scholarly journals Brackish water desalination using electrodialysis: predictive mass transfer and concentration distribution model along the electrodialyzer

2017 ◽  
Vol 77 (3) ◽  
pp. 597-607 ◽  
Author(s):  
Azadeh Ghorbani ◽  
Abbas Ghassemi
Keyword(s):  
Flow Rate ◽  
Concentration Distribution ◽  
Driving Forces ◽  
Water Desalination ◽  
Distribution Model ◽  
Navier Stokes ◽  
Feed Flow Rate ◽  
Feed Concentration ◽  
Ion Removal ◽  
Negative Effect

Abstract This study employs theory and experimental data from a laboratory-scale electrodialyzer to predict sodium chloride (NaCl) mass transport and concentration distribution along the electrodialyzer as a function of feed concentration, feed flow rate, applied voltage, and pressure. Moreover, a model was developed to predict the ion removal as a function of driving forces through solving the complete Navier–Stokes, continuity, and steady state Nernst–Planck equations by the finite difference numerical method. The findings of the experiments confirmed that concentration distributions are nonlinear along both the dilute and concentrate compartments. The results also demonstrated that increases in pressure and feed flow rate have a negative effect on salt removal, linear and nonlinear for pressure and flow rate, respectively. In the investigated ranges, higher voltage increased salt removal at a constant feed concentration.

scholarly journals Performance Investigation of O-Ring Vacuum Membrane Distillation Module for Water Desalination

2016 ◽  
Vol 2016 ◽  
pp. 1-11 ◽  
Author(s):  
Adnan Alhathal Alanezi ◽  
H. Abdallah ◽  
E. El-Zanati ◽  
Adnan Ahmad ◽  
Adel O. Sharif
Keyword(s):  
Flow Rate ◽  
Membrane Distillation ◽  
Membrane Module ◽  
Water Desalination ◽  
Feed Flow Rate ◽  
Permeate Flux ◽  
Vacuum Degree ◽  
Flat Sheet ◽  
Vacuum Membrane Distillation ◽  
Feed Temperature

A new O-ring flat sheet membrane module design was used to investigate the performance of Vacuum Membrane Distillation (VMD) for water desalination using two commercial polytetrafluoroethylene (PTFE) and polyvinylidene fluoride (PVDF) flat sheet hydrophobic membranes. The design of the membrane module proved its applicability for achieving a high heat transfer coefficient of the order of 103 (W/m2 K) and a high Reynolds number (Re). VMD experiments were conducted to measure the heat and mass transfer coefficients within the membrane module. The effects of the process parameters, such as the feed temperature, feed flow rate, vacuum degree, and feed concentration, on the permeate flux have been investigated. The feed temperature, feed flow rate, and vacuum degree play an important role in enhancing the performance of the VMD process; therefore, optimizing all of these parameters is the best way to achieve a high permeate flux. The PTFE membrane showed better performance than the PVDF membrane in VMD desalination. The obtained water flux is relatively high compared to that reported in the literature, reaching 43.8 and 52.6 (kg/m2 h) for PVDF and PTFE, respectively. The salt rejection of NaCl was higher than 99% for both membranes.

Separation of Methanol/Water Mixtures from Dilute Aqueous Solutions Using Pervaporation Technique

2012 ◽  
Vol 550-553 ◽  
pp. 3004-3007 ◽  
Author(s):  
Verawat Champreda ◽  
David Stuckey ◽  
Apichat Boontawan
Keyword(s):  
Experimental Data ◽  
Flow Rate ◽  
Operating Temperature ◽  
Separation Performance ◽  
Permeation Flux ◽  
Feed Flow Rate ◽  
Feed Concentration ◽  
Dilute Aqueous Solutions ◽  
Factor Α ◽  
Feed Temperature

The composite polydimethylsiloxane PERVAPTM 4060 was used for separation of methanol/water solutions by using pervaporation technique. The effect of feed concentration, feed temperature, and feed flow rate were investigated for the separation performance. The experimental data showed that increasing of the feed methanol concentration from 0.5 to 10 wt% resulted in an increase in total permeation flux up for to 35 % whilst the separation factor (α) decreased by 85%. The results also showed that increasing operating temperature from 40 to 60 °C caused an increases in methanol permeance up to 130%.

Controllability of Distillation Sequences for the Separation of Ternary Mixture

2011 ◽  
Vol 6 (1) ◽  
Author(s):  
Rajasekhar Nadendla ◽  
A. Venu Vinod
Keyword(s):  
Flow Rate ◽  
Ternary Mixture ◽  
Control Level ◽  
Aspen Plus ◽  
Pi Controller ◽  
Step Change ◽  
Feed Flow Rate ◽  
Feed Concentration ◽  
Relay Feedback ◽  
Controller Gain

The present work aims at finding the best distillation sequence in terms of control properties for the separation of a ternary mixture of n-pentane, n-hexane and n-heptane. The study has been carried out using ASPEN PLUS. The different sequences have been compared for regulatory problem (step change in feed concentration and feed flow rate) and servo problem (step change in product composition). PI controller has been used to control level and composition in the various configurations studied. Auto tuning of the controller has been carried out using relay feedback test. Ziegler–Nichols method was used to calculate controller gain (KI) and integral time (τI) of PI controller. Controller parameters have been fine tuned using these tuning maps.

scholarly journals A Systematic Framework for Optimizing a Sweeping Gas Membrane Distillation (SGMD)

Membranes ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 254
Author(s):  
Nawras N. Safi ◽  
Salah. S. Ibrahim ◽  
Nasser Zouli ◽  
Hasan Shaker Majdi ◽  
Qusay F. Alsalhy ◽  
...  
Keyword(s):  
Flow Rate ◽  
Gas Flow ◽  
Membrane Distillation ◽  
Feed Flow Rate ◽  
Permeate Flux ◽  
Gas Flow Rate ◽  
Feed Concentration ◽  
Sweeping Gas ◽  
Feed Temperature ◽  
Systematic Framework

The present work has undertaken a meticulous glance on optimizing the performance of an SGMD configuration utilized a porous poly (vinylidene fluoride-co-hexafluoropropylene) (PVDF-co-HFP) membrane. This was carried out by conducting a systematic framework for investigating and optimizing the pertinent parameters such as sweeping gas flow rate, feed temperature, feed concentration and feed flow rate on the permeate flux. For this purpose, the Taguchi method and design of experiment techniques were harnessed to statistically determine optimum operational conditions. Besides that, a comprehensive surface and permeation characterization was conducted against the hand-made membranes. Results showcased that the membrane performance was ultimately controlled by the feed temperature and was nearly (~680) % higher when the temperature raised from 45 to 65 °C. Also, to a lesser extent, the system was dominated by the feed flow rate. As the adopted feed flow rate increases (from 0.2 to 0.6 L/min), around 47.5% increment was bestowed on water permeability characteristics. In contra, 34.5% flux decline was witnessed when higher saline feed concentration (100 g/L) was utilized. In the meantime, with raising the sweeping gas flow rate (from 120 to 300 L/h), the distillate was nearly 129% higher. Based on Taguchi design, the maximum permeate flux (17.3 and 17 kg/m2·h) was secured at 35 g/L, 0.4 L/min, 65 °C and 300 L/h, for both commercial and prepared membranes, respectively.

scholarly journals Removal of Dyes from Wastewater by Ceramic Membrane

2019 ◽  
Vol 70 (5) ◽  
pp. 1715-1719
Author(s):  
Ramy Mohamed Jebir Al-Alawy ◽  
Baker M. Abod ◽  
Firas Hashim Kamar ◽  
Aurelia Cristina Nechifor
Keyword(s):  
Flow Rate ◽  
Ceramic Membrane ◽  
Cross Flow ◽  
Rejection Rate ◽  
Feed Flow Rate ◽  
Acid Orange 7 ◽  
Feed Concentration ◽  
Acid Orange ◽  
High Feed ◽  
Oil Concentration

The current study aimed to investigate the elimination of dyes from sewerage, using microfiltration membrane mechanism. Three dyes were applied, acid yellow-23, disperse blue -79 and acid orange -7. Experiments were performed with feed concentration (40 -120) ppm, feed flow rate (25 -65) l/h and time (0.25 -1.5) h. The membrane used ceramic membrane, constructed as a candle. It was discovered that water flow diminishes with an elevation in running time, feeding oil concentration and enhancing with elevation in the feed flow rate. In addition, it was determined that the elimination (rejection) rate of dyes enhances with elevation in the flow rate, and the elimination (rejection) rate diminishes as time passes. In cross flow microfiltration, the rejection concentration (concentrate) goes up as time passes, with high feed concentration and flow rate. It was also discovered that the modal infusion concentration declines with high feed concentration and working time. In addition, it was found that product rate goes down as time passes and with high feed concentration. Increasing feed concentration of dyes was associated with an increase in the concentration of rejecting solution. The highest elimination of disperse blue -79, Acid Yellow- 23 and acid orange -7, are 97%, 96.4% and 95.8%, respectively. The maximum recovery percentage of disperse blue - 79, acid yellow- 23 and acid orange -7are 57.7%, 58.5% and 59% respectively.

Research on New Pervaporation Membranes and the Effect of Treatment of Wastewater Containing Phenol

2014 ◽  
Vol 700 ◽  
pp. 466-469
Author(s):  
Ke Ma ◽  
Yu Yun Fu
Keyword(s):  
Flow Rate ◽  
Separation Factor ◽  
Dibutyltin Dilaurate ◽  
Permeation Flux ◽  
Feed Flow Rate ◽  
Feed Concentration ◽  
Dimethyl Siloxane ◽  
Effect Of Treatment ◽  
Cross Linker ◽  
Feed Temperature

The pervaporation membranes were prepared by using poly dimethyl siloxane (PDMS) as precursor, toluene as solvent, triethoxy methylsilane as cross linker, dibutyltin dilaurate as catalyst. The PDMS membranes were evaluated with permeation flux and separation factor. The effects of cross linker dosage and the operation parameters during the process of pervaporation were investigated. It was shown from the results that: The selectivity of the membranes increased while the permeation flux first increased and then decreased as the linker dosage increased; the selectivity of the membranes decreased while the permeation flux increased as the feed temperature increased; the selectivity and the permeation flux of the membranes both increased as the feed concentration increased; the selectivity and the flux also both increased as the feed flow rate increased; the selectivity increased while the permeation flux decreased as the separation press increased. When the proportion of the PDMS, solvent, cross linker and catalyst were immobile, The permeation flux and separation factor could be 98mg/(m2·h) and 5.12 when the feed temperature was 60°C, feed concentration was 0.5g/L, feed flow rate was 0.6L/min and separation press was 6KPa.

Performance of Air Gap Membrane Distillation Unit for Water Desalination

2014 ◽  
Author(s):  
Atia E. Khalifa ◽  
Dahiru U. Lawal ◽  
Mohamed A. Antar
Keyword(s):  
Flow Rate ◽  
Membrane Distillation ◽  
Air Gap ◽  
Water Desalination ◽  
Feed Water ◽  
Feed Flow Rate ◽  
Permeate Flux ◽  
Air Gap Membrane Distillation ◽  
Gap Width ◽  
Feed Temperature

Due to water scarcity in the Arabic gulf region, water desalination technologies are considered extremely important. The present work represents a fundamental study on the effect of basic operating and design variables on the flux of an air gap membrane distillation (AGMD) unit for water desalination. The flat sheet, channeled air gap membrane distillation module was designed and manufactured locally. The effect of feed flow rate, feed temperature, coolant water temperature, the air gap width, and the water salinity on the module flux are investigated. Analytical model for heat and mass transfer is used to predict the flux and the model results are compared to the experimental ones. Results showed that the technique has good potential to be used for water desalination. The permeate flux is increased by increasing feed flow rate, feed temperature, decreasing the air gap width, decreasing coolant temperature, and decreasing salinity of feed water. For a given feed flow rate, the width of the air gap and the feed water temperature are found to be the most effective parameters in increasing the distillate flux. Predicting the permeate flux with analytical models for heat and mass transfer showed good agreement with experimental results.

Water Desalination Using Direct Contact Membrane Distillation System

2015 ◽  
Author(s):  
Hafiz M. Ahmad ◽  
Atia E. Khalifa ◽  
Mohamed A. Antar
Keyword(s):  
Flow Rate ◽  
Direct Contact ◽  
Membrane Distillation ◽  
Operating Conditions ◽  
Water Desalination ◽  
Feed Flow Rate ◽  
Direct Contact Membrane Distillation ◽  
Rejection Factor ◽  
System Output ◽  
Feed Temperature

Membrane distillation (MD) is a separation technique used for water desalination, which operates at low feed temperatures and pressures. Direct contact membrane distillation (DCMD) is one of the common MD configurations where both the hot saline feed stream and the cold permeate stream are in direct contact with the two membrane surfaces. An experimental study was performed to investigate the effect of operating conditions such as feed temperature, feed flow rate, permeate temperature, and permeate flow rate on the system output flux. To check the effect of membrane degradation, the MD system was run continuously for 48 hours with raw seawater as feed and the reduction in system flux with time was observed. Results showed that increasing the feed temperature, decreasing the permeate temperature, increasing the feed and permeate flow rate yield an increase in flux. The effects of feed temperature and feed flow rate are the most significant parameters. After 48 hours of system continuous operation flux was reduced by 42.4 % but the quality of permeate (as measured by its TDS) is still very high with salt rejection factor close to 100 %. For the DCMD system under consideration, the GOR values remain between 0.8 and 1.2, for the tested range of operating temperatures.

scholarly journals Analytical Determination of the Optimal Feed Temperature for Hydrogen Peroxide Decomposition Process Occurring in Bioreactor with a Fixed-Bed of Commercial Catalase

Catalysts ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 35
Author(s):  
Ireneusz Grubecki
Keyword(s):  
Hydrogen Peroxide ◽  
Flow Rate ◽  
Fixed Bed ◽  
Decomposition Process ◽  
Fixed Bed Reactor ◽  
Analytical Determination ◽  
Feed Flow Rate ◽  
Feed Concentration ◽  
Optimal Feed ◽  
Feed Temperature

The hydrogen peroxide-immobilized commercial catalase system was chosen to estimate the optimal feed temperature (OFT) for fixed-bed reactor (FXBR). This feed temperature was obtained based on analytical solution by maximizing the time-averaged substrate conversion under a constant feed flow rate and temperature constraints. In calculations a set of partial differential equations describing the conservation equation for fixed-bed reactor, assuming plug flow and kinetic equation for the rate of enzyme parallel deactivation was taken into account. The model is based on kinetic, and mass-transfer parameters estimated previously in a real decomposition process of hydrogen peroxide (HP). The simulation showed that the OFT is strongly dependent on hydrogen peroxide feed concentration, feed flow rate and diffusional resistances expressed by biocatalyst global effectiveness factor. It has been shown that the more significant diffusional resistances and the higher HP conversions are, the higher the optimal feed temperature is. The calculated values of the OFT were verified with the experimental results obtained in the model reactor at selected values of the feed flow rate. Presented analysis poses a significant simplification in a numerical computational procedure and can be very useful for engineers to select the temperature condition at which bioreactor productivity is expected to be maximal.

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