Effects Of Agitation Speed Research Articles

Effect of Agitation Speed: Three Different Dissolution Methods on in-vitro Release of Plain Disulfiram Implant

Effect of Agitation Speed: Three Different Dissolution Methods on in-vitro Release of Plain Disulfiram Implant

Effect of agitation speed on methylene blue discoloration kinetics via ambient air cold plasma

AbstractThis research investigates the kinetics of methylene blue (MB) discoloration using ambient air cold plasma, with a focus on the impact of agitation speed (100 and 750 rpm). The study revealed pseudo‐first‐order kinetics for MB discoloration, pinpointing optimal conditions at 35.00°C and 100 rpm. These parameters minimized half‐life times, correlated with observed kobs values. A decreasing pH trend, more pronounced at 750 rpm, was attributed to increased acidic nitrogen species (HNO3 and HNO2) production, adversely affecting dye discoloration. Concurrently, enhanced electrolyte concentration was noted from rising conductivity due to plasma production of reactive species followed by solubilization in the aqueous phase. The calculated thermodynamic activation parameters comprised: Ea = 7.96 kJ mol−1, ΔH‡ = +5.53 kJ mol−1, ΔS‡ = −253.23 J K−1 mol−1, and ΔG‡ = +79.77 kJ mol−1 (100 rpm); and Ea = 12.94 kJ mol−1, ΔH‡ = +13.78 kJ mol−1, ΔS‡ = −239.06 J K−1 mol−1, and ΔG‡ = +80.58 kJ mol−1, (750 rpm). The lowest Ea and ΔG‡ values at 100 rpm reinforced lower agitation favoring the reaction. The study demonstrated a linear decay of the reaction rate constant with the square root of ionic strength. This result, besides the negative activation entropy and moderate activation enthalpy led to a proposition to the determinant step for the transition state formation, involving an associative step between a solvated electron and the protonated substrate. The optimal dye discoloration rate and energy yield were observed at 35.00°C and 100 rpm, with values of 97.2% and 3.371 × 10−2 g kW−1 h−1, respectively.

Study on the preparation of glycerylphosphorylcholine by transesterification under supported sodium methoxide

Abstract Glycerylphosphorylcholine (GPC) was prepared by transesterification using supported sodium methoxide as catalyst and natural lecithin as raw material. Sodium methoxide has been proved to be an effective catalyst for the preparation of GPC, which is easy to recover and reuse. After six repeated uses, its stability is satisfactory. The effects of agitation speed, catalyst dosage, and reaction temperature on the reaction were investigated, respectively, and the optimum conditions for preparing GPC catalyzed by supported sodium methoxide were found: the concentration of phosphorylcholine was 0.1 mol·L−1, the stirring speed was 600 rpm, the amount of catalyst was 7.5 g·L−1, the reaction temperature was 45°C, and the reaction time was 4 h; then, the conversion rate of phosphatidylcholine could reach 99%. At the same time, the reaction kinetic model was established based on the mechanism of the transesterification, and the experimental data were compared with the calculated values; it was found that the experimental data fitted the model well. Finally, the reaction activation energy obtained by the Arrhenius equation is 41.6 kJ·mol−1, which indicates that the supported sodium methoxide has good catalytic performance in this reaction system.

Agitation role (Dissolved Oxygen) in production of laccase from newly identified Ganoderma multistipitatum sp. nov. and its effect on mycelium morphology

BackgroundAgitation speed influenced the production rate of laccase. Orbital speed not only influenced the enzyme production, but was also effective to dissolve the oxygen during growth of mycelium, spores, and chlamydospores. Shear effects of speed greatly influenced the morphology of mycelium.MethodsGanoderma multistipitatum was identified by ITS marker. Phylogenetic tree was constructed for species identification. Qualitatively by plate method contained guaiacol indicator, while quantitatively by submerged fermentation and Central Composite Design applied on agitation parameter for maximum laccase potential of this species. The effects of agitation speed on mycelium morphology were observed under compound and scanning electron microscope.ResultsStatistical optimization of agitation conditions were performed by using response surface methodology to enhance the production of laccase from Ganoderma multistipitatum sp. nov. Maximum laccase yield (19.44 × 105 ± 0.28 U/L) was obtained at 150 rpm grown culture, which was higher than predicted value of laccase production (19.18 × 105 U/L) under aerobic conditions (150 rpm). The 150 rpm provided the continuous flush of oxygen. The DO (dissolved oxygen) was maximum (65%) for “27 h” incubation at 150 rpm during laccase synthesis. The statistical value of laccase production was minimum under anaerobic or nearly static condition of 50 rpm. The predicted (12.78 × 105 U/L) and obtained (12.82 × 105 U/L) yield was low at 50 rpm. Optimization of orbital shaking for aeration conditions were performed by the use of “Response Surface Methodology”. The submerged shaking flasks were utilized as a nutrients growth medium to maximize the production of laccase from G. multistipitatum. The minimum incubation time highly influenced the laccase yield from 7 to 15 days via utilization of less cost-effective medium under a promising and eco-friendly method. The morphological effects of rpm on mycelium were examined under compound and scanning electron microscopy. Higher rpm (200, 230) shear the mycelium, while 150 to 200 rpm exhibited smoother and highly dense branches of mycelia.ConclusionThe shear forces of 200 rpm caused the damages of mycelium and cells autolysis with less laccase production. This study concluded that 150 rpm saved the life of mycelium and enhanced the production rate of enzymes.

Effect of temperature and pressure on the reduction of U(VI) to U(IV) by hydrogen over Pt/SiO2: Reaction kinetics and modeling

The kinetics of catalytic reduction of U(VI) by H2 over Pt/SiO2 was investigated as a function of various parameters. The effect of agitation speed and particle size on the reduction of U(VI) was studied initially to eliminate the mass transfer resistance. Later, the effect of catalyst loading, concentration of U(VI), HNO3, N2H4, H2 pressure and temperature on the reduction of U(VI) was studied. Langmuir–Hinshelwood– Hougen–Watson (LHHW) approach was employed to derive kinetic model equations and understand the reaction mechanism. Among the various models, the model – IX corresponding to the adsorption of nitric acid on the catalyst surface was found to be suitable for explaining the concentration profiles of U(VI) and HNO3 in all the temperature and pressure range. The activation energy of the reaction was determined to be around 22.6 kJ mol−1 indicating the reduction of U(VI) with H2 was falling in chemical and diffusion controlled regime.

Vital Conditions to Remove Pollutants from Synthetic Wastewater Using Malaysian Ganoderma lucidum

Mycoremediation, a fungal-based technology, has seen tremendous growth as an effective alternative to treat industrial wastewater due to its ability to oxidise pollutant loadings. Considering the non-toxic properties and high potential degradation performance of Ganoderma lucidum, this research aims to study the performance of a Malaysian G. lucidum strain, the effect of agitation speed, and different carbon-to-nitrogen (C/N) ratio concentrations of synthetic wastewater in degrading chemical oxygen demand (COD) and ammonia. Different agitation speeds (25 rpm, 50 rpm and 100 rpm) and C/N ratios (C10N1, C13.3N1 and C16.7N1) were chosen as parameters to be analysed in this study. The best degradation of COD and ammonia with a percentage removal in the range of 95% to 100% within 30 h of treatment. ANOVA analysis was done using the response surface methodology to verify the obtained results, and it was found that mycoremediation using 100 rpm agitation provided the best results, removing more than 95% of COD and ammonia from synthetic wastewater. The microscopic analysis also showed that the structure of G. lucidum changed after wastewater treatment. This result proved that the Malaysian G. lucidum strain has a good potential in treating synthetic domestic wastewater, especially with high organic content, as a naturally sustainable bioremediation system.

Optimization and kinetic study of biodiesel production from beef tallow using calcium oxide as a heterogeneous and recyclable catalyst

• Biodiesel was produced from beef tallow animal fat. • CaO catalyst obtained from CaCO 3 provides high catalytic performance. • The independent variables of time, reaction temperature, methanol to oil molar ratio, and catalyst amount were optimized using response surface methodology five-level-four-factor central composite design. • 71.31% of biodiesel yield was obtained in optimized conditions of 8:1 methanol to oil ratio, 4% catalyst loading, 60 °C reaction temperature at 90 mins. Production of biodiesel from beef tallow animal fat has largely remained unexplored. Beef tallow is a low-cost and abundant animal fat, while calcium oxide catalyst is a renewable and highly catalytic material obtained from limestone. Therefore, this study reports on the optimization and kinetic study of biodiesel production using calcium oxide solid catalyst. Several characteristics, were determined by SEM (scanning electron microscopy), XRD (X-ray diffraction spectrometry), XRF (X-ray fluorescence), TGA (Thermo-gravimetric analyses), BET (Brunnauer, emmitt and teller analysis) and FTIR (Fourier Transform Infrared) analysis. Process variables optimization for biodiesel production were studied using RSM-CCD approach. The R 2 values were found to be 0.9592 and 0.9595, which show that the model was significantly fit with the experimental data. Maximum FAME conversion was 72% for the synthesized catalyst under optimum process conditions (the four parameters studied in the acid catalyzed esterification of beef tallow resulted in an optimum FFA of 0.60 at operating conditions of acid catalyst amount of 7.1%, methanol to oil ratio of 9:1, reaction temperature of 60 °C and a reaction time of 96 min. The obtained FFA from the actual experimental data showed a close correlation with the predicted FFA result where a predicted FFA of 0.61 was obtained. Components of FAME present in biodiesel was shown by the GCMS analysis. More research is needed on the effect of agitation speed, pressure of reacting mixtures and effect of alcohol and catalyst on process optimization.

Transesterification of methyl oleate for sustainable production of biolubricant: Process optimization and kinetic study

Trimethylolpropane fatty acid triester (TFATE) is a promising biolubricant as an environmentally friendly substitute to conventional mineral-based lubricants. However, the issues of extensive energy consumption from vacuum maintenance and feedstock saponification caused by strong alkaline catalysts exist in current TFATE-based biolubricant synthesis. Here, sustainable production of biolubricant was achieved with methyl oleate (MO) from non-edible oil sources as the feedstock and moderate alkaline K2CO3 as the catalyst. Nitrogen gas stripping method instead of vacuum was adopted for methanol removal. The effects of agitation speed, N2 flow rate, catalyst amount, MO to trimethylolpropane (TMP) molar ratio and temperature on MO conversion and TFATE selectivity were examined. The TFATE selectivity reached 95.6% under the optimized conditions. Leaching tests indicated neglectable K2CO3 dissolution in reaction products. The kinetic parameters for the three consecutive transesterification reactions were calculated. In addition, the synthesized biolubricants exhibit low acid value and volatility, moderate iodine value, superior thermal stability, and good rheological and frictional properties.

Evaluation of using electric arc furnace slag as an adsorbent for dyes removal

ABSTRACT The adsorption of two common textile dyes – orange G and methyl violet – onto an electric arc furnace slag was studied. Batch study shows that adsorption of orange G and methyl violet were dependent highly on pH value. Removal of orange G decreased with the increase of initial pH with optimum pH observed at 3. Moreover, the total removal percentage was low and did not exceed 45% at optimum pH. However, the removal of methyl violet increased with initial pH, and maximum removal (about 94%) was observed at pH 11. Based on the obtained data, methyl violet dye was chosen to study the effect of agitation speed, initial dye concentration, adsorbent dosage and adsorbent particle size on adsorption capacity. For the adsorbent under investigation, equilibrium adsorption capacity qe (mg/g) for orange G and methyl violet dyes were 17.4 mg/g and 3.29 mg/g, respectively. Also, batch studies show that the adsorption rate for methyl violet was rapid at the beginning and slowed down till equilibrium.In contrast, the orange G adsorption rate was slow until it approached equilibrium. The Pseudo-Second order model well represented the kinetics studies data. The value of K2 increased with adsorbent dosage while the K2 value decreased with an increase in initial dye concentration and adsorbent particle size. Equilibrium data were evaluated using Langmuir and Freundlich isotherm models and it was found that the Langmuir isotherm model best fitted to the experiments data.

Effect of agitation speed on microencapsulation of healing agent in PMMA shell and study on the mechanical properties of epoxy/PMMA microcapsules

In this study, the effect of agitation speed as a key process parameter on the morphology and particle size of epoxy-Poly (methyl methacrylate) (PMMA) microcapsules was investigated. Thus, a new interpretation is presented to relate between the microcapsule size to rotational speed so as to predict the particle size at different agitation speeds from the initial capsule size. The PMMA shell capsules containing EC 157 epoxy and hardener as healing materials were fabricated through the internal phase separation method. The process was performed at 600 and 1000 rpm mechanical mixing rates. Scanning electron microscopy (SEM) revealed the formation of spherical microcapsules with smooth surfaces. According to static light scattering (SLS) results, the average diameter size of the epoxy/PMMA capsules at two mixing rates were 7.49 and 5.11

Aeration and Stirring in Yarrowia lipolytica Lipase Biosynthesis during Batch Cultures with Waste Fish Oil as a Carbon Source

Yarrowia lipolytica is one of the most studied non-conventional forms of yeast, exhibiting a high secretory capacity and producing many industrially important and valuable metabolites. The yeast conceals a great biotechnological potential to synthesize organic acids, sweeteners, microbial oil, or fragrances. The vast majority of bioprocesses are carried out in bioreactors, where suitable culture conditions are provided. In the current study, the effect of agitation speed (200–600 rpm) and air flow rate (0.0375–2.0 dm3/(dm3 × min)) on the biomass yield and lipase activity of Y. lipolytica KKP 379 is analyzed in a growth medium containing waste fish oil. The increase of aeration intensity limited the period of oxygen deficit in the medium. Simultaneously, an increase in lipolytic activity was observed from 2.09 U/cm3 to 14.21 U/cm3; however, an excessive agitation speed likely caused oxidative or shear stresses, and a reduction in lipolytic activity was observed. Moreover, it is confirmed that the synthesis of lipases is related to oxygen consumption, pH, and the yeast growth phase, and appropriate process selection may provide two advantages, namely, the maximum use of the waste carbon source and the production of lipolytic enzymes that are valuable in many industries.

Reaction kinetic studies on the immobilized-lipase catalyzed enzymatic resolution of 1-phenylethanol transesterification with ethyl butyrate

The enzyme-catalyzed transesterification reaction is an important route to realize the resolution of racemic optically active secondary alcohols. However, this route suffers from the high environment and engineering risks due to the usage of vinyl ester as acyl donor. In this work, an alternative acyl donor, ethyl butyrate, was used because it is more environment-friendly and catalyst-friendly. The kinetic studies on transesterification of 1-phenylethanol with ethyl butyrate catalyzed by immobilized-lipase Novozym™ 435 were carried out. The effects of agitation speed, reaction temperature, catalyst loading and initial molar ratio of reactants were investigated. The Ping-Pong-Bi-Bi and pseudo-homogeneous models were used to correlate the experimental data to estimate the kinetic parameters. The concentration-based Ping-Pong-Bi-Bi model was translated into its activity-based form to describe the non-ideality of the lipase-catalyzed reaction system. The activity-based Ping-Pong-Bi-Bi kinetic model performed best among all the models used.

Ultrasonically-Assisted Dissolution of Sugarcane Bagasse during Dilute Acid Pretreatment: Experiments and Kinetic Modeling

Ultrasonic irradiation is known to enhance various physicochemical processes. In this work, the effect of ultrasound on the dissolution of sugarcane bagasse was studied, with the specific aims of quantifying the effect at low solids loading and mild reaction conditions, and determining whether the enhancement of dissolution by ultrasound is independent of temperature. The effects of agitation speed, reaction time, and sonication were examined on the dissolution of the biomass substrate at varying reaction temperatures during the pretreatment process. Sugarcane bagasse was mixed with a 0.3 M solution of sulfuric acid in a reaction vessel to undergo pretreatment. A kinetic model was applied to the mass dissolution of the biomass, as sonicated runs showed higher mass losses at each reaction time, compared to the non-sonicated runs. The ultrasonic enhancement in mass dissolution was seen to increase for an increase in the reaction time. It was observed that the induction period for the dissolution was eliminated by the application of ultrasound. Ultrasound was found to be more effective than temperature at enhancing mass dissolution at low solids loadings, and the effect of ultrasound was also found to be dependent on the temperature employed.

Enhancement of exopolysaccharide production from Ganoderma lucidum using a novel submerged volatile co-culture system

Based on the impact of volatile organic compounds (VOCs) on secondary metabolite pathways, a novel submerged volatile co-culture system was constructed, and the effects of thirteen fungal and bacterial VOCs were investigated on Ganoderma lucidum exopolysaccharides production. The results demonstrated at least a 2.2-fold increase in exopolysaccharide (EPS) specific production yield in 6 days submerged volatile co-culture of G. lucidum with Pleurotus ostreatus. Therefore, P. ostreatus was selected as a variable culture, and the effects of agitation speed, inoculum size, initial pH, and co-culture volume on EPSs production were investigated using a Taguchi L9 orthogonal array. Finally, the highest concentration of EPSs (3.35 ± 0.22 g L−1) was obtained under optimized conditions; initial pH 5.0, inoculum size 10%, 150 rpm, and 3:1 volume ratio of variable culture to main culture.

Effect of agitation speed and aeration rate on fructosyltransferase production of Aspergillus oryzae IPT-301 in stirred tank bioreactor.

Fructooligosaccharides (FOS) are prebiotic substances that have been extensively incorporated in different products of food industry mostly for their bifidogenic properties and economic value. The main commercial FOS production comes from the biotransformation of sucrose and intracellular and extracellular microbial enzymes-fructosyltransferases (FTase). Aspergillus oryzae IPT-301 produces FTase. In order to increase its production, this study focuses on evaluating the effects of different agitation speed and aeration rates which affect yields in a stirred tank bioreactor. Agitation had more influence on cell growth than aeration. The maximum intracellular FTase activity and the volumetric productivity of total intracellular FTase were obtained at 800rpm and 0.75 vvm, and reached values of 2100 U g-1 and 667 U dm-3h-1, respectively. The agitation speed had a strong influence on the activity of extracellular FTase produced which reached the maximum amount of 53 U cm-3. The higher value of total activity obtained was 22,831 U dm-3 at 0.75 vvm and 800rpm. Aeration rates and agitation speed showed strong influence upon the growth and production of fructosyltransferase from Aspergillus oryzae IPT-301 in media containing sucrose as carbon source. The control of aeration rate and agitation speed can be a valuable fermentation strategy to improve enzyme production.

Optimization of Culture Condition for Biosorption of Lead using Pseudomonas aeruginosa isolated from Gold Mining Site of Anka, Zamfara State

Pseudomonas aeruginosa was used as a biosorbent for biosorption of lead from heavy metal contaminated gold mining soil of Anka, in Zamfara State. The effects on the degree of biosorption by Pseudomonas aeruginosa were studied: these include Contact time, pH, Temperature, Biomass load and Agitation speed. The effects of contact time were studied at 24, 48, and 72h. Results show highest uptake (98.3%) of lead at 48h and the least (97.8%) at 24h. Effect of pH studied at pH 3, 4, 5, 6, and 7, with pH 6 recording the highest lead removal of 99.0% while pH 3 recorded the least percentage biosorption. The effect of Temperature was studied at 25, 35, 45, 55, and 650C, the highest percentage biosorption (99.3%) recorded at 55⁰C and the lowest 98.1%) was at both 35 and 45⁰C. Effect of biomass load was studied using different volumes (0.5, 1.0, 1.5, 2.0, and 2.5ml) of the innoculum: generally the values obtained did not show variation with change in biomass load. Effect of agitation speed was studied at 2000, 2500, and 3000rpm; the highest lead removal was at 2000 rpm. Biosorption of heavy metals is an excellent technology and represents a potentially cost-effective way for heavy metal decontamination from the environment.

Kinetic study on the reaction of palmitic acid with ethanol catalyzed by deep eutectic solvent based on dodecyl trimethyl ammonium chloride

This study explored the direct esterification of palmitic acid and ethanol using a deep eutectic solvent (DES) as catalyst to produce biodiesel. Three novel deep eutectic solvents (DTAC-PTSA, DTAC-2PTSA, DTAC-3PTSA) were successfully prepared by mixing dodecyl trimethyl ammonium chloride (DTAC) and p-toluenesulfonic acid monohydrate (PTSA) in a molar ratio of 1: z (z=1, 2, 3). After testing, DTAC-3PTSA was found to have the best catalytic performance among the three types of DESs and was therefore selected as the catalyst for subsequent experiments. The effects of agitation speed, ethanol to palmitic acid molar ratio (α), temperature and catalyst dosage were studied by investigating the change of palmitic acid conversion rate with time under different conditions, respectively. Then, the pseudo-homogeneous (PH) model was utilized to describe the kinetic behavior of this reaction between 328.15–348.15 K and it was found to work well for the experimental data obtained. Moreover, the catalytic performance of DTAC-3PTSA was detected to have no significant change in the cycle test. Therefore, DTAC-3PTSA can be considered as a substitute for traditional catalysts to produce biodiesel and the kinetic data obtained here can be used for further up-scaling study.

Operation parameters optimization of a hybrid dead-end/cross-flow forward osmosis system for microalgae dewatering by response surface methodology

The high energy consumption of the microalgae dewatering process results in microalgae being less economically feasible as a new bioenergy material. As an energy-saving method, forward osmosis (FO) filtration can be applied in microalgae dewatering to reduce membrane fouling and energy consumption. In this study, a novel hybrid dead-end/cross-flow FO system was proposed to obtain highly efficient microalgae dewatering. The effects of agitation speed, draw solution concentration, and pH on microalgae and membrane flux reduction volume concentration factors were investigated using Box-Behnken design (BBD) of response surface methodology (three factors and three levels). The results demonstrated that the higher the draw solution concentration and agitation speed, the higher the volume concentration factors. When the draw solution concentration and agitation speed reached their maximums (5M and 500r, respectively), the maximum volume concentration factor was obtained (3.73). pH exhibited the greatest influence on flux reduction. The flux reduction decreased more with an increase in pH (pH>7). When the pH was neutral or acidic, the influence of pH on flux was insignificant. This study provided a more efficient method for dewatering and reduced energy consumption by applying a BBD to optimize the operation parameters of a novel hybrid dead-end/cross-flow FO system for microalgae dewatering.

Investigation of the Potentials of the Binding Properties of Mango, Cashew and Blended Gums

This research is aimed at production and investigation of the potentials of blending mango gum with cashew gum on its binding properties as a substitute for gum Arabic. The high demand for adhesives has led to the search for other alternatives to Arabic and cashew gum due to their high cost and non-availability. Thus, the need to investigate the potentials of mango gum as well as the possibility of replacing mango gum with cashew gum to be employed as an adhesive. The raw gum was extracted from the mango tree, dried, sorted, underwent size reduction of the gum exudates, sieved into different mesh sizes, dissolved in distilled water and centrifuged to remove impurities and other polysaccharides. The binding properties of the extracted mango gum was monitored in terms of physicochemical properties such as viscosity, pH and specific gravity of the gum using capillary viscometer, pH meter and density bottle respectively. The variation of the agitation speed between 250, 500 and 750 rpm, particle size of the raw MG between 75 µm, 212 µm and 300 µm and the replacement of MG with CG from 0-50% at interval of 10% respectively. The effect of agitation speed, particle size of the raw MG and the replacement of MG with CG were investigated in terms of the viscosity, pH and specific gravity of the gum and found that the best quality gum was obtained at particle size of 75 µm, pH of 4.7, agitation speed of 500 rpm and specific gravity of 1.06 respectively. Results indicated that the use of additives such as glycerine, starch and zinc oxide enhanced the binding properties of the gum and MG as well as gums blended with CG were found to fall within the limits to be considered to possess good binding properties. An increase in MG replacement with CG up to 50 %, resulted in a decrease in viscosity and specific gravity of the blended gum by 21.32 % and 3.77 % respectively while pH experienced an increase from 4.4-5.7 i.e. more alkaline in nature.

Coupling minimum cross-entropy model with experimental data to determine the drop size distribution for lanthanum extraction in ARDC column

ABSTRACT The influence of reactive extraction on the drop size distribution for lanthanum extraction was studied in the pilot plant asymmetric rotating disc column. The effect of agitation speed, the flow rate of aqueous and organic phases were investigated on the Sauter mean drop size and size distribution, extraction efficiency, and stripping percent. The prediction of drop size distribution was performed by using the minimum cross-entropy principle (MinCE). The higher values of extraction efficiency and stripping percent indicated that this column is the appropriate equipment for extraction. The outcome of this study provides valuable insights for the prediction of size distribution.