ultrafiltration

Unfortunately, Koch has discontinued the ultrafiltration membrane HFM-100. The HFM-180 is a viable alternative to the 100 and 116, it is PVDF with a separation range of 100,000. The good news is we will be adding 4 new membranes in the next couple of weeks.

Compare the specifications for all of our UF membrane designations here.

We have to say goodbye to one of our less-popular Ultrafiltration flat sheet membrane designations today, as HFM-116 has been discontinued by Koch Membrane Systems. This UF designation is (was) most often used for clarification and concentration of fluids. For our past HFM-116 customers and others looking for a UF membrane to meet these needs, we recommend you take a look at the HFM-100 designation instead. The HFM-100 is also made from PVDF and has the same 50,000 Molecular Weight Cut-Off value as HFM-116.

Compare the specifications for all of our UF membrane designations here.

A recently completed test in Poland found that enhancing ultrafiltration (UF) flat sheet membranes with an anionic polymer increased the membrane’s ability to purify samples of galvanized wastewater. For this experiment, the researchers tested multiple concentrations of wastewater infused with zinc, nickel, and copper ions against EW and MW designation flat sheet membranes that were infused with a polyelectrolyte, in this case polysodium 4-styrenesulfonate (PSSS) with cation-exchange properties. The result was a more-efficient metal binding agent, enabling 97-99% retention of the target metals.

The EW membrane is made with Polysulfone while the MW is a modified Polyacrylonitrile known as Ultrafilic. Both designations ably treated the galvanized wastewater, but the MW membrane did have 2-3 times higher permeate flux values due to the membrane’s higher permeability.

In addition to membrane separation, common treatment options for galvanized wastewater include chemical processing and the ion exchange method. Unlike these other methods however, an effective membrane separation methodology has the potential to remove higher concentrations of effluent in a continuous process so these findings could impact how galvanic wastewater is processed in the future.

You can read the published paper here.

We’re sorry to say that we have just been informed that one of our ultrafiltration (UF) range flat sheet membrane designations, SelRO MPF-U20-S, has been discontinued. This means that we will no longer be able to offer our catalog numbers YMMPFU20S1818, YMMPFU20S195, YMMPFU20S475, or YMMPFU20S425. The SelRO MPF-U20-S designation was made from a proprietary Koch Membrane Systems polymer and used for a variety of research and industrial applications.

While this particular designation will be missed, we still have several other UF designations for sale that can meet your separation needs. To determine which designation is best for you, check out the Sterlitech UF specifications table.

Also, we have a very limited stock of these items still available so get in touch with us immediately if you are interested in your last chance to secure this membrane!

One of the most promising new frontiers in filtration technology involves infusing different membrane types with nanomaterials in order to improve performance or to pass along certain material attributes. Here we will look into one prominent example from recent years, the incorporation of carbon nanotubes (CNTs) into ultrafiltration membranes used in water treatment. We’ll also look at how our stirred cells have aided in this specialized membrane manufacturing process.

First off, what is there to gain by using CNT’s to manufacture water treatment membranes? While scientists have identified several potential advantages for CNT implementation, since the process is still in the R&D phase they have not necessarily been proven in all cases. One key possible benefit is that membranes made with these materials would be much stronger than traditional membranes, thus reducing instances of membrane breakage and fouling, two problems that contribute significantly to high maintenance costs in water treatment. Another unique advantage is that CNTs have antibacterial properties that may reduce biofilm formation and therefore prevent or limit biofouling. Lastly, the process of manufacturing ultrafiltration membranes with CNTs allows the producer to chemically modify the membrane surface which can further reduce fouling by tailoring the membrane for specific organic solutes.

As with standard membrane manufacturing processes, the stirred cell is an ideal piece of equipment for establishing the permeability of the test membranes. For this particular study on the effectiveness of polysulfone ultrafiltration membranes manufactured with CNTs, the cell (an HP4750 in this case) was set to perform dead-end filtration with ultrapure water at 38 bars of pressure (about 551 psi).

The HP4750 Stirred Cell

In order to determine permeability, the HP4750 was directly connected to the pressure regulator of the compressed air tank. Each membrane was compacted at 38 bars until the flow rate was stable (minimum of 30 minutes). Then the flow rate was measured by weighing the permeate as a function of the pressure applied (between 5 and 35 bars). To confirm the results, this test was performed in triplicate.

Permeability is an important test characteristic for determining the membrane’s susceptibility to fouling and its overall efficiency. In the study cited here, researchers found no statistically significant difference in permeability between CNT and non-CNT amended membranes. These findings supported their conclusion that their process for grafting CNTs onto membranes was ineffective. In the conclusion the authors note that because the CNTs only partially dispersed in the host material that they were prevented from taking on the mechanical properties of the CNTs.

While this particular study did not yield the desired results, new methods of integrating nanomaterials onto membranes are constantly being explored and hopefully it’s only a matter of time until these superior membranes become available.

Visit here to read the full study:
http://cohesion.rice.edu/engineering/pedroalvarez/emplibrary/85.pdf