Polymide Membrane

Dehumidifiers with enhanced polyimide membranes (white disc) will probably be vitality environment friendly with a smaller carbon footprint. Credit score: Dharmesh Patel/Texas A&M Engineering

Texas A&M researchers have enhanced the dehumidification effectivity of a polymer that might assist develop extra energy-efficient techniques with a smaller carbon footprint.

On sultry summer season afternoons, heating, air flow, and air con (HVAC) techniques present much-needed aid from the cruel warmth and humidity. These techniques, which regularly include dehumidifiers, are at the moment not vitality environment friendly, guzzling round 76% of the electrical energy in business and residential buildings.

In a brand new examine, Texas A&M College researchers have described an natural materials, referred to as polyimides, that makes use of much less vitality to dry air. Moreover, the researchers stated polyimide-based dehumidifiers can carry down the worth of HVAC techniques, which at the moment value hundreds of {dollars}.

“On this examine, we took an current and quite sturdy polymer after which improved its dehumidification effectivity,” stated Hae-Kwon Jeong, McFerrin Professor within the Artie McFerrin Division of Chemical Engineering. “These polymer-based membranes, we expect, will assist develop the following technology of HVAC and dehumidifier applied sciences that aren’t simply extra environment friendly than present techniques but additionally have a smaller carbon footprint.”

The outcomes of the examine are described within the Journal of Membrane Science.

Dehumidifiers take away moisture from the air to a cushty degree of dryness, thereby enhancing air high quality and eliminating mud mites, amongst different helpful capabilities. Essentially the most generally out there dehumidifiers use refrigerants. These chemical compounds dehumidify by cooling the air and lowering its potential to hold water. Nonetheless, regardless of their reputation, refrigerants are a supply of greenhouse gases, a serious offender for international warming.

Instead materials for dehumidification, naturally occurring supplies often known as zeolites have been extensively thought of for his or her drying motion. In contrast to refrigerants, zeolites are desiccants that may take up moisture inside their water-attractive or hydrophilic pores. Though these inorganic supplies are inexperienced and have glorious dehumidification properties, zeolite-based dehumidifiers pose challenges of their very own.

“Scaling up is a giant drawback with zeolite membranes,” Jeong stated. “First, zeolites are costly to synthesize. One other concern comes from the mechanical properties of zeolites. They’re weak and wish actually good supporting buildings, that are fairly costly, driving up the general value.”

Jeong and his group turned to an economical natural materials referred to as polyimides which might be well-known for his or her excessive rigidity and tolerance for warmth and chemical compounds. On the molecular degree, the fundamental unit of those high-performance polymers are repeating, ring-shaped imide teams linked collectively in lengthy chains. Jeong stated the engaging forces between the imides offers the polymer its attribute power and thus a bonus over mechanically weak zeolites. However the dehumidification properties of the polyimide materials wanted enhancement.

The researchers first created a movie by fastidiously making use of polyimide molecules on a number of nanometers-wide alumina platforms. Subsequent, they put this movie in a extremely concentrated sodium hydroxide resolution, triggering a chemical course of referred to as hydrolysis. The response prompted the imide molecular teams to interrupt and develop into hydrophilic. When seen below a high-powered microscope, the researchers uncovered that the hydrolysis reactions result in the formation of water-attractive percolation channels or highways inside the polyimide materials.

When Jeong’s group examined their enhanced materials for dehumidification, they discovered that their polyimide membrane was very permeable to water molecules. In different phrases, the membrane was able to extracting extra moisture from the air by trapping them within the percolation channels. The researchers famous that these membranes may very well be operated repeatedly with out the necessity for regeneration for the reason that trapped water molecules depart from the opposite facet by a vacuum pump that’s put in inside a typical dehumidifier.

Jeong stated his group fastidiously designed their experiments to partial hydrolysis whereby a managed variety of imide teams develop into hydrophilic.

“The power of polyimides comes from their intermolecular forces between their chains,” Jeong stated. “If too many imides are hydrolyzed, then we’re left with weak materials. Then again, if the hydrolysis is just too low, the fabric received’t be efficient at dehumidification.”

Though polyimide membranes have proven nice promise of their potential use in dehumidification, Jeong stated their efficiency nonetheless lags behind zeolite membranes.

“This can be a new strategy to enhance the property of a polymer for dehumidification and much more optimizations have to be achieved with a purpose to additional improve the efficiency of this membrane,” Jeong stated. “However one other key issue for engineering purposes is it must be low cost, particularly if you need the expertise to be fairly inexpensive for householders. We’re not there but however are definitely taking strides in that route.”

Reference: “Enhancing air-dehumidification efficiency of polyimide membranes by producing hydrophilic Poly(amic acid) domains utilizing partial hydrolysis” by Sunghwan Park and Hae-Kwon Jeong, 28 December 2020, Journal of Membrane Science.
DOI: 10.1016/j.memsci.2020.119006

Sunghwan Park within the chemical engineering division additionally contributed to this examine.

This analysis is funded by the Nationwide Science Basis and the Qatar Nationwide Analysis Fund.

By Rana

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