scholarly journals Investigation of design space for freeze-drying injectable ibuprofen using response surface methodology

2021 ◽  
Vol 71 (1) ◽  
pp. 81-98
Author(s):  
Maja Preskar ◽  
Danijel Videc ◽  
Franc Vrečer ◽  
Mirjana Gašperlin
Keyword(s):  
Moisture Content ◽  
Statistical Model ◽  
Specific Surface ◽  
Response Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Freeze Drying ◽  
Design Space ◽  
Residual Moisture Content ◽  
Residual Moisture

AbstractThis study explores the use of a statistical model to build a design space for freeze-drying two formulations with ibuprofen. A 2 × 3 factorial experimental design was used to evaluate independent variables (filling volume and annealing time) and responses as residual moisture content, specific surface area and reconstitution time. A statistical model and response surface plots were generated to define the interactions among the selected variables. The models constructed for both formulations suggest that 1 mL of filled volume and no annealing should be used to achieve optimal residual moisture content, specific surface area and reconstitution time. The proposed models were validated with additional experiments, in which the responses observed were mainly in close agreement with the predicted ones. Additionally, the established models demonstrate the reliability of the evaluation procedure in predicting the selected responses.

scholarly journals Effect of the Freeze-Drying Process on the Physicochemical and Microbiological Properties of Mexican Kefir Grains

Processes ◽  
2019 ◽  
Vol 7 (3) ◽  
pp. 127 ◽  
Author(s):  
Alicia Conde-Islas ◽  
Maribel Jiménez-Fernández ◽  
Denis Cantú-Lozano ◽  
Galo Urrea-García ◽  
Guadalupe Luna-Solano
Keyword(s):  
Moisture Content ◽  
Water Activity ◽  
Freeze Drying ◽  
Survival Rates ◽  
Freezing Temperature ◽  
Freezing Time ◽  
Residual Moisture Content ◽  
Drying Process ◽  
Residual Moisture ◽  
Kefir Grains

The purpose of this study was to investigate how the properties of Mexican kefir grains (MKG) are affected by the operating parameters used in the freeze-drying process. The factors investigated were the freezing time (3–9 h), freezing temperature (−20 to −80 °C), pressure (0.2–0.8 mbar), and lyophilization time (5–20 h). The maximum range of change and one-way analysis of variance showed that lyophilization time and freezing time significant affects (p < 0.05) the response variables, residual moisture content and water activity, and pressure had a significant effect on the color difference and survival rate of probiotic microorganisms. The best drying conditions were a freezing time of 3 h, a freezing temperature of −20 °C, a pressure of 0.6 mbar, and a lyophilization time of 15 h. Under these conditions, we obtained a product with residual moisture content below 6%, water activity below 0.2, and survival rates above 8.5 log cfu per gram of lactic acid bacteria and above 8.6 log for yeast.

scholarly journals Characteristics of Smoldering on Moist Rice Husk for Silica Production

2021 ◽  
Vol 14 (1) ◽  
pp. 317
Author(s):  
Shengtai Yan ◽  
Dezheng Yin ◽  
Fang He ◽  
Junmeng Cai ◽  
Thomas Schliermann ◽  
...  
Keyword(s):  
Moisture Content ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Rice Husk ◽  
Silica Content ◽  
Muffle Furnace ◽  
High Quality

In order to assess the possibility of silica production via smoldering of moist rice husk, experiments of washed (moist) rice husk (7 kg with moisture content of 51%) in a newly designed smoldering apparatus was performed. The temperature inside the fuel bed during smoldering was recorded, and characteristics of ash were analyzed. Results showed that the highest temperature in the middle of the naturally piled fuel bed was about 560.0 °C, lower than those in most of combustors. Some volatiles from the lower part of the fuel bed adhere to its upper ash during piled smoldering. Silica content and specific surface area of ash from smoldering of washed (moist) rice husk were 86.4% and 84.9 m2/g, respectively. Compared to our experiments, they are close to smoldering of unwashed rice husk (89.0%, 67.7 m2/g); different from muffle furnace burning (600 °C, 2 h) of washed (93.4%, 164.9 m2/g) and un-washed (90.2%, 45.7 m2/g) rice husk. The specific surface area is higher than those from most industrial methods (from 11.4 to 39.3 m2/g). After some improvements, the smoldering process has great potential in mass product of high quality silica directly from moist rice husk.

Technology of obtaining nanocomposites for sorption purification of aqueous media

2021 ◽  
Vol 9 ◽  
pp. 68-78
Author(s):  
T. S. Kuznetsova ◽  
◽  
I. V. Burakova ◽  
T. V. Pasko ◽  
A. E. Burakov ◽  
...  
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Sorption Capacity ◽  
Specific Surface Area ◽  
Freeze Drying ◽  
Organic Dyes ◽  
Aqueous Media ◽  
Porous Space ◽  
Supercritical Conditions ◽  
Composite Nanomaterial

The paper presents a technique for obtaining a universal composite nanomaterial for effective sorption water purification from pollutants of various chemical nature. The proposed material is a nanocomposite based on reduced graphene oxide modified with a functional organic component — polyaniline, which also includes oxidized carbon nanotubes as a structure former. The use of polyaniline makes it possible to significantly increase the activity and sorption capacity of the developed graphene material. The authors were developed a number of nanocomposites, which differ in the final stage of the pre-prepared hydrogel technology: drying in air (drying oven), freeze drying, drying under supercritical conditions (supercritical fluid — isopropyl alcohol). In addition, the effect of carbonization as an additional stage (T = 800 °C, argon) was studied in the article. The materials surface morphology was evaluated using scanning electron microscopy. The specific surface area and the parameters of the porous space were determined by nitrogen adsorption. The materials specific surface area increases depending on the choice of drying technology for the initial hydrogel (drying oven — 80 m2/g → freeze drying — 180 m2/g → supercritical drying — 290 m2/g), and also increases after the carbonization stage and reaches a value of ~ 350 m2/g. The nanocomposites sorption capacity to the organic dyes (methylene blue (MB) and solar yellow (SY)), as well as to heavy metals (for example, zinc ions) was determined. It was found that the value of MB sorption is up 1380 to 1800 mg/g, for SY — up 159 to 300 mg/g, for zinc — up 31 to 230 mg/g. At the same time, the sample processed under supercritical conditions, followed by carbonization, were shown the best characteristics.

scholarly journals The influence factors for gas adsorption with different ranks of coals

2017 ◽  
Vol 36 (3-4) ◽  
pp. 904-918 ◽  
Author(s):  
Deyong Guo ◽  
Xiaojie Guo
Keyword(s):  
Moisture Content ◽  
Specific Surface ◽  
Pore Structure ◽  
Adsorption Capacity ◽  
Surface Area ◽  
Specific Surface Area ◽  
Pore Volume ◽  
Gas Adsorption ◽  
Total Pore Volume ◽  
Factors Influencing

In this paper, scanning electron microscopy, low-temperature N2 adsorption and CH4 isothermal adsorption experiments were performed on 11 coal samples with Ro,max between 0.98 and 3.07%. The pore structure characteristics of coals (specific surface area, total volume distribution) were studied to assess the gas adsorption capacity. The results indicate that there is significant heterogeneity on coal surface, containing numerous channel-like pores, bottle-shaped pores and wedge-shaped pores. Both Langmuir volume (VL) and Langmuir pressure (PL) show a stage change trend with the increase of coalification degree. For different coalification stages, there exist different factors influencing the VL and PL values. For low-rank coals (Ro,max < 1.1%), the increase of VL values and decrease of PL values are mainly due to the abundant primary pore and fracture within coal. For middle-rank coals (1.1% < Ro,max < 2.1%), the moisture content, vitrinite content and total pore volume are all the factors influencing VL, and the reduction of PL is mainly attributed to the decrease of moisture content and inertinite content. Meanwhile, this result is also closely related to the pore shape. For high-rank coals (Ro,max > 2.1%), VL values gradually increase and reach the maximum. When the coal has evolved into anthracite, liquid hydrocarbon within pore begins pyrolysis and gradually disappears, and a large number of macropores are converted into micropores, leading to the increase of specific surface area and total pore volume, corresponding to the increase of VL. In addition, the increase of vitrinite content within coal also contributes to the increase of VL. PL, reaches the minimum, indicating that the adsorption rate reaches the largest at the low pressure stage. The result is mainly controlled by the specific surface area and total pore volume of coal samples. This research results will provide a clearer insight into the relationship between adsorption parameters and coal rank, moisture content, maceral composition and pore structure, and it is of great significance for better assessing the gas adsorption capacity.

Discrepancy between thermodynamic and kinetic stabilities of thetert-butanol hydrates and its implication for obtaining pharmaceutical powders by freeze-drying

2019 ◽  
Vol 55 (29) ◽  
pp. 4262-4265 ◽  
Author(s):  
A. G. Ogienko ◽  
A. S. Stoporev ◽  
A. A. Ogienko ◽  
M. S. Mel’gunov ◽  
T. P. Adamova ◽  
...  
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Freeze Drying ◽  
Pharmaceutical Powders ◽  
Drying Time ◽  
Freeze Dried

The substitution of sublimed “H1 + Ih” for “H2 + Ih” leads to both a reduction of primary drying time and a significant increase in specific surface area of the trehalose freeze-dried cakes.

scholarly journals Effect of moisture content on some physical properties of Canarium schweinfurthii Engl. fruits

2016 ◽  
Vol 62 (No. 4) ◽  
pp. 162-169 ◽  
Author(s):  
J.C. Ehiem ◽  
V.I.O. Ndirika ◽  
U.N. Onwuka
Keyword(s):  
Moisture Content ◽  
Physical Properties ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Geometric Mean ◽  
Physical Parameters ◽  
True Density ◽  
Effect Of Moisture ◽  
Mass Volume

The effect of moisture content on some physical properties of three varieties of Canarium schweinfurthii Engl. fruits (small, large and long) was studied at 40.91%, 34.92%, 23.44%, 18.5% and 11.03% moisture content on wet basis in order to solve problems associated with designing and development of processing and handling equipment for these fruits. The physical parameters investigated were major, intermediate, minor diameters, geometric mean diameter, unit mass, volume, sphericity, density, bulk density, roundness, aspect ratio, porosity, surface and specific surface area. The results obtained showed that the physical parameters decreased linearly with a decrease in moisture content. Major diameter and true density of all the fruit varieties were not affected significantly (P &lt; 0.05) by moisture content. Canarium schwein-furthii Engl. fruits are not round but spherical and oblong, hence, they can rather roll than slide. Among the studied varieties, small Canarium schweinfurthii Engl. is less bulky, has the highest specific surface area and is more porous.

Preparation of High Specific Surface Area Nano-Alumina by Vacuum Freeze Drying

2010 ◽  
Vol 26 (04) ◽  
pp. 1171-1176 ◽  
Author(s):  
LIU Xiang-Zhi ◽  
◽  
◽  
PIAO Ling-Yu ◽  
MAO Li-Juan ◽  
...  
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Freeze Drying ◽  
High Specific Surface Area ◽  
Nano Alumina

scholarly journals Porous Starch Materials via Supercritical- and Freeze-Drying

Gels ◽  
2019 ◽  
Vol 5 (1) ◽  
pp. 12 ◽  
Author(s):  
Victor Baudron ◽  
Pavel Gurikov ◽  
Irina Smirnova ◽  
Steve Whitehouse
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Freeze Drying ◽  
Supercritical Drying ◽  
Freezing Temperature ◽  
High Specific Surface Area ◽  
Drying Procedures ◽  
Open Cell Foam ◽  
Cell Foam

The production of porous materials based on starch has been explored with supercritical drying—yielding aerogel—and freeze-drying. The two drying procedures were applied on the same gelling solution of amylomaize starch pasted at 140 °C and for two concentrations (5 and 10 wt.%). After gelation and retrogradation, water from the samples to be supercritically dried was exchanged to ethanol. The resulting starch aerogel presented high specific surface area (197 m2/g). Freeze-drying was assessed by investigating the effect of the gelation, retrogradation, freezing temperature, and sublimation pressure. The resulting starch materials were macroporous, with limited specific surface area and limited mechanical integrity. Cohesive open cell foam with pore size of ~20 µm was produced by quenching the hot starch melt in liquid nitrogen. The highest specific surface area obtained with freeze-drying was 7.7 m2/g for the hot starch melt frozen at −20 °C.

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