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Flow properties of fine powders in powder coating

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Particuology 2010年第1期8卷 19-27页

作者： jesse zhu Particle Technology Research Centre Department of Chemical and Biochemical EngineeringThe University of Western Ontario

Three types of nanoparticles and their combinations were blended into a fine powder, which has been used in the powder coating industry. To study their effects on flow properties, the modified powder samples were characterized using a variety of techniques that tested the powder under different powder states ranging from dynamic to static. It was found that all three nanoparticles improved the flow properties of the powder to some degree, though the amounts of the nanoparticles needed were different depending on their physical properties. Secondly, inconsistency among these powder characterization techniques was also found. This is attributed to the different states of the powder samples during a measurement including dynamic, dynamic-static and static states. It was confirmed that characterization techniques which test the flow properties of a powder under all three states are needed to fully describe the flow properties of the powder. Finally, the effects of combinations of nanoparticles were explored, and it was found that combinations of nanoparticles can intensify, weaken or combine the effects of their component nanoparticles. The effects of nanoparticle combinations are not a simple summation of the effects of their comnonent nanoparticles.

关键词： Fine powders Nanoparticle Flow property Flow property characterization Powder coating

Circulating turbulent fluidization-A new fluidization regime or just a transitional phenomenon

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Particuology 2010年第6期8卷 640-644页

作者： jesse zhu Particle Technology Research Centre and Department of Chemical and Biochemical Engineering University of Western OntarioLondonOntarioN6A 5B9Canada

While circulating fluidized bed （CFB） reactor has many advantages over the more conventional turbulent fluidized bed （TFB） reactor, it does at least have one significant shortcoming-the rather dilute solids volume concentration in CFB reactor gives rise to less ideal reaction intensity. On the other hand, while having higher reaction intensity, TFB reactor has one fatal drawback of particle back-mixing, making it not suitable for certain reactions such as catalytic reaction where the catalyst requires frequent regeneration. This paper describes some key issues in the development of a circulating turbulent fluidized bed （CTFB） reactor that combines the advantages of both TFB and CFB, that is, to have the high reaction intensity as in TFB but and also to have a suppressed solids back-mixing as in CFB due to a continuous net upflow of solids flux through the bed. Experimental results show enough evidence to suggest that a new fluidization regime is formed, the characteristics of which appears to be distinct from those observed in a regular TFB and from those in either the bottom or the upper sections of regular CFB and/or high-density CFB （HDCFB）. Fundamentally, the difference is that particle-particle interaction （collision） dominates the motion of particles in CTFB and TFB, while gas-particle interaction （drag force） is the key element that determines the two phase flow in CFB including HDCFB.

关键词： Circulating-turbulent fluidized bed Flow regime Circulating-turbulent fluidizationTurbulent fluidized bed Circulating fluidized bed

Experimental study on reactor performance of gas-solids low-velocity fluidized beds

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Particuology 2022年第7期20卷 21-28页

作者： Jiangshan Liu jesse zhu Particle Technology Research Centre Department of Chemical and Biochemical EngineeringThe University of Western OntarioLondonOntarioN6A 3K7Canada

Reactor performance of bubbling fluidized bed(BFB)and turbulent fluidized bed(TFB)was carefully examined and systematically compared using catalytic ozone decomposition as a model reaction,based on a complete mapping of local flow structures and spatial distributions of ozone conversion and solids *** clearly has a higher conversion and shows better reactor performance than BFB as a result of the vigorously turbulent flow and the relatively homogeneous gas–solids mixing in ***,the intensive interaction between gas and solids in TFB leads to greater gas–solids contact efficiency of TFB over that of *** to gas bypassing and backmixing caused by bubbling behaviours and two-phase structure,BFB deviates significantly from a plug flow reactor and sometimes from a continuously stirred tank *** flow structures essentially dictate the reactor performance in the low-velocity fluidized beds.

关键词： Bubbling fluidized bed Turbulent fluidized bed Conversion distribution Flow structure Reactor performance Gas–solids contact efficiency

An update on electrostatic powder coating for pharmaceuticals

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Particuology 2017年第2期15卷 1-7页

作者： Qingliang yang Yingliang Ma jesse zhu Kwok Chow Kaiqi Shi Particle Technology Research Centre Department of Chemical and Biochemical Engineering University of Western Ontario London Ontario N6A 589 Canada Powder Pharma Coatings Mississauga Ontario LSR 2Y9 Canada Ningbo Weston Powder Pharma Coatings Co. Ltd. Ningbo Zhejiang 315042 China

Derived from dry powder coating of metals, electrostatic powder coating for pharmaceuticals is a technology for coating drug solid dosage forms. In this technology, coating powders, containing coating polymers, pigments, and other excipients, are directly sprayed onto the surface of the solid dosage forms through an electrostatic gun without using any organic solvent or water. The deposited coating powders are further cured to form a coating film. Electrostatic powder coating technology has many advantages compared to other pharmaceutical coating methods. It can eliminate the limitations caused by the organic solvent in solvent coating such as environmental issues and health problems. And electrostatic powder coating technology also surpasses aqueous coating due to its shorter processing time and less energy consumption, leading to a lower overall cost. Furthermore, the utilization of electrical attraction can promote the movement of coating powders towards the substrate, leading to an enhanced coating powder adhesion and coating efficiency, which make it more promising compared to other dry coating technologies. The objective of this review is to summarize the coating principles, apparatus, and formulations of different electrostatic powder coating technologies, giving their advantages and limitations and also analyzing the future application in the industry for each technology

关键词： Electrostatic powder coating Solid dosage forms Plasticizers Powder adhesion Film formation Curing

Fabrication of Bi-Bi3O4Cl plasmon photocatalysts for removal of aqueous emerging contaminants under visible light

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Journal of Environmental Sciences 2022年第8期34卷 87-100页

作者： Zeqing Long Hui Song Guangming Zhang jingsi Gao Jia zhu School of Energy&Environmental Engineering Hebei University of TechnologyXiping roadBeichen districtTianjin 300130China School of Environment&Natural Resources Renmin University of ChinaBeijing 100872China School of Construction and Environment Engineering Shenzhen PolytechnicShenzhen 518055China Shanxi Aerospace Qinghua Equipment Co. Ltd.Changzhi 046012China

Photocatalytic oxidation of emerging contaminants(ECs) in water has recently gained extensive attentions. In this study, bismuth oxychloride-based plasmon photocatalysts(BiBiOCl) exhibiting high performance were successfully developed by reducing Bion the surface of BiOCl. Consequently, the photocatalysts were used to remove ECs from *** effects of developmental process and Bi metal plasmon resonance on the photoelectric performances of Bi-BiOCl were investigated through a series of characterizations. The UV-vis diffuse reflection and photoluminescence spectra revealed that the light absorption range of the photocatalyst gradually increased and the electron recombination rate gradually decreased with the introduction of Bi metals. The optimal removal rates of ciprofloxacin and tetrabromobisphenol A by Bi-BiOCl were 93.8% and 96.4%;the respective reaction rate constants were 5.48 and 4.93 times higher than that of BiOCl. The mechanism study indicated that main reactants in the photocatalytic system were ·O-2radicals and photogenerated holes, and the existence of oxygen vacancies and Bi metals promoted electron transfer in photocatalyst. In conclusion, this research produces a novel, green, highly efficient, and stable visible light photocatalyst for the removal of ECs from water.

关键词： Plasmon photocatalysts Environmental purification Bi3O4Cl Emerging contaminants Hazardous substance

Preamble for special issue honouring Professor Mooson Kwauk

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Particuology 2010年第6期8卷 491-492页

作者： jesse zhu Department of Chemical and Biochemical Engineering University of Western OntarioLondonOntarioCanada N6A 5B9

Two years after assuming a new name and format change, the year 2010 marks the 8th anniversary of Particuology. To commemorate this special occasion for the journal, the thematic editors met in Montreal at the 8th World Congress of Chemical Engineering and decided to compile a truly special issue. Instead of producing another ＂conventional＂ special issue of the more ＂regular＂ research papers on some given subjects, we have decided to take a more innovative format for this issue to present short discussion papers that provide quick overviews of the current status of selected subiects and then discuss forward thinking for the future.

关键词： Preamble for special issue honouring Professor Mooson Kwauk EMMS very

Dry powder platform for pulmonary drug delivery

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Particuology 2008年第4期6卷 225-238页

作者： Derek Ivan Daniher jesse zhu Graduate Program in Biomedical Engineering Department of Chemical and Biochemical EngineeringThe University of Western OntarioLondonOntarioCanada

The phenomenon of particle interaction involved in pulmonary drug delivery belongs to a wide variety of disciplines of particle technology, in particular, fluidization. This paper reviews the basic concepts of pulmonary drug delivery with references to fluidization research, in particular, studies on Geldart group C powders. Dry powder inhaler device-formulation combination has been shown to be an effective method for delivering drugs to the lung for treatment of asthma, chronic obstructive pulmonary disease and cystic fibrosis. Even with advanced designs, however, delivery efficiency is still poor mainly due to powder dispersion problems which cause poor lung deposition and high dose variability. Drug particles used in current inhalers must be 1–5 μm in diameter for effective deposition in small-diameter airways and alveoli. These powders are very cohesive, have poor flowability, and are difficult to disperse into aerosol due to cohesion arising from van der Waals attraction. These problems are well known in fluidization research, much of which is highly relevant to pulmonary drug delivery.

关键词： Dry powder inhaler Interparticle forces Aerosol Pulmonary drug delivery Carrier particle Fluidization

Numerical investigations on gas-solid flow in circulating fluidized bed risers using a new cluster-based drag model

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Particuology 2022年第4期20卷 9-23页

作者： Zeneng Sun Chao Zhang jesse zhu Department of Chemical and Biochemical Engineering.The University of Western Ontario LondonOntarioN6A 3K7Canada Department of Mechanical and Materials Engineering The University of Western OntarioLondonOntarioN6A 3K7Canada

A cluster-based drag model is proposed for the gas-solid circulating fluidized bed(CFB)riser by including the cluster information collected from image processing and wavelet analysis into the calculation of system *** performance of the proposed drag model is compared with some commonly used drag models.A good agreement with the experimental data is achieved by the proposed cluster-based drag *** analysis of the proposed cluster-based drag model based on the local distributions of solids holdup and particle velocity is *** clustering phenomenon in the low-density and high-density CFB risers and the effect of the cluster size on the simulation accuracy are also numerically studied by the proposed drag model.

关键词： Drag model Clustering effect Gas-solid flow structures Circulating fluidized bed

Improving flow and fluidization quality of fine and ultrafine particles via nanoparticle modulation

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Nano Research 2023年第10期16卷 12013-12025页

作者： Jiaying Wang Yuanyuan Shao jesse zhu Department of Chemical and Biochemical Engineering The University of Western OntarioLondonOntario N6A 3K7Canada School of Chemical Engineering and Technology Tianjin UniversityTianjin 300072China Beacons of Excellence Research and Innovation Institute University of NottinghamNingbo 315100China

Fine and ultrafine particles possess great potential for industrial applications ascribed from their huge specific surface area and ability to provide good gas–solid ***,these powders are inherently cohesive,making it challenging to achieve smooth flow and *** challenge can be well-resolved by nanoparticle modulation(nano-modulation),where a small amount of nanoparticles is uniformly mixed with the cohesive fine/ultrafine *** nano-modulation,the fluidization system of cohesive powders exhibits distinguishable minimum fluidization velocity,enlarged bed expansion ratio(particularly the dense phase expansion),and scarcer,smaller,and slower moving bubbles,indicating improved flow and fluidization *** purpose of the current work is to systematically summarize the state-of-the-art progress in the fluidization and utilization of fine and ultrafine particles via the nanoparticle modulation ***,a broader audience can be enlightened regarding this promising fine/ultrafine particle fluidization technology,so as to provoke their attention and encourage interdisciplinary integration and industry-academia collaborative research.

关键词： fine particle ultrafine particle cohesive powder flowability fluidization nanoparticle modulation