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K Li - One of the best experts on this subject based on the ideXlab platform.
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UV-Enhanced Sacrificial Layer Stabilised Graphene Oxide Hollow Fibre Membranes for Nanofiltration
Scientific Reports, 2015Co-Authors: J Y Chong, N F D Aba, Cecilia Mattevi, Bo Wang, K LiAbstract:Graphene oxide (GO) membranes have demonstrated great potential in gas separation and liquid filtration. For upscale applications, GO membranes in a Hollow Fibre geometry are of particular interest due to the high-efficiency and easy-assembly features at module level. However, GO membranes were found unstable in dry state on ceramic Hollow Fibre substrates, mainly due to the drying-related shrinkage, which has limited the applications and post-treatments of GO membranes. We demonstrate here that GO Hollow Fibre membranes can be stabilised by using a porous poly(methyl methacrylate) (PMMA) sacrificial layer, which creates a space between the Hollow Fibre substrate and the GO membrane thus allowing stress-free shrinkage. Defect-free GO Hollow Fibre membrane was successfully determined and the membrane was stable in a long term (1200 hours) gas-tight stability test. Post-treatment of the GO membranes with UV light was also successfully accomplished in air, which induced the creation of controlled microstructural defects in the membrane and increased the roughness factor of the membrane surface. The permeability of the UV-treated GO membranes was greatly enhanced from 0.07 to 2.8 L m(−2) h(−1) bar(−1) for water, and 0.14 to 7.5 L m(−2) h(−1) bar(−1) for acetone, with an unchanged low molecular weight cut off (~250 Da).
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high performance polybenzimidazole based asymmetric Hollow Fibre membranes for h2 co2 separation
Journal of Membrane Science, 2011Co-Authors: S.c. Kumbharkar, K LiAbstract:Abstract We demonstrated for the first time the development of polybenzimidazole (PBI) based asymmetric Hollow Fibre membrane for H2/CO2 separation at high temperatures. High molecular weight PBI was synthesised in-house by a solution polycondensation method. Hollow Fibre membranes were fabricated by conventional dry-jet wet spinning technique. Defect free asymmetric PBI Hollow Fibre membranes were successfully produced, which eliminated the step of silicone rubber coating and were tested in the high temperature range of 100–400 °C. The effect of bore fluid chemistry was found to have a significant effect on the morphology as well as gas performance of the Hollow Fibre membranes. Suppressing the formation of macrovoids was found to show improvement in the mechanical properties of the Fibres produced. The PBI Fibres showed an increment in H2 permeance with up to ∼8 folds, but with relatively small increment in CO2 permeance of up to ∼2 folds at 400 °C. Present PBI Hollow Fibre membranes showed H2 permeance of about 2.6 × 10−6 cm3 (STP)/cm2 s cmHg and H2/CO2 selectivity of about 27. Ability to show the good separation characteristics at elevated temperatures depicts the potential of the present high performance PBI membranes for high temperature applications.
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stability of pvdf Hollow Fibre membranes in sodium hydroxide aqueous solution
Chemical Engineering Science, 2011Co-Authors: Awanis N Hashim, K LiAbstract:Abstract The stability of PVDF Hollow Fibre membranes in sodium hydroxide (NaOH) aqueous solutions were investigated in this study. PVDF Hollow Fibre membranes were prepared from each of the three commercial raw PVDF materials (Kynar 761, Solef 1015 and Solef 6010) from two major suppliers (Atofina Chemicals Inc., USA and Solvay, Belgium) for comparison purposes. The effect of NaOH concentration, treatment time and temperature on mechanical properties, thermal properties and crystalline structure of the PVDF Hollow Fibre membranes were investigated through mechanical strength measurement, surface area analysis, XRD, FTIR and DSC analyses. The obtained results indicate that the reaction between PVDF and NaOH was initiated even at low concentrations of NaOH and was aggravated with the extended treatment time, resulting in the decrease in mechanical strength and crystallinity of PVDF Hollow Fibre membranes. The reaction was accelerated and intensified by increasing the concentration of NaOH and/or treatment temperature. At 70 °C, the mechanical integrity of the PVDF membranes was completely destroyed in 4 wt% NaOH solution within 24 h or in 10 wt% NaOH solution within 8 h. The deterioration of stability in NaOH solutions is considered universal for all PVDF employed in this study, irrespective of the raw materials or the corresponding Hollow Fibre membranes.
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development of a catalytic Hollow Fibre membrane micro reactor for high purity h2 production
Journal of Membrane Science, 2011Co-Authors: Mukhlis A. Rahman, Benjamin F K Kingsbury, Francisco Garciagarcia, M Irfan D Hatim, K LiAbstract:Abstract This article describes development of a catalytic Hollow Fibre membrane micro-reactor (CHFMMR) for high purity H2 production. Asymmetric Al2O3 Hollow Fibres produced by a phase-inversion and sintering technique were employed as a single substrate for both coating of the Pd membrane and impregnation of the 30%CuO/CeO2 catalyst. The Pd membrane was first deposited onto the outer layer of Al2O3 Hollow Fibre using the electroless plating (ELP) technique, followed by impregnation of the 30%CuO/CeO2 catalyst into the inner finger-like structure of the substrate using the sol–gel Pechini method. Performance of the proposed reactor was carried out using water gas shift (WGS) reaction as a sample reaction. A comparative study of conversion obtained in the WGS reaction as a function of the reaction temperature (from 200 °C to 500 °C) in a fixed-bed reactor, a catalytic Hollow Fibre micro-reactor (CHFMR) and the CHFMMR using different flow rates of a sweep gas (from 45 to 70 ml/min) was performed, concluding that the conversion is the highest in the CHFMMR. It is important to highlight that, at 500 °C and a sweep gas flow rate of 75 ml/min, a conversion of 17% higher than the corresponding thermodynamic equilibrium conversion was achieved in the CHFMMR. In the operation of the CHFMMR, high purity H2 has been obtained in the shell side, which was 78% of the total H2 produced in the WGS reaction.
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fabrication of ultrathin la0 6sr0 4co0 2fe0 8o3 δ Hollow Fibre membranes for oxygen permeation
Chemical Engineering Science, 2009Co-Authors: Barbara Zydorczak, Zhentao Wu, K LiAbstract:Abstract An ultrathin La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3 - δ (LSCF) Hollow Fibre membrane for enhanced oxygen permeation flux was fabricated using a wet spinning/sintering method. The membrane exhibits a highly asymmetric structure comprising of a very thin dense outer layer supported by finger-like structures that are fully open on the inner surface. Oxygen permeation measurements were conducted using sweep gas as an operating mode. Effects of operating temperatures and flow rates of the sweep gas on the oxygen permeation fluxes were investigated in details. The highest oxygen permeation flux, i.e. 0.096 cm 3 /cm 2 s (5.77 cm 3 /cm 2 min) was obtained from the ultrathin Hollow Fibre membrane at 1323 K (1050 °C) and the sweep gas flow rate of 2.42 cm 3 /s. The results indicate that the oxygen permeation flux obtained is much higher (4.9–11.2 times) than that obtained from conventional LSCF Hollow Fibre membranes mainly due to the reduced thickness of the membrane as well as the porous surface on the permeate side. In addition, despite a very thin dense layer, the LSCF Hollow Fibre membrane possessed a reasonable mechanical strength (113.22 MPa).
Bo Meng - One of the best experts on this subject based on the ideXlab platform.
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High performance BaCe0.8Y0.2O3−a (BCY) Hollow Fibre membranes for hydrogen permeation
Ceramics International, 2014Co-Authors: Naitao Yang, Bo Meng, Kun ZhangAbstract:Abstract In this work, BaCe 0.8 Y 0.2 O 3− α (BCY) perovskite Hollow Fibre membranes were fabricated by a phase inversion and sintering method. BCY powder was prepared by the sol–gel technique using ethylenediaminetetraacetic acid (EDTA) and citric acid as the complexing agents. Gel calcination was carried out at high temperature to form the desired crystal structure. The qualified BCY Hollow Fibre membranes could not be achieved even the sintering was carried out at temperatures up to 1550 o C due to the poor densification behavior of the BCY material. The addition of sintering aid (1 wt% Co 2 O 3 ) inside BCY powder as the membrane starting material significantly improved the densification process, leading to the formation of gas-tight BCY Hollow Fibres. The optimum sintering temperature of BCY Hollow Fibre membrane was 1400 °C to achieve the best mechanical strength. H 2 permeation through the BCY Hollow Fibre membranes was carried out between 700 and 1050 °C using 25% H 2 –He mixture as feed gas and N 2 as sweep gas, respectively. For comparison purpose, the disk-shaped BCY membrane with a thickness of 1 mm was also prepared. The measured H 2 permeation flux through the BCY Hollow Fibres reached up to 0.38 mL cm −2 min −1 at 1050 °C strikingly contrasting to the low values of less than 0.01 mL cm −2 min −1 from the disk-shaped membrane. After the permeation test, the microstructure of BCY Hollow Fibre membrane was still maintained well without signals of membrane disintegration or peeling off.
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Ionic conducting ceramic-carbonate dual phase Hollow Fibre membranes for high temperature carbon dioxide separation
Journal of Membrane Science, 2014Co-Authors: Meng Zuo, Shujuan Zhuang, Naitao Yang, Xiaoyao Tan, Bo Meng, Shaomin LiuAbstract:In this work, the gas tight ceramic-carbonate dual phase Hollow Fibre membranes were developed in stages. To this end, oxygen ionic conducting ceramic of yttria stabilized zirconia (YSZ) Hollow Fibre was firstly prepared and structurally optimised for its application as the porous support to infiltrate the melting carbonate phase at high temperatures. The dual phase Hollow Fibre membranes were characterised by SEM, XRD, room-temperature gas leakage detection and CO2permeation test at temperatures between 550°C and 950°C. The maximum CO2flux measured reached 0.22mLcm-2min-1at 950°C. © 2014 Elsevier B.V.
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Dense composite electrolyte Hollow Fibre membranes for high temperature CO2 separation
Separation and Purification Technology, 2014Co-Authors: Shujuan Zhuang, Meng Zuo, Naitao Yang, Xiaoyao Tan, Bo Meng, Ying Li, Shaomin LiuAbstract:Inorganic membranes for high temperature CO2 separation has potential applications in clean energy delivery for CO2 capture. In this work, the gas tight oxygen ion conducting perovskite and carbonate composite electrolyte Hollow Fibre membranes were developed for CO2 separation at high temperatures. For this purpose, the La0.6Sr0.4Co0.2Fe0.8O3−α (LSCF) perovskite Hollow Fibre was firstly prepared as the porous support to impregnate and immobilize the carbonate phase. The composite electrolyte Hollow Fibre membranes were characterised by SEM, XRD, room-temperature gas leakage detection and CO2 permeation test at temperature regime from 500 to 900 °C. The maximum CO2 flux measured reached 1.0 mL cm−2 min−1 at 900 °C, which was improved by a factor up to 5 when compared with the previously developed membranes due to the much thinner separating layer achieved in the current membrane.
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Preparation and Properties of Asymmetric Porous Aluminium-Oxide Ceramic Hollow Fibre Membranes
Key Engineering Materials, 2013Co-Authors: Hai Bo Mu, Xiao Wei Li, Bo MengAbstract:Asymmetric porous aluminium-oxide ceramic Hollow Fibre membranes have been prepared by the phase inversion / sintering technique. The effect of non-solvent such as ethanol, isopropanol and ethylene glycol monomethylether(2-methoxyethanol) on the geometry and performance of Hollow Fibres was investigated. Morphologies of Al2O3 ceramic Hollow Fibre membranes were characterized using a scanning electron microscope (SEM). The effective porosity and the mechanical strength were determined by Archimedes method, and three point method, respectively. The prepared Al2O3 Hollow Fibre membranes show the asymmetric structure with a finger-like layer and a sponge-like layer. The effective porosity of the prepared Hollow Fibre membranes exceeds 47%, and the bending strength of the Hollow membranes exceeds 63 MPa. The Al2O3 Hollow Fibre membranes with moderate permeation characteristics for gas and pure water are prepared by the introduction of nonsolvent in membrane casting solution. The separation factors of H2 to N2 or CO2 of the Hollow fibers with nonsolvent are over 2.0.
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Preparation and characterization of BaCe0.95Tb0.05O3−α Hollow Fibre membranes for hydrogen permeation
Journal of The European Ceramic Society, 2012Co-Authors: Jian Song, Xiuxia Meng, Bo MengAbstract:Abstract BaCe 0.95 Tb 0.05 O 3− α (BCTb) perovskite Hollow Fibre membranes were fabricated by spinning the slurry mixture containing 66.67 wt% BCTb powder, 6.67 wt% polyethersulphone (PESf) and 26.67 wt% N-methyl-2-pyrrolidone (NMP) followed by sintering at elevated temperatures. The influence of sintering temperature on the membrane properties was investigated in terms of crystal phase, morphology, porosity and mechanical strength. In order to obtain gas-tight Hollow Fibres with sufficient mechanical strength, the sintering temperature should be controlled between 1350 and 1450 °C. Hydrogen permeation through the BCTb Hollow Fibre membranes was carried out between 700 and 1000 °C using 50% H 2 –He mixture as feed on the shell side and N 2 as sweep gas in the Fibre lumen. The measured hydrogen permeation flux through the BCTb Hollow Fibre membranes reached up to 0.422 μmol cm −2 s −1 at 1000 °C when the flow rates of the H 2 –He feed and the nitrogen sweep were 40 mL min −1 and 30 mL min −1 , respectively.
Kang Li - One of the best experts on this subject based on the ideXlab platform.
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BaCe0.85Tb0.05Co0.1O3−δ perovskite Hollow Fibre membranes for hydrogen/oxygen permeation
International Journal of Hydrogen Energy, 2013Co-Authors: Jian Song, Liping Li, Kang LiAbstract:Abstract Co-doped BaCe 0.85 Tb 0.05 Co 0.1 O 3− δ (BCTCo) nanopowder was synthesized via a sol–gel method using ethylenediaminetetraacetic acid (EDTA) and citric acid as the chelating agents. Using the resultant powder, BCTCo perovskite Hollow Fibre membranes were then fabricated by the combined phase inversion and sintering technique. Properties of the BCTCo powder and the Hollow Fibre membranes in terms of crystalline phase, morphology, electrical conductivity, porosity, mechanical strength and hydrogen/oxygen permeation were investigated by a variety of characterization methods. The results indicated that doping of cobalt in the BCTb oxide led to a higher electrical conductivity and lower calcination temperature for the powder precursor to a perovskite structure as well as sintering temperature for the Hollow Fibre precursors to gastight membranes. In order to obtain gastight and robust Hollow Fibre membranes, the sintering temperature should be controlled between 1300 and 1450 °C. The maximum hydrogen flux through the BCTCo Hollow Fibre membranes reached up to 0.385 mL cm −2 min −1 at 1000 °C under 50% H 2 –He/N 2 gradient, which is higher than that of the un-doped BCTb Hollow Fibre membranes with the same effective thickness, and especially much higher than that obtained from other proton conductors due to the asymmetric structure of the membrane designed. Moreover, the BCTCo Hollow Fibre membrane also exhibited noticeable oxygen permeation fluxes, i.e. 0.122 mL cm −2 min −1 at 1000 °C under the air/He gradient. However, doping of cobalt might damage the mechanical stability of the perovskite membranes in the hydrogen-containing atmosphere.
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Structurally modified polybenzimidazole Hollow Fibre membranes with enhanced gas permeation properties
Journal of Membrane Science, 2012Co-Authors: S.c. Kumbharkar, Kang LiAbstract:Abstract Asymmetric Hollow Fibre membranes of structurally modified polybenzimidazole (PBI) were fabricated for the first time using dry-jet wet spinning technique. The modified-PBI membranes for gas separation were shown to exhibit higher flux, but lower selectivities compared to conventional PBI membranes. However, further post modification of these Hollow Fibre membranes by crosslinking reaction substantially enhanced the ideal gas-pair selectivities. The crosslinking reaction was demonstrated to improve not only the gas permeation properties, but also the mechanical properties of the modified-PBI Hollow Fibre membranes. The modified-PBI membranes showed good combinations of gas flux and selectivities for industrially important gas pairs such as CO2/N2, O2/N2 and H2/N2 with the ideal selectivities of 37, 8 and 115.9, respectively, while the permeation fluxes of H2, O2 and CO2 were at about 12.97, 0.89 and 4.1 GPU, respectively. Development of such modified-PBI Hollow Fibre membranes with improved gas permeation properties in combination with their known excellent thermal and chemical properties depicts their potential for gas separation applications at harsh environment.
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On-board H2 generation by a catalytic Hollow Fibre microreactor for portable device applications
Catalysis Communications, 2011Co-Authors: Mukhlis A. Rahman, F.r. García-garcía, Kang LiAbstract:Abstract A novel catalytic Hollow Fibre microreactor (CHFMR) that uses an asymmetric YSZ Hollow Fibre has been developed for on-board H 2 generation to be used in portable device applications. In the development of CHFMR, the 10 wt.%Ni/MgO–CeO 2 catalyst that was selected as a catalyst for the ethanol steam reforming (ESR) was impregnated into the inner surface of YSZ Hollow Fibres using the sol–gel Pechini technique. The catalytic activity tests were performed in the YSZ Hollow Fibres and the results were compared with fixed-bed reactors. An excellent catalyst utilisation in the CHFMR enables a small quantity of catalyst to be used for the ESR. The result shows that 8 units of CHFMR that only has an 18 mg catalyst produced a relatively similar amount of H 2 compared to a fixed-bed reactor that used 100 mg.
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Inorganic Hollow Fibre membranes in catalytic processing
Current opinion in chemical engineering, 2011Co-Authors: Kang LiAbstract:Inorganic Hollow Fibre membranes combine the advantages of inorganic membranes and Hollow Fibre geometry such as high area/volume ratio, high temperature resistance and high chemical and mechanical stabilities. This article presents a short review on the recent development of inorganic Hollow Fibre membranes and, in particular, highlights their applications in catalytic processing. The preparation of inorganic Hollow Fibre membranes, incorporation of catalysts within the membrane and applications of the membrane in a variety of catalytic processes are presented. The challenges and prospects of the inorganic Hollow Fibre membranes in catalytic processing are also presented and discussed.
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Fabrication of ultrathin La0.6Sr0.4Co0.2Fe0.8O3–δ Hollow Fibre membranes for oxygen permeation
Chemical Engineering Science, 2009Co-Authors: Barbara Zydorczak, Zhentao Wu, Kang LiAbstract:Abstract An ultrathin La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3 - δ (LSCF) Hollow Fibre membrane for enhanced oxygen permeation flux was fabricated using a wet spinning/sintering method. The membrane exhibits a highly asymmetric structure comprising of a very thin dense outer layer supported by finger-like structures that are fully open on the inner surface. Oxygen permeation measurements were conducted using sweep gas as an operating mode. Effects of operating temperatures and flow rates of the sweep gas on the oxygen permeation fluxes were investigated in details. The highest oxygen permeation flux, i.e. 0.096 cm 3 /cm 2 s (5.77 cm 3 /cm 2 min) was obtained from the ultrathin Hollow Fibre membrane at 1323 K (1050 °C) and the sweep gas flow rate of 2.42 cm 3 /s. The results indicate that the oxygen permeation flux obtained is much higher (4.9–11.2 times) than that obtained from conventional LSCF Hollow Fibre membranes mainly due to the reduced thickness of the membrane as well as the porous surface on the permeate side. In addition, despite a very thin dense layer, the LSCF Hollow Fibre membrane possessed a reasonable mechanical strength (113.22 MPa).
R Hughes - One of the best experts on this subject based on the ideXlab platform.
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preparation of porous aluminium oxide al2o3 Hollow Fibre membranes by a combined phase inversion and sintering method
Ceramics International, 2003Co-Authors: K Li, R HughesAbstract:Abstract Al 2 O 3 Hollow Fibre membranes were prepared by a combined phase-inversion and sintering method. An organic binder solution (dope) containing suspended aluminium oxide (Al 2 O 3 ) powders, either in mono size or a distributed size, is spun to a Hollow Fibre precursor, which is then sintered at elevated temperatures. In spinning the Hollow Fibre precursor, polyethersulfone (PESf), N -methyl-2-pyrrolidone (NMP) and polyvinyl pyrrolidone (PVP) were used as a polymer binder, a solvent and an additive, respectively. The Al 2 O 3 Hollow Fibre membranes prepared were characterized using a scanning electron microscope (SEM) and gas permeation techniques. Effects of Al 2 O 3 particle size and size distribution, the sintering temperature and Al 2 O 3 /PESf ratio on the structure and performance of the resulting membranes were studied extensively. The prepared Al 2 O 3 Hollow Fibre membranes retains its asymmetric structure (mainly resulted from the phase inversion technique) even after the sintering process. Preparation of the Al 2 O 3 Hollow Fibre membrane with a high mechanical strength and moderate permeation characteristics is feasible if the Al 2 O 3 powders with a distributed particle size in the spinning (dope) solution is employed.
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preparation and characterisation of srce0 95yb0 05o2 975 Hollow Fibre membranes
Journal of Membrane Science, 2001Co-Authors: K Li, R HughesAbstract:Abstract A mixed proton and electronic conducting Hollow Fibre membrane, SrCe 0.95 Yb 0.05 O 2.975 (SCYb), has been prepared by spinning a polymer solution containing suspended SCYb particles to a Hollow Fibre precursor, which is then sintered at elevated temperatures. The SCYb powders having a sub-micron size, i.e. an essential size for fabrication of the Hollow Fibre with good mechanical strength, were synthesised through a polymerised water-soluble complex method. By controlling weight ratio of the SCYb ceramic powder to the polymer binder and sintering temperatures, the SCYb ceramic Hollow Fibres with gas-tight properties can be prepared. Some primary factors affecting microstructures, gas tightness and mechanical strength of the mixed conducting Hollow Fibre membranes were studied in details.
Xiaoyao Tan - One of the best experts on this subject based on the ideXlab platform.
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Ionic conducting ceramic-carbonate dual phase Hollow Fibre membranes for high temperature carbon dioxide separation
Journal of Membrane Science, 2014Co-Authors: Meng Zuo, Shujuan Zhuang, Naitao Yang, Xiaoyao Tan, Bo Meng, Shaomin LiuAbstract:In this work, the gas tight ceramic-carbonate dual phase Hollow Fibre membranes were developed in stages. To this end, oxygen ionic conducting ceramic of yttria stabilized zirconia (YSZ) Hollow Fibre was firstly prepared and structurally optimised for its application as the porous support to infiltrate the melting carbonate phase at high temperatures. The dual phase Hollow Fibre membranes were characterised by SEM, XRD, room-temperature gas leakage detection and CO2permeation test at temperatures between 550°C and 950°C. The maximum CO2flux measured reached 0.22mLcm-2min-1at 950°C. © 2014 Elsevier B.V.
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Dense composite electrolyte Hollow Fibre membranes for high temperature CO2 separation
Separation and Purification Technology, 2014Co-Authors: Shujuan Zhuang, Meng Zuo, Naitao Yang, Xiaoyao Tan, Bo Meng, Ying Li, Shaomin LiuAbstract:Inorganic membranes for high temperature CO2 separation has potential applications in clean energy delivery for CO2 capture. In this work, the gas tight oxygen ion conducting perovskite and carbonate composite electrolyte Hollow Fibre membranes were developed for CO2 separation at high temperatures. For this purpose, the La0.6Sr0.4Co0.2Fe0.8O3−α (LSCF) perovskite Hollow Fibre was firstly prepared as the porous support to impregnate and immobilize the carbonate phase. The composite electrolyte Hollow Fibre membranes were characterised by SEM, XRD, room-temperature gas leakage detection and CO2 permeation test at temperature regime from 500 to 900 °C. The maximum CO2 flux measured reached 1.0 mL cm−2 min−1 at 900 °C, which was improved by a factor up to 5 when compared with the previously developed membranes due to the much thinner separating layer achieved in the current membrane.
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polyvinylidene fluoride pvdf Hollow Fibre membranes for ammonia removal from water
Journal of Membrane Science, 2006Co-Authors: Xiaoyao Tan, W.k. Teo, S P Tan, K LiAbstract:Polyvinylidene fluoride (PVDF) Hollow Fibre membranes with asymmetric structures and good hydrophobicity have been prepared by a phase-inversion method and have been applied to removal of ammonia from water. Aqueous solution containing sulfuric acid was used as stripping solution to accelerate the removal of ammonia. A mathematical model was presented to simulate the ammonia removal in PVDF Hollow Fibre modules. Experimental results indicate that the post-treatment with ethanol is useful to improve both the hydrophobility and the effective surface porosity of the resulting PVDF Hollow Fibre membranes, and thus favors the ammonia removal. Increasing the pH value of water is capable of promoting the removal of ammonia. The initial concentration of ammonia and the feed velocity of the acid stripping solution have negligible effects on the ammonia removal. The ammonia stripping rate increases as the feed velocity is increased up to 0.59 m/s or Re > 0.32, after which the feed velocity shows no effect. All the experimental data are in excellent agreement with the modeling results. © 2005 Elsevier B.V. All rights reserved.