GOVPH

Nathaniel P. Dugos

Sex: Male

Education:

Doctor of Philosophy in Chemical Engineering, De La Salle University

Master of Science in Chemical Engineering, De La Salle University

Field of Specialization

Carbon Capture and Storage
Tissue Engineering

Energy Engineering

Researches:

Article title: A Comprehensive Review on the Drying Kinetics of Common Tubers

Authors: Flordelisa H. Cosme-De Vera, Allan N. Soriano, Nathaniel P. Dugos, Rugi Vicente C. Rubi

Publication title: Applied Science and Engineering Progress 14(2): 146-155, 2021

Abstract:

Sun-drying has been conventionally used in the production of tuber-derived commodities such as cassava, potato, sweet potato, and yam. Recent developments in the drying process involves the use of different drying equipment to improve quality and profitability. The importance of drying parameters in the operation of drying equipment necessitates drying kinetic studies on common tubers. This article aims to review the drying kinetics studies conducted on common tubers. Particular interest is on the effect of the drying process parameters like temperature and velocity of heating air medium, the physico-chemical pretreatment method, and sample preparation on the drying rate and time. The different best fit drying kinetic models for specific tubers have also been extensively studied. The role of drying process parameters and best fit model equations on the design of the drying equipment has been emphasized.

Article title: Effect of Decellularization Parameters on the Efficient Production of Kidney Bioscaffolds

Authors: Tosha Mae Manalastas, Nathaniel Dugos, Gliceria Ramos, John Martin Mondragon

Publication title: Applied Biochemistry and Biotechnology May 2020

Abstract:

The most preferred decellularization technique in creating bioscaffolds for complex organs such as kidneys is through detergent perfusion. Detergents such as sodium dodecyl sulfate (SDS) flow to the kidneys to remove cells but using this technique alone requires long treatment times. Coupling this technique with sonication treatment decreases decellularization time but may cause damages in the microarchitecture of the kidney. This study evaluated the effects of decellularization parameters specifically SDS concentration (0.25%, 0.625%, and 1.0%wt/vol), flowrate (15, 30, and 45 mL/min), and sonicator power (0, 60, and 120 W) on the length of time needed to produce acellular and intact bioscaffolds. Decellularization was carried out by perfusing SDS to the renal artery of the cadaveric porcine kidney while exposed to sonication treatment. Results showed that a significant decrease in decellularization time was observed in producing acellular scaffold when perfusion decellularization was coupled with sonication. In addition, SDS concentration, SDS flowrate, and sonicator power had significant effects on the decellularization time while only sonicator power had a significant effect on the microarchitecture integrity of the scaffold. Lastly, H&E results showed that the produced bioscaffold showed complete cell removal with only minimal to moderate disruptions on the microarchitecture of the kidney.

Article title: Determination of Diffusion Coefficients and Antioxidant Activities of Ascorbic Acid in Guava Juice using Cyclic Voltammetry

Authors: K. B. A. Ang, C. M. Lee, H. M. O. Yu, M. Uy, et al.

Publication title: IOP Conference Series Materials Science Engineering 778:012037, 2020

Abstract:

Ascorbic acid is the most abundant antioxidant present in guava (Psidiumguajava L.). There had only been few studies concerning the determination of diffusion coefficient and antioxidant activity of ascorbic acid in guava juice using cyclic voltammetry specifically at varying temperatures. Thus, this study on the effect of temperature on diffusion coefficient and antioxidant activity on ascorbic acid found in guava was done using cyclic voltammetry. The temperatures tested were at 15°C, 25°C, 36°C, and 45°C. Electrodes used in the experiment were glassy carbon as the working electrode, platinum wire as the counter electrode, and Ag/AgCl electrode as the reference electrode. The results showed that the peak currents of ascorbic acid in guava juice at 15°C, 25°C, 36°C, and 45°C were -0.5720, -0.5380, -0.5000, and -0.4760 μA, respectively. The diffusion coefficients of the ascorbic acid were obtained using the Randles-Sevcik equation at all given temperatures and the values were 2.1489 x10−5, 2.1711 x10−5, 2.2070 x10−5, and 2.2250 x10−5 cm2/s, respectively. The antioxidant activities, in terms of concentration, at the said temperatures were found to be 0.3374, 0.3212, 0.3015, and 0.2899 mM, respectively. It is concluded that at higher temperature, ascorbic acid in guava juice has a higher diffusion coefficient but lower antioxidant activity. The present results can be used by other researchers doing similar work on fate and transport of the studied system.

Article title: Sonication-assisted perfusion decellularization of whole porcine kidney

Authors: Sreypich Say, Nathaniel P. Dugos, Susan A. Roces, John Martin Mondragon

Publication title: International Journal of Biology and Biomedical Engineering 13, 2019

Abstract:

Bioengineering of kidneys is a potential treatment option in addressing common problems such as incompatibility and shortage of donor organs. The first step in the kidney bioengineering process involves perfusion decellularization wherein the use of chemicals is considered the most preferred preparation method to date. However, the use of chemicals alone requires long treatment time and excessive chemical usage hence, in this study perfusion decellularization was enhanced by sonication treatment at varying sonication power (150, 200 and 250 W ). Scaffolds produced were evaluated for cell removal and preservation of structural integrity. Results revealed that decellularization with sonication using 150 W, 200 W and 250 W required a treatment time of 24 h, 16 h, and 12 h respectively compared to the 28 h treatment time of decellularization without sonication. Cells were almost and completely removed as indicated by histological analysis. Meanwhile, preservation of renal structures such as glomerulus, tubules, and blood vessels were observed except for the kidney scaffolds produced from decellularization with 250 W sonication where minimal disruption of the glomerular basement membranes and thinning of blood vessels were observed. Overall, decellularization with 200 W of sonication power resulted in an acellular renal ECM scaffold and preserved ECM structure. It can also be concluded that the higher sonication power used, the shorter is the decellularization time needed to prepare a kidney scaffold thus reducing the amount of chemicals used.

Article title: Plasma-Enhanced Chemical Vapor Deposition of Indene for Gas Separation Membrane

Authors: Myat Kyaw, Shinsuki Mori, Nathaniel Dugos, Susan Roces, et al.

Publication title: ASEAN Journal of Chemical Engineering 19(1): 47-53, October 2019

Abstract:

Polyindene (PIn) membrane was fabricated onto a zeolite 5A substrate by using plasma-enhanced chemical vapor deposition (PECVD) at low temperature. Membrane characterization was done by taking Scanning Electron Microscopy (SEM) and FT-IR measurements and the new peak was found in the plasma-derived PIn film. Membrane performance was analyzed by checking permeability of pure gases (H2, N2, and CO2) through the membrane. PECVD-derived PIn membrane showed high gas barrier properties and selectivities of 8.2 and 4.0 for H2/CO2 and H2/N2, respectively, at room temperature.

Article title: Gas permeation properties and preparation of carbon membrane by PECVD method using indene as precursor

Authors: M. Kyaw, N. Dugos, S. Mori, S. Roces, et al.

Publication title: Journal of Physics Conference Series 1295: 012057, September 2019 

Abstract:

This work could demonstrate a new approach to the fabrication of gas separation membrane using indene as polymeric precursor for low pressure PECVD system. Membrane characterization was done by taking Scanning Electron Microscopy (SEM) and FTIR measurements. For membrane performance testing, permeability and selectivity of the membrane were evaluated with pure gases of H2, N2, and CO2 using a differential permeation technique. PECVD-derived polyindene membrane showed selectivities of 8.2 and 4.0 for H2/CO2 and H2/N2, respectively, at room temperature. Polyindene (PIn) membrane was successfully fabricated onto a zeolite 5A substrate via radio frequency plasma-enhanced chemical vapor deposition (RF-PECVD) at room temperature.

Article title: Effect of sonication power on perfusion decellularization of cadaveric porcine kidney

Authors: Sraypich Say, Nathaniel Dugos, Susan Roces, John Martin Mondragon

Publication title: MATEC Web Conferences 268: 01009, 2019

Abstract:

Kidney problems rank 7th among the top 10 causes of mortality among Filipinos. One of the potential future treatment options is the use of bioengineered kidney. The preparation of scaffolds is the first step in kidney bioengineering and perfusion decellularization using chemicals is considered the most preferred preparation method to date. However, the use of chemicals alone requires long treatment time hence, in this study perfusion decellularization is to be enhanced by sonication treatment at varying sonication power. Decellularization was carried out by perfusing the kidney with 1% SDS and was subjected to sonication treatment with a 2h sonication and 2h rest cycle. The cycle is repeated until the kidney is clear and transparent. Washing using 1% Triton X-100 and 1x PBS then follows to remove residual SDS. The extent of cell removal was determined by H&E staining. The results showed that decellularization with sonication using 150W, 200W and 250W required a treatment time of 24h, 16h and 12h respectively compared to the 28h treatment time of decellularization without sonication. The result clearly shows that with higher sonication power, the shorter is the decellularization time needed to prepare a good kidney scaffold.

Article title: Optimized Ultrasound-Assisted Oxidative Desulfurization Process of Simulated Fuels over Activated Carbon-Supported Phosphotungstic Acid

Authors: Peniel Jean Gildo, Nathaniel Dugos, Susan Roces, Meng-Wei Wan

Publication title: MATEC Web of Conferences 156: 03045, 2018

Abstract:

Recent technological advancements respond to the call to minimize/eliminate emissions to the atmosphere. However, on the average, fuel oils which is one of the major raw materials, is found to increase in sulfur concentration due to a phenomenon called thermal maturation. As such, a deeper desulfurization process is needed to obtain low/ultra-low sulfur fuel oils. In the present study, the ultrasound assisted oxidative desulfurization (UAOD) processes using the H2O2 and HPW-AC oxidizing system applied to simulated fuel (~2800 ppm sulfur in the form of dibenzothiophene, benzothiophene, and thiophene dissolved in toluene), were optimized. After the pre-saturation of the HPW-AC with the simulated fuel, H2O2 was added just before the reaction was commenced under ultrasonic irradiation. After the application of both 2k-factorial design of experiment for screening and Face-Centered Design of Experiment for optimization, it was found that 25.52 wt% of H2O2 concentration, 983.9 mg of catalyst dose, 9.52 mL aqueous phase per 10 mL of the organic phase and 76.36 minutes of ultrasonication time would render 94.74% oxidation of the sulfur compounds in the simulated fuel. After the application of the optimized parameters to kerosene and employing a 4-cycle extraction using acetonitrile, 99% of the original sulfur content were removed from the kerosene using the UAOD optimized parameters. The desulfurization process resulted in a low-sulfur kerosene which retained its basic fuel properties such as density, viscosity and calorific value.

Article title: Adsorption of benzothiophene sulfone over clay mineral adsorbents in the frame of oxidative desulfurization

Authors: Angelo Earvin Sy Choi, Susan Roces, Nathaniel Dugos, Meng-Wei Wan

Publication title: Fuel 205(1): 153-160, October 2017

Abstract:

The adsorption of benzothiophene sulfone (BTO) from model fuel oil was investigated using three different clay mineral adsorbents. The adsorption characteristics of clay mineral adsorbents such as activated clay, bentonite and kaolinite were evaluated using Fourier transform infrared spectroscopy and Brunauer, Emmett and Teller surface area analyzer. A batch process was conducted to determine the adsorption performances at varying contact time, reaction temperature and initial concentration. Increasing adsorption capacities followed the order of kaolinite < bentonite < activated clay. The equilibrium isotherms using Langmuir and Freundlich models yielded a good fit (R2 > 0.98) indicating a monolayer and heterogeneous adsorption. A second order reaction kinetic model showed high suitability (R2 > 0.97) based on the experimental data. Results showed that adsorption follows a two-step process: (1) fast adsorption rate for the first two hours and (2) markedly slow adsorption rate until equilibrium. The clay minerals have different functional groups present in its surface which determines the essential adsorption characteristics. The thermodynamic parameters for BTO adsorption onto clay mineral adsorbents indicated an endothermic reaction. Activated clay and kaolinite were spontaneous and non-spontaneous, respectively, while bentonite was found to be only non-spontaneous at 25 °C. In comparison with conventional adsorbents, activated clay was found to be superior in the application of sulfone adsorption in fuel oil.

Full text available upon request to the author

Article title: Synthesis and characterization of hybrid composite aerogels from alginic acid and graphene oxide

Authors: C. J. U. Co, A. T. Quitan, J. Q. Borja, N. P. Dugos, et al.

Publication title: IOP Conference Series Materials Science and Engineering 206(1): 012053, June 2015

Abstract:

Aerogels are one class of solid adsorbents that are gaining considerable attention because of their very high porosity, high specific surface area, and extremely low density. However, most aerogels being studied and used recently are synthetic in nature, which are usually mesoporous silica and metal-organic frameworks (MOFs). As research focus is geared towards sustainable engineering, it is desired to utilize biomass to synthesize aerogels. This study thus aims to produce alginic acid-graphene oxide hybrid composite aerogels and compare them with its existing synthetic counterparts. Alginic acid (AA) is an abundant marine biopolymer that easily forms gels, while graphene oxide (GO) is a nanomaterial consisting of many functional groups. Aerogels made up of AA and GO were successfully synthesized using a sol-gel method. The hydrogel was converted into an aerogel by drying with supercritical carbon dioxide. The percentage of graphene oxide was varied from 0 to 20%. The aerogels were characterized by scanning electron microscopy (SEM), Fourier Transform Infrared Spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetric analysis (TGA) and nitrogen adsorption–desorption measurements. The addition of GO increased the specific surface area of the aerogel up to a certain point, after which it decreased. The 10% GO-AA aerogel showed the most favourable porosity characteristics with a specific surface area of 177.26 m²/g and average pore diameter of 53.2 nm. There had been no observable difference in the thermal behaviour of the aerogels with a change in the concentration of graphene oxide.

Article title: Adsorptive removal of dibenzothiophene sulfone from fuel oil using clay material adsorbents

Authors: Angelo Earvin Sy Choi, Susan Roces, Nathaniel Dugos, Aries Arcega, et al.

Publication title: Journal of Cleaner Production 161(10): 267-276, September 2017

Abstract:

Dibenzothiophene sulfone (DBTO) adsorption utilizing clay material adsorbents such as activated clay, bentonite and kaolinite were investigated in this study. The properties of each adsorbent were characterized using Fourier transform infrared spectroscopy, scanning electron microscope, Brunauer, Emmett and Teller surface area analyzer and zeta potential. The effects of pH (1.0–5.0), contact time (5 min–48 h), temperature (298–328 K) and initial concentration (10–1000 mg/L) were examined in a batch adsorption process to determine the suitability of clay material adsorbents in DBTO removal. Kinetic models of pseudo-first order, pseudo-second order and intraparticle diffusion were used to assess the experimental data. Results showed high correlation to the pseudo-second order kinetic model (R2 > 0.99) that implies chemisorption as the rate-limiting step. Isotherm models of Langmuir, Freundlich, Temkin and Dubnin-Radushkevich were used to evaluate the equilibrium experimental data. DBTO adsorption showed a good fit towards the Freundlich isotherm (R2 > 0.99) which indicates a heterogeneous adsorption onto the adsorbent. Thermodynamic studies indicated that DBTO adsorption onto clay material adsorbents was endothermic. Utilizing the adsorbent of activated clay was spontaneous while kaolinite was non-spontaneous at 298–328 K. Bentonite was found to be only non-spontaneous at 298 K. Activated clay displayed a good potential in adsorbing sulfones to achieve low sulfur fuel oil in an oxidative desulfurization process.

Full text available upon request to the author

Article title: Process Optimization of Carbon Dioxide Adsorption using Nitrogen-Functionalized Graphene Oxide via Response Surface Methodology Approach

Authors: Fritzie Hannah B. Baldovino, Nathaniel P. Dugos, Susan A. Roces, Armando T. Quitain, et al.

Publication title: ASEAN Journal of Chemical Engineering 17(2): 106-113, January 2017

Abstract:

This paper presents a response surface methodology approach in the optimization of the carbon dioxide temperature-programmed adsorption process using a new material referred as nitrogen-functionalized graphene oxide. This material was synthesized by loading nitrogen groups to graphene oxide using aqueous ammonia in supercritical condition. Later on, it was utilized as a sorbent for carbon dioxide adsorption. This process was optimized by implementing a response surface methodology coupled with a Box-Behnken design for the effects of three factors: adsorption temperature, carbon dioxide flow rate, and the amount of adsorbent. In analyzing the response surface, a model equation was generated based on the experimental data by regression analysis. This model equation was then utilized to predict optimum values of response. Furthermore, response optimizer was also conducted in identifying factor combination settings that jointly optimize the best response.

Article title: Oxidation by H2O2 of bezothiophene and dibenzothiophene over different polyoxometalate catalysts in the frame of ultrasound and mixing assisted oxidative desulfurization

Authors: Angelo Earvin Sy Choi, SusanRoces, Nathaniel Dugos, Meng-WeiWan

Publication title: Fuel 180(15): 127-136, September 2016

Abstract:

Desulfurization involves the removal of refractory sulfur compounds in fossil-fuel derived oils. In this study, an ultrasound and mixing assisted oxidative desulfurization of synthetic oil containing sulfur compounds of benzothiophene and dibenzothiophene were carried out using different polyoxometalate catalysts, H2O2 oxidant and a phase transfer agent. The effects of reaction time (2–30 min) and temperature (30–70 °C) were examined in the oxidation of benzothiophene and dibenzothiophene. Results showed high correlation to the pseudo first-order reaction kinetics (R2 > 0.97) and Arrhenius equation (R2 > 0.99) that draws out the rate constant and activation energy of each catalyst tested in the oxidation process. Oxidation of benzothiophene and dibenzothiophene using different polyoxometalate catalysts showed a catalytic activity trend of Na3PW12O40 > H3PW12O40 > H3PM12O40 > H4SiW12O40. Furthermore, ultrasound and mixing assisted oxidative desulfurization showed comparable results (<5% difference) in oxidation efficiency and better performance in the kinetic reaction rate and activation energy as compared to conventional oxidation step in the oxidative desulfurization technique.

Full text available upon request to the author

Article title: Operating cost study through a Pareto-optimal fuzzy analysis using commercial ferrate (VI) in an ultrasound-assisted oxidative desulfurization of model sulfur compounds

Authors: Angelo Earvin Sy Choi, SusanRoces, Nathaniel Dugos, Meng-WeiWan

Publication title: Clean Technologies and Environmental Policy 18(5), June 2016

Abstract:

There is a need for transportation fuel such as diesel oil to undergo a desulfurization process prior to its usage in order to comply with stringent environmental regulations. Predominant organic sulfur compounds present in fuel oils comprise benzothiophene (BT) and dibenzothiophene (DBT). High sulfur compound reduction is attainable through a desulfurization process but this often leads to risking higher operating cost due to longer reaction time and the use of large amounts of oxidizing agent and phase transfer agent. Fuzzy logic, which is often used in multi-objective decision-making models, is able to meet the desired objective and satisfy the given constraints at the same time. In this study, a pareto-optimal fuzzy analysis is used in order to determine the best conditions in the ultrasound-assisted oxidative desulfurization process and at the same time achieving the lowest possible operating cost for reducing BT and DBT. Process parameters investigated include ultrasonication time (10–30 min), phase transfer agent (100–300 mg), organic to aqueous phase ratio (10:30–30:10), and ferrate concentration (100–300 ppm) for the reduction of model sulfur compounds. Results through fuzzy optimization indicated optimum results of 93.79 % BT conversion with operating cost of US$ 0.830 and 88.36 % DBT conversion with operating cost of US$ 0.769.

Article title: Mixing-assisted oxidative desulfurization of model sulfur compounds using polyoxometalate/H2O2 catalytic system

Authors: Angelo Earvin Sy Choi, SusanRoces, Nathaniel Dugos, Meng-WeiWan

Publication title: Sustainable Environment Research 26(4), April 2016

Abstract:

Desulfurization of fossil fuel derived oil is needed in order to comply with environmental regulations. Dibenzothiophene and benzothiophene are among the predominant sulfur compound present in raw diesel oil. In this study, mixing-assisted oxidative desulfurization of dibenzothiophene and benzothiophene were carried out using polyoxometalate/H2O2 systems and a phase transfer agent. The effects of reaction time (2-30 min) and temperature (30-70 °C) were examined in the oxidation of model sulfur compounds mixed in toluene. A pseudo first-order reaction kinetic model and the Arrhenius equation were utilized in order to evaluate the kinetic rate constant and activation energy of each catalyst tested in the desulfurization process. Results showed the order of catalytic activity and activation energy of the different polyoxometalate catalysts to be H3PW12O40 > H3PM12O40 > H4SiW12O40 for both dibenzothiophene and benzothiophene.

Article title: Synthesis and Characterization of Nitrogen-Functionalized Graphene Oxide in High-Temperature and High-Pressure Ammonia

Authors: F. H. Baldovino,   A. T. Quitain,  Nathaniel P. Dugos, Susan A. Roces, et al.

Publication title: RSC Advances 6(115): 113924-113932, November 2016

Abstract:

A novel and efficient approach to the synthesis of nitrogen-functionalized graphene oxide (GO) using aqueous ammonia, NH3 (aq.), under high-temperature and high-pressure conditions was investigated. Nitrogen groups (N-groups) were incorporated in GO in different ways; by replacing the carbon (C) atoms and reacting with the oxygenated functionalities present in GO. Reaction mechanisms were proposed, showing how N-groups were attached to GO. Functionalization was confirmed using Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), nuclear magnetic resonance (NMR) spectroscopy and elemental analysis (EA). Raman spectroscopy, X-ray diffraction spectroscopy (XRD), and scanning electron microscopy (SEM) were employed to further characterize GO modification. Functionalization was carried out to increase GO adaptability to a wide range of applications, including carbon dioxide (CO2) capture and electrochemical oxygen reduction as reported.

Full text available upon request to the author

Article title: A Skeletal Kinetic Model For Biodiesel Fuels Surrogate Blend Under Diesel-Engine Conditions

Authors: Chit Wityi Oo, Masahiro Shioji, Hiroshi Kawanabe, Susan A. Roces, et al.

Publication title: ASEAN Journal of Chemical Engineering 15(1), 2015

Abstract:

The biodiesel surrogate fuels are realistic kinetic tools to study the combustion of actual biodiesel fuels in diesel engines. The knowledge of fuel chemistry aids in the development of combustion modeling. In order to numerically simulate the diesel combustion, it is necessary to construct a compact reaction model for describing the chemical reaction. This study developed a skeletal kinetic model of methyl decanoate (MD) and n-heptane as a biodiesel surrogate blend for the chemical combustion reactions. The skeletal kinetic model is simply composed of 45 chemical species and 74 reactions based on the full kinetic models which have been developed by Lawrance Livermore National Laboratory (LLNL) and Knowledge-basing Utilities for Complex Reaction Systems (KUCRS) under the diesel like engine conditions. The model in this study is generated by using CHEMKIN and then it is used to produce the ignition delay data and the related chemical species. The model predicted good reasonable agreement for the ignition delays and most of the reaction products at various conditions. The chemical species are well reproduced by this skeletal kinetic model while the good temperature dependency is found under constant pressure conditions 2MPa and 4MPa. The ignition delay time of present model is slightly shorter than the full kinetic model near negative temperature coefficient (NTC) regime. This skeletal model can provide the chemical kinetics to apply in the simulation codes for diesel-engine combustion.

Article title: Optimization analysis of mixing-assisted oxidative desulfurization of model sulfur compounds using commercial ferrate(VI)

Authors: Angelo Earvin Sy Choi, SusanRoces, Nathaniel Dugos, Cybelle Morales Futalan, et al.

Publication title: Desalination and Water Treatment 57(37), 2016

Abstract:

Mixing-assisted oxidative desulfurization of benzothiophene (BT) and dibenzothiophene (DBT) was investigated using commercial ferrate(VI). The effect of operating parameters such as temperature (50–70°C), agitation speed (7,600–14,000 rpm), and mixing time (10–30 min) were examined in relation to sulfur reduction. Optimization experiments were carried out using Box–Behnken design under response surface methodology to evaluate the significance of operating variables. Results show that optimum sulfur reduction of 84.35% for BT could be attained at 15.42 min, 12,198 rpm, and 52.22°C. Moreover, a 93.68% sulfur reduction for DBT could be achieved at 14.43 min, 8,704 rpm, and 51.26°C. Using the optimized conditions, diesel oil was oxidized and showed a sulfur reduction of 58.03 and 93.15% for BT and DBT, respectively.

Article title: Ignition and combustion characteristics of various biodiesel fuels (BDFs)

Authors: Chit Wityi Oo, Masahiro Shioji, Shinji Nakao, Nguyen Ngoc Dung, et al.

Publication title: Fuel 158(15): 279-287, October 2015

Abstract:

The fundamental data of ignition and combustion characteristics of various biodiesel fuels (BDFs) are exhibited for finding the optimal condition in diesel engines. The experimental research has been conducted in a constant-volume vessel with the pre-burn system under diesel-engine conditions. The ignition delays and heat release rates were investigated under different ambient temperatures and pressures. This study used diesel oil and various BDFs such as jatropha methyl ester (JME), coconut methyl ester (CME), soybean methyl ester (SME) and palm methyl ester (PME). The experimental results on fuel-spray development and combustion characteristics were affected by the properties of biodiesel fuels (BDFs), which may support potentially the optimal design of diesel engine fueled with BDFs. Evaporation and mixing are promoted at the tip of fuel jet with lower distillation temperature and lower viscosity, resulting in a shorter length dense region in the spray. These properties may disturb the mixture formation of BDFs at spray tip although the penetration lengths are almost same. The ambient temperature (Ti) and ambient pressure (pi) strongly influenced the ignition and combustion processes of BDF and diesel oil. Though ignition delays of all BDFs are shorter than that of diesel oil in the whole temperature range from 600 K to 1200 K, CME exhibits the significant shortest delay, suggesting a dominant effect of physical properties of mixing process. At the ambient temperature 800 K and 4 MPa, all of BDFs and diesel oil predict the similar histories of heat release rate. The pre-mixture combustion with longer ignition delay dominates the combustion process at 700 K, but its period is almost constant irrespective of BDF. Ignition delay becomes longer than the injection period for high density and viscosity tested fuels, resulting in a very slow combustion.

Full text available upon request to the author

Article title: A skeletal kinetic model for biodiesel fuels surrogate blend under diesel-engine conditions

Authors: Chit Wityi Oo, Masahiro Shioji, Hiroshi Kawanabe, Susan A. Roces, et al.

Publication title: 2014 International Conference on Humanoid, Nanotechnology, Information Technology, Communication and Control, Environment and Management (HNICEM)

Abstract:

The biodiesel surrogate fuels are realistic kinetic tools to study the combustion of actual biodiesel fuels in diesel engines. The knowledge of fuel chemistry aids in the development of combustion modeling. In order to numerically simulate the diesel combustion, it is necessary to construct a compact reaction model for describing the chemical reaction. This study developed a skeletal kinetic model of methyl decanoate (MD) and n-heptane as a biodiesel surrogate blend for the chemical combustion reactions. The skeletal kinetic model is simply composed of 45 chemical species and 74 reactions based on the full kinetic models which have been developed by Lawrance Livermore National Laboratory (LLNL) and Knowledge-basing Utilities for Complex Reaction Systems (KUCRS) under the diesel like engine conditions. The model in this study is generated by using CHEMKIN and then it is used to produce the ignition delay data and the related chemical species. The model predicted good reasonable agreement for the ignition delays and most of the reaction products at various conditions. The chemical species are well reproduced by this skeletal kinetic model while the good temperature dependency is found under constant pressure conditions 2MPa and 4MPa. The ignition delay time of present model is slightly shorter than the full kinetic model near negative temperature coefficient (NTC) regime. This skeletal model can provide the chemical kinetics to apply in the simulation co des for dieselengine combustion.

Full text available upon request to the author

Article title: Carbon Dioxide Absorption in a Fabricated Wetted-Wall Column Using Varying Concentrations of Aqueous Ammonia

Authors: H.E.E. Ching, L.M.P. Co, S.I.C. Tan, S.A. Roces, et al.

Publication title: ASEAN Journal of Chemical Engineering 13(2), 2013

Abstract:

Due to the continued increasing levels of CO2 emissions that is contributing to climate change, CO2 mitigation technologies, particularly carbon capture and storage, are being developed to address the goal of abating CO2 levels. Carbon capture technologies can be applied at the pre-combustion, oxy-fuel combustion, and post-combustion stages, the latter being the most widely used due to its flexibility. Among the several CO2 separation processes available for carbon capture, absorption is the most widely used where amine solutions are used as absorbents. This paper highlights the use of a wetted wall column fabricated by Siy and Villanueva (2012) and simulated flue gas to determine the performance of CO2 absorption in terms of the percentage of CO2 absorbed, the steady state time, and the overall gas mass transfer coefficient. The concentrations used were 1, 5, 10, and 15% NH3(aq) at a constant temperature range of 12-17ºC, solvent flow rate of 100 mL/min, and simulated flue gas flow rate of 2 L/min. It was found that increasing the solvent concentration resulted in a proportional increase both in the percentage of CO2 absorbed and the overall gas mass transfer coefficient. The average percentage of CO2 absorbed ranged within 52.25% to 95.29% while the overall mass transfer coefficient ranged from 0.1843 to 0.7746 mmol/m2∙s∙kPa. However, erratic behavior was seen for the time required for the system to reach steady state. Using Design ExpertTM for analysis, the results showed that the effect of varying the concentration had a significant effect on the percentage of CO2 absorbed and the overall gas mass transfer coefficient. The results proved that the greater the aqueous ammonia concentration, the greater the percentage of CO2 absorbed. The range of 5-10% aqueous ammonia is recommended because the percentage of CO2 absorbed peaks at an average of 92% beyond the range of 5-10%.

Article title: Stability and Emission Characteristics of Diesel-Ethanol-Coconut Methyl Ester Blends for the Diesel Engines

Authors: Tanti Ardiyati, Nathaniel P. Dugos, Susan A. Roces, Masaaki Suzuki, et al.

Publication title: ASEAN Journal of Chemical Engineering 14(2), 2014

Abstract:

The stability and emission characteristics of diesel-ethanol-coconut methyl ester (CME) blends were studied to determine the most suitable fuel blends to be applied in diesel engines. This is done in order to assess the potential of the blends as a substitute for commercially available diesel fuel used in diesel engine. The stability results of the blends using 100% and 99.5% ethanol purity showed that the fuel blends containing ethanol up to 10% and CME of 5% and greater exhibited high mutual solubility at any temperature range and were resistant to microbial growths after 3 months storage. Engine operations at low speed especially at idle-no load and using a bigger size engine lead to a minimum ignition delay and result in lower fuel consumption rate. The emission test results with the new- blended fuels showed a reduction in CO2 and increasing percentage by volume of CO2 compared to commercially available diesel. The blends could deliver an efficient combustion and could run efficiently since production of the CO2 gases is higher than that of CO. The blends of 80% diesel, 5% ethanol, 10% CME; and 80% diesel, 10% ethanol, 10% CME could reduce the smoke opacity compared to commercially available diesel.

Article title: Short communication: Interdependent ranking of sources and sinks in CCS systems using the analytic network process

Authors: M.A.B. Promentilla, J.F.D.Tapia, C.A. Arcilla, N.P. Dugos

Publication title: Environmental Modelling & Software 50: 21-24, December 2013

Abstract:

CO2 capture and storage (CCS) is widely regarded as an important low-carbon technology for reducing greenhouse gas emissions from large industrial point sources. It entails the capture of a relatively pure CO2 from exhaust gases using different techniques, and then storing this captured gas in various geological sinks. Large-scale deployment of CCS requires the comprehensive evaluation of candidate sources and sinks present in a given geographical region. In this study, we propose an analytic network process (ANP) approach to rank simultaneously the potential CO2 sources and sinks in a CCS system. Such ranking can be used to identify sites for CCS demonstration projects. This ANP decision model allows us to incorporate the feedback dependency that exist in the preference ranking of sources and sinks due to the importance of geographic proximity as a decision criterion. A case study is then solved to demonstrate the proposed model.

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Article title: Effect of MgCI2 and CaCI2 on the Bubble Point of Mixed- Solvents (Toluene-Isopropyl Alcohol-H20 System)

Authors: Nathaniel P. Dugos, Noel P. Cabigon, Yolanda P. Brondial

Publication title: ASEAN Journal of Chemical Engineering 6(2), 2006

Abstract:

This study investigated the effect of CaCl2 and MgCI2,both alkaline earth metal salts on the boiling points of a mixed-solvent system composed of toluene, isopropyl alcohol and water. The effect of the concentration of the salt on the boiling point of this ternary system was also examined. Results showed that mixed- solvents added with CaCl2 boil at higher temperatures than those with MgCl2even though the latter salt is higher in molal concentration. This proves that MgCI2, which has a smaller ionic radius than CaCl2 is more effective in reducing the molecular affinity to polar and associating solvents (water and isopropyl alcohol) than to the non-polar solvent (toluene). The mixed- solvent system added with MgCl2 registered higher boiling point deviation than those with CaCI2, though both showed positive deviations. Based on the results, either of the two salts can be an effective mass separating agent. However it is shown that MgCl2is better than CaCl2 because the solutions with MgCI2 generally exhibited lower boiling points. Though the difference in temperature deviations of the two salts is statistically not significant, a difference in temperature of one degree is economically significant considering the cost of energy.