Page 67 - Blog

Here is an article that does a great job of explaining what efficiency ratings mean on a filter and how they are calculated, courtesy of the American Filtration & Separation Society.  This is very useful information for filter users and purchasing agents on the practical effects the filter efficiency will have in a real world setting. You can read the whole thing here.

Over the years we have seen an increased use of filtration equipment in juice processing, particularly regarding ultrafiltration (UF) or microfiltration (MF)for the clarification of apple juice.  Since it has been demonstrated that membrane filtration can produce yields of 95%-99% - compared to only 80-94% through conventional processes – it is no wonder that filtration methods are growing in prevalence.  The greater yield combined with the reduced time and labor costs have translated to hundreds of thousands of dollars saved for juice processing plants! If you are considering juice filtration, here a couple of tips to keep in mind:

• The juice must be clear.  Of the four common types of apple juice produced – natural, crushed, clarified, and clear – only clear juice is suitable for membrane processing.
• Consider ceramic membranes.  More and more fruit juice installations are installing ceramic membranes.  While these do have  a higher cost than other materials, they do offer

One of the biggest issues for crossflow filtration is figuring out how to control the loss of permeate flux in the process. Whether using reverse osmosis (RO), ultrafiltration (UF), or microfiltration (MF), the loss due to polarization and membrane fouling prevents many potential users in the biological or chemical processing fields from adopting this method. If you are using crossflow filtration, or considering using it, and fear the effects of permeate loss, then you may want to consider this technique courtesy of North Carolina A&T University and the U.S. National Energy Technology Laboratory. Their study (see here) produced drastically improved results by implementing flow reversal to enhance the membrane flux. They found that by periodically reversing the flow direction of the feed stream at the membrane surface results in prevention and mitigation of membrane fouling. This particular study conducted experiments with bovine serum albumin, Detran T-70, and apple juice. We’d love to

We ran across an interesting patent that involves silver membranes – As part of a system designed to detect and identify chemical and biological contaminants in the air!  In the proposed sampling method and system, the silver membrane is used to capture liquid, solid, and gas constituents that would then be analyzed by means of spectroscopy for contaminants. 

For more versatility, the surface of the membrane can be modified physically or chemically in order to increase the surface area and/or provide specific affinity towards analytes of interest.   For instance, a pure length of silver membrane would trap solid particulate materials while a silver membrane treated with a metal oxide such as magnesium oxide would adsorb volatile organic compounds from a gas or liquid state.   The suitable thickness for the silver membranes is between 10 - 50 microns, with 30 microns being the preferred thickness.  The standard thickness for Sterlitech silver membranes is between 30 - 50 microns.

Had your fill of liquids?  You're probably not alone.  According to a new survey by Laboratory Equipment magazine, over 90% of lab researchers use liquid handling equipment, and about 60% are using their equipment either continuously or several times daily.  As for filtration equipment, 52% of respondents are using it - now we just need to get the other 48% on board!!! You can check out the full results over at the Laboratory Equipment site: Liquid Handling Dominates Lab Activities

One of the important characteristics in membrane selection is whether you want a membrane that is Hydrophobic or Hydrophilic. Here we'll define these terms, as well as provide some examples of membrane materials and applications for both types. Hydrophilic literally means “water loving.” Hydrophilic membranes will attract water, and in the process push away other molecules in order to allow water access to the membrane. This keeps contaminants away from the membrane allowing it stay clean and functioning for a longer period of time. Because of this trait hydrophilic membranes are especially well suited for medical applications and biological assays. Hydrophobic on the other hand, literally means “afraid of water.” These membranes will block the passage of water and are commonly used for applications involving separation of water from other materials, such as venting gases.

From time to time we hear from customers that they have "scratched" their silver membranes.  This occasionally leads them to ask: Is there some sort of coating on the membrane that is being rubbed off?

Answer: Our silver membranes are made of 99.97% pure silver and do not have any coating on them.  What may appear to be scratching is actually a polishing of the silver surface, which makes the silver reflective.  This can be done when the membrane is rubbed with a metal object, such as tweezers.  We also posted a brief video demonstrating the effect.  You can watch it here.