Papers by Keyword: Spray Drying

Abstract: ZnO is a semiconductor material that is widely used for many applications in industries such as solar cells, dye-sensitized solar cells, food packaging, photocatalytic, anti-microbial, light-emitting diode devices, and gas sensors. In this study, ZnO nanoparticles (NPs) have been successfully synthesized using two methods, namely spray pyrolysis and a consecutive method. The consecutive method is a combination of sol-gel and spray drying methods. The objective of this study is to investigate the photocatalytic performance of ZnO fabricated using those methods. Both methods used the same precursor, zinc acetate dehydrate as a source of zinc, but with different solvents and additives. Based on the X-ray diffraction pattern, the ZnO NPs synthesized using spray pyrolysis and a consecutive method exhibited similar polycrystalline hexagonal wurtzite structures. The large crystal sizes of ZnO NPs were obtained using a consecutive method, sol-gel followed by spray drying, in comparison with those from the ZnO spray pyrolysis. In contrast, the particle size of ZnO prepared by the consecutive method was in a smaller range. The SEM analysis implied that the ZnO structures had surface defects. In the UV-driven photocatalytic degradation of methylene blue, ZnO produced by the consecutive method exhibited slightly higher degradation performance than ZnO spray pyrolysis. This performance was attributed to the larger crystal size of ZnO NPs, which provided a longer carrier movement at semiconductor surfaces and reduced electron-hole recombination. Additionally, ZnO NPs produced using the consecutive method underwent agglomeration that leads to a smaller contact surface with methylene blue, obstructing the degradation process.

Abstract: Supersaturated astaxanthin (AST)-loaded self-microemulsifying delivery system (SMEDS) was developed and formulated with polymeric precipitation inhibitors (PPIs) to improve the dissolution profile of AST. Based on our preliminary in vitro polymer screening test, hydroxypropyl cellulose (HPC-L) and polyvinyl alcohol (PVA8/88) were selected as PPIs and studied further in this work. Microemulsions prepared from AST SMEDS (composed of AST, rice bran oil, Kolliphor^® RH40, and Span^® 20) were mixed with maltodextrin (MD) as a solid carrier and each PPI solution and then solidified using a spray drying technique. Particle size of spray-dried S-MD-HPC powder had larger circular equivalent (CE) diameter (14.69 ± 0.75 μm) than the other formula and showed particle agglomeration in SEM images. Spray-dried S-MD-PVA powder had 8.94 ± 0.37 μm CE diameter, and smooth surface of particles was observed. Amorphous phase transformation and chemical compatibility of both spray-dried powder formulations were detected by FT-IR, PXRD, and DSC. S-MD-HPC had marginally slower dissolution rate and release profile of AST compared to those of S-MD-PVA; however, both HPC and PVA polymers exhibited the ability for AST precipitation prevention and solubilization enhancement. Although AST degradation was caused by high temperature, physicochemical properties of the spray-dried AST SMEDS (S-MD-HPC and S-MD-PVA) powders after reconstitution were not significantly changed upon storage at 30°C/ RH 75%. This study illustrated a novel platform of spray-dried AST SMEDS in combination with HPC or PVA as a polymeric precipitation inhibitor for improvement of AST loading, solubility, and stability.

Abstract: Microencapsulation of drugs is used for a long time to improve their properties. It was carried out a comparative assessment of the physical and physicochemical methods of microencapsulation on the example of some drugs. The spray drying method was selected from the physical methods. Physicochemical method based on simple coacervation was implemented by changing the solvent. A study and comparison of the properties of the products were obtained by UV and IR spectroscopy, liquid chromatography, electron microscopy. It was carried out a comparative assessment of the release profile of the active substance from microcapsules obtained by various methods. Using the example of furacilin microcapsules has been shown an increase in the biological activity of substances encapsulated in water-soluble polymers. The particle size distribution was determined by analyzing their trajectories. The main advantages and disadvantages of the two investigated encapsulation methods are outlined.

Abstract: The aim of this work was to extract the avocado oil from avocado skin. This oil was used to prepare the emulsion and encapsulation using spray drying. For the oil extraction, the efficiency of microwave assisted extraction (MAE) and soxhelt method was evaluated. The results indicated that MAE at 600 W for 15 min using 2-methyltetrahydrofuran gave the highest yield percentage. The emulsion preparation of avocado oil from MAE was prepared using the wall materials of maltodextrin and the Hi-Cap. The combinations of maltodextrin and Hi-Cap showed 100% stability for 24 hours, with no phase separation. The viscosity of the emulsions was reported at 11.00-13.00 mPa·s. The droplets mean diameter was between 2.05 to 2.08 µm. The microencapsulation of avocado oil was performed in a laboratory scale spray dryer. The encapsulation efficiency of three combinations of wall materials (F1 to F3) was valued of 60-80% which indicated that the increase on maltodextrin content, when combined to Hi-Cap, led to lower encapsulation efficiency. For particle characterization, the moisture content was 1.10-1.35 % and the bulk density was 0.35-0.37 g/cm³. Therefore, the proportion of wall materials had significant influence on the emulsion properties and on the encapsulation efficiency of avocado oil.

Abstract: The effects of drying air temperature and flow rate, spraying air flow rate and slurry feed rate were investigated on the morphology, size distribution, density and flowability of spray-dried hydroxyapatite granules. The granules were of good spherical shape and smooth surface, but low flowability. The granules of uniform size distribution were obtained at high spraying air flow rate and granules of small sizes were collected at high spraying and drying air flow rates, high slurry feed rate and low drying air temperature. Thus, by adjusting the spray drying conditions we can control the granule properties.

Abstract: Alumina/zirconia composite materials are widely used for biomedical applications because of their high biocompatibility and good mechanical properties. In this work, the effects of slurry solid content and binder type are studied on the characteristics of spray-dried composite particles. The tap density and particle size of composite particles increase while the compressibility index decreases with increasing solid content of slurry. An analysis of the SEM micrographs of spray-dried particles confirms the formation of dense composite particles of round shape without internal holes with 70 wt.% slurry using PVA+PEG co-binder.

Abstract: The effect of heat on the quality of spray dried Tongkat Ali extract was investigated at three different air inlet temperatures (100°C, 180°C and 2200C). Response surface methodology employing the Box-Behnken Design was employed to hunt for the optimum operating conditions at these temperatures. Good retentions of eurycomanone, total polysaccharides and glycosaponins were exhibited during the spray drying process. However, protein was found to be susceptible to thermal degradation during the spray drying process. Use of high air inlet temperatures (i.e. 1800C and 2200C) in spray drying led to greater process yield, lower moisture contents, produced non-sticky particles, and resulted in good powder size distribution of Tongkat Ali extract compared to spray drying at 1000C.

Abstract: This works presents a steady state behavior modeling and simulation study of spray dryer operational parameters and their influence on final product. Experimental data of skim milk drying was used to validate the simulator. However, the model is general and can be used for other materials of known properties. Changing sorption isotherm equation and adjusting specific heat capacity of solids, required quality specifications can be estimated by the simulator to any product, which can also determine the best operational parameters of the dryer.

Abstract: In this work, spherical LiFePO₄/C composite had been synthesized by co-precipitation and spray drying method. The structure, morphology and electrochemical properties of the samples were characterized by X-ray diffraction (XRD), scanning electron micrograph (SEM), transmission electron microscope (TEM), constant current charge-discharge tests and electrochemical impedance spectroscopy (EIS) tests. The spherical LiFePO₄/C particles consisted of a number of smaller grains. The results showed that the morphology of LiFePO₄/C particles seriously affected the Li-ion diffusion coefficient and electrochemical properties of lithium ion batteries. Electrochemical tests revealed the spherical LiFePO₄/C composite had excellent Li-ion diffusion coefficient which was calculated to be 1.065×10^-11 cm²/s and discharge capacity of 149 (0.1 C), 139 (0.2 C), 133 (0.5 C), 129 (1 C) and 124 mAhg^-1(2 C). After 50 cycles, the capacity retention rate was still 93.5%.

Abstract: Fruit-milk powder contain various nutritional and therapeutic values. Constipation in children is associated with the lack of fiber from food intake. Child’s diet during their first years of life depends greatly on milk as their main food supply. The primary objective of drying milk incorporated with fruits is to preserve it in a shelf-stable powdered form of high quality without a need for refrigeration. Milk powder are mainly produced using spray-drying and freeze-drying. The parameters needed to be taken into consideration are identified as the factors affecting the physical properties of dried milk powder. A review of the drying technology is presented. Keywords: Milk powder, spray drying, freeze drying, fruits