Preparation of high emissivity NiCr_2O_4 powders with a spinel structure by spray drying

Spray-drying was used to produce the high emissivity NiCr2O4 powders with a spinel structure. Preliminary investigations focused on fabricating the high emissivity powders for infrared radiation coatings and finding the relationship between microstructure and emissivity. The NiCr2O4 powders were characterized for composition, microstructure, and infrared emissivity by X-ray diffraction （XRD）, scanning electron microscopy （SEM）, infrared radiant instrument, and Fourier transform infrared spectra （FT-IR）. Thermogravimetry and differential thermal analysis show that the appropriate baking temperature for NiCr2O4 powder preparation is about 1200？C. The emissivity measurement and FT-IR spectra show that, because of the special spinel structure, the NiCr2O4 powders have a high emissivity about 0.91. Spray-drying is a suitable method to produce the high emissivity ceramic powders.

Structural and functional properties of hydrolyzed/glycosylated ovalbumin under spray drying and microwave freeze drying

Ovalbumin(OVA),the main protein in egg white,affects most of the functional properties of egg white protein in food processing.The aim of this study was to investigate the effects of spray drying(SD)and microwave freeze drying(MFD)on the preparation of hydrolyzed/glycosylated ovalbumin(HGOVA)and provide useful information on the applications of egg protein powders in the food industry.Results demonstrated that the structure of HGOVA was considerably changed,and its functional properties were improved compared with those of native OVA.SD and MFD processing did not lead to dissociation of HGOVA subunits.SD-HGOVA exhibited higher protein solubility,emulsifying activity,foaming capacities,and gel hardness than MFD-HGOVA.However,MFD-HGOVA was better than the SD-HGOVA in terms of color,emulsion stability,foam stability,water/oil absorption capacity,and thermal stability.Selection of an appropriate drying method could enhance the potential applications of HGOVA in the food industry.

Preparation of spherical spinel LiCr_(0.04)Mn_(1.96)O_4 cathode materials based on the slurry spray drying method

Regular spherical chromium doped spinel lithium manganese oxides （LiCr0.04Mn1.96O4） with an average particle size of about 20μm were prepared by the slurry spray drying process. The materials were compared with non-spherical LiCr0.04Mnl.96O4 materials prepared by the common drying process, and all materials were characterized by X-ray diffraction （XRD）, scanning electron microscopy （SEM）, laser particle analyzer and Brunaner-Emmett-Teller （BET） specific surface area test. Electrochemical performances of these cathode materials were studied by cyclic voltammetry （CV）, electrochemical impedance spectroscopy （EIS） and Li/LiCr0.04Mn1.9604 battery test. The results show that the spherical active material is single spinel structure, compact, and with narrow particle size distribution and low BET specific surface area. Compared with the non-spherical material, the spherical material prepared by the spray drying process shows a lower electrochemical impedance, a fewer electrochemical polarization and a better charge/discharge rate capability and capacity retention at elevated temperatures.

Preparation of dry flowable formulations of Clonostachys rosea by spray drying and application for Sclerotinia sclerotiorum control

A dry flowable formulation of Clonostachys rosea with fungicidal activity against Sclerotinia sclerotiorum was prepared by spray drying. The formulation was optimized by a four-factor, three-level orthogonal experiment to screen inert ingredients and spray-drying conditions. The optimal dry flowable formulation of C. rosea included 30% C. rosea （ratio of conidia powder and its fermentation broth is 1：3）, 3% Morwet EFW, 4% K12, 10% Morwet D425, 9% sodium salt of polynaphthalene sulphonic acid （NNO）, 5% croscarmellose sodium, 5% （NH4）2SO4, 0.5% carboxymethyl cellulose sodium （CMC-Na）, 1% oxalic acid and palygorskite （carrier） up to 100%. The formulation exhibited good physical characteristics, such as high dispersibility, viability and a long shelf life. Plate antagonism tests and pot trials indicated that the dry flowable formulation was very effective against S. sclerotiorum, with control efficiency of up to 88.30%. This dry flowable formulation of C. rosea is a new potential commercial fungicide for spray drying to control S. sclerotiorum.

Synthesis and Characterization of Y_ (0.9-x)Gd_xEu_(0.1)BO_3 Phosphors by Spray Drying Process

Y 0.9-xGd xEu 0.1BO 3 phosphors were synthesized by spray drying (SD) method, and the results were compared with those by conventional solid state (SS) and citrate gel (CG) methods. The PL intensity of phosphors increases with the increase of x value in Y 0.9-xGd xEu 0.1BO 3 (prepared by SD) due to an energy migration process like Gd 3+-(Gd 3+) n-Eu 3+ occurred in the material. Compared with the latter two methods, the phosphor particles prepared by spray drying method have a better morphology, such as homogeneous size (about 1～3 μm) with spherical shape and smooth surface. Furthermore, the spray drying-derived phosphors have higher photoluminescence (PL) intensity than those by citrate gel method, but still a little lower than those by the solid state method.

Preparation and Characterization of Porous Spherical LiFePO_4/C by Spray Drying and Carbothermal Method

The porous spherical LiFePO4/C powders were prepared by spray drying and carbothermal method （SDCTM）. Cheaper trivalent iron ion was used as the precursor. The pure olivine phase can be prepared with the spray drying and subsequent heat-treatment. The average particle size is around 10μm, and the value of porosity is 63.04%. The results indicate that the initial discharge capacity decreases with increasing charge/ discharge rate and reduces from 138.8 mAh · g^-1 at C/20 rate to 98.3 mAh ·g^-1 at 2C rate, while the polarization between the charge and discharge plateaux is enlarged from 53 mv to 347 mv. However, the average discharge efficiency is up to 99.5% at 2C rate compared to 80.6% at C/20 rate from the second cycle.

A General Strategy for Efficiently Constructing Multifunctional Cluster Fillers Using a Three-Fluid Nozzle Spray Drying Technique for Dental Restoration

Multifunctional fillers are greatly required for dental resin composites(DRCs).In this work,a spray dryer with a three-fluid nozzle was applied for the first time to construct high-performance complex nanoparticle clusters(CNCs)consisting of different functional nanofillers for dental restoration.The application of a three-fluid nozzle can effectively avoid the aggregation of different nanoparticles with opposite zeta potentials before the spray drying process in order to construct regularly shaped CNCs.For a SiO_(2)–ZrO_(2) binary system,the SiO_(2)–ZrO_(2) CNCs constructed using a three-fluid nozzle maintained their excellent mechanical properties((133.3±4.7)MPa,(8.8±0.5)GPa,(371.1±13.3)MPa,and(64.5±0.7)HV for flexural strength,flexural modulus,compressive strength,and hardness of DRCs,respectively),despite the introduction of ZrO_(2) nanoparticles,whereas their counterparts constructed using a two-fluid nozzle showed significantly decreased mechanical properties.Furthermore,heat treatment of the SiO_(2)-ZrO_(2) CNCs significantly improved the mechanical properties and radiopacity of the DRCs.The DRCs containing over 10%mass fraction ZrO_(2) nanoparticles can meet the requirement for radiopaque fillers.More importantly,this method can be expanded to ternary or quaternary systems.DRCs filled with SiO_(2)-ZrO_(2)-ZnO CNCs with a ratio of 56:10:4 displayed high antibacterial activity(antibacterial ratio>99%)in addition to excellent mechanical properties and radiopacity.Thus,the three-fluid nozzle spray drying technique holds great potential for the efficient construction of multifunctional cluster fillers for DRCs.

Development of Polycaprolactone/Poly(Vinyl Alcohol)/Clay Microparticles by Spray Drying

In this study, nanostructured microparticles was developed with polycaprolactone (PCL), poly(vinyl alcohol) (PVAL) and nanoparticles of the commercial sodium clay NT-25®by using the spray drying technique. The systems obtained were characterized by Nuclear Magnetic Resonance (NMR), Scanning Electron Microscopy (SEM), Fourier Transform Infrared Spectroscopy (FTIR), X-ray Diffraction (XRD), Dynamic Laser Light Scattering (DLS) and Differential Scanning Calorimetry (DSC). The NMR 13C and FTIR techniques showed that both polymers were present in the microparticles and the DSC analysis revealed a small variation in the glass transition temperature of the PCL. The XRD and SEM analyses showed that the microparticles produced were amorphous and had a concave morphology. The NT-25 nanoload reduced the microparticles’ size due to the multiple interactions formed in the hybrid nanocomposite material. Therefore, it was possible to develop microparticles by using biodegradable and biocompatible polymers, with different polarities, allowing the incorporation of hydrophilic and hydrophobic materials and enabling the inclusion of otherwise incompatible materials in the same system.

Structure-dependent re-dispersibility of graphene oxide powders prepared by fast spray drying

The graphene oxide powder(GOP)obtained from the spray drying process often exhibits poor redispersibility which is considered due to the partial reduction of GO sheets.The reduction of drying temperature can effectively increase the redispersibility of GOP,but result in a decreased drying efficiency.Herein,we found that the redispersibility of GOP is strongly affected by its microstructure,which is determined by the feed concentration.With the increase of feed concentration,the GO nanosheet assembly varies from the disordered stacking to relatively oriented assembly,making the morphology of the GOP transform from balllike(the most crumpled one)to flakelike(the least crumpled one),and the 0.8 mgml 1 is the threshold concentration for the morphology,structure,and redispersibility change.Once the feed concentration reaches 0.8 mg ml 1,the appearance of the nematic phase in droplet ensures the relatively oriented assembly of GO sheets to form the layered structure with a low crumpling degree,which greatly improves the polar parts surface tension of the solid GOP,making the GOP easier to form hydrogen bonding with water during the redispersion process,thus stabilizing dispersion.This work provides useful information for understanding the relationships between the morphology,microstructure,and final redispersibility of GOPs.

Microwave Sintering of W-15Cu Ultrafine Composite Powder Prepared by Spray Drying & Calcining-continuous Reduction Technology

The effects of microwave sintering and conventional H2 sintering on the microstructure and properties of W-15Cu alloy using ultrafine W-15Cu composite powder fabricated by spray drying ＆ calcining-continuous reduction technology were investigated. In comparison to the conventional HE sintering processing, microwave sintering to W-15Cu can be achieved at lower sintering temperature and shorter sintering time. Furthermore, higher performances in microwave sintered compacts were obtained, but high microwave sintering temperature or long microwave sintering time could result in coarser microstructures.

Microencapsulation of Lipase and Savinase Enzymes by Spray Drying Using Arabic Gum as Wall Material

Enzymes have been used in detergents over the years. They can improve the detergent’s efficiency due to their activities against hard stains. Nevertheless, enzymes cannot maintain their properties indefinitely, since they are exposed to stress factors, like temperature, pH, mechanical processes and others. Consequently, enzymes lose their structure and they are not functional. For this reason, microencapsulating these proteins is a feasible solution to improve their use in industrial processes and commercial products. Spray drying technology has been selected because a lot of scientific literature proved its useful application in a variety of industries. In particular, savinase and lipase are the two encapsulated enzymes in this work. Savinase attacks proteins and lipase removes fats, so they are suitable enzymes for detergent industry. Arabic gum has been used as wall material. Morphology, size and activity of the obtained microcapsules have been analyzed in order to find the best conditions to produce them. In conclusion, useful microcapsules of lipase and savinase can be obtained with the mentioned technology.

Microencapsulation of L-Ascorbic Acid by Spray Drying Using Sodium Alginate as Wall Material

L-ascorbic acid is a water soluble vitamin (vitamin C) widely used as an additive in foods and cosmetics. It has high instability against certain environmental factors;the main cause of its deterioration is oxidation. Microencapsulation is an effective protection technique of L-ascorbic acid from its degradation reactions. This work is focused on the encapsulation of L-ascorbic acid by spray drying technique using sodium alginate as wall material. The microcapsules morphology was observed by scanning electron microscopy (SEM) and the encapsulation efficiency was determined by spectrophotometric analysis. Results showed that encapsulation efficiency was of 93.48% and after 30 days was of 92.55%;differences were not significant, so that the stability of L-ascorbic acid was not affected. Encapsulation yields obtained were low, at around 30%, but the microcapsules morphology obtained is spherical.

Mathematical model and numerical investigation of the influence of spray drying parameters on granule sizes of mold powder

In this work,the formation mechanism of the droplet-to-granule was investigated in detail based on mold powder manufacturing.A specific mathematical model of two-stage spray drying was established to describe droplet and granule motion,heat and mass transfer,and granule morphology during spray drying.Then,the relationships between spray drying parameters(inlet temperature,atomization pres-sure,slurry mass flow rate)and the properties of the drying tower(temperature and velocity fields)and mold powder granules(temperature,evaporation rates,moisture content,and diameter)were simulated and calculated using ANSYS/Fluent software.To ensure that the granule size of mold powder was controlled within the ideal range(0.2-0.6 mm)for producing granules with appropriate mechanical and metallurgical properties,the following optimum spray drying parameters were chosen based on the results of the numerical simulation:inlet temperatures,873 K;slurry atomization pressure,1.8 MPa;slurry mass flow rate,0.05 kg s-1.Among these parameters,the slurry mass flow rate has the most significant effect on granule size.

A homogenous solid polymer electrolyte prepared by facile spray drying method is used for room-temperature solid lithium metal batteries

The aggregation of inorganic particles with high mass ratio will form a heterogeneous electric field in the solid polymer electrolytes(SPEs),which is difficult to be compatible with lithium anode,leading to inadequate ionic conductivity.Herein,a facile spray drying method is adopted to increase the mass ratio of inorganic particles and solve the aggregation problems of fillers simultaneously.The polyvinylidene fluoride(PVDF)with lithium bis(trifluoromethanesulfonyl)imide(LiTFSI)covers the surface of each Li_(6.4)La_(3)Zr_(1.4)Ta_(0.6)O_(12)(LLZTO)granules during the nebulization process,then forming flat solid electrolytes via layer-by-layer deposition.Characterized by the atomic force microscope,the obtained solid electrolytes achieve a homogenous dispersion of Young’s modulus and surface electric field.As a result,the as-prepared SPEs present high tensile strength of 7.1 MPa,high ionic conductivity of 1.86×10^(−4)S·cm^(−1)at room temperature,and wide electrochemical window up to 5.0 V,demonstrating increased mechanical strength and uniform lithium-ion migration channels for SPEs.Thanks to the as-prepared SPEs,the lithiumsymmetrical cells show a highly stable Li plating/stripping cycling for over 1,000 h at 0.1 mA·cm^(−2).The corresponding Li/LCoO_(2)batteries also present good rate capability and excellent cyclic performance with capacity retention of 80%after 100 cycles at room temperature.

Numerical investigation of droplet pre-dispersion in a monodisperse droplet spray dryer

Monodisperse droplet spray dryers have great advantages in particle formation through spray drying because of their ability to produce uniform sized particles. Experimental analyses of this system have shown that droplets atomized through the piezoceramic nozzle need to be sufficiently well dispersed before entering the drying chamber to achieve sufficiently dried particles. However, the dispersion dynamics cannot be readily observed because of experimental limitations, and key factors influencing the dispersion state currently remain unclear. This study carried out numerical simulations for droplet dispersions in the dispersion chamber, which allow this important process to be visualized. The system- atic and quantitative analyses on the dispersion states provide valuable data for improving the design of the dispersion chamber, and optimizing the spray drying operation.

Effects of freeze-drying and spray drying processes on functional properties of phosphorylation of egg white protein

Egg white protein(EWP)was phosphorylated with Sodium Tripolyphosphate(STP)at pH 4.5.Freeze drying and spray drying were used for drying purpose and the effects of these drying methods on the functional properties were investigated.The functional properties of native and modified proteins were also determined.The results demonstrated that phosphorylation of EWP markedly improved its functional properties,and that it was more effective for the food industry.The freeze-dried STP-EWP powders were superior in terms of solubility,emulsion stability,water holding capacity,oil and water absorption capacity and heat gel strength than spray-dried STP-EWP powders.The results in viscosity showed no significant differences between freeze-dried and spray dried.The spray-dried powders were better in terms of foaming ability and foam stability than freeze-dried powders.However,the spray drying required the longest time to produce.Freeze drying was found to be the best method in terms of production of modified EWP powders with superior functional properties.

On the spray drying of uniform functional microparticles

Spray drying is a typical method to produce particles in dry powder forms at industrial scale. Most spray-dried products often show a wide range of particle properties even within the same batch. At Monash University, we utilise a microfluidic spray drying approach to generate uniform microparticles with tightly controlled characteristics and sizes in a scalable, almost waste-flee process. The technique is useful to correlate the effects of formulation and spray drying conditions on the properties of spray-dried particles, and can be used to test new formulations for targeted applications such as encapsulation and release of active ingredients. The synthesis route can be applied to other self-assembling systems, includ- ing mesoporous, crystalline, and hierarchically structured microparticles. As spray drying is commonly used in commercial scales, the understanding of how functional particles are formed in relation to formulations and process conditions could assist in developing a cost effective, energy and material-efficient route to produce powders with better properties and ease of handling for more advanced applications such as selective adsorption and bio-separation.

Shell-formation mediated surface composition of uniform two-component microparticles fabricated by micro-fluidic spray drying: Effect of component size and solubility

This work is aimed to study the effects of component size and solubility on the surface composition of spray dried(SD)uniform two-component particles fabricated by micro-fluidic spray dryer.Various precursor liquid consisting of small molecular of methionine(Met,33 g/L)or lysine(Lys,739 g/L)and large-sized silica(12 nm)were prepared by adjusting the mass ratio of components.X-ray energy disper-sive results showed that the respective enrichment degree(De)of Met and Lys on the surface of SD-M1S9 and-L1S9 prepared at 150 C were 182±9% and 125±14%.The De of hydrophobic Met for SD-M1S1 and-M9S1 were 46±9% and 4±2%,respectively,whereas relative hydrophilic Lys mainly distributed internal of the particle meanwhile the De of silica on the surface for SD-L1S1 and-L9S1 were 17±4%and 12±1%,respectively.Drying temperature(120 and 180℃)showed more apparent effect on the De of amino acid for the particles of less amino acid.The possible formation mechanism of surface composition and the surface composition impact on the wettability of particles were explored.These results provide new guidance for manufacturing functional SD powders with various components.

Optimization of drying conditions and components to reduce wall sticking during spray drying of infant formula milk

Wall sticking,which greatly reduces productivity and product quality,has been a big challenge of spray drying.Structure of drying tower and atomizer,as well as drying conditions are the main influencing factors.This research explored the possibility to reduce wall sticking by optimizing drying conditions and components to obtain higher recovery rate of powdered infant formula milk(PIFM).Response surface experimental results indicated that inlet air temperature(T),feed concentration(C),feeding speed(S),as well as interaction term of TC and quadratic terms of C^(2) and S^(2) had significant influences on recovery rate for determined milk formula.According to mixture experiments at optimized drying conditions,whey protein(P),fat(F)and lactose(L)contents,as well as interaction term FL had significant effects on recovery rate.Positive effects were observed for F and L contents on recovery rate,while negative effects were observed for P and FL.Under the optimized drying condition of 136℃,19.80%and 4.07 mL/min,respectively,for T,C and S,the maximum recovery rate of 58.98%was obtained for PIFM with P,F and L content of 18%,31%and 51%,respectively.Wall sticking phenomena could be reduced by optimizing drying conditions and mildly adjusting components of infant formula milk.

Studies on the spray dried lactose as carrier for dry powder inhalation

The purpose of this study was to investigate the spray dried lactose as carrier for dry powder inhalation(DPI).The lactose particles were prepared by spray drying,then the particle size,shape and crystal form were characterized by laser diffraction,scanning electron microscopy(SEM),X-ray diffraction(XRD)and differential scanning calorimetry(DSC).The spray dried lactose particles were spherical and amorphous,but would transfer to crystal form when storage humidity was above 32%.Thus,the humidity of the storage environment should be controlled below 30%strictly in order to maintain the amorphous nature of spray dried lactose which is a great benefit to DPI development.