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Effects of Edge Functional Groups on Desalination Performance in Graphene Oxide Membranes

Only 0.78% of the total water on our blue planet can be used in our daily life. Through water treatment, oceans and other saline water, which account for 97.4% of total global water, have the potential to cover this shortage. Membrane-based technology is the currently favored process for desalination, as it consumes low energy, has low operation cost and has great efficiency.

Commercial membranes are currently made of polymers. These membrane channels are hard to control and therefore have low monovalent ion rejection. Furthermore, some of them have a low tolerance for the chlorine used for sterilization and anti-biofouling. Compared with traditional polymer cross-linked membranes, two-dimensional graphene oxide (GO) based membranes have higher chemical and physical stability. GO nanosheets, which act as an important part, can naturally form a well-packed layer-by-layer membrane structure. This kind of unique membrane structure promotes water permeance via low surface friction while maintaining high salt rejection via edge functional groups of GO nanosheets. Hence, the GO membrane has great potential for industrial water treatment applications. GO nanosheet functionalization can greatly improve membrane performance through channel modification. These characteristics are hard to accurately study via experimental methods because of the nanoscale. Therefore, numerical molecular dynamics (MD) simulations are used to zoom into the nanoscale membranes.

Using MD simulation, surface friction of layer-by-layer membrane with various surface oxidation has been widely investigated. Higher surface oxidation has been proved to improve water slip length inside membrane channels. Furthermore, this higher surface attraction can also increase ion adsorption on the surface of channels that additionally increases the ion rejection rate. The edge functionalization on the layer-by-layer GO-based membrane, whose sieving effect has been proposed from experimental works, is rarely studied. It has been reported that edge functional groups have a significant influence on water permeance. Both interaction and geometric effects of edge functional groups were identified with different GO membrane structures. The study of edge functionalization effects is only limited to water transport performance at present. No work about their desalination performance has been reported, although similar researches have been widely studied on single-layer porous GO membranes. In real experiments, however, it’s very hard to prepare membranes with uniform pore size and keep membranes to a single layer structure in atomic thickness. Layer-by-layer membrane structure assembled by functionalized GO nanosheets is much easier. In addition, filtration efficiency can be largely decreased if the pore size is not well-controlled. Therefore, a study of desalination effects of edge functional groups on layer-by-layer GO membrane is still left untouched but necessary to be processed.

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Face Mask Efficacy in the Age of Coronavirus

Face masks and their availability continues to dominate the news as we cope with the expanding spread of coronavirus in most countries around the world. As filtration leaders, we want to provide a short tutorial on the various kinds of face masks that people are using with the intent to protect themselves and/or others.

A basic rule of air filters is that the more effective they are at removing air contaminants, the more resistant to air flow they are. The air filtration industry has long battled the opposing goals of efficacy and air flow, because as a filter becomes more effective, the greater the energy required to move air through it. In a face mask situation, the more effective (resistant) a filter is, the harder it is to breathe – so you can understand the quandary that we have in developing masks that let in breathing air but not viruses.

The primary danger of wearing a mask that doesn’t do what the wearer thinks it is doing is that it provides a false sense of security, and the wearer might take risks he or she wouldn’t otherwise take, putting themselves or others at risk.

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AFS Presents Three Filtration Fundamentals Webinars in April: Intro to Solid/Liquid Separation I and II, and Meltblown/Nanofiber Technologies

The American Filtration and Separations Society is committed to professional education as one of our primary missions. Even when gathering physically is on hold for the foreseeable future, we are forging ahead with online learning for several of our hallmark courses. For filtration professionals among the millions of people working from home, we present these valuable opportunities to expand your knowledge.

During the week of April 20, AFS will present the following courses:

Tuesday, April 21, 8:00 a.m. – 12:00 p.m. central time: Intro to Solids/Liquids I – Principles
Tuesday, April 21, 1:00 – 5:00 p.m. central time: Meltblown and Nanofiber Technologies
Friday, April 24, 8:00 a.m. – 12:00 p.m. central time: Intro to Solids/Liquids II – Equipment, Operation and Testing

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WFC13 Announces New Dates: September 2021

It is with great pleasure that WFC 13 and AFS leadership announce new dates for the 13th World Filtration Congress: September 20-24, 2021 | Hilton Bayfront, San Diego, CA, USA

We thank everyone for their patience as we worked with the Hilton to identify new dates. In these uncertain times, WFC 13 and AFS leadership agreed to confirm dates later in 2021 to hopefully reduce risk of a repeat pandemic. The Hilton Bayfront has implemented a number of updated processes regarding sanitation. As we negotiated with the hotel, we took into consideration our contracted space in case social distancing is still enforced at the time of the Congress. The safety of all WFC 13 participants is our primary concern.

AFS and WFC 13 staff are working with the confirmed WFC 13 speakers and exhibitors to re-confirm their availability. The content that was to be presented last month will be very similar to what will be presented in September, 2021. Speakers will have the opportunity to update abstracts in 2021 with new information and data. WFC 13’s technical program is unmatched.

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Global Filtration Industry Leaders Step Up to Fight Louisiana Outbreak

Two face mask donations are benefiting the community in Lake Charles, LA, in their battle against Covid-19.

Jiangsu Jiulang High-Tech Co., Ltd., a company of the National Engineering Research Center for Special Separation Membrane of Nanjing Tech University (NJTECH) in China has donated 1,500 KN95 respirators to frontline healthcare workers in Lake Charles, LA.  The donation was not just a gift of assets but also a gift of logistics, because a donation of medical supplies requires an FDA Emergency Use Authorization in order to ship the masks – no quick or easy task.

The KN95 masks have the most advanced membrane air filtration technology, which uses a nanofiber 3D spiderweb structure with a pore size of within 0.1 to 0.5 microns. Filtration efficiencies for 0.3 um non-oily particles is over 98%, and is effective for dust, aerosols, bacterial and viruses. The masks meet GB2626-2006 and En 149-2001 standards for PPE use and will be shipped directly to frontline medical facilities.

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AFS Elects Seven to Board of Directors for 2020-2022 Term

The American Filtration and Separations Society (AFS) is pleased to announce the election of seven industry professionals to its Board of Directors. Their terms will begin in September of this year.

Kenneth WinstonKenneth Winston, Consultant in Houston, TX, has been elected 2nd Vice Chair.

Kenneth also serves AFS as President of the Southwest Chapter. A veteran technical and commercial manager in oil, gas, energy and chemical projects, with business development and process engineering degrees and experience, his career has covered three decades in four dozen countries on six continents.

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AFS Learning Center Short Course Webinars Continue in June: Liquid Filtration Testing Basics and Reverse Osmosis System Design

The American Filtration and Separations Society continues to provide world-class filtration educational programming through our new AFS Learning Center. Taught by filtration industry veterans, AFS Short Courses are well known for their high quality and offer .4 CEU credits for each class. AFS members and attendees to any of our 2020 short course webinars will receive a discount.

During the month of June, AFS will present the following courses:

Thursday, June 11, 8:00 a.m. – 12:00 p.m. central time: Liquid Filtration Testing Basics
Thursday, June 18, 8:00 a.m. – 12:00 p.m. central time: Reverse Osmosis System Design

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Guest blog by Kathleen Owen, ASHRAE Fellow, ETF member and Air Pollution Control Engineer for Owen Air Filtration Consulting

Have you been asked how MERV filters catch PM2.5?  Obviously, it’s easy to go to the ASHRAE Standard 52.2 MERV table and see that a MERV 13 filter is ≥ 85% in the 1-3 µm particle diameter size range.  This is often the answer you need.  Still the questions keep coming, including from ASHRAE SSPCs 62.1 and 62.2.  With ISO 16890 providing an ePM and these ASHRAE committees deciding to specify filters using particulate matter efficiencies, it became clear that ASHRAE 52.2 needed to address this issue.

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Using a Gas Liquid Porometer to Reliably Measure Pore Size and Distribution for Filter Media Used in Face Masks

Surgical masks and respirators are typically made of nonwoven polypropylene fabric and mostly consist of three (or more) layers. The first and third layers are generally spunbond, while the middle layer is meltblown. This composition is commonly referred to as SMS technology (Spunbond/Meltblown/Spunbond).

Three layers of respirator fabricThree layers of respirator fabric

While the efficiency of face masks is measured by norms defined by ASTM or NIOSH, producers of nonwoven materials need to have insight into the pore size of their material as well.

This document briefly explains how the pore size distribution of these nonwoven materials can be measured using a gas liquid porometer with the ‘pressure scan’ method.

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Next AFS SW Chapter Meeting: Molecular Separators for Promoting Process Separations in Industrial Applications

The July meeting of the Southwest Chapter of the American Filtration & Separations Society was held Tuesday, July 14. The speaker was Dr. David Engel of NexoSolutions, who presented on Molecular Separators for Promoting Process Separations in Industrial Applications.

There are a number of different methods for enabling process separations. Depending on the technical and economic objectives at each facility, the method selection may differ. Possible avenues or process separations can vary from mechanical devices to thermal means, and also chemically induced. This presentation discusses certain aspects related to the use of “molecular engineering” to promote or enhance the separation process of solids from liquids and liquid from liquids.

Dr. David Engel, NexoSolutions, has more than 20 years of industrial experience in a variety of areas of chemical engineering and chemistry. David is the inventor in 21 United States Invention Patents and author of over 90 technical papers and conferences. He has worked in several capacities for companies such as Eastman Kodak Company, Eli Lilly and General Electric. David has specialized in materials chemistry, process optimization and new technology development. He is the Managing Director of NexoSolutions and Board of Directors at Exion Systems. He holds a B.S. in Industrial Chemistry and a Ph.D. in Organic Chemistry. David is currently a committee member on the AFS Southwest Region, committee member for the GPA Technical Section M and member of the advisory boards of Gas Processing & LNG Magazine, and International Refining and Petrochemical Conference.

Next AFS Webinar: Aspects of Designing Media and Filters for Air Filtration

The American Filtration and Separations Society continues to provide world-class filtration educational programming through our new AFS Learning Center. Taught by filtration industry veterans, AFS Short Courses are well known for their high quality and offer .4 CEU credits for each class. AFS members and attendees to any of our 2020 live webinars will receive a discount.

Our next Short Course is Aspects of Designing Media and Filters for Air Filtration, which will be presented on Thursday, July 30, 8:00 a.m. – 12:00 p.m. central time.

This course gives the basis for a better understanding of air filtration theory when applied to filter media and filters, and how other filter requirements, such as environmental regulations, durability and manufacturability have an impact on filter media design. The theoretical principles and practical knowledge gained during this course will allow the participant to be able to properly design and specify filters and filter media for specific applications.

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Intro to Solid/Liquid Separation I and II Short Course Webinars Open for Registration at the AFS Learning Center

The American Filtration and Separations Society continues to provide world-class filtration educational programming through our new AFS Learning Center. Taught by filtration industry veterans, AFS Short Courses are well known for their high quality and offer .4 CEU credits for each class. AFS members and attendees to any of our 2020 short course webinars will receive a discount.

Introduction to Solid/Liquid Separation I and II are among our most popular courses, and our team of industry experts will deliver this renowned series again in August:

Wednesday, Septmeber 16, 8:00 a.m. – 12:00 p.m. central time: Intro to Solids/Liquids I – Principles | REGISTER HERE
Friday, September 18, 8:00 a.m. – 12:00 p.m. central time: Intro to Solids/Liquids II – Equipment, Operation and Testing | REGISTER HERE

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N95 Mask Material Inventor and AFS Fellow Peter Tsai Exits Retirement to Join Covid-19 Response

Peter Tsai

Long-time AFS member and supporter Peter Tsai has recently received international attention for coming out of retirement to join the battle against Covid-19. As the inventor of the synthetic fabric used to make the N95 mask that is critical in protecting front-line healthcare workers and stemming the spread of coronavirus, Peter started receiving a barrage of requests in mid-March for his knowledge about the nonwoven electrostatically charged material.

With a massive global shortage of the N95 masks, scientists, engineers and clinicians primarily wanted to know: Can the material be sterilized and reused? – and – How can production be scaled up to meet demand? With a willing and curious spirit that has always defined his signature approach, Peter didn’t hesitate to leave the comforts of retirement to help answer these questions. He started working 20 hours a day and even built a lab in his own home to test his ideas.

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Next AFS SW Chapter Meeting: Molecular Separators for Promoting Process Separations in Industrial Applications

The August meeting of the Southwest Chapter of the American Filtration & Separations Society was held Tuesday, August 11, on the topic of Asymmetrical Cake Filtration on Tubular Elements and the Effects on Scalability. Bradley Moakler, North American Regional Manager for DrM Inc., presented.

Proper design of a solid-liquid tubular element filter requires a thorough understanding of all variables within a process. Most small-scale filtration studies are performed with either a downward flow nutsche pressure filter or vacuum filter due to simplicity and overall space and batch requirements. Although this may produce successful results in terms of quality and throughput, several other factors such as cake homogeneity, particle sedimentation, and cake discharge cannot be effectively assessed which can present inaccuracies in sizing and operating a commercial tubular element filter. This presentation examines the inaccuracies that can develop upon scaling to a tubular element filter.

Bradley MoaklerBradley Moakler holds a B.S. in Chemical Engineering from the University of Nevada, Reno. After graduating, he worked as a process engineer for three years in the separations circuit at Molycorp, a rare earth mineral processing mine. He is currently working as North American Regional Manager for DrM Inc., a subsidiary of DrM, Dr. Mueller AG Switzerland, and has been with the company for approximately five years. His work mainly involves sales engineering, process development, and business development.

Join an AFS Committee to Benefit More from Your Membership

When you join AFS, you’ve taken only the first step to realizing value from aligning with the nation’s foremost association for filtration professionals. Members receive discounts on virtual courses and conferences, access to exceptional continuing education and networking opportunities, and free attendance at all AFS chapter meetings. These are all great reasons to join AFS, but people who get the most from their AFS memberships are those who join a committee and start forming long-lasting bonds with other AFS members.

The following active AFS committees and their respective chairs are currently seeking new volunteers:

  • Articles and By-Laws – Chair, Jim Walker
    • Shall ensure that the Articles and By-laws of the Society are consistent with the purpose and needs of the Society.
  • Chapter Affairs – Chair, Wenping Li
    • Shall represent the local chapters at the National Board of Directors meetings and organize, coordinate and implement with the local chapter’s programs to support their activities and growth. The Committee will annually prepare a listing of National Board of Directors members and assign them each to a local chapter closest to their region to reinforce the support of National AFS at a local level.
  • Finance Committee – Chair, Jim Walker
    • Shall recommend financial policies, annually audit the financial transactions, shall arrange for and have conducted an external audit, and shall assist the Treasurer in long-range planning.
  • Marketing and Communications – Chair, Felicia Littlejohn
    • The Marketing and Communications Committee is responsible for content made public by the AFS. In addition, this committee creatively promotes the Society, its conferences and initiatives, promotes AFS to the general public and industry professionals, creates videos, posts to social media, and conducts interviews and surveys to collect feedback from current and potential members.
  • Membership – Chair, John Hancock
    • Shall conduct programs directed toward recruiting new individual members and effectuating membership renewal. The Committee shall also recruit and support active participation by leading companies in the field of filtration and separations.  This committee shall act as the interface between the Corporate Sponsors and the Society.
  • Publications – Chair, Bharath Raghavan
    • Shall maintain and update the master calendar, shall publish a newsletter containing, among other subjects, Chapter and industry information, and shall seek a new journal partnership.
  • Users Committee – Chair, Andrew Goodby
    • Shall encourage the participation of filtration and separations end users in Society functions and advise the AFS Board of Directors in developing programs to increase the activity and membership of vendors and end-users. This Committee shall also conduct and annual New Product/Engineering Merit competition and recognition program for Corporate Sponsors of the Society.  This Committee shall also administer the AFS “Uncle” program for the local chapters to present papers, market AFS and recruit new members for the Chapters and Society.

To volunteer for a committee, please email Lyn Sholl, Executive Director