Page 54 - Blog

Sterlitech offers a wide selection of membranes that have been pre-cut for use with our Sepa CF II Cells, CF042 Crossflow Cells, and HP4750 Stirred Cells.  However, if you want to cut your own membranes for use with any of these systems, you can follow the simple instructions below. HP4750: For this procedure you will need the following materials: a template (the porous stainless support disk works well for this), the membrane you want to cut, scissors, and a pair of latex gloves. 1. Take your template and place the membrane you want to cut against it.  Be sure to have latex gloves on to avoid contaminating the membrane surface. 2. Cut along the edge of the template with the scissors.  Hold the scissors at an angle towards the center of the template to avoid under-trimming.

Once finished, the membrane should sit perfectly flat on supports without any bending and extend outside of the inner O-ring to avoid leakage.

Sepa CF II Cell/CF042: To cut membranes for the Sepa CF II or CF042,

Place a polycarbonate (PCT) or polyester (PET) membrane under an electron microscope and you'll see something similar to the picture here: a smooth surface perforated with neat, cylindrical holes. In this aspect, PCT and PET membranes stand out from other membrane types such as PTFE, nylon, or silver which provide irregular, tortuous paths for permeates to follow. So how are the regular little pores created? Are they drilled, punched, molded or torn into the membrane? If you guessed etched in with the help of a nuclear reactor, then you are absolutely right.

Every PCT or PET membrane filter starts as a roll of plastic film stock. The film is exposed in a controlled manner to charged particles in a nuclear reactor. The charged particles pass through the film, leaving behind sensitized tracks. The density of these tracks in the film depends on the amount of time that the film is exposed to the reactor. More time in the reactor with result in more tracks and greater pore density in the finished

Water, whether seawater or freshwater, is rarely just H₂O.  Dissolved nitrites and nitrates in particular play a key role in the survival of aquatic flora like seaweeds.  In 2005, Matthew R. McIlvin and Mark A. Altabet devised a now common method to analyze the isotopic composition of nitrogen and oxygen dissolved in water in the form of nitrates and nitrites.  The method, which can be found here, requires the removal of all organic matter in the samples. The Grade F borosilicate glass fiber filter, with fine porosity, medium flow rate, and a 0.7 micron size particle retention, is the tool of choice for removing organic matter from water samples.

Sterlitech Corporation prides itself in manufacturing and marketing some of the most advanced filtration products around.  Our filters use materials like PTFE, PVDF, and PES, and others with inconveniently long chemical names that also make their synthetic nature really obvious.  But they're not going to be the focus of this story.  Instead, we will be shining a spotlight on three natural materials that, in addition to being quite tasty, make excellent filters: papayas, oysters, and coconut. Papayas Originally native to Mexico and Central America, the papaya is now grown in tropical regions around the world.  The papaya is usually eaten raw when it's ripe and used in cooking when it's unripe.  The seeds are edible as well, although they're surprisingly spicy. The seeds of the papaya are also the reason why papaya make such good filters.  A recent study published by a group of German and Nigerian Scientists used a combination of crushed papaya seeds and kaolinite clay

We are unveiling a new Water and Wastewater Analysis page on our website. This new page neatly gathers products especially useful in water analysis such as MCE membranes, microbiological filter funnels, and petri dishes into one spot.  The products we currently feature are:

• Microbiological filter funnels
• Sterile MCE membrane filters
• Glass fiber filters
• Petri Dishes

With the ever increasing value of clean water, this section is certain to grow.  Keep an eye on our site as we add the latest water and wastewater analysis lab equipment.

The world can change a lot in fifty years. Fifty years ago, there was no Zimbabwe, Hershey still sold chocolate bars for a nickel, and the Beatles were new on the scene.  Filtration technology has also been touched by the hand of time, improving with each new innovation brought about by a new application, driven by tightening standards and commercial demand.  Today’s industrial and scientific filters are capable of durability, specificity, and affordability that were only dreamt of 50 years ago. During the first half of the twentieth century, the filtration industry relied on natural materials such as wool, cotton, and wood fiber, which were usually supported by metallic screens, to make filters for a wide variety of applications.  But as the century wore on, the industrial processes that relied on filtration to either extract suspended solids or clarify a fluid began to demand ever increasing performance from the filters they used. Luckily, the filtration industry was able