NEWS RELEASE February 2020
FILTXPO Shows How Filter Media Has Important Uses Beyond Particle Capture
FILTXPO will be held in Chicago February 25-28. It is going to be an entirely different experience than the previous conferences. INDA has taken the position that it can help its non-woven media members best by providing knowledge about the solutions and help them become proactive in developing new solutions. INDA has acquired Filtration News who provides insights on solutions. It has expanded the exposition to cover solutions in a number of areas. McIlvaine Company is writing monthly “true cost” feature articles for Filtration News which assess lowest total cost of ownership based on the filter impact on the total solution.
The total solution can be more than just particle capture. Filter media is utilized for absorption, adsorption, catalysis, and even killing of viruses.
Coronavirus: The use of ultraviolet light to kill viruses is a function of contact time. A HEPA filter can provide the residence time. Ultraviolet light applied to the filter media then kills the viruses. Attendees will be keenly aware of the virus challenges since none of the Chinese exhibitors will be in attendance due to the coronavirus. Many of the INDA members are challenged by large demand for face masks. There will be accelerated development of N 95 masks using copper oxide or other biocidal agents as well as design developments for reducing cost, increasing efficiency, and making them more user friendly.
There will be the need to adopt cleanroom technology in an emergency. If the cruise ship which allowed 300 people to become positive for coronavirus had been operated as a pharmaceutical cleanroom, the number of infections could have been reduced.
Catalysis: Filter media is being impregnated with metal particles which have a catalytic effect in converting VOCs and NOx. Instead of two big vessels in an air pollution control system it can be reduced to just one.
Adsorption: Combining filtration and adsorption has become routine with activated carbon layers in filter media. This capability is being exploited for household odors and water purification. By injecting activated carbon ahead of a fabric filter in an air pollution control system mercury and VOCs can be captured.
Absorption: The catalytic filter can be preceded by injection of sodium or calcium compounds in the gas stream. This means one vessel is used instead of three to remove acid gases, NOx, and particulate. By using ceramic filtration elements gas can be cleaned at 850F and the heat recaptured. This has a net effect of reducing CO2 and reducing operational cost.
The biggest near-term opportunity for filter media companies involves the so-called dry scrubber. Spray driers using lime slurry or circulating loops using powdered lime are situated ahead of a fabric filter. The filter cake acts to complete the absorption. Even though a large percentage of fabric filters are now expected to remove both acid gases and particulate, they are still designed for what can be described as LIFO vs FIFO operation. They need to be redesigned so that the first lime forming the cake reacts and is pulsed away making room for fresh lime.
Biopharmaceuticals offer a big opportunity for filter media companies to innovate. FILTXPO has several sessions on this subject. This includes a paper on membrane chromatography using non-woven media with lots of potential advantages as explained in the abstract below.
High Productivity Nonwoven Membrane Adsorbers For Biological Product Capture
Ruben Carbonell, Ph.D.
Chief Technology Officer - NIIMBL and Professor of Chemical and Biomolecular Engineering, North Carolina State University
Packed bed chromatography is by far the most common technique used for high resolution separations of proteins. Membrane chromatography is a relatively new technique developed for the purpose of operating at higher flow rates and at reduced process times relative to resin-based column chromatography. Higher flow rates are possible with membranes because the resulting pressure drops are significantly lower than in resin columns, and dynamic binding capacities do not decrease significantly with shorter residence times because of the lack of diffusional resistance to product capture on the membrane surface. In addition, membrane adsorbers are generally single-use devices that eliminate the difficulties and costs often associated with packing a chromatographic column, and the cleaning and validation steps required of multi-use columns.
One significant drawback associated with the use of membrane adsorbers in a capture mode is that their dynamic binding capacities are generally lower than those of column chromatography resins. As a result, the industrial application of membrane adsorbers has been largely limited to flow-through polishing applications in which low concentration impurities bind to the membrane media, while product flows through. Indeed, with the development of novel membrane materials with higher binding capacities the use of membrane adsorbers for product capture is of increasing interest.
To this end, our laboratory has developed strong and weak anion and cation exchange membranes based on poly(butylene) terephthalate (PBT) nonwoven fabrics grafted with glycidyl methacrylate (GMA). The presence of the glycidyl methacrylate layer allows functionalization with cation and anion exchange groups that have dynamic binding capacities (DBCs) at very short residence times (0.1 – 0.5 minutes) that are similar to the DBCs obtained in some of the best available ion exchange chromatography resins at longer residence times. Consequently, these nonwoven membranes have a considerably larger productivity than their resin counterparts. The relatively inexpensive nonwoven membrane materials enable single-use disposable operation, and the membranes can produce high yields (>97%) and purities (>96%) of IgG from CHO cell culture. The availability of such devices could have a significant impact on current bioprocess operations by providing an alternative single-use disposable product capture step with a significantly higher productivity than resin packed column chromatography.