Papers by Kheireddine Taieb Aroua
Equilibrium of CO2 in aqueous diethanolamine (DEA) and Amino Methyl Propanol (AMP) solutions
Chemical Engineering Communications, 1996
Equilibrium data of CO2 in aqueous solutions of DEA and AMP for a range of CO2 partial pressure (... more Equilibrium data of CO2 in aqueous solutions of DEA and AMP for a range of CO2 partial pressure (0.5-100 kPa) and temperature (25-80°C) obtained using a stirred cell reactor is presented in this paper. The data were analyzed using the Deshmukh and Mather Model. It has been found that this model is able to predict results which are close to the experimental data in terms of the total CO2 loadings and the pH of the solution, an additional parameter which was monitored in this work. Comparison was also made with other published results using the different interaction parameters generated in this work. Good agreement between predicted and experimental values were also observed.
Equilibrium concentration profiles of species in CO2-alkanolamine-water systems
Gas Separation and Purification, 1996
Equilibrium concentrations of species and gas loading in aqueous solutions of alkanolamine loaded... more Equilibrium concentrations of species and gas loading in aqueous solutions of alkanolamine loaded with CO2 are being compared with predicted profiles obtained from the Deshmukh-Mather Model. A new technique is being proposed based on titration using a base, NaOH, to determine the concentrations of the different species at equilibrium. The technique is reliable and easy to perform to give reproducible results. Experimental and predicted concentrations of species are in good agreement over a range of gas loading between 0.4 and 1.0 for aqueous AMP solutions. For DEA, the predicted and measured values complement each other at high loading typically above 0.6. At low loading, there is a significant difference between the sets of values for carbamate and bicarbonate. These differences are likely due to the value of the equilibrium constant for the carbamate formation, which is taken as an adjustable parameter in the model, to give the best fit to the experimental data of either CO2 partial pressure or gas loading.
Temperature dependency of the equilibrium constant for the formation of carbamate from diethanolamine
Journal of Chemical and Engineering Data, 1997
The equilibrium constant for the formation of diethanolamine carbamate was determined experimenta... more The equilibrium constant for the formation of diethanolamine carbamate was determined experimentally at (303, 313, 323, and 331) K for ionic strengths up to 1.8 mol dm-3, the inert electrolyte being NaClO4. A linear relationship was found to hold between log K and I0.5. The thermodynamical constant has been determined and expressed by the equation log K1 = -5.12 + 1.781 × 103 K/T.
Activation energy for the oxidation of Malaysian coal chars
Journal of the Institute of Energy, 1997
The oxidation of two Malaysian coal chars has been studied by means of a thermal gravimetric anal... more The oxidation of two Malaysian coal chars has been studied by means of a thermal gravimetric analyser (TGA). The weight-loss data were analysed by the Temperature Program Reaction (TPR) technique, which employed the random pore model of Bhatia & Perlmutter1. All experiments were conducted within a temperature range of 698-773 K (isothermal condition) and heating rates of 2-10 K min-1 (dynamic condition) with char samples in the size range 53-75 μm. It was found that the random pore model can accurately describe the oxidation of char to yield activation energy that is similar to that obtained from model free kinetics, provided the structural parameter ψ, which is an input to the model, is taken as an adjustable parameter.
Chemical Engineering Research & Design, 1998
Equilibrium data on the absorption of CO2 in aqueous solutions of single and mixed amine was anal... more Equilibrium data on the absorption of CO2 in aqueous solutions of single and mixed amine was analysed using the Modified Kent Eisenberg model. The experimental value of the examined constant for the formation of carbamate, instead of the fitted value as usual was analysed using the Modified Kent Eisenberg model. The experimental value usually used by other investigators, was applied in the analysis. Data on CO2 loading in aqueous solutions of DEA and MDEA at various temperature (303-323 K) and CO2 partial pressure (0.09-100 kPa) obtained from a stirred reactor was fitted to generate the different parameters in the model. Using these constants, the model was applied to predict the CO2 loading in solutions of DEA and MDEA reported in the literature. Prediction was also made on the loading in solutions of mixed DEA/MDEA obtained from experiments conducted over a range of composition (DEA:MDEA = 0-1) at different temperatures of 303-323 K, as well as those reported in the literature. In all cases, it was found that the model was able to give a relatively good CO2 loading over a wide range of operating conditions both in solutions of single and mixed amine using the constants generated from single amine experiments. It also suggested that the experimental value of the equilibrium constant for the formation of carbamate obtained from an earlier work can be taken as the true value for the reaction.
Equilibrium constant for carbamate formation from monoethanolamine and its relationship with temperature
Journal of Chemical and Engineering Data, 1999
The equilibrium constant for the formation of carbamate from monoethanolamine (MEA) was evaluated... more The equilibrium constant for the formation of carbamate from monoethanolamine (MEA) was evaluated at various temperatures of 298, 308, 318, and 328 K and ionic strength up to 1.7 M. The equilibrium constant has been estimated by extrapolating the value of the calculated apparent equilibrium constant to zero ionic strength. A relationship on its variations with temperature is also proposed.
International Journal of Thermophysics, 2004
Solubilities of CO2 in aqueous solutions of activated methyldiethanolamine (MDEA) has been invest... more Solubilities of CO2 in aqueous solutions of activated methyldiethanolamine (MDEA) has been investigated for temperatures and CO 2 partial pressures ranging from 40 to 80°C and 0.1 to 100 kPa, respectively. Piperazine (PZ) is used as activator, with a concentration ranging from 0.01 to 0.1 M, keeping the amine total concentration in the aqueous solution at 2 M. The experimental solubility results were represented by the mole ratio of CO2 per activated amine present in the liquid mixture. The addition of piperazine, as activator for MDEA, increased the solubility of CO2 in the region of low CO2 partial pressure compared to pure MDEA. The CO2 loading increased with decreasing temperature, increasing CO2 partial pressure, and increasing PZ concentration.
Solubility of CO2 in aqueous piperazine and its modeling using the Kent-Eisenberg approach
Chemical Engineering & Technology, 2004
A systematic investigation of the equilibrium solubility of CO2 in aqueous piperazine solutions w... more A systematic investigation of the equilibrium solubility of CO2 in aqueous piperazine solutions was conducted in a double-jacketed stirred cell reactor. The solubilities of CO2 in the solution were measured at 20, 30, 40, and 50 °C with CO2 partial pressures ranging from 0.4-95 kPa. Generally the aqueous piperazine solution exhibits the same characteristics as conventional alkanolamines. Increasing the CO2 partial pressure increases the gas loading, however increasing the temperature or concentration decreases the CO2 loading. The values of the CO2 loading obtained confirm that the piperazine forms stable carbamates. The equilibrium solubility data were analyzed using a Kent-Eisenberg approach. Representation of the model is generally in good agreement with that of the experimental data, especially at high temperature.
Fluid Phase Equilibria, 2005
The equilibrium of CO2 and carbamate concentration data for the absorption of CO2 in aqueous solu... more The equilibrium of CO2 and carbamate concentration data for the absorption of CO2 in aqueous solutions of single and mixed amines was analyzed using the Deshmukh-Mather model. Data on CO2 loading in aqueous solutions of DEA and MDEA and their mixtures at various temperature (303-323 K) and CO2 partial pressure (0.09-100 kPa) together with carbamate concentrations in case of DEA and its mixtures with MDEA were fitted simultaneously to generate the different interaction parameters required to calculate the activity coefficients in the model. Using the generated interaction parameters, the model was applied to correlate the CO2 loading in solutions of DEA and MDEA and their mixtures reported in the literature as well as those obtained in our laboratory and was found to be able to give a good estimation of CO2 loading and carbamate concentration over a wide range of operating conditions in both single and mixed amine solutions.
Treatment of skim latex serum using gas sparged ultrafiltration
Developments in Chemical Engineering and Mineral Processing, 2005
The major pollutants from a natural rubber processing factory have high organic content and emit ... more The major pollutants from a natural rubber processing factory have high organic content and emit an offensive smell due to the biodegradation of the organic matter. In latex concentrate factories, the main sources of effluent are the skim latex serum and washings from all process equipment. This paper presents an application of membrane technology that involves gas sparging for the treatment of skim latex serum. A semi-pilot-scale system using a PVDF vertical tubular membrane (MWCO 100,000) was installed as the experimental setup. Nitrogen gas was bubbled vertically upwards at flowrates ranging from 300 to 500 ml/min. Results obtained thus far show that gas sparging has increased the permeate flux between 1.37% and 146.34% compared to non-gas sparged conditions. In terms of permeate quality, the reductions achieved for suspended solids, total solids, COD, BOD, total nitrogen and ammoniacal nitrogen were 83%, 95%, 67%, 77%, 51%, 74%, respectively, for the gas-sparged condition. Under non gas-sparging conditions, reductions achieved for suspended solids, total solids, COD, BOD, total nitrogen and ammoniacal nitrogen were 92%, 96%, 67%, 72%, 60%, 75%, respectively.
Biochemical Engineering Journal, 2006
Medium-chain-length (mcl) polyhydroxyalkanoates (PHAs) are biodegradable polyesters accumulated i... more Medium-chain-length (mcl) polyhydroxyalkanoates (PHAs) are biodegradable polyesters accumulated intracellularly as energy resources by bacterial species such as Pseudomonas putida. The most popular method for PHA recovery in the downstream processing is solvent extraction using chloroform and methanol. An alternate method is bioseparation using enzymatic digestion process which eliminates the need for hazardous solvents. This research focuses on an attempt to optimize the recovery of PHAs by solubilisation of non-PHA granules through enzymatic treatments such as; Alcalase (to digest the denatured proteins), sodium dodecyl sulfate (SDS) to assist solubilisation, ethylene diamine tetra acetic acid (EDTA) to complex divalent cations and lysozyme to digest the peptidoglycan wall enveloping the cell. The experiment was designed through Taguchi's design of experiment (DOE) using Qualitek-4 software. The results show that Alcalase enzyme used had the most significant effect on the treatment process and contributed to about 71.5% in terms of process factor importance among the different factors on treatment performance for PHA recovery. It is desired to recover the PHA granules in water suspension after the enzymatic treatment by removing the solubilised non-PHA cell material through crossflow ultrafiltration system and purified through continuous diafiltration process. Final purity of PHA in water suspension obtained using GC analysis is 92.6%, with a nearly 90% recovery, thus concluding that this method is indeed a suitable alternative.
Fuel Processing Technology, 2007
Palm shell based activated carbon prepared by K2CO3 activation is used as precursor in the produc... more Palm shell based activated carbon prepared by K2CO3 activation is used as precursor in the production of carbon molecular sieve by chemical vapor deposition (CVD) method using benzene as depositing agent. The influences of deposition temperature, time, and flow rate of benzene on pore development of carbon molecular sieve (CMS) and methane (CH4) adsorption capacity were investigated. The parameters that varied are the deposition temperature range of 600 to 1000 °C, time from 5.0 to 60 min, and benzene flow rate from 3.0 to 15 mL/min. The results show that in all cases, increasing the deposition temperature, time, and flow rate of benzene result in a decrease in adsorption capacity of N2, pore volume and pore diameter of CMS. The BET surface area of CMS (approximately 1065 m2/g) and the adsorption capacity of CH4 were at a maximum value at a deposition temperature of 800 °C, time of 20 min and benzene flow rate of 6 mL/min. The product has a good selectivity for separating CH4 from carbon dioxide (CO2), nitrogen (N2), and oxygen (O2).
Bioresour Technol, 2007
Palm shell was used to prepare activated carbon using potassium carbonate (K2CO3) as activating a... more Palm shell was used to prepare activated carbon using potassium carbonate (K2CO3) as activating agent. The influence of carbonization temperatures (600-1000 °C) and impregnation ratios (0.5-2.0) of the prepared activated carbon on the pore development and yield were investigated. Results showed that in all cases, increasing the carbonization temperature and impregnation ratio, the yield decreased, while the adsorption of CO2 increased, progressively. Specific surface area of activated carbon was maximum about 1170 m2/g at 800 °C with activation duration of 2 h and at an impregnation ratio of 1.0.
J Hazard Mater, 2007
This study deals with the removal of chromium species from aqueous dilute solutions using polymer... more This study deals with the removal of chromium species from aqueous dilute solutions using polymer-enhanced ultrafiltration (PEUF) process. Three water soluble polymers, namely chitosan, polyethyleneimine (PEI) and pectin were selected for this study. The ultrafiltration studies were carried out using a laboratory scale ultrafiltration system equipped with 500,000 MWCO polysulfone hollow fiber membrane. The effects of pH and polymer composition on rejection coefficient and permeate flux at constant pressure have been investigated. For Cr(III), high rejections approaching 100% were obtained at pH higher than 7 for the three tested polymers. With chitosan and pectin, Cr(VI) retention showed a slight increase with solution pH and did not exceed a value of 50%. An interesting result was obtained with PEI. The retention of Cr(VI) approached 100% at low pH and decreased when the pH was increased. This behavior is opposite to what one can expect in the polymer-enhanced ultrafiltration of heavy metals. Furthermore, the concentration of polymer was found to have little effect on rejection. Permeate flux remained almost constant around 25% of pure water flux.
http://link.springer.com/article/10.1007/s11814-007-5003-6, 2007
In this paper, the CO2 absorption rates into aqueous solutions of Methydiethanolamine (MDEA) at v... more In this paper, the CO2 absorption rates into aqueous solutions of Methydiethanolamine (MDEA) at various concentrations of 1, 2, 3 and 4 M and temperatures varying from 293 to 323 K were measured by using a laboratory stirred reactor. The kinetics experiments were conducted under a pseudo first order regime. The data were analyzed by means of chemical absorption theory and the kinetic parameters associated with the reaction, such as the reaction order and the reaction rate constants, were evaluated. The effect of temperature on the reaction rate constant was assessed and the activation energy was evaluated at about 44.12 kJoule/mol.
Special issue on process systems engineering
Asia-Pacific Journal of Chemical Engineering, 2007
Process Systems Engineering is broadly defined as an
academic and technological field related to... more Process Systems Engineering is broadly defined as an
academic and technological field related to methodologies
for chemical engineering systems. These methodologies
include steps of planning, design, operation,
and control of various operations in chemical process
systems. However, the context of Process Systems Engineering
has been expanded from the design of unit
operations to the design of chemical processes and large
process systems. It has also evolved from design problems
to include operational problems, and from singleobjective
optimization to multi-objective optimization.
These advances have been made possible in a short
period of time due to the rapid development of computer
technology today. The papers of this special edition
have been compiled to demonstrate the changes
and advances that have been made in the field of Process
Systems Engineering in various aspects involving
Chemical Engineering and its related processes. It also
reflects some of the important issues facing process
engineers within this Asia-Pacific region at large.
Chemical characterization of medium-chain-length polyhydroxyalkanoates (PHAs) recovered by enzymatic treatment and ultrafiltration
Journal of Chemical Technology and Biotechnology, 2007
Background: Medium-chain-length polyhydroxyalkanoates (PHAs) are biodegradable polyesters accumul... more Background: Medium-chain-length polyhydroxyalkanoates (PHAs) are biodegradable polyesters accumulated intracellularly as energy resources by bacterial species such as Pseudomonas putida. The most popular method for PHA recovery is solvent extraction using trichloromethane (chloroform) and methyl alcohol (methanol). An alternative method is enzymatic treatment, which eliminates usage of these hazardous solvents. This research focuses on the characterization of PHAs recovered by enzymatic treatments and ultrafiltration. Comparisons are made with conventional solvent extracted PHA. Results: The purity of PHA in water suspension recovered by enzymatic treatments as analyzed by gas chromatography was 92.6%. Enzymatically recovered PHA was comparable to conventional solvent-extracted PHA, which had a purity of 95.5%. PHA was further characterized for functional group analysis, structural composition analysis and molecular weight determination. It was found that the molecular weight of the PHA recovered by enzymatic treatment was less than solvent-extracted PHA, probably due to degradation of the lipopolysaccharide layer. However, functional group and structural composition analyses showed similar results for PHA recovered by both methods. Conclusion: PHAs recovered through enzymatic digestion treatment have good comparability with solvent-extracted PHAs. Thus enzymatic digestion has great potential as an alternative recovery method.
Journal of Food Engineering, 2007
Response surface methodology (RSM) was employed for simultaneous analysis of the effects of enzym... more Response surface methodology (RSM) was employed for simultaneous analysis of the effects of enzymatic treatment conditions of incubation time, incubation temperature and enzyme concentration on physical characteristics such as turbidity, clarity, viscosity, and color. In this study, a two-factor central composite design was used to establish the optimum conditions for the enzymatic treatment for clarification of carambola fruit juice. Carambola fruit juice was treated with pectinase enzyme at different incubation time (20-100 min), incubation temperature (30-50 °C) and enzyme concentration (0.01-0.10 v/v%). These three variables were used as independent variables, whose effects on turbidity, clarity, viscosity and color were evaluated. Significant regression models describing the changes on turbidity, clarity, viscosity and color with respect to the independent variables were established with coefficient of determination, R 2, greater than 0.70. The results indicated that the enzyme concentration was the most important factor affecting the characteristics of the carambola fruit juice as it exerted a significant influence on most of the dependent variables. The recommended enzymatic treatment condition from the study was at 0.10% enzyme concentration at 30 °C for 20 min.
Modification of granular activated carbon using low molecular weight polymer for enhanced removal of Cu2+ from aqueous solution
Water Science and Technology, 2007
Palm shell activated carbon was modified via surface impregnation with polyethyleneimine ( PEI) t... more Palm shell activated carbon was modified via surface impregnation with polyethyleneimine ( PEI) to enhance removal of Cu2+ from aqueous solution in this study. The effect of PEI modification on batch adsorption of Cu2+ as well as the equilibrium behavior of adsorption of metal ions on activated carbon were investigated. PEI modification clearly increased the Cu2+ adsorption capacities by 68% and 75.86% for initial solution pH of 3 and 5 respectively. The adsorption data of Cu2+ on both virgin and PEI-modified AC for both initial solution pH of 3 and 5 fitted the Langmuir and Redlich-Peterson isotherms considerably better than the Freundlich isotherm.
Colloids and Surfaces a-Physicochemical and Engineering Aspects, 2007
Palm shell activated carbon (AC) was impregnated with low (LMW) and high molecular weight (HMW) p... more Palm shell activated carbon (AC) was impregnated with low (LMW) and high molecular weight (HMW) polyethyleneimine (PEI) via batch adsorption. The maximum amount of LMW PEI adsorbed on AC was determined to be approximately 425 mg/g carbon while the maximum adsorbed HMW PEI was 2.8 mg/g carbon. The LMW PEI adsorption data fitted the Langmuir isotherm better than the Freundlich isotherm. The PEI impregnated AC were characterized via nitrogen adsorption, scanning electron microscopy, elemental analysis, thermogravimetric, Fourier transform infra red and pH drift analyses. Only LMW PEI could be successfully impregnated as monolayers on the surface of the micropores. This impregnation leads to drastic reduction of surface area and pore volume whereas impregnation of HMW PEI does not significantly affect the physical characteristics of the AC. LMW PEI impregnation appears to enhance Cd2+ adsorption capacity of the AC while HMW PEI impregnation is found to have an opposite effect. This result shows that LMW PEI impregnation technique may have the potential to improve the batch adsorption capacity of AC for other transition metal ion adsorption as well.
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Papers by Kheireddine Taieb Aroua
academic and technological field related to methodologies
for chemical engineering systems. These methodologies
include steps of planning, design, operation,
and control of various operations in chemical process
systems. However, the context of Process Systems Engineering
has been expanded from the design of unit
operations to the design of chemical processes and large
process systems. It has also evolved from design problems
to include operational problems, and from singleobjective
optimization to multi-objective optimization.
These advances have been made possible in a short
period of time due to the rapid development of computer
technology today. The papers of this special edition
have been compiled to demonstrate the changes
and advances that have been made in the field of Process
Systems Engineering in various aspects involving
Chemical Engineering and its related processes. It also
reflects some of the important issues facing process
engineers within this Asia-Pacific region at large.