Page 11 - Filtration Resources

If the goal of your vacuum filtration is purification using a membrane with an absolute pore size, Sterlitech recommends utilizing glass filter holder assemblies. Compared to Buchner funnels, these systems create a tight seal to prevent liquid bypass around the membrane. Without this seal, the benefit of a highly retentive membrane disappears.

What is membrane preconditioning and why is it recommended to precondition new flat sheet or spiral wound membranes prior to use? Membrane preconditioning is a filtration step using deionized water as feed solution and is typically performed at a pressure equal to or higher than the anticipated testing pressure. During this process membrane pores are wetted and the membrane structure may go through compaction or swelling, affecting both the permeate flux and the rejection values. Preconditioning will help ensure that the membrane performs according to the specs provided by the manufacturer.

When introducing a new control fluid to hydraulic systems, it is important to ensure that the new liquid or mixture is of equal or superior quality to the previous fluid. If the new mixture is incompatible, precipitate may form and result in an overall inferior fluid. This can speed up clogging or damage the system.

Membrane filtration is an effective way to remove pollutants and microorganisms from water and wastewater. However, membrane fouling lowers efficiency over time when considering rejection values and water flux. Fouling is typically biological or particulate; fouling rate is a function of the membrane pore size relative to the size of the foulants and also the interactions between the membrane and the foulants. Membrane surface charges and affinity for water directly affect membrane biofouling intensity. Applying electric charge to the membrane surface is one of the methods that has been recently trending for mitigating biofouling [1]. Use of an electroconductive nano-carbon-based membrane has also been reported for mitigating membrane fouling by integrating membrane filtration [2].

Last month we examined filter selection strategies for maximizing service life in continuous use applications. In this 3rd installment, we will examine the use of prefilters to extend service life.

In the area of a former military building complex in the Chaoyang District of Beijing is a unique and thriving artistic community. In the middle of this art district, is a strange 7-meter tall tower shaped like an avant-garde metallic pineapple. Designed by Dutch artist Daan Roosegaarde, it is both an artistic creation and a functional tool meant to test a possible solution for Beijing’s worsening air pollution. The tower is a giant silver-colored ionizer and particulate trap designed to pull in and hold tiny pollutants, known collectively as PM 2.5’s. The tower works by releasing charged ions into the air nearby, causing the PM 2.5 particles to become trapped on the metallic fins as they are pulled from the air.

Last month, we described the considerations associated with predicting filter service life and how total throughput can be estimated through experimentation. In this second installment, we will examine four filter selection strategies for maximizing service life in continuous-use applications. These aspects consider chemical compatibility, temperature, binding characteristics, and pore size.

For consumers using disk, syringe, and capsule filters it is a common FAQ: How long will my filter last? Or, to put it another way: How much fluid can I expect to pass through my filter before it clogs? This seems to be a simple and reasonable question for a filter consumer: Would any of us purchase a product without an understanding of its service life? However, this apparently simple question is deceivingly complex as a multitude of factors influence filter service life. Service life can be defined as the total volume of fluid that is passed through a normal flow filter until it becomes clogged; this is commonly referred to as total throughput. It is nearly impossible to predict total throughput, even with a good understanding of the application. So, as a filter manufacturer, how would we suggest approaching this challenge?

In order to provide a safe work environment, better control of vapor wastes needs to be implemented. EZ waste technology has become readily available to improve the containment of volatile liquids and prevent vapors from escaping into laboratory air. Learn about how to prevent the dangers of hazardous waste and the technology behind the closed waste system with an activated carbon filter, such as the EZ waste system. Download EZwaste whitepaper for more detail and additional instruction.

Sterlitech Corporation is proud to announce the launch of gold-sputtered polycarbonate membrane filters. “Why gold? What is sputtered?” you may ask. Well, some particles are just too small to see with an ordinary light microscope, for these things we need get down to details not seen by traditional microscopy.