Grantee Research Project Results
Final Report: Durable Hydrophobic Membranes with Reduced Fouling for Water Purification Systems
EPA Contract Number: 68HERC21C0038Title: Durable Hydrophobic Membranes with Reduced Fouling for Water Purification Systems
Investigators: Harrison, William L
Small Business: NanoSonic Inc.
EPA Contact: Richards, April
Phase: I
Project Period: March 1, 2021 through August 31, 2021
Project Amount: $100,000
RFA: Small Business Innovation Research (SBIR) - Phase I (2021) RFA Text | Recipients Lists
Research Category: Small Business Innovation Research (SBIR) , SBIR - Water , SBIR - Clean and Safe Water
Description:
A major issue with all membrane-based water purification systems is membrane fouling. Membrane fouling reduces the performance of the water purification system, reduces the quality of the water, and increases maintenance and energy costs. During this US EPA project, NanoSonic demonstrated a spray deposited process for the rapid prototyping and fabrication of durable membranes with improved antifouling characteristics using modifications of our commercial HybridShield® Icephobic (HS-IP) coating. The sprayed HybridShield coating’s hydrophobic nature and morphology creates a surface that retards or prohibits the adhesion and growth of foulants. The HybridShield surface is smooth compared to most original manufactured membranes yielding less surface areas (pores, crevices, etc.) for fouling, yet nanoporous, which allows good water permeability to be achieved. The HS-IP modified membranes were characterized by goniometry, microscopy, spectrophotometry, colorimetry, and water permeability techniques.
Summary/Accomplishments (Outputs/Outcomes):
Four commercial water purification membranes were successfully coated with NanoSonic’s HS-IP variants. Slight compositional modifications were used to enhance adhesion to the polyamide, polysulfone, cellulose acetate and PVDF commercial membranes. Water contact goniometry was used to qualitatively characterize the added hydrophobic active layer. HS-IP modified membranes showed significantly lower fouling to colloidal silica dioxide, a model polysaccharide compound (sodium alginate), and model protein (BSA). The water permeability of the HS-IP modified membranes was comparable or higher than the native uncoated membrane. Two different sized silica dioxide foulants were significantly reduced by the added thin HS-IP coating (<500 nm); HS-IP modified membranes showed up to 2 times higher water flux. The polysaccharide exposure studies showed no change in contact angle or colorimetry experiments, which suggests no adhesive to the modified surface. The BSA showed reduced fouling on HS-IP membranes versus the commercial membranes. Preliminary wastewater solution water flux experiments show promise in HS-IP membranes resistance to fouling.
Conclusions:
NanoSonic’s HS-IP-modified commercial membranes shows significantly improved antifouling characteristics toward colloidal and biological foulants, which will result in reduced replacement, maintenance, and labor costs. The HS-IP spray deposition method should prove to be amenable to current manufacturing processes with no complex equipment.
Polymeric membranes are cost-effective, and provide good selectivity for a wide range of applications. The water treatment membrane market is projected to reach $8.3 billion by 2024, at a CAGR of 9%. The major drivers for the membranes market include increasing population and urbanization, rising awareness about wastewater reuse, and global industrialization. Additionally, the shift from chemical treatment of water to physical treatment methods, increased regulations on water treatment/discharge all points towards higher membrane needs.
NanoSonic’s developmental water purification membrane coating is very promising as a value-added spray deposited engineered coating for several polymer membrane types. The HybridShield Icephobic base polymer is a proprietary polysiloxane copolymer with exceptional hydrophobicity on many non-porous surfaces (e.g., glass, metals) with demonstrated robustness to wear (via taber abrasion experiments). HybridShield® Icephobic is actively sold on our company’s webpage and directly to defense primes. The modified HS-IP coating variants developed during this project shall also be offered through the website and marketed to water purification membrane manufacturers. The deposition may simple enough using commercial grade equipment, to be used by others fabricators or the water system facilities to prepare custom membranes. or other surfaces with tailorable hydrophobicity. HybridShield Icephobic has found applications on wind turbines, drone wings, and other platforms.
The durability of the applied coatings shall be proven during Phase II through monitoring typical wear (abrasion) and cycling (wet-dry) experiments. Complimentary accelerated tests will help project prolonged service life, which results in reduce replacement, maintenance, and man-hour costs. The global water consumption rate is increasing by 100% every twenty years. The rising scarcity for potable water, coupled with the growing population and increasing water demand, are the major concerns which are driving the demand for membrane water and wastewater treatment market across the globe. DuPont (US), Toray (Japan), Hydranautics (US), Koch Separation Solutions (US), and Pentair (UK) are some of the leading players with a substantial market share. Our HS-IP spray deposited engineered coating is complimentary to these membranes with enhanced antifouling behavior.
NanoSonic has demonstrated the ability to successfully develop, market and sell products based on its product lines and other license the technology. Our marketing team has worked to bring our rich history of R&D products to the civil market through several avenues. First, NanoSonic’s Chief Development Officer works with the President and CEO, CTO, and CFO to develop price points for current products, projecting cost breaks for scale-up, and overall financial planning. The team is also responsible for working with the legal team to develop first right of refusal agreements and Alliance Agreements with our partners. Our CEO handles our NDAs. Finally, NanoSonic also has a dedicated ITAR Compliance Officer who submits our ITAR products for Commodity Jurisdictions, assists with self-classification, and submits civil products for EAR99. NanoSonic’s Facilities Security Officer reviews the submissions and maintains separate procedures for our classified work.
The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.