Lei Shao

Beijing University of Chemical Technology, Peping, Beijing, China

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Publications (100)245.45 Total impact

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    ABSTRACT: This work investigated the degradation of methyl orange by ozone in the presence of ferrous and persulfate ions (O3/Fe(2+)/S2O8(2-)) in a rotating packed bed. The effects of various operating parameters such as initial pH, rotational speed, gas-liquid ratio, ozone inlet concentration and reaction temperature on the degradation rate of methyl orange were studied with an aim to optimize the operation conditions. Results reveal that the degradation rate increased with an increase in rotational speed, gas-liquid ratio and ozone inlet concentration, and reached a maximum at 25 °C and initial pH 4. Contrast experiments involving ozone and ferrous ions (O3/Fe(2+)) were also carried out, and the results show approximately 10% higher degradation rate and COD removal in the O3/Fe(2+)/S2O8(2-) process than in the O3/Fe(2+) process. Additionally, the intermediates of the degradation process were analyzed to ascertain the degradation products.
    No preview · Article · Mar 2016 · Chemosphere

  • No preview · Article · Dec 2015 · Water Science & Technology
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    ABSTRACT: The preparation of basic magnesium carbonate (BMC) by the simultaneous absorption of NH3 and CO2 into MgCl2 solution in a rotating packed bed (RPB) was studied. The influences of the operating conditions including the rotation speed, liquid volumetric flow rate, gas volumetric flow rate, reaction temperature and initial concentration of MgCl2 solution on the crystal structure and morphology of BMC were investigated. The scanning electron microscope image of the as-prepared BMC showed that the BMC particles had a unique rose-like structure with a mean size of 5.3 μm, a petal thickness of 20 nm and a particle size distribution mainly in the range of 2.8–7 μm.
    No preview · Article · Nov 2015 · Powder Technology
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    ABSTRACT: In this study, simulated coking wastewater was treated by the O3/Fenton process in a rotating packed bed (RPB) and the results were compared with those by the O3 process. Contrast experiments indicated that the degradation rates of phenol, aniline, quinoline and NH3-N in the wastewater reached 100%, 100%, 95.68% and 100% respectively under the optimum operating conditions in the O3/Fenton process and were much higher than those in the O3 process. The BOD5/COD value of the simulated coking wastewater treated in the O3/Fenton process reached 0.46 and was 135% higher than that in the O3 process. The degradation pathways of phenol, aniline, quinoline and NH3-N in the simulated coking wastewater were also discussed. The results indicated that a combination of the advanced oxidation processes and the RPB can enhance the treatment efficiency of coking wastewater.
    No preview · Article · Oct 2015 · RSC Advances
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    ABSTRACT: A rotor-stator reactor (RSR) is a novel multiphase device which can greatly intensify mass transfer and micromixing processes. However, liquid flow in the reactor is still not very clear. In this work, two different liquids, water and water-in-oil (W/O) microemulsion were used to study liquid flow in the RSR. A high-speed camera was employed to obtain continuous and clear images of liquid flow, and the effects of various operating conditions such as the number of rotor-ring/stator-ring layers, the rotation speed and the liquid volumetric flow rate on the average diameter as well as the average velocity of liquid droplets and the average angle of velocity vector were investigated. Correlations were established to predict the average diameter and the average velocity of the liquid droplets, and the predicted values were found to be in agreement with the experimental values with deviations generally within 15%.
    No preview · Article · Sep 2015 · Chemical Engineering Science
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    ABSTRACT: In industrial gas processing, there is an increasing interest in gas absorption processes for the selective removal of H2S from gas streams with a high CO2/H2S ratio. In this work, the selective absorption of H2S from a gas mixture with CO2 into N-methyldiethanolamine (MDEA) in a microporous tube-in-tube microchannel reactor (MTMCR) was studied. A high H2S removal efficiency of 99.85% could be achieved. The effects of various parameters such as MDEA concentration, liquid and gas flow rates, gas–liquid ratio, absorbent temperature, mean micropore size and annular channel width of MTMCR on H2S removal efficiency and selectivity were explored. The results indicated that MDEA concentration, liquid and gas flow rates had significant influence on H2S removal efficiency and selectivity. With the increase of MDEA concentration and liquid flow rate, H2S removal efficiency increased while selectivity decreased. Increasing gas flow rate resulted in H2S removal efficiency decrease and the selectivity increase. The smaller micropore size and annular channel width led to higher H2S removal efficiency and lower selectivity. Furthermore, the micropore size had a bigger effect on H2S selective removal process than the annular channel width. The results obtained imply a great potential for MTMCR applied to the selective absorption of H2S.
    No preview · Article · Sep 2015 · Chemical Engineering and Processing
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    ABSTRACT: Loading functional small molecules into nano-thin films is fundamental to various research fields such as membrane separation, molecular imprinting, interfacial reaction, drug delivery etc. Currently, a general demand for enhancing the loading rate without affecting the film structures exists in most infiltration phenomena. To handle this issue, we have introduced a process intensification method of a high gravity technique, which is a versatile energy form of mechanical field well-established in industry, into the investigations on diffusion/infiltration at the molecular level. By taking a polyelectrolyte multilayer as a model thin film and a photo-reactive molecule, 4,4'-diazostilbene-2,2'-disulfonic acid disodium salt (DAS), as a model small functional molecule, we have demonstrated remarkably accelerated adsorption/infiltration of DAS into a poly(allylamine hydrochloride) (PAH)/poly(acrylic acid) (PAA) multilayer by as high as 20-fold; meanwhile, both the film property of the multilayer and photoresponsive-crosslinking function of DAS were not disturbed. Furthermore, the infiltration of DAS and the surface morphology of the multilayer could be tuned based on their high dependence on the intensity of the high gravity field regarding different rotating speeds. The mechanism of the accelerated adsorption/infiltration under the high gravity field was interpreted by the increased turbulence of the diffusing layer with the thinned laminar boundary layer and the stepwise delivery of the local concentration gradient from the solution to the interior of the multilayer. The introduction of mechanical field provides a simple and versatile strategy to address the paradox of the contradictory loading amount and loading rate, and thus to promote applications of various membrane processes.
    No preview · Article · Jun 2015 · Soft Matter
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    ABSTRACT: The layer-by-layer (LbL) assembled multilayer has been widely used as good barrier film or capsule due to the advantages of its flexible tailoring of film permeability and compactness. Although many specific systems have been proposed for film design, there remains a challenge to develop a versatile strategy to control film compactness. We introduced the simple mechanical energy of a high gravity field to the LbL assembly process to tailor the multilayer permeability through adjusting film compactness. By taking poly-(diallyldimethylammonium chloride) (PDDA) and poly{1-4[4-(3-carboxy-4-hydroxyphenylazo)benzenesulfonamido]-1,2-ethanediyl sodium salt} (PAzo) as a model system, we investigated the LbL assembly process under a high gravity field. The results showed that the high gravity field introduced effectively accelerated the multilayer deposition process by 20-fold compared with conventional dipping assembly; the adsorption rate was positively dependent on the rotating speed of the high gravity equipment and the concentration of the building block solutions. More interestingly, the film compactness of the PDDA/PAzo multilayer prepared under the high gravity field increased remarkably with the growing rotational speed of the high gravity equipment, as demonstrated through comparisons of surface morphology, cyclic voltammetry curves and photo-isomerization kinetics of PDDA/PAzo multilayers fabricated through the conventional dipping method and through LbL assembly under a high gravity field, respectively. In this way, we have introduced a simple and versatile external form of mechanical energy into the LbL assembling process to improve film compactness, which should be useful for further applications in controlled ion permeability, anti-corrosion, and drug loading.
    No preview · Article · May 2015 · ACS Applied Materials & Interfaces
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    ABSTRACT: CeO2 nano-support was prepared by the reaction of water-in-oil microemulsion with NH3 gas in a rotor–stator reactor (RSR). The influences of different parameters including reaction temperature, rotation speed and final pH of the suspension on the properties of the CeO2 nano-support were investigated by BET and XRD. CeO2 nano-support with a diameter of about 5 nm, size distribution of 4–6 nm and specific surface area of 104 m2/g was obtained under the optimum operating conditions of reaction temperature of 40 °C, rotation speed of 800 rpm and final pH of the suspension of 11 and was deposited with Au for CO oxidation reaction. The results demonstrated that CeO2 nano-support prepared by the microemulsion-gas method in the RSR had a small particle size and narrow size distribution and showed high catalytic activity after it was deposited with Au. Full CO conversion was achieved at 115 °C by using the as-prepared Au/CeO2 catalyst.
    No preview · Article · Mar 2015 · Powder Technology
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    ABSTRACT: CdTe-based quantum dots (QDs) with high photoluminescence quantum yield (PL QY) were synthesized in a short time (less than 45 minutes). Mercaptosuccinic acid (MSA) was employed as a stabilizer and N2H4 as a growth promoter to accelerate the growth of CdTe and CdSexTe1-x QDs. Red-emitting CdTe QDs with PL QY of 25% were obtained and the highest PL QY reached 55%. CdSexTe1-x QDs with emission peak position of 518 nm to 750 nm was obtained. The rapid growth of the QDs depends on the interaction between MSA and Cd2+, and N2H4 plays a key role in accelerating the growth to a certain level. Thus, the QD particle size can be controlled by manipulating N2H4 concentration in the solution. A low N2H4 concentration seems feasible to obtain high-quality QDs.
    No preview · Article · Mar 2015 · New Journal of Chemistry
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    ABSTRACT: A gas-microemulsion reaction precipitation method was employed to prepare nano-Ce0.5Zr0.5O2 by absorption of NH3 into water-in-oil (W/O) microemulsion in a rotor–stator reactor . The effects of different operating conditions including final pH of the microemulsion, reaction temperature, initial Ce3+ and Zr4+ concentration, rotation speed, and gas–liquid volumetric ratio were investigated. Nano-Ce0.5Zr0.5O2 with an average diameter of about 5.5 nm, a specific surface area of 215.6 m2/g and a size distribution of 4–8 nm was obtained under the optimum operating conditions. The as-prepared nano-Ce0.5Zr0.5O2 was loaded with Au to prepare nano-Au/Ce0.5Zr0.5O2 catalyst which was subsequently used for CO oxidation test. CO conversion rate reached 100 % at room temperature, indicating high catalytic activity of the nano-Au/Ce0.5Zr0.5O2 catalyst.
    No preview · Article · Jan 2015 · Journal of Nanoparticle Research
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    ABSTRACT: In this study, simulated amoxicillin wastewater was treated by the O3/Fenton process in a rotating packed bed (RPB) and the results were compared with the Fenton process and the O3 followed by Fenton (O3 + Fenton) process. The chemical oxygen demand (COD) removal rate and the ratio of 5-day biological oxygen demand to chemical oxygen demand (BOD5/COD) in the O3/Fenton process were approximately 17% and 26%, respectively, higher than those in the O3 + Fenton process with an initial pH of 3. The COD removal rate of the amoxicillin solution reached maximum at the Fe(II) concentration of 0.6 mM, temperature of 25 °C, rotation speed of 800 rpm and initial pH of 3. The BOD5/COD of the amoxicillin solution increased from 0 to 0.38 after the solution was treated by the O3/Fenton process. Analysis of the intermediates indicated that the pathway of amoxicillin degradation in the O3/Fenton process was similar to that in the O3 + Fenton process. Contrast experiment results showed that amoxicillin degradation was significantly intensified in the RPB. Copyright © 2014 Elsevier Ltd. All rights reserved.
    Full-text · Article · Jan 2015 · Journal of Environmental Management
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    ABSTRACT: This article presents experimental and modelling studies on the absorption of NH3 into water in a rotor-stator reactor (RSR). The influences of operating parameters such as the rotation speed of rotor, liquid flow rate, and gas flow rate on the overall volumetric mass transfer coefficient (Kya) of NH3 were investigated. It was found that Kya increased with an increasing rotation speed, liquid flow rate, and gas flow rate. A correlation to predict the Kya of NH3 in the RSR was established and found to be in agreement with the experimental data with deviations within 10 %. A comparison was made between the Kya of NH3 in the RSR and RPB, and the result showed that Kya of NH3 in the RSR was 13 % higher than that in the RPB, thus signifying that the RSR has better intensification effect for mass transfer limited processes than the RPB.
    Preview · Article · Jan 2015 · The Canadian Journal of Chemical Engineering
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    ABSTRACT: This study was conducted to investigate the effect of inorganic salts on the mass-transfer coefficient of O3 and decolorization of azo dye (Acid Red 14, AR14) solution through ozonation in a microporous tube-in-tube microchannel reactor (MTMCR). The overall volumetric mass-transfer coefficient (KGa) of O3 in the MTMCR was deduced by material balance. The effects of different salts on the KGa of O3 and decolorization efficiency of the AR14 solution were studied, and results show that both were significantly affected by the inorganic salts. Although the KGa of O3 and the decolorization efficiency of AR14 increased with increasing salt concentration and pH, the effect of NaNO3 was much weaker than that of NaCl, Na2SO4, Na2CO3, and NaHCO3. The enhanced KGa of O3 and decolorization could be due to the generation of species with high oxidizing ability in the presence of the salts.
    No preview · Article · Dec 2014 · Industrial & Engineering Chemistry Research
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    ABSTRACT: End effect is a significant phenomenon in a rotating packed bed (RPB). The mass transfer accomplished in the end zone can be one magnitude higher than what is achieved in the bulk zone of the packing. In order to make full use of the end effect, a novel multiliquid-inlet rotating packed bed (MLI-RPB) was developed, which artificially created the extra end zones in the bulk zone along the radial direction of the rotor. The effective interfacial area (a) and liquid-side volumetric mass-transfer coefficient (kLa) of the MLI-RPB were measured using a system of CO2 chemisorption into NaOH solution. Mass-transfer experiments were also conducted in a traditional RPB with the same size as the MLI-RPB. Compared with the traditional RPB, higher values of a and kLa were obtained in the MLI-RPB, showing a great potential for the industrial applications.
    No preview · Article · Dec 2014 · Industrial & Engineering Chemistry Research
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    ABSTRACT: Erythorbic acid assistant synthesis of CdS quantum dots (QDs) was conducted by homogeneous mixing of two continuous liquids in a high-throughput microporous tube-in-tube micro-channel reactor (MTMCR) at room temperature. The effects of the micropore size of the MTMCR, liquid flow rate, mixing time and reactant concentration on the size and size distribution of CdS QDs were investigated. It was found that the size and size distribution of CdS QDs could be tuned in the MTMCR. A combination of erythorbic acid promoted formation technique with the MTMCR may be a promising pathway for controllable mass production of QDs.
    No preview · Article · Dec 2014 · Materials Research Bulletin
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    ABSTRACT: Absorption of NH3 into water-in-oil (W/O) microemulsion in a rotor-stator reactor (RSR) was investigated in this work. The microemulsion comprised triton X-100, 1-pentanol, cyclohexane and water while the gas phase was a mixture of NH3 and N2. Experiments were performed to study the mass transfer process between the gas and the microemulsion. The effects of water content on the physical properties of the microemulsion as well as the influences of operating conditions including water content of the microemulsion, rotation speed, liquid volumetric flow rate and gas volumetric flow rate on the mass transfer coefficient (Kya) were investigated. The results showed that the density and viscosity of the microemulsion increased with an increasing water content whereas the Henry's constant of the NH3-microemulsion system decreased. Kya increased with an increase in water content of the microemulsion, rotation speed, liquid volumetric flow rate and gas volumetric flow rate. A comparison of the Kya of NH3 in the RSR and in a packed tower showed that the Kya of NH3 in the RSR was 65% higher than that in the packed tower under the same operating conditions, thus revealing that the RSR has higher mass transfer efficiency than the packed tower.
    No preview · Article · Nov 2014 · Chemical Engineering and Processing
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    ABSTRACT: Rapid construction of layer-by-layer (LbL) self-assembled multilayers on non-planar substrates is challenging because most conventional LbL processes are time consuming, which restricts further applications of LbL in industry and its commercialization. Therefore, herein we introduced the high gravity (HG) technique, which is a well-established industrial chemical engineering process for intensification of mass transfer, into the LbL assembly process to realize rapid film deposition on porous nickel foam. By using a model system of electrostatically driven PDDA/AuNPs multilayers, the adsorption kinetics, LbL procedure and film morphology have been examined under both conventional dipping conditions and a HG field. The results show that the time to reach saturated adsorption of building blocks with the HG field has been shortened remarkably by up to 16 times while the film quality remains identical. In this way, the fabrication of LbL multilayers can be highly accelerated in the presence of a HG field without disturbing the film quality on non-planar substrates. Moreover, the mechanism for the rapid construction of LbL multilayers using the HG technique is interpreted using the boundary layer theory that the highly turbulent flow in the HG field enhanced the mass transfer rate for the rapid adsorption of building blocks onto substrates.
    No preview · Article · Nov 2014 · RSC Advances
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    ABSTRACT: The emission of SO2 leads to serious environmental problems, which has attracted increasing attention. In this work, a cocurrent rotating packed bed (CO-RPB) with a novel SiC structured packing was employed as a process intensification candidate to upgrade existing desulfurization systems. The effects of rotating speed, gas flow rate, liquid flow rate, SO2 inlet concentration, total salt concentration, and alkalinity on the SO2 removal efficiency were investigated by adopting the ammonia-based solution as the absorbent. The experimental results showed that the SO2 concentration at the RPB outlet can meet the new Chinese emission standard very well. In addition, the gas-side volumetric overall mass transfer coefficient (Kya) was deduced based on the mass balance equation, and its correlation was also proposed. The predicted Kya calculated by the correlation was in good agreement with the experimental data, and the deviation was within the range of ±8%.
    No preview · Article · Oct 2014 · Industrial & Engineering Chemistry Research
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    ABSTRACT: The homogeneous catalytic oxidation of ammonium sulfite in a microporous tube-in-tube microchannel reactor (MTMCR) was studied in this paper. It was found that the oxidation rate of ammonium sulfite in the MTMCR is 360 times higher than that in a packing column and could be further boosted about 4–6 times by the Co2+ catalyst. The effects of different operating parameters on the oxidation of ammonium sulfite were investigated. Experimental results indicated that the oxidation ratio of ammonium sulfite increased with the increase of the oxygen volumetric flow rate, but decreased with the increase of the liquid volumetric flow rate and sulfite concentration, and a smaller micropore size and annular channel width resulted in a higher oxidation ratio of ammonium sulfite. The oxidation ratio reached 80% under the optimum operating conditions in the catalytic oxidation process. This study reveals that the MTMCR is a potential intensification device for the oxidation process of ammonium sulfite.
    No preview · Article · Oct 2014 · The Chemical Engineering Journal

Publication Stats

2k Citations
245.45 Total Impact Points

Institutions

  • 2003-2016
    • Beijing University of Chemical Technology
      • College of Materials Science and Engineering (SMSE)
      Peping, Beijing, China
  • 2005-2011
    • University of New Orleans
      • Advanced Materials Research Institute (AMRI)
      New Orleans, Louisiana, United States