Mathematical analysis of the effects of operating conditions and rheological behaviour of reaction medium on biodiesel synthesis under ultrasound irradiation

Fuel ◽  
2016 ◽  
Vol 184 ◽  
pp. 637-647 ◽  
Author(s):  
Baharak Sajjadi ◽  
Perumal Asaithambi ◽  
A.R. Abdul Aziz ◽  
Shaliza Ibrahim
Catalysts ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 337
Author(s):  
Sara Mesa Medina ◽  
Ana Rey ◽  
Carlos Durán-Valle ◽  
Ana Bahamonde ◽  
Marisol Faraldos

Two commercial activated carbon were functionalized with nitric acid, sulfuric acid, and ethylenediamine to induce the modification of their surface functional groups and facilitate the stability of corresponding AC-supported iron catalysts (Fe/AC-f). Synthetized Fe/AC-f catalysts were characterized to determine bulk and surface composition (elemental analysis, emission spectroscopy, XPS), textural (N2 isotherms), and structural characteristics (XRD). All the Fe/AC-f catalysts were evaluated in the degradation of phenol in ultrapure water matrix by catalytic wet peroxide oxidation (CWPO). Complete pollutant removal at short reaction times (30–60 min) and high TOC reduction (XTOC = 80 % at ≤ 120 min) were always achieved at the conditions tested (500 mg·L−1 catalyst loading, 100 mg·L−1 phenol concentration, stoichiometric H2O2 dose, pH 3, 50 °C and 200 rpm), improving the results found with bare activated carbon supports. The lability of the interactions of iron with functionalized carbon support jeopardizes the stability of some catalysts. This fact could be associated to modifications of the induced surface chemistry after functionalization as a consequence of the iron immobilization procedure. The reusability was demonstrated by four consecutive CWPO cycles where the activity decreased from 1st to 3rd, to become recovered in the 4th run. Fe/AC-f catalysts were applied to treat two real water matrices: the effluent of a wastewater treatment plant with a membrane biological reactor (WWTP-MBR) and a landfill leachate, opening the opportunity to extend the use of these Fe/AC-f catalysts for complex wastewater matrices remediation. The degradation of phenol spiked WWTP-MBR effluent by CWPO using Fe/AC-f catalysts revealed pH of the reaction medium as a critical parameter to obtain complete elimination of the pollutant, only reached at pH 3. On the contrary, significant TOC removal, naturally found in complex landfill leachate, was obtained at natural pH 9 and half stoichiometric H2O2 dose. This highlights the importance of the water matrix in the optimization of the CWPO operating conditions.


2015 ◽  
Vol 4 (4) ◽  
Author(s):  
Seyed Mohammad Safieddin Ardebili ◽  
Teymor Tavakoli Hashjin ◽  
Barat Ghobadian ◽  
Gholamhasan Najafi ◽  
Stefano Mantegna ◽  
...  

AbstractThis work investigates the effect of simultaneous ultrasound-microwave irradiation on palm oil transesterification and uncovers optimal operating conditions. Response surface methodology (RSM) has been used to analyze the influence of reaction conditions, including methanol/palm oil molar ratio, catalyst concentration, reaction temperature and irradiation time on biodiesel yield. RSM analyses indicate 136 s and 129 s as the optimal sonication and microwave irradiation times, respectively. Optimized parameters for full conversion (97.53%) are 1.09% catalyst concentration and a 7:3.1 methanol/oil molar ratio at 58.4°C. Simultaneous ultrasound-microwave irradiation dramatically accelerates the palm oil transesterification reaction. Pure biodiesel was obtained after only 2.2 min while the conventional method requires about 1 h.


2018 ◽  
Vol 67 ◽  
pp. 02010 ◽  
Author(s):  
Sari Dafinah Ramadhani ◽  
Saphira Nurina Fakhri ◽  
Setijo Bismo

The disadvantages of conventional biodiesel synthesis trigger the birth of new biodiesel synthesis methods using the DBD plasma reactor. The conventional methods with homogeneous and heterogeneous catalysts have significant constraints that the formation of glycerol compounds in large enough quantities that require considerable energy. The aim of present experiment is to design DBD non-thermal plasma reactor coaxial pipe type and to do its performance test in converting biodiesel The feed stock used are palm oil, ethanol, and argon gas as plasma carrier. Such a chemical reactor, this plasma reactor is also influenced by reaction kinetics and hydrodynamic factors. From this research, it can be seen that the optimum feed and gas flowrate being operated is 1.64 and 41.67 mL/s. The plasma reactor is used in the form of a quartz glass tube surrounded by a SS-314 spiral coil as an outer electrode. The applied operating conditions are 1 : 1 molar ratio of methanol/oil, ambient temperature of 28 - 30 °C, and pressure 1 bar. From this performance test, it is found that this plasma reactor can be used to synthesize biodiesel from palm oil and methanol without catalyst, no formation of soap, and minimal byproducts.


2016 ◽  
Vol 14 (1) ◽  
pp. 235-249
Author(s):  
Felipe A. Perdomo-Hurtado ◽  
Rubén Vázquez-Medina

AbstractThis paper proposes a predictive mechanistic model to describe the classical pseudo-homogeneous second order kinetic law; the objective of the model is to study the transesterification process of any triglycerides feed stock into the synthetized biodiesel in a batch reactor, which contains a jacket heat exchanger system and a stirrer. The developed model consists of a set of ordinary differential equations which represent the mass and the energy balance for each chemical component in the reactor, accomplished by the temperature’s dynamics in the heat exchanger system, as well as, a reaction kinetic scheme, where the apparent rate and activation energies follow the Arrhenius equation (Noureddini and Zhu 1997, 1457), and the physical-chemical properties of oils, biodiesel and products have been considered. The physical-chemical properties required for products, intermediates and reactants were estimated implementing molecular group contribution methods. The constants in the reactions rates were taken directly from relevant works oriented to experimental study of the kinetic triglycerides methanolysis. The model’s usefulness was verified comparing the produced results against experimental results obtained in the biodiesel synthesis from sunflower (Vicente et al. 2005, 5447), Brassica carinata (Vicente et al. 2005, 899) and soybean (Noureddini and Zhu 1997, 1457) oils. In each case, the model matched the experimental results. Using the proposed model, it is possible to evaluate how the operating conditions and variables like the type of feed, the temperatures of the reactor and the jacket, the heat transfer, the stirrer rate and the changes on thermophysical properties of the species affect the conversion and reactor performance.


Author(s):  
Negisa Ebadipour ◽  
Sébastien Paul ◽  
Benjamin Katryniok ◽  
Franck Dumeignil

Polyglycerols (PGs) are biocompatible and highly functional polyols with a wide range of applications, such as emulsifiers, stabilizers, antimicrobial agents, in many industries including cosmetics, food, plastic and biomedical. The demand increase for biobased PGs encourages researchers to develop new catalytic systems for glycerol polymerization. This review focuses on alkaline homogeneous and heterogeneous catalysts. The performances of the alkaline catalysts are compared in terms of conversion and selectivity, and their respective advantages and disadvantages are commented. While homogeneous catalysts exhibit a high catalytic activity, they cannot be recycled and reused, whereas solid catalysts can be partially recycled. The key issue for heterogenous catalytic systems, which is unsolved so far, is linked to their instability due to partial dissolution in the reaction medium. Further, this paper also reviews the proposed mechanisms of glycerol polymerization over alkaline-based catalysts and discuss the various operating conditions with an impact on the performances. More particularly, temperature and amount of catalyst proved to have a significant influence on glycerol conversion and on its polymerization extent.


2021 ◽  
Author(s):  
Ejaz Khan

In an attempt to elucidate the effect of some operating conditions on the rate and extent of enzymatic hydrolysis of lignocellulosic materials in a stirred tank reactor, wheat straw was hydrolyzed by mixing with two pitched-blade impellers mounted on a shaft under various atmospheric conditions: static air in headspace, N₂ gas flowing over the surface of the medium, and minimal static air by a lid touching the surface of the medium. The presence of N₂ gas over the reaction medium produced by the highest 6.9 % (w/w) conversion in 36 hours. The initial conversion when N₂ gas flowed in the headspace (2.9 % w/w), and when a lid was used (2.9 % w/w) as compared to conversion in air presence (2.3 % w/w), seems to indicate that the enzyme activity was affected due to oxidation in the presence of air. The observed low conversion yield was probably the result of the non sterile conditions imposed by industrial requirements for the production of biofuel ethanol from agricultural lignocellulosics.


Catalysts ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 1021
Author(s):  
Negisa Ebadipour ◽  
Sébastien Paul ◽  
Benjamin Katryniok ◽  
Franck Dumeignil

Polyglycerols (PGs) are biocompatible and highly functional polyols with a wide range of applications, such as emulsifiers, stabilizers and antimicrobial agents, in many industries including cosmetics, food, plastic and biomedical. The demand increase for biobased PGs encourages researchers to develop new catalytic systems for glycerol polymerization. This review focuses on alkaline homogeneous and heterogeneous catalysts. The performances of the alkaline catalysts are compared in terms of conversion and selectivity, and their respective advantages and disadvantages are commented. While homogeneous catalysts exhibit a high catalytic activity, they cannot be recycled and reused, whereas solid catalysts can be partially recycled. The key issue for heterogenous catalytic systems, which is unsolved thus far, is linked to their instability due to partial dissolution in the reaction medium. Further, this paper also reviews the proposed mechanisms of glycerol polymerization over alkaline-based catalysts and discusses the various operating conditions with an impact on performance. More particularly, temperature and amount of catalyst are proven to have a significant influence on glycerol conversion and on its polymerization extent.


2018 ◽  
Vol 18 (3) ◽  
pp. 438-449 ◽  
Author(s):  
Ziaeddin Abed ◽  
Samideh Khoei ◽  
Behafarid Ghalandari ◽  
Jaber Beik ◽  
Ali Shakeri-Zadeh ◽  
...  

Objective: To study the effects of ultrasound irradiation on the release profile of 5-fluorouracil (5-Fu) loaded magnetic poly lactic co-glycolic acid (PLGA) nanocapsules. Also, the controlled drug-release behaviour of the nanocapsules was mathematically investigated. Methods: The nanocapsules were synthesized, dispersed in phosphate buffered saline (PBS), transferred to a dialysis bag, and finally, irradiated by various ultrasound parameters (1 or 3MHz; 0.3-1W/cm2; 5-10 minutes). The release profile of the irradiated nanocapsules was recorded for 14 days. To find the in vitro drug release mechanism in the absence and presence of various intensities of ultrasound, the obtained data were fitted in various kinetic models for drug release. Results: The results demonstrated that the ultrasound speeded up the rate of drug release from the nanocapsules. The mathematical analysis illustrated that when the ultrasound intensity is increased, the probability of controlled release behaviour of the nanocapsules is raised. We found that drug release from the irradiated nanocapsules follows an erosion-controlled mechanism with the decrease in the velocity of diffusion. Conclusion: In conclusion, to attain a controlled drug-delivery strategy in the area of cancer therapy, the drug release profile of the nano-carriers may be well-controlled by ultrasound.


Author(s):  
C R Evans ◽  
K L Johnson

The rheological behaviour of the lubricant in an elastohydrodynamic contact depends upon the properties of the fluid and the imposed conditions of load, speed and temperature. For a lubricant of known rheological properties, it is shown how a ‘map’ can be constructed in which different areas of the map correspond to different regimes of behaviour. The coordinates chosen for the map are non-dimensional pressure and a parameter which is closely related to the film thickness. Given the load, speed and temperature, the operating conditions can be located as a point in the map. Maps have been constructed for three fluids: a mineral oil, polyphenyl ether 5P4E and a traction fluid. In general the maps display four regimes: (a) Newtonian, (b) Eyring, (c) viscoelastic and (d) elastic-plastic. Appropriate constitutive equations are proposed for each regime from which the traction forces can be predicted. The maximum traction coefficients calculated in this way are well supported by experiment.


2013 ◽  
Vol 554-557 ◽  
pp. 928-935
Author(s):  
Hamdi Aguir ◽  
Hedi Bel Hadj Salah

The simulation of the metal forming processes requires accurate constitutive models describing the material behaviour at finite strain, and taking into account several conditions. The choice of a rheological model and the determination of its parameters should be made from a test that generates such conditions. The major difficulty encountered is that there is no experimental test satisfying all these criteria. The use of more than one test seems well adapted, and is utilized to characterize the rheological behaviour at operating conditions corresponding to metal forming applications. Inverse analysis is then considered. Therefore, the difficulty lies with the long computing time that was taken when an optimization procedure is coupled with a finite element computation (FEC) to identify the material parameters. In order to solve the computing time problem, this paper proposes a hybrid identification method based on an artificial neural network and a genetic algorithm (ANN-GA). The proposed strategy is applied to identify the damage material parameters of the AISI 304 steel and using the bulge test.


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