scholarly journals Membrane cleaning using electric pulse in dead end ultrafiltration of proteinaceous solution

2017 ◽  
Vol 18 (2) ◽  
Author(s):  
A.L. Ahmad' ◽  
And I.A. Azid
Keyword(s):  
Ionic Strength ◽  
Pulse Duration ◽  
Filter Cake ◽  
Polymeric Membrane ◽  
Pulse Interval ◽  
Water Recovery ◽  
Membrane Cleaning ◽  
Electric Pulses ◽  
Average Percentage ◽  
Dead End

Dead end ultrafiltration of Bovine Serum Albumine (BSA) using a polymeric membrane has been studied. Membrane fouling for such fine biological product due to the formation of filter cake and adsorption of the proteinaceous solution is the major bottleneck for such separation process. The application of electric pulses has shown an effective means in cleaning the membrane and reducing the fouling rate for dead-end ultrafiltration of BSA. The flux is significantly increased by both electrophoretic motion of solutes away from the membrane surface and electro-osmosis occurring in the filter cake. An automated experimental rig equipped with data acquisition system has been developed to test the effectiveness and performance of such membrane cleaning. The improvement of flux becomes more pronounced with increasing electric field strength. The effects of other processing variables such as pulse interval, pulse duration, ionic strength of the electrolyte, pH of the solution and solution concentration were studied on this membrane cleaning technique. Data are analysed for its average flux, average cake concentration, average percentage of cake and water recovery for every cleaning condition. It is found out that the chemical and physical properties of the solution (pH and ionic strength of the electrolyte) have a great effect on this membrane cleaning method. Protein solution at pH 8 and 0.0 lM ionic strength of the electrolyte gave the best membrane cleaning performance. Shorter pulse interval and with relatively 10 seconds pulse duration are the optimum conditions on application of pulse to remove the filter cake from the membrane.

Prevention of Membrane Fouling Using Electric Pulse in Dead End Microfiltration of Titanium Suspensions

2012 ◽  
Author(s):  
Abdul Latif Ahmad ◽  
Suzylawati Ismail
Keyword(s):  
Ionic Strength ◽  
Pulse Duration ◽  
Applied Voltage ◽  
Membrane Fouling ◽  
Electric Pulse ◽  
Membrane Surface ◽  
Pulse Interval ◽  
Electric Pulses ◽  
Average Percentage ◽  
Dead End

Denyutan elektrik merupakan salah satu kaedah yang berkesan untuk menyingkirkan bahan–bahan endapan pada permukaan membran polimerik dan mampu mencegah permukaan daripada tersumbat. Hasil–hasil dapatan uji kaji pencegahan permukaan membran dari tersumbat menggunakan denyutan elektrik bagi proses penurasan mikroampaian titanium dibentangkan. Kesan beberapa pembolehubah proses seperti selang masa antara denyutan elektrik, jangkamasa sesuatu denyutan elektrik, pH larutan, kekuatan ionik bagi elektrolit dan kekuatan voltan sesuatu denyutan elektrik telah dikaji dari segi prestasi dan keberkesanannya dalam mencegah membran dari tersumbat. Didapati bahawa fluks meningkat secara ketara dengan adanya pergerakan elekroforetik butiran bahan endapan menjauhi permukaan membran dan berlakunya proses elektroosmosis di dalam bahan endapan itu sendiri. Keputusan–keputusan telah dianalisis dari segi purata fluks, purata kepekatan bahan endapan, peratus purata perolehan semula bahan endapan dan peratus perolehan semula air. Didapati bahawa sifat fizikal dan kimia larutan (pH dan kekuatan ionik elektrolit) memberi kesan yang besar ke atas kaedah pencegahan permukaan membran dari tersumbat. Ampaian titanium pada pH 8 dan dengan kekuatan ionik elektrolit 0.01M memberi prestasi terbaik dalam pembersihan permukaan membran. Selang masa antara dua denyutan yang singkat dan jangkamasa 10 saat sesuatu denyutan dengan kekutan voltan 100V merupakan keadaan optimum bagi denyutan elektrik untuk menyingkirkan bahan–bahan endapan dari permukaan membran menggunakan denyutan elektrik. Kata kunci: pemisahan membran; penurasan mikro; membran tersumbat; denyutan elektrik;titanium dioksida. Electric pulse in an effective means of removing particulate materials from polymeric membrane and preventing the membrane fouling. The experimental results for dead end microfiltration of titanium suspension to prevent membrane fouling using electric pulses are presented. The effect of processing variables such as the pulse interval, pulse duration, pH of the solution, ionic strength of the electrolyte and the strength of the applied voltage for dead end microfiltration of titanium suspensions were studied on the performance and effectiveness of this prevention of membrane fouling. The flux was significantly increased by both electrophoretic motion of particles away from the membrane surface and electroosmosis occurring in the filtercake. The results were analyzed for its average flux, average cake concentration, average percentage recovery of cake and average percentage recovery of water. It is found that the physical and chemical properties of the solution (pH and ionic strength of the electrolyte) have a great effect on this membrane fouling prevention method. Titanium suspension at pH 8 and ionic strength of 0.01M electrolyte strength gave the best membrane cleaning performance. Shorter pulse interval with 10 seconds pulse duration with 100V applied voltage were the optimum conditions to remove the filtercake from the membrane surface. Key words: membrane separation; microfiltration; membrane fouling; electric pulses; titanium dioxide

Nanofiltration performance of lead solutions: effects of solution pH and ionic strength

2010 ◽  
Vol 10 (2) ◽  
pp. 193-200 ◽  
Author(s):  
Wuthikorn Saikaew ◽  
Supatpong Mattaraj ◽  
Ratana Jiraratananon
Keyword(s):  
Ionic Strength ◽  
Membrane Surface ◽  
Aromatic Polyamide ◽  
Solution Chemistry ◽  
Lead Ion ◽  
Solution Ph ◽  
Dead End ◽  
Flux Decline ◽  
Charged Membrane ◽  
Double Layer Thickness

Nanofiltration performance (i.e. rejection and flux decline) of lead solutions was investigated using a dead-end test cell at room temperature. An aromatic polyamide NF-90 membrane was chosen to determine the impacts of solution chemistry. The experimental results revealed that solution flux decline was dependent on solution pH, ionic strength, and type of lead solutions. Solution flux conducted with different types of lead solutions (i.e. PbCl2 and Pb(NO3)2) decreased with increased solution pH. Solutions having high pH exhibited greater flux decline than those having low solution pH, while lead ion rejections were relatively high. Increased ionic strengths resulted in a greater flux decline, while lead ion rejections decreased with decreasing solution pH and increasing ionic strengths. Such results were related to low solution pH, suggesting an increase in fixed charge of proton (H+), decreasing electrical double layer thickness within membrane, thus allowing increased lead concentration passing through the membrane surface. Solution flux and rejection decreased further at higher ionic strengths, which caused a reduced negatively charged membrane, and thus decreased rejections. It was also found that lead ion for PbCl2 solution exhibited higher rejections than that of Pb(NO3)2 solution.

Drinking water production by coagulation-microfiltration and adsorption-ultrafiltration

1998 ◽  
Vol 37 (10) ◽  
pp. 135-146 ◽  
Author(s):  
Akira Yuasa
Keyword(s):  
Drinking Water ◽  
Activated Carbon ◽  
Hollow Fiber ◽  
Cross Flow ◽  
Ceramic Membranes ◽  
Cellulose Acetate Membrane ◽  
Water Recovery ◽  
Dead End ◽  
Iron Manganese ◽  
Gac Adsorption

Microfiltration (MF) and ultrafiltration (UF) pilot plants were operated to produce drinking water from surface water from 1992 to 1996. Microfiltration was combined with pre-coagulation by polyaluminium chloride and was operated in a dead-end mode using hollow fiber polypropylene and monolith type ceramic membranes. Ultrafiltration pilot was operated in both cross-flow and dead-end modes using hollow fiber cellulose acetate membrane and was combined occasionally with powdered activated carbon (PAC) and granular activated carbon (GAC) adsorption. Turbidity in the raw water varied in the range between 1 and 100 mg/L (as standard Kaolin) and was removed almost completely in all MF and UF pilot plants to less than 0.1 mg/L. MF and UF removed metals such as iron, manganese and aluminium well. The background organics in the river water measured as KMnO4 demand varied in the range between 3 and 16 mg/L. KMnO4 demand decreased to less than 2 mg/L and to less than 3 mg/L on the average by the coagulation-MF process and the sole UF process, respectively. Combination of PAC or GAC adsorption with UF resulted in an increased removal of the background organics and the trihalomethanes formation potential as well as the micropollutants such as pesticides. Filtration flux was controlled in the range between 1.5 and 2.5 m/day with the trans-membrane pressure less than 100 kPa in most cases for MF and UF. The average water recovery varied from 99 to 85%.

Experimental Study on High-Speed WEDM Finishing in Gas Based on Central Composite Design

2013 ◽  
Vol 662 ◽  
pp. 319-322
Author(s):  
Tong Wang ◽  
Yu Mei Lu ◽  
Chao Qun Wang ◽  
Kun Jiang ◽  
Fei Xie ◽  
...  
Keyword(s):  
Regression Model ◽  
Central Composite Design ◽  
Pulse Duration ◽  
High Speed ◽  
High Reliability ◽  
Cutting Speed ◽  
Pulse Interval ◽  
Five Factors ◽  
Verification Test ◽  
Central Composite

Using cutting speed and the roughness as index, the five factors as pulse duration, peak current, offset, ratio of pulse interval to pulse duration and worktable feed were chosen in dry finishing. Based on the single factor experiment, the central composite design (CCD) method is used to study the effects of the five factors and their interactions on cutting speed and the surface roughness and develop empirical models for cutting speed and roughness Ra. Significant order influencing cutting speed and roughness are found. The results of the verification test show that Ra regression model and cutting speed regression model have high reliability, and can achieve significant prediction effect.

Firing Activity of the Weakly-Electric Fish Marcusenius Macrolepidotus (Mormyridae, Teleostei): Logarithmic Repartition of Inter-Pulse Intervals, and Sequential Inequality Testing

Behaviour ◽  
1989 ◽  
Vol 109 (3-4) ◽  
pp. 258-283 ◽  
Author(s):  
Christian Graff
Keyword(s):  
Parametric Method ◽  
Electric Activity ◽  
Weakly Electric Fish ◽  
Electric Signal ◽  
Pulse Interval ◽  
Neural Firing ◽  
Firing Activity ◽  
Electric Pulses ◽  
Mormyrid Fish ◽  
The Difference

AbstractThe electric activity of mormyrid fish consists of short electric pulses, all identical, but separated by variable time intervals (inter-pulse interval or IPI). Temporal structures are here extracted from the sequence of IPIs, to show non-randomness in mormyrid electric signal. The electric activity of isolated Marcusenius macrolepidotus is comparable to that of other mormyrids. The pulse waveform is biphasic and symmetrical, it lasts 0.3 to 0.5 ms and its amplitude is about 13 volts. The pulses follow each other with extremely variable IPIs (14-500 ms) with large instantaneous variations. Two new methods of analysis have been developed here. The first is based on the fact that when IPIs are grouped in populations, longer IPI populations have a wider range than shorter ones, a lognormal rather than a normal distribution. The IPIs are therefore classified according not to absolute- but to relative differences: binwidths are in percent, not in milliseconds. The second, non-parametric method (sequential inequality testing), was first used for neurone firing activity. It considers the sign (+ or -) of the difference between successive IPIs, and compares the sequence of these signs with a theoretical random model. When M. macrolepidotus is resting, the sequence of longer and shorter IPIs is not random, as shown by redundancies of patterns of + and - signs. These redundancies and the IPI populations are typical for each individual. When the fish increases its locomotor activity (either spontaneously for a few seconds, or provoked over more than 20 s) the IPIs are shorter. The patterns of + and - are different when the fish is swimming and when resting. Behavioral and electrophysiological data suggest that receiving conspecifics may recognize these rhythm features. The analysis methods developed here may be useful to other stochastic phenomena, such as neural firing activity.

Experimental Study of the Dry and Near-Dry Electrical Discharge Milling Processes

2008 ◽  
Vol 130 (1) ◽  
Author(s):  
Jia Tao ◽  
Albert J. Shih ◽  
Jun Ni
Keyword(s):  
Pulse Duration ◽  
Surface Finish ◽  
Discharge Current ◽  
Electrical Discharge ◽  
Experimental Studies ◽  
Fractional Factorial ◽  
Pulse Interval ◽  
Water Mixture ◽  
Dry Edm ◽  
Fine Surface

This study investigates the dry and near-dry electrical discharge machining (EDM) milling to achieve a high material removal rate (MRR) and fine surface finish for roughing and finishing operations, respectively. Dry EDM uses gas and near-dry EDM applies a liquid-gas mixture as the dielectric medium. Experimental studies leading to the selection of oxygen gas and copper electrode for high MRR dry EDM and the nitrogen-water mixture and graphite electrode for fine surface finish near-dry EDM are presented. Near-dry EDM exhibits the advantage of good machining stability and surface finish under low discharge energy input. A 25−1 fractional factorial design is applied to investigate the effect of discharge current, pulse duration, and pulse interval on the MRR and surface finish in dry and near-dry EDMs. Lower pulse duration and lower discharge current are identified as key factors for improving the surface finish in near-dry EDM.

scholarly journals EXCITATION OF PLASMA BY ELECTRIC PULSES IN NEON MEDIUM

2019 ◽  
pp. 203-206
Author(s):  
D.Yu. Zaleskyi ◽  
G.A. Krivonosov ◽  
G.V. Sotnikov
Keyword(s):  
Relaxation Time ◽  
Steady State ◽  
Pulse Duration ◽  
Supply Voltage ◽  
Unstable Mode ◽  
Plasma Source ◽  
Pulse Front ◽  
Electric Pulses ◽  
Front Duration ◽  
Voltage Frequency

We studied characteristics of the neon plasma source excited in the atmosphere under the following conditions: gas pressure is about 2 Torr, rectangular pulses have an amplitude from 200 to 800 V, pulse duration is from 0.2 to 10 μs, repetition rate is from 0.2 up to 1 kHz. There is a mode with a stable and unstable mode of existence of the plasma when the voltage on the electrodes of the plasma source varies from 800 to 350 V and from 350 to 250 V before the extinction of the plasma. The pulse from the PMT output in a steady state plasma has a decay of about 100 μs, the duration of which does not depend on the magnitude of the voltage, frequency and pulse duration. With a decrease in the supply voltage U, the pulse front duration with a photomultiplier is increased from 74 to 450 ns. It is shown that a large neon plasma relaxation time of 100 µs compared with a beam pulse duration of 1…2 µs allows only one time to change the phase of the accelerating field.

Properties of Filter Cake Formed during Dead-End Microfiltration of O/W Emulsion

2013 ◽  
Vol 46 (9) ◽  
pp. 593-600 ◽  
Author(s):  
Da-Qi Cao ◽  
Eiji Iritani ◽  
Nobuyuki Katagiri
Keyword(s):  
Filter Cake ◽  
Dead End

Effects of Click Duration on the Latency of the Early Evoked Response

1984 ◽  
Vol 27 (1) ◽  
pp. 70-76 ◽  
Author(s):  
Randall C. Beattie ◽  
Robyn Boyd
Keyword(s):  
Hearing Loss ◽  
Pulse Duration ◽  
Normative Data ◽  
Normal Hearing ◽  
Evoked Response ◽  
Electric Pulses ◽  
Clinically Significant

The effect of click duration on the latency of waves I, III, and V was investigated by testing 20 normal-hearing subjects at 60 dB HL using electric pulses of 25, 50, 100, 200, and 400 µs. Alternating condensation and rarefaction clicks were used. The results revealed similar and nonsignificant latency differences for the 25-, 50-, and 100-µs pulses. However, the 100 µs duration is preferred to the 25-µs pulse because the latter reduced the maximum measurable hearing loss by about 13 dB. The results also showed that latencies increased approximately 0.10 ms as duration increased from 100 to 200 µs and by 0.20 ms when duration increased from 100 to 400 µs. Although such differences by themselves are small, they can combine with other stimulus or recording variables to be clinically significant. Therefore, it is important to control click duration when normative data are generated. A second experiment was conducted to assess the interaction of polarity (condensation, rarefaction, and alternating) and pulse duration (100 and 400 µs) on the wave V latency. These data revealed no latency differences among polarities at either duration.

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