Kinetics of the direct reaction between ozone and phenol by high-gravity intensified heterogeneous catalytic ozonation

In this study,high-gravity intensified heterogeneous catalytic ozonation is utilized for treatment of phenol-containing wastewater,and the kinetics of the direct reaction between ozone and phenol in the presence of excess tertiary butanol(TBA)is investigated.It is revealed that the direct reaction between ozone and phenol in the rotating packed bed(RPB)follows the pseudo-first-order kinetics with a reaction rate constant higher than that in the conventional bubbling reactor(BR).Under different conditions of temperature,initial pH,high-gravity factor,and gaseous ozone concentration,the apparent reaction rate constant varies in the range of 0.0160–0.115 min-1.An empirical power-exponential model is established to characterize the effects of these parameters on the direct reaction between ozone and phenol by high-gravity intensified heterogeneous catalytic ozonation.

Preparation of WC/CoCrFeNiAl0.2 high-entropy-alloy composites by high-gravity combustion synthesis

The WC/CoCrFeNiAl0.2 high-entropy alloy(HEA)composites were prepared through high-gravity combustion synthesis.The preparation method is presented below.First,using a designed suitable multiphase thermite system,the molten CoCrFeNiAl0.2 HEA was fabricated using low-cost metal oxides.The molten HEA was subsequently infiltrated into the WC layer to fabricate WC/CoCrFeNiAl0.2 composites in a highgravity field.The porosity of the WC/CoCrFeNiAl0.2 composites was down-regulated,and their compressive yield strength was up-regulated when the high-gravity field was increased from 600g to 1500g because this infiltration process of a HEA melt into the WC layer is driven by centrifugal force.The WC particles in the composites exhibited a gradient distribution along the direction of the centrifugal force,which was attributed to the combined action of the high-gravity field and the temperature gradient field.The Vickers hardness of the sample was down-regulated from 9.53 to 7.41 GPa along the direction of the centrifugal force.

Oxidation of benzyl alcohols to ketones and aldehydes by O3 process enhanced using high-gravity technology

In this study,a practical process for ozonization of benzyl alcohols to ketones and aldehydes in a rotating packed bed(RPB-O3)reactor has been developed.Using 1-phenylethanol as a model reactant,the performance of RPB-O3 process in different solvents has been compared with the commonly used stirred tank reactor(STR-O3).Ethyl acetate was the optimum solvent for the conversion of 1-phenylenthanol to acetophenone in RPB-O3 process,with 78%yield after 30 min.In a parallel STR-O3 experiment,the yield of acetophenone was50%.Other experimental variables,i.e.O3 concentration,reaction time,high-gravity factor and liquid flow rate were also optimized.The highest yield of acetophenone was obtained using O3 concentration of 80 mg·L-1,reaction time of 30 min,high gravity factor of 40 and liquid flow rate of 120 L·h-1.Under the optimized reaction conditions,a series of structurally diverse primary and secondary alcohols was oxidized with(19%–92%)yield.The ozonization mechanism was studied by Electron Paramagnetic Resonance(EPR)spectroscopy,monitoring the radical species formed upon self-decomposition of O3.The characteristic quadruple peak with the 1:2:2:1 intensity ratio that corresponds to hydroxyl radicals(·OH)was observed in the electron paramagnetic resonance(EPR)spectrum,indicating an indirect oxidation mechanism of alcohols via·OH radical.

High-gravity technology intensified Knoevenagel condensation-Michael addition polymerization of poly (ethylene glycol)-poly (n-butyl cyanoacrylate) for blood-brain barrier delivery

Poly(ethylene glycol)-poly(n-butyl cyanoacrylate)(PEG-PBCA)is a remarkable drug delivery carrier for permeating blood-brain barrier.In this work,a novel high-gravity procedure was reported to intensify Knoevenagel condensation-Michael addition polymerization of PEG-PBCA.A series of PEG-PBCA containing different block ratios were synthesized with narrow molecular weight distribution of polydispersity indexes less than 1.1.Furthermore,the reaction time reduced 60%compared to conventional stirred tank reactor process.Chemical structures of as-prepared polymers were characterized.In vitro drug delivery performance was evaluated.The cytotoxicity of PEG-PBCA to brain microvessel endothelial cells(BMVEC)decreases with the extension of the PEG chain and the shortening of the PBCA chain.The polymer cellular uptake to BMVECs was better after improving hydrophilicity by PEG block.Results of bloodbrain barrier permeability demonstrated that medium length of PBCA chain and short PEG chain are favorable for hydrophobic Nile red permeation,while long PEG chain and short PBCA chain are beneficial to delivery water-soluble doxorubicin hydrochloride(Dox).The average apparent permeability coeffi-cient increased 1.7 and 0.25 times than that of raw Nile red and Dox,respectively.High-gravity intensi-fied condensation polymerization should have great potential in brain drug delivery system.

Preparation of Al2O3-Supported Nanoscale FeS Based on High-Gravity Technology and Its Application for Removing Chromium (Ⅵ) in Wastewater

AbstFeS has an excellent performance in removing heavy metal chromium(Ⅵ)in wastewater due to its good adsorption and reduction.The properties of easy aggregation and oxidization of nano-FeS,however,limit the applications of FeS in engineering.In this study,one FeS adsorbent supported by Al_(2)O_(3) was prepared using high-gravity technology in IS-RPB(Impinging Stream Rotating Packed Bed)to overcome polymerization and oxidation of nano-FeS.Experimental results showed that FeS was uniformly loaded on the surface and pores of Al_(2)O_(3).The specific surface area of FeS/Al_(2)O_(3) is 125 m2·g^(-1) which is nearly 1.6 times that of pure FeS.The adsorption capacity of FeS/Al_(2)O_(3) for chromium(Ⅵ)is 200 mg·g^(-1),1.4 times that of pure FeS.pH value and ionic strength are strongly correlated with the chromium removal performance of FeS/Al_(2)O_(3).Over 98%of chromium can be removed when pH values of FeS/Al_(2)O_(3) ranged from 4 to 6.Higher adsorption capacity is achieved with higher ionic strength in FeS/Al_(2)O_(3).The FeS/Al_(2)O_(3) maintained more than 95%of the adsorption capacity after being preserved for one month,but only 70%for pure FeS.The removal processes of chromium(Ⅵ)conformes to a pseudo-second-order kinetic model(R2≥0.9986),indicating that the rate-limiting step is a chemical sorption process instead of a mass transfer.

Preparation of pH-Responsive Doxorubicin Nanocapsules by Combining High-gravity Antisolvent Precipitation with In-situ Polymerization for Intracellular Anticancer Drug Delivery

Owing to the low pH value in tumor and cancer cells,drug delivery systems based on pH-responsive polymer nanocarriers have been extensively explored for anticancer chemotherapy.Herein,we developed a pH-responsive doxonibicin(EXDX)nanocapsule(named as DNanoCapsule)prepared by combining in-situ polymerization teclinique with high-gravity antisolvent precipitation technique throngh an amphiphilic polymerized surface ligand.DNanoCapsules show an obvious spherical core-shell structure with a single DOX nanoparticle encapsulated in the polymer layer.Dissolution rate studies prove that the DNanoCapsules have robust dnig-release profiles under acidic environments due to the division of the pH-sensitive cross-linker,which triggers thecollapse of the polymer layer.The in vitro investigations demonstrated that the DNanoCapsules exhibited higli cellular uptake efficiency and cytotoxicity for both HeLa and MCF-7 cancer cells.Tlierefore,this work may provide a promising strategy to design and develop various stimuli-responsive drug nanocapsules tor the treatment of cancer or other diseases.

Preparation of nitrogen-doped graphene by high-gravity technology and its application in oxygen reduction

Electrochemical oxygen reduction is key to many clean and sustainable energy technologies, including proton exchange membrane fuel cells and metal-air batteries. However, the high activation barriers in the oxygen reduction reaction often make it the bottleneck of energy conversion processes; thus, high- performance oxygen reduction electrocatalysts are desired. At present, the best commercially available oxygen reduction catalyst is based on the precious metal Pt. However, it suffers from resource scarcity and unsatisfactory operational stability, hindering its widespread and large-scale application in clean and sustainable technologies. Nitrogen-doped graphene has excellent electrocatalytic properties for oxygen reduction. In this paper, a scalable method to prepare nitrogen-doped graphene with high quality was introduced, in which the graphene oxide prepared by high-gravity technology and urea was reacted under hydrothermal conditions. Accompanying the hydrothermal reaction, graphene oxide reduction and nitrogen doping were accomplished at the same time. The effect of the content of nitrogen on the performance of nitrogen-doped graphene was investigated. When the mass ratio （graphene oxide]urea） was 1：400, the nitrogen-doped graphene had the best oxygen reduction performance, Compared with the undoped samples, the initial reduction voltage of the nitrogen-doped samples distinctly shifted 45 mV to the right. When the voltage was - 1,0 V, the electron transfer number was 4.1, indicating good oxygen reduction activity. The preparation method is feasible, simple, and can be easily scaled up.

High-gravity intensified iron-carbon micro-electrolysis for degradation of dinitrotoluene

The application of iron–carbon(Fe–C)micro-electrolysis to wastewater treatment is limited by the passivation potential of the Fe–C packing.In order to address this problem,high-gravity intensified Fe–C micro-electrolysis was proposed in this study for degradation of dinitrotoluene wastewater in a rotating packed bed(RPB)using commercial Fe–C particles as the packing.The effects of reaction time,high-gravity factor,liquid flow rate and initial solution pH were investigated.The degradation intermediates were determined by gas chromatography-mass spectrometry,and the possible degradation pathways of nitro compounds by Fe–C micro-electrolysis in RPB were also proposed.It is found that under optimal conditions,the removal rate of nitro compounds reaches 68.4%at 100 min.The removal rate is maintained at approximately 68%after 4 cycles in RPB,but it is decreased substantially from 57.9%to 36.8%in a stirred tank reactor.This is because RPB can increase the specific surface area and the renewal of the liquid–solid interface,and as a result the degradation efficiency of Fe–C micro-electrolysis is improved and the active sites on the Fe–C surface can be regenerated for continuous use.In conclusion,high-gravity intensified Fe–C micro-electrolysis can weaken the passivation of Fe–C particles and extend their service life.

Devolatilization of high viscous fluids with high gravity technology

Volatile organic compounds(VOCs)are generally toxic and harmful substances that can cause health and environmental problems.The removal of VOCs from polymers has become a key problem.The effective devolatilization to remove VOCs from high viscous fluids such as polymer is necessary and is of great importance.In this study,the devolatilization effect of a rotating packed bed(RPB)was studied by using polydimethylsiloxane as the viscous fluid and acetone as the VOC.The devolatilization rate and liquid phase volume(KLa)have been evaluated.The results indicated that the optimum conditions were the high-gravity factor of 60,liquid flow rate of 10 L·h^(-1),and vacuum degree of 0.077 MPa.The dimensionless correlation of KLa was established,and the deviations between predicted and experimental values were less than±28%.The high-gravity technology will result in lower mass transfer resistance in the devolatilization process,enhance the mass transfer process of acetone,and improve the removal effect of acetone.This work provides a promising path for the removal of volatiles from polymers in combination with high-gravity technology.It can provide the basis for the application of RPB in viscous fluids.

Nitrogen-Doped Graphene Foam as a Metal-Free Catalyst for Reduction Reactions under a High Gravity Field

Herein,we report on the effect of a high gravity field on metal-free catalytic reduction,taking the nitrobenzene(NB)reduction and methylene blue(MB)degradation as model reactions in a highgravity rotating tube reactor packed with three-dimensional(3D)nitrogen-doped graphene foam(NGF)as a metal-free catalyst.The apparent rate constant(kapp)of the metal-free catalytic reduction of NB in the rotating tube reactor under a high gravity level of 6484g(g=9.81 m s-2)was six times greater than that in a conventional stirred reactor(STR)under gravity.Computational fluid dynamics(CFD)simulations indicated that the improvement of the catalytic efficiency was attributed to the much higher turbulent kinetic energy and faster surface renewal rate in the high-gravity tube reactor in comparison w让h those in a conventional STR.The structure of the 3D metal-free catalysts was stable during the reaction process under a high gravity field,as confirmed by X-ray photoelectron spectroscopy(XPS)and Raman spectra.In the other model reaction,the rate of MB degradation also increased as the high gravity level in creased gradually,which aligns with the result for the NB catalytic reduction system.These results demonstrate the potential to use a high-gravity rotating packed tube reactor for the process intensification of metal-free catalytic reduction reactions.

Preparation and characterization of NaY zeolite in a rotating packed bed

NaY Zeolite was synthesized in a rotating packed bed （RPB） for the first time. A Si-A1 gel with a specific composition was used as the structure-directing agent. The as-synthesized NaY Zeolite was characterized with scanning electron microscopy （SEM）, X-ray diffraction （XRD） and specific surface area （BET）. The characterization result showed that the NaY Zeolite had a particle size of approximately 200 rim, n（SiO2）/n（Al203） ratio of 5.03, crystallinity of 96% and specific surface area of 714 m2/g. The experimental results indicated that the structure of NaY Zeolite was related to the synthesis conditions （such as reactors, crystallization time and so on）. The micromixing efficiency was proven to be the most important factor for synthesis of NaY Zeolite in the high-gravity environment in RPB.