mixtures.

In this paper, gas-assisted magnetic separation (GAMS), a technique that combines magnetic separation with flotation, was investigated for the potential large-scale separation of proteins. The GAMS process includes adsorption of target proteins and magnetic separation to recover protein-loaded magnetic particles from the dilute biosuspension with the assistance of bubbles. Microsized ethylenediamine-functionalized poly(glycidyl methacrylate) superparamagnetic microspheres (MPMs) and bovine serum albumin (BSA) were used as a model system. The feasibility of GAMS for capturing BSA-loaded MPMs from an appropriate medium was shown. High recovery of BSA-loaded MPMs was obtained by simple adjustment of the initial solution pH without extra detergents and antifoaming agents. The GAMS conditions were consistent with the adsorption conditions, and no proteins were desorbed from the MPMs during this process. Under the optimal conditions, the separation rate and recovery percentage reached 410 mL/min and 98% in 0.61 min, respectively. Conformational changes of BSA during the GAMS process were investigated by fluorescence spectroscopy and circular dichroism spectrometry. (C) 2015 Chinese Society of Particuology and Institute of Process Engineering, Chinese Academy of Sciences. Published by Elsevier B.V. All rights reserved.

A novel method combining a solid base catalyst (Na2SiO3) and a cheaper ionic liquid (1-butyl-3-methylimidazolium, [BMIm]Cl), was proposed and used for the pretreatment of lignocellulosic biomass such as spruce, willow and soybean straw. The addition of calcined Na2SiO3 in [BMIm]Cl pretreatment significantly destroyed the recalcitrant cell wall architecture, removed lignin and hemicellulose, decreased cellulosic crystallinity, and strongly broke lignocellulosic morphology, which enhanced the biomass accessibility for enzymatic hydrolysis. The combined pretreatment seemed more suitable for willow and soybean straw than spruce. According to single factor experiments, the maximum enzymatic hydrolysis yield and glucose yield of willow were 98.6% and 39.5 g/100 g biomass, respectively, 2.6-fold of single pretreatment with [BMIm]Cl.

Two novel strongly basic magnetic adsorbents, quaternary ammonium-modified polystyrene and chitosan magnetic microspheres (Pst-MIMCl and CTS-GTMAC), were prepared using the in situ coprecipitation and emulsion cross-linking methods under mild conditions, with features of strong magnetic responsiveness and high quaternary ammonium group contents. The Cr(VI) adsorption/desorption properties and mechanisms of strongly and weakly basic magnetic adsorbents were compared through simulated wastewater. The strongly basic adsorbent exhibited low pH dependence, and the main adsorption mechanism was ion exchange. The weakly basic adsorbent exhibited high pH dependence, and the major adsorption mechanism was electrostatic attraction. Besides, the strongly basic adsorbent required higher desorption conditions than the weakly basic adsorbent owing to the difference of the desorption mechanisms. Furthermore, the removal selectivity of the strongly and weakly basic magnetic adsorbents was estimated by the chromium plating wastewater. The results demonstrated that the strongly basic magnetic adsorbents exhibited higher selectivity than the weakly basic magnetic adsorbents. In addition, the Pst-MIMCl was selected as the optimal magnetic adsorbent for Cr(VI) recovery from wastewater, with the advantages of strongly magnetic responsiveness, wide pH applicable range, high removal efficiency, high adsorption selectivity and good reusability.

In this study, a method combined low-field magnetic separation (MS) with flotation, named as gas-assisted magnetic separation (GAMS), was applied for the removal of cadmium from wastewater. With bubbles' assistance, the speed of magnetic separation can be greatly improved and the limitation of magnetic force on the capture distance can be overcome. Thus, GAMS is much more efficient and easily scalable than MS. In this work, ethanediamine-modified magnetic poly-(glycidyl methacrylate) microspheres (EMPs) were synthesized as the adsorbent for cadmium. And GAMS was used to separate the EMPs and Cd-loaded EMPs. The effects of pH, gas flow rate, concentration of Cd-loaded EMPs, loading volume, and ionic strength on GAMS were investigated. The results indicated that the EMPs and Cd-loaded EMPs could be rapidly and remotely removed from the solution with GAMS. And the separation time decreased with the increase of gas flow rate and NaCl concentration, but grew with the rise of pH value, loading volume, and concentration of the EMPs. This work showed the great potential of GAMS in the area of water treatment. (C) 2015 Elsevier B.V. All rights reserved.

A novel Heck reaction catalyst consisting of a palladium(II) complex of meso-tetra(p-hydroxyphenyl)porphyrin (MTP) and cross-linked chloromethylated polystyrene microspheres (PMs) was successfully prepared via covalent ether bonds between the chloride groups in the PMs and the hydroxyl groups in MTP. The catalyst was characterized using scanning electron microscopy, Fourier-transform infrared spectroscopy, and inductively coupled plasma atomic emission spectroscopy (ICP-AES). This polystyrene-supported palladium-complex was an efficient heterogeneous catalyst for cross-coupling of aryl iodides with ethyl acrylate. The reaction of iodobenzene and ethyl acrylate under N-2 at 100 degrees C and a catalyst concentration of 0.1% gave a gas chromatography product yield of 99.8%, which is much higher than that achieved using a free palladium(II) complex of MTP as the catalyst (41.3%). The catalyst was recycled up to six times without significant loss of catalytic activity. These results suggest that the immobilized palladium(II)-MTP catalyst has potential applications in synthetic and industrial chemistry. (C) 2014 Chinese Society of Particuology and Institute of Process Engineering, Chinese Academy of Sciences. Published by Elsevier B.V. All rights reserved.

The chemical reduction of carbon dioxide (CO2) has always drawn intensive attentions as it can not only remove CO2 which is the primary greenhouse gas but also produce useful fuels. Industrial synthesis of methanol utilizing copper-based catalysts is a commonly used process for CO2 hydrogenation. Despite extensive efforts on improving its reaction mechanism by identifying the active sites and optimizing the operating temperature and pressure, it is still remains completely unveiled. The selectivities of CO2 electroreduction at copper electrode could mainly be towards carbon monoxide (CO), formic acid (HCOOH), methane (CH4) or ethylene (C2H4), which depends on the chemical potentials of hydrogen controlled by the applied potential. Interestingly, methanol could hardly be produced electrochemically despite utilizing metallic copper as catalysts in both processes. Moreover, the mechanistic researches have also been performed aiming to achieve the higher selectivity towards more desirable higher hydrocarbons. In this work, we review the present proposals of reaction mechanisms of copper catalyzing CO2 reduction in industrial methanol synthesis and electrochemical environment in terms of density functional theory (DFT) calculations, respectively. In addition, the influences of the simulation methods of solvation and electrochemical model at liquid-solid interface on the selectivity are discussed and compared.

A novel adsorbent, polyethylenimine-functionalized poly(vinyl alcohol) (PVA-PEI) magnetic microspheres, was prepared by a process involving: (1) synthesis of magnetic poly(vinyl acetate) microspheres (PVAc) using modified suspension polymerization, (2) preparation of PVA magnetic microspheres by methanolysis of PVAc and (3) two-step reaction with epichlorohydrin and polyethylenimine to yield amino groups. Magnetic measurement illustrated that the PVA-PEI microspheres were superparamagnetic, with a high saturated magnetization of 36.7 emu/g. Once generated, the PVA-PEI microspheres were used as adsorbent to remove Cr(VI) from an aqueous solution. The results demonstrated that the optimized pH value was observed at 2.0. The adsorption rate was extremely fast and the equilibrium was reached within 8 min. The adsorption isotherms of the adsorbent were preferably fitted to the Langmuir model, with the maximum adsorption capacity of 88.4 mg/g at 25 degrees C. Thermodynamic parameters indicated the spontaneous and exothermic nature of adsorption. In addition, the Cr(VI) ions were successfully eluted by a 0.1 mol/L NaOH solution, with the desorption efficiency of over 99%, and the adsorbent exhibited a good reusability. These results implied that the PVA-PEI microspheres should be considered as a potential adsorbent to remove Cr(VI) from wastewater. (C) 2014 Elsevier B.V. All rights reserved.

The non-uniform distribution of the electrode potential within submerged cavities is an important consideration in understanding the mechanisms of various electrochemical processes. In the present paper, the actual potential distributions inside cavities have been measured under conditions of gas evolving and oxide film formation on titanium electrodes in neutral media using scanning micro-reference electrode technique. The experimental results show that the bubbles motion and films growth inside cavities which differ greatly from that on flat or vertical electrodes, exert substantial effects on the potential distribution characteristic. The anomalous high-amplitude of potential variation and the unexpected local potential increase in the bottom part of cavities caused by the coalescing bubble covering cavities has been experimentally revealed. Moreover, under oxide film formation, once the completed oxide film is generated, the potential and current will be redistributed inside cavities. By improving the upper surface coarseness, a uniform potential distribution inside cavities can be achieved.

Polyethylenimine-grafted poly(glycidyl methacrylate) (PGMA-PEI) microspheres were prepared using the dispersion polymerization method and a two-step reaction with ethylenediamine (EDA) and polyethylenimine (PEI). The PGMA-PEI microspheres were then characterized by Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) and tested for their ability to remove hexavalent chromium (Cr(VI)) from an aqueous solution in batch tests. The results demonstrated that Cr(VI) adsorption depended significantly on pH. The optimized pH value for the Cr(VI) adsorption was 2.0. The adsorption isotherms of PGMA-PEI microspheres with Cr(VI) fit the Langmuir model. The maximum adsorption capacities were 460.83, 485.44 and 505.05 mg g(-1) for PGMA-PEI600, PGMA-PEI1800 and PGMA-PEI10,(172) microspheres, respectively. The adsorption reached equilibrium within 10min and the experimental data fit the pseudo-second-order model. The obtained thermodynamic parameters (Delta G(0), Delta H-0 and Delta S-0) showed that the adsorption of Cr(VI) was an endothermic and spontaneous process. Competition from coexisting ions of K+, Na+, Ca2+, Cu2+, Cl-, NO3-, H2PO4-, and HPO42- was insignificant except SO42-. The regeneration study revealed that PGMA-PEI microspheres could be repeatedly used with no significant loss of adsorption efficiency. (C) 2014 Elsevier B.V. All rights reserved.

A novel amino-functionalized magnetic cellulose composite was prepared by a process involving: (1) synthesis of magnetic silica nanoparticles using the co-precipitation method followed by the hydrolysis of sodium silicate, (2) coating with cellulose through the regeneration of cellulose dissolved in 7 wt% NaOH/12 wt% urea aqueous solvent, (3) grafting of glycidyl methacrylate using cerium initiated polymerization and (4) ring-opening reaction of epoxy groups with ethylenediamine to yield amino groups. Once generated, the resulting composite was tested for its ability to remove Cr(VI) from an aqueous solution in batch experiments. The results demonstrated that Cr(VI) adsorption was highly pH dependent. The optimized pH value was 2.0. The adsorption isotherms of the adsorbent fit the Langmuir model, with the maximum adsorption capacity of 171.5 mg/g at 25 degrees C. The adsorption rate was considerably fast, and the adsorption reached equilibrium within 10 min. The obtained thermodynamic parameters showed that the adsorption of Cr(VI) onto the adsorbent was an exothermic and spontaneous process. In addition, the Cr(VI) ions could be effectively desorbed using a 0.1 mol/L NaOH solution and the adsorbent exhibited a good reusability. The composite material should be a promising adsorbent for Cr(VI) removal, with the advantages of high adsorption capacity, rapid adsorption rate and convenient recovery under magnetic field. (C) 2013 Elsevier B.V. All rights reserved.

Micron-sized polyethylenimine-functionalized poly(glycidyl methacrylate) superparamagnetic microspheres (m-PGMA-PEI) were prepared by a process involving: (1) synthesis of PGMA microspheres using the dispersion polymerization method; (2) ring-opening reaction of epoxy groups on PGMA microspheres with ethylenediamine (EDA) to yield amino groups; (3) in situ coprecipitation of Fe3O4 nanoparticles into the pores of microspheres; (4) Michael addition of amino groups with methyl acrylate (MA) to yield ester groups; and (5) amidation of the terminal ester groups with polyethylenimine (PEI). Once generated, the resulting m-PGMA-PEI microspheres were tested for their ability to remove Cr(VI) from an aqueous solution in batch experiments. The results demonstrated that Cr(VI) adsorption was significantly pH dependent. The optimized pH value was 2.0. The adsorption isotherm of the adsorbent fit the Langmuir model, with the maximum adsorption capacity of 492.61 mg/g. The Cr(VI) adsorption rate was rapid, and the adsorption reached equilibrium within 15 min. The thermodynamic parameters (Delta G(0), Delta H-0, Delta S-0) demonstrated that the adsorption process was endothermic and spontaneous in nature. The presence of the coexisting anions involving Cl-, NO3-, H2PO4- and HPO42- had no remarkable influence on Cr(VI) adsorption except SO42-. The regeneration study proved that the m-PGMA-PEI microspheres could be repeatedly utilized with no significant loss of adsorption efficiency. (C) 2013 Elsevier B.V. All rights reserved.

The chemical reduction of carbon dioxide (CO2) has always drawn intensive attentions as it can not only remove CO2 which is the primary greenhouse gas but also produce useful fuels. Industrial synthesis of methanol utilizing copper-based catalysts is a commonly used process for CO2 hydrogenation. Despite extensive efforts on improving its reaction mechanism by identifying the active sites and optimizing the operating temperature and pressure, it is still remains completely unveiled. The selectivities of CO2 electroreduction at copper electrode could mainly be towards carbon monoxide (CO), formic acid (HCOOH), methane (CH4) or ethylene (C2H4), which depends on the chemical potentials of hydrogen controlled by the applied potential. Interestingly, methanol could hardly be produced electrochemically despite utilizing metallic copper as catalysts in both processes. Moreover, the mechanistic researches have also been performed aiming to achieve the higher selectivity towards more desirable higher hydrocarbons. In this work, we review the present proposals of reaction mechanisms of copper catalyzing CO2 reduction in industrial methanol synthesis and electrochemical environment in terms of density functional theory (DFT) calculations, respectively. In addition, the influences of the simulation methods of solvation and electrochemical model at liquid-solid interface on the selectivity are discussed and compared.

A novel, bioadsorbent material of polyethylenimine-modified magnetic chitosan microspheres enwrapping magnetic silica nanoparticles (Fe3O4-SiO2-CTS-PEI) was prepared under relatively mild conditions. The characterization results indicated that the adsorbent exhibited high acid resistance and magnetic responsiveness. The Fe3O4 loss of the adsorbent was measured as 0.09% after immersion in pH 2.0 water for 24 h, and the saturated magnetization was 11.7 emu/g. The introduction of PEI obviously improved the adsorption capacity of Cr(VI) onto the adsorbent by approximately 2.5 times. The adsorption isotherms and kinetics preferably fit the Langmuir model and the pseudo-second-order model. The maximum adsorption capacity was determined as 236.4 mg/g at 25 degrees C, which was much improved compared to other magnetic chitosan materials, and the equilibrium was reached within 60 to 120 min. The obtained thermodynamic parameters revealed the spontaneous and endothermic nature of the adsorption process. Furthermore, the Cr(VI)-adsorbed adsorbent could be effectively regenerated using a 0.1 mol/L NaOH solution, and the adsorbent showed a good reusability. Due to the properties of good acid resistance, strong magnetic responsiveness, high adsorption capacity, and relatively rapid adsorption rate, the Fe3O4-SiO2-CTS-PEI microspheres have a potential use in Cr(VI) removal from acidic wastewater. (C) 2015 Wiley Periodicals, Inc.