Filtration Resources
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October 13, 2022
What is the purpose of spacers and shims used with the membrane test cells, and do I need them?
Crossflow velocity (CFV) refers to the linear rate of flow of the feed solution as it passes tangentially over the surface of the membrane filter and is measured in meters or feet per second. Some of the feed solution will permeate through the membrane filter, while the balance will flow along the surface of the membrane and collect as concentrate that can be recirculated through the system. The crossflow velocity has a direct impact on the fouling rate and the occurrence of concentration polarization — where a concentration gradient forms in the fluid adjacent to the membrane surface.
To calculate crossflow velocity (CFV) you will need to divide the volumetric flow rate of the feed solution in the flow channel by the cross-sectional area
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October 13, 2022
Oktoberfest is an annual beer festival held over the course of two weeks during September-October in Munich, Germany. Its origins date back to October 12, 1810, when the festival was first held to celebrate the marriage of Prince Louis of Bavaria, who later became King, to Princess Therese von Sachsen-Hildburghausen. Over the years, the festival has evolved to include an amusement park and fun-fair, food and drink stalls, and several large and lively beer halls, where much of the merry-making takes place.
The Oktoberfest is a huge attraction for both locals and tourists alike. More than six million revelers attend Oktoberfest each year, consuming more than 2 million gallons of beer during the two week event.
While
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August 13, 2022
Ultrafiltration and Nanofiltration membranes are used in a wide range of applications and industries to separate unwanted dissolved compounds from water, wastewater, and other liquids. But, in order for a membrane to efficiently perform a desired separation, an appropriate molecular weight cut-off (MWCO) must be selected. Molecular weight is generally most accurate when selecting an Ultrafiltration membrane; it is more of a guide or approximation when working with Nanofiltration.
What is Molecular Weight Cut-Off (MWCO)?
Molecular weight cut-off (MWCO) can be defined as a nominal rating given to membranes based on the lowest molecular weight (measured in Daltons or Kilodaltons) at which they are able to retain more than 90% of a solute with a known molecular weight.
For example, a membrane with a molecular weight cut-off of 1,000
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July 13, 2022
Organic Solvent Nanofiltration (OSN) or Organophilic Nanofiltration (oNF) offers an attractive solution for challenging separations in the molecular range between ultrafiltration and reverse osmosis, focusing on the treatment of organic liquids across several industries. Sterlitech is pleased to announce the addition of industrially proven, BORSIG OSN flat sheet membranes to its product offerings. Available in A4 size (210 x 297 mm) sheets, and easily cut down to other shapes or sizes, they can be used with any of our flat sheet membrane test cells.
Applications include, but are not limited to:
- Homogeneous catalyst recovery from reaction mixtures
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July 13, 2022
Membranes don’t always perform as expected, but asking the right questions can reduce down time due to troubleshooting. Below are a few common filtration performance challenges and troubleshooting tips.
Observation 1: No Flow
If you are pulling vacuum or applying pressure to the membrane, and not seeing any permeation the issue may be that you are using the separator paper (often blue in color) instead of the membrane. Check the color of the filter (most are white or translucent) to verify if the issue is attributed to the using the non-porous separator paper. This mix up is more common than you might think!
Observation 2: Low Flow Rate
Most published flow rates for membranes are based on water. If your flow rate is much lower than the published rate, consider the liquid you are using
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June 22, 2022
Ammonia nitrogen (TAN), a major pollutant in wastewater, consists of non-ionized ammonia (NH3) and ammonium ions (NH4 +), which are pH- and temperature-dependent. To determine its presence in water is important because of its harmful effects on both humans and aquatic organisms.
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June 17, 2022
What is a hydrophilic PCTE membrane?
Polycarbonate track-etched (PCTE) membranes are characterized by durability, low protein binding, controlled porosity, and surface smoothness. PCTE membranes come in hydrophilic and hydrophobic materials, which affects the membrane “wet-ability”. Wet-ability refers to the ability of a membrane to draw water into the pore structure.
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March 11, 2022
You’ve just finished testing a coupon with your new Membrane Test Cell, and are ready to evaluate the performance of a different coupon to compare results.
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February 04, 2022
The aluminum oxide (AO) membrane filters are extremely brittle and will fracture if subjected to bending. Great care must be used when handling and placing the filters. They cannot be handled using fingers. They must be handled with smooth membrane tweezers or with vacuum tweezers, such as SPI 00016-AB or similar. When choosing vacuum tweezers, make sure to select one that apply continuous vacuum with an electrically powered motor. Continuous vacuum is required since the AO membrane is permeable and will have some small airflow. Don't bother trying
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December 13, 2021
Sterlitech presents a new addition to its membrane line: Polyethylene. A comparable alternative to the discontinued polypropylene membranes, these polyethylene membranes provide several advantages over Polyethylene membranes, including but not limited to