Cross-flow Filtration Method Research Articles

Anti-fouling performance investigation of micron-submicron hierarchical structure PVDF membranes in water-in-oil emulsion separation

Membrane technology was widely used in the field of oil-water separation. In the process of water-in-oil emulsion treatment, surface contamination of hydrophobic and lipophilic membranes was a difficult problem. Therefore, the effect of hydrophobic membrane surface micro-rough structure on oil-water separation performance and its anti-fouling behavior has been investigated as a major focus of current research. Superhydrophobic-superoleophilic polyvinylidene fluoride (PVDF) membranes with micron-submicron hierarchical structure were prepared by combining thermally induced phase separation (TIPS) with rolling embossing. The influence of the roller temperature on the structure and performance of the membrane were discussed. The best achieved superhydrophobicity with a high water contact angle (WCA) of 154.8° and rolling angle (SA) of 1.9°, which was similar with lotus-effect. Meanwhile, the N2 flux was 197 L m−2 s−1 and LEP was 4.08 bar. Besides, the tensile strength of PVDF membrane was 1.89 MPa. The embossed membrane showed good lipophilicity, and the residence time of kerosene on the membrane surface was only 0.14 s. PVDF membranes with lotus leaf effect showed excellent demulsification performance and high recyclability in water in oil emulsion. The oil flux and rejection rate were 1258 L m−2 h−1 and 99.14%, respectively. In the separation experiment of PVDF membranes in diesel emulsion containing inorganic pollutant CaCO3, the results showed that the anti-fouling effect of PVDF membranes by cross-flow filtration method was obviously better than that by dead-end filtration method. When the operating temperature and pressure were 0.1 MPa and 45 °C, respectively, embossed membrane showed relatively excellent separation performance in cross-flow filtration. This study provided some guidance for the anti-fouling performance of roughened surface superhydrophobic-superoelophilicity membrane in oil-water separation experiment.

Using Different Size of Montmorillonite Particles for Filtration-Adsorption of Nickel Metal in Electroplating Liquid Waste

This study aims to know the effect of montmorillonite particle, which were granule and gravel of montmorillonite,prepared from the sintering method and its effectiveness in filtration-adsorption process of the nickel-metal in electroplating liquid waste. The granule and gravel of montmorillonite wereprepared by compaction and sintering processes at a temperature of 900oC. The characterization of granule montmorillonite shows the notoriously random micropore material, which the pore surface area was 8.393 m2/g. While the gravel montmorillonite has a pore surface area of 4,381 m2/g. The test was carried out by flowing electroplating waste with the crossflow filtration method and batch adsorption. The most effective decrease in the concentration of nickel-metal occurred in the granules of montmorillonite with a mass ratio of material through filtration and adsorptionwas 2:3. The effectiveness of filtration-adsorption process for removing nickel metal from liquid waste of electropaling was 83.51%.

Study on Oily Wastewater Treatment with Multifunctional Ceramic Membrane

We used cross-flow filtration method and made use of a certain degree of silicon carbide ceramic membrane at different filtration time, different operating temperature to treat with waste water so as to study the flux of membrane flux and the change of water quality and the amount of recoil cleaning on the recovery of membrane flux .The results show that: the silicon carbide ceramic membrane can effectively dispose the oily waste water. The energy consumption is lower and the membrane flux is stable, simultaneously, multiple recoil cleaning can also make the membrane flux fully recover when the filtration time is 15min, the membrane flux is large, the temperature is 35 degrees centigrade.

The composition of dissolved iron in the dusty surface ocean: An exploration using size-fractionated iron-binding ligands

Abstract The size partitioning of dissolved iron and organic iron-binding ligands into soluble and colloidal phases was investigated in the upper 150 m of two stations along the GA03 U.S. GEOTRACES North Atlantic transect. The size fractionation was completed using cross-flow filtration methods, followed by analysis by isotope dilution inductively-coupled plasma mass spectrometry (ID-ICP-MS) for iron and competitive ligand exchange-adsorptive cathodic stripping voltammetry (CLE-ACSV) for iron-binding ligands. On average, 80% of the 0.1–0.65 nM dissolved iron ( 99% of dissolved iron in the ocean is organically complexed. Disentangling the chemical form of iron in the upper ocean has important implications for surface ocean biogeochemistry and may affect iron uptake by phytoplankton.

Assessment and comparison of Anopore and cross flow filtration methods for the determination of dissolved iron size fractionation into soluble and colloidal phases in seawater

The two most frequently used methods for determining the size fractionation of dissolved iron (dFe) in seawater, 0.02 µm pore size Anopore membrane filtration and cross flow filtration using a 10 kDa regenerated cellulose filter, were evaluated and compared. Anopore filtration was found to produce consistent soluble Fe (sFe) concentrations in the filtrate even after > 1 L unfiltered seawater was filtered, indicating that clogging is not an issue for typical open ocean filtration volumes. Cross flow filtration (CFF) only achieved a 70% to 75% mass balance regardless of flow rate and seawater preconditioning; however, Fe losses arose largely from the colloidal (not soluble) size fraction, and Fe loss was constrained to Fe clogging in/on the CFF membrane. Both Anopore membrane and cross flow filtration methods reproducibly size fractionated dFe in seawater samples. Additionally, sFe arising from these two filtration methods were compared for the first time using seawater samples from the North Pacific and Atlantic Oceans. sFe from CFF was always lower than sFe from Anopore filtration, with the ratio of sFe in CFF/Anopore filtration averaging 68 ± 23% (n = 23). This sFe difference is attributed to a combination of the smaller effective pore size of the regenerated cellulose CFF system and the spatial variability in the concentration and composition of dFe in the 10 kDa ‐ 0.02 µm size fraction. Finally, the advantages and disadvantages of each method were reviewed to offer future users a suite of factors with which to choose their ideal ultrafiltration method.

Effects of land use and changes in cover on the transformation and transportation of iron: A case study of the Sanjiang Plain, Northeast China

Wetland reclamation has been ongoing in the Sanjiang Plain since the mid-1950s, which has resulted in major changes in wetlands and the agriculture ecosystem in the region that have influenced the iron output to the Sea of Okhotsk and limited the primary productivity in the North Pacific Ocean. This study was conducted to investigate the chemical forms of iron in different aquatic environments (agricultural water including groundwater, paddy water, and canal water; wetland water including marsh water, marsh streams, and main streams) with the cross-flow filtration method to reveal the transportation and transformation characteristics of iron in response to major land use changes. In addition, the factors affecting iron behavior in different water bodies were reviewed. In marsh water and streams, the concentrations of dissolved iron were higher due to the high organic matter contents and marsh water becoming the main iron source for river water. The conversion of dissolved iron into acid-labile iron occurred during the discharge of wetland water into marsh rivers. Iron primarily existed in both the >0.7 and <0.01 μm size fractions, accounting for about 58.3% and 26.4% of the total dissolved iron, respectively. In agricultural irrigation systems, ferrous ion entered the paddy fields from groundwater, and a fraction of this ferrous iron was subsequently converted into high molecular weight and medium molecular weight iron (colloid iron) in paddy and canal water. However, the concentrations of total dissolved iron decreased by 62.5% from underground to the surface due to the formation of precipitates. Despite this, water discharge in agriculture is still an important iron source for rivers and has the potential to supplement iron due to its higher acid-labile iron concentrations. Land use and cover change and agricultural irrigation increased the iron content of surface soil, but reduced the output of iron in water systems. Overall, the concentration of total dissolved iron in water systems has been reduced to 42.6% by wetland reclamation.

Fractionation of Single Wall Carbon Nanotubes by Length Using Cross Flow Filtration Method

A novel system for fractionating single wall carbon nanotubes (SWCNTs) by length via a three-step cross-flow filtration has been developed in which three membrane filters of different pore sizes, 1.0, 0.45, and 0.2 microm, were used. SWCNTs dispersed in water with the help of sodium carboxymethylcellulose (CMC) detergents were successfully sorted into four samples, and the atomic force microscopy (AFM) observation of those samples confirmed that their length distribution peaks are within the expected ranges from pore sizes of used filters. However, the result of the similar filtration process using a different detergent, sodium dodecylbenzenesulfonate (SDBS), showed no pronounced correlation between the length distribution of SWCNTs and the pore size. The observed difference in the sorting phenomena caused by the detergent type suggests that the permeation property depends on the complex structure resulting from the dispersed SWCNTs and detergent molecules.

Production of Natural Coagulant from Moringa Oleifera Seed for Application in Treatment of Low Turbidity Water

This study focused on developing an efficient and cost effective processing technique for Moringa oleifera seeds to produce natural coagulant for use in drinking water treatment. The produced natural coagulant can be used as an alternative to aluminum sulphate and other coagulants and used worldwide for water treatment. This study investigates processing Moringa oleifera seeds to concentrate the bio-active constituents which have coagulation activity. Moringa oleifera seeds were processed for oil extraction using electro thermal soxhlet. Isolation and purification of bio-active constituents using chromatography technique were used to determine the molecular weight of the bio-active constituents. The molecular weight of bio-active constitu-ents found to be in a low molecular weight range of between 1000 – 6500 Dalton. The proposed method to isolate and purify the bio-active constituents was the cross flow filtration method, which produced the natu-ral coagulant with very simple technique (oil extraction; salt extraction; and microfiltration through 0.45 µm). The turbidity removal was up to 96.23 % using 0.4 mg/L of processed Moringa oleifera seeds to treat low initial turbidity river water between 34-36 Nephelometric Turbidity Units (NTU) without any additives. The microfiltration method is considered to be a practical method which needs no chemicals to be added com-pared to other researchers proposed methods. The natural coagulant produced was used with low dosages to get high turbidity removal which considered to be a breakthrough in this study and recommended to be scaled up for industry level. The product is commercially valuable at the same time it is minimizing the cost of water treatment.

Design, fabrication and characterization of nano‐filters in silicon microfluidic channels based on MEMS technology

Since most clinical assays are performed on cell-free serum or plasma, micro-analytical systems for blood tests require integrated on-chip microfluidics for the isolation of plasma or serum from crude blood samples. In this paper, we present a crossflow filtration method using novel silicon nano-filters for plasma separation. The microfluidic chip is made of a silicon substrate containing micropillar arrays, feed channels, side channels and nano-gap structures, sealed with a PDMS-glass compound cover. The design of the silicon filtration structures were optimized using numerical analysis and the optimal MEMS fabrication procedures were obtained. The filtration structures including nano-filters were characterized using SEM and subsequently used to isolate plasma from whole blood in a continuous manner. Compared with micro-gap structures in silicon microfluidic channels, the nano-gap structures have been used to separate plasma from whole blood samples with higher selectivity, where a maximum plasma selectivity of 97.7% has been obtained. Common problems of clogging and jamming in filtration applications have seldom been noticed in our device. The presented microfluidic filtration device for plasma isolation could be integrated into microTAS for point-of-care diagnostics in the near future.

MONITORING AND CONTROL OF RECOMBINANT PROTEIN PRODUCTION – FROM UP-STREAM TO INTEGRATED DOWN-STREAM PROCESSES

The production of intra cellular heterologous proteins with Escherichia coli has a demand of a global monitoring and control system for optimization of complex and uncertain process behavior.Moreover the expression of APIs – active pharmaceutical ingredients and its secretion by the yeast Pichia pastoris enables the development of Integrated Bioprocesses with direct product harvest via cross flow filtration methods. This paper describes some associated monitoring and control problems.

Sucrose density gradient centrifugation and cross-flow filtration methods for the production of arbovirus antigens inactivated by binary ethylenimine

BackgroundSucrose density gradient centrifugation and cross-flow filtration methods have been developed and standardised for the safe and reproducible production of inactivated arbovirus antigens which are appropriate for use in diagnostic serological applications.MethodsTo optimise the maximum titre of growth during the propagation of arboviruses, the multiplicity of infection and choice of cell line were investigated using stocks of Ross River virus and Barmah Forest virus grown in both mosquito and mammalian cell lines. To standardise and improve the efficacy of the inactivation of arboviral suspensions, stocks of Ross River virus, Barmah Forest virus, Japanese encephalitis virus, Murray Valley encephalitis virus and Alfuy virus were chemically inactivated using binary ethylenimine at a final concentration of 3 mM. Aliquots were then taken at hourly intervals and crude inactivation rates were determined for each virus using a plaque assay. To ensure complete inactivation, the same aliquots were each passaged 3 times in Aedes albopictus C6/36 cells and the presence of viral growth was detected using an immunofluorescent assay. For larger quantities of viral suspensions, centrifugation on an isopycnic sucrose density gradient or cross-flow filtration was used to produce concentrated, pure antigens or partially concentrated, semi-purified antigens respectively.ResultsThe results of the propagation experiments suggested that the maximum viral titres obtained for both Ross River virus and Barmah Forest virus were affected by the incubation period and choice of cell line, rather than the use of different multiplicity of infection values. Results of the binary ethylenimine inactivation trial suggested that standardised periods of 5 or 8 hours would be suitable to ensure effective and complete inactivation for a number of different arboviral antigens.ConclusionTwo methods used to prepare inactivated arbovirus antigens have been standardised to minimise production failure and expenditure and to provide reagents that conform to the highest quality and safety requirements of a diagnostic serology laboratory. The antigens are suitable for use in either enzyme linked immunosorbent assays or haemagglutination inhibition assays and the optimised protocols can be directly applied to produce antigens from new or emerging arboviral pathogens.

Preparation of chlorinated poly(vinyl chloride)‐g‐poly(N‐vinyl‐2‐pyrrolidinone) membranes and their water permeation properties

AbstractChlorinated poly(vinyl chloride) (CPVC) membranes for microfiltration processes were prepared with the combined process of a solvent evaporation technique and the water‐vapor induced‐phase‐inversion method. CPVC membranes with a mean pore size of 0.7 μm were very hydrophobic. These membranes were subjected to surface modification by ultraviolet (UV)‐assisted graft polymerization with N‐vinyl‐2‐pyrrolidinone (NVP) to increase their surface wettability and decrease their adsorptive fouling. The grafting yields of the modified membranes were controlled by alteration of UV irradiation time and NVP monomer concentration. The changes in chemical structure between the CPVC membrane and the CPVC‐g‐poly(N‐vinyl‐2‐pyrrolidinone) membrane and the variation of the topologies of the modified PVC membranes were characterized by Fourier transform infrared spectroscopy, gel permeation chromatography, and field emission scanning electron microscopy. According to the results, the graft yield of the modified CPVC membrane reached a maximum at 5 min of UV exposure time and 20 vol % NVP concentration. The filtration behavior of these membranes was investigated with deionized water by a crossflow filtration measurement. The surface hydrophilicity and roughness were easily changed by the grafting of NVP on the surface of the CPVC membrane through a simultaneous irradiation grafting method by UV irradiation. To confirm the effect of grafting for filtration, we compared the unmodified and modified CPVC membranes with respect to their deionized water permeation by using crossflow filtration methods. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 3188–3195, 2003

Methodology for accelerated pre-selection of UF type of membranes for large scale applications

This paper describes two assessment methods for UF type of membranes for large-scale applications. The combination of those two methods results in quite clear and unambiguous answers to the question what membranes are of interest for long-term testing. With the first method, calld dead-end filtration method, information is generated on the suitability of the membrane and on the combination of the membrane material, the module hydraulics and assembly. With this method the evolution of TMP is monitored upon filtration cycles of 20 minutes with raw water at a flux rate of 120 l/h.m 2, alternated with backwash cycles with permeate of 40 seconds at 1.2 bar negative TMP. The second method, called cross-flow filtration method, gives exclusively information on the suitability of the membrane material. This is being done by the measurement of the absolute value of the so-called “plateau fluxes” in cross-flow mode at 0.2 m/s linear velocity. For this purpose raw water concentrates are being used. Three “open” UF type of membranes, all three in hollow fibre configuration were assessed with these two methods. It was shown that the PSf based membrane (Koch PM100) reached already after 4 filtration cycles a TMP of 1 bar and showed the lowest plateau flux (25 l/h.m 2). This indicated that the membrane suffered from interaction with the raw water. Moreover, it is possible that something was wrong with the hydraulics of this membrane. The two other membranes were PES/PVP based. These membranes showed much less TMP increase over time. The first membrane of this type was X-Flow UFC, the second Stork Friesland Superfil 015-010. It was no problem to operate the first membrane for 18 hours without addition of chemicals for cleaning. The second membrane reached the maximum allowed TMP of 1 bar after 16 hours of operation at the end of the filtration cycle. Moreover, for both membranes a higher plateau flux value (35 l/h.m 2) was found. Both observations indicate that this type of membrane material is much more interesting than PSf. It was also shown the X-Flow membrane gives the lowest absolute TMP values, which is attributed to its higher pure water permeability (740 l/h.m 2.bar) as compared to the Stork Friesland membrane (pure water permeability of 350 l/h.m 2.bar) and the Koch membrane (pure water permeability of 290 l/h.m 2.bar). A last observation was a TMP increase of only 0.1 bar per cycle for the X-Flow membrane, as compared to 0.2 bar for the two others. This observation is in agreement with earlier made FESEM pictures of the inner surfaces. This means that the X-Flow membrane rather acts as a depth filter, whereas the two other membranes act as a surface filter.

New enzyme reactor with forced flow of the substrate through an enzyme immobilized ceramic membrane.

A new enzyme reactor system for low-molecular-weight substrates, utilizing forced flow through an enzyme-immobilized membrane, was developed. Invertase was physically immobilized within a porous ceramic membrane by filtering an enzyme solution, and a sucrose solution was forced through the membrane by pressure, using a crossflow filtration method. The reaction rate of the forced-flow system was more than 10 times greater than that observed in a diffusion-controlled system. The reaction rate in both systems was mathematically modeled, and the simulated results were in good agreement with the experimental results. The reaction rate in the forced-flow system was easily controlled by pressure, and its productivity was greater than those reported in other reactor systems.