Featured Research

from universities, journals, and other organizations

Molecular 'sieves' harness ultraviolet irradiation for greener power generation

Date:
June 12, 2013
Source:
University of Cambridge
Summary:
New research shows that exposing polymer molecular sieve membranes to ultraviolet (UV) irradiation in the presence of oxygen produces highly permeable and selective membranes for more efficient molecular-level separation, an essential process in everything from water purification to controlling gas emissions.

Image shows fluorescence of solution (left) and membrane (right) made of a polymer of intrinsic microporosity (PIM-1) under irradiation of ultraviolet (UV) light. The ultraviolet irradiation induces oxidation and surface densification of the polymeric molecular sieve membranes.
Credit: Nature Publishing Group.

New research shows that exposing polymer molecular sieve membranes to ultraviolet (UV) irradiation in the presence of oxygen produces highly permeable and selective membranes for more efficient molecular-level separation, an essential process in everything from water purification to controlling gas emissions.

Published in the journal Nature Communications, the study finds that short-wavelength UV exposure of the sponge-like polymer membranes in the presence of oxygen allows the formation of ozone within the polymer matrix. The ozone induces oxidation of the polymer and chops longer polymer chains into much shorter segments, increasing the density of its surface.

By controlling this 'densification', resulting in smaller cavities on the membrane surface, scientists have found they are able to create a greatly enhanced 'sieve' for molecular-level separation -- as these 'micro-cavities' improve the ability of the membrane to selectively separate, to a significant degree, molecules with various sizes , remaining highly permeable for small molecules while effectively blocking larger ones.

The research from the University of Cambridge's Cavendish Laboratory partly mirrors nature, as our planet's ozone layer is created from oxygen hit by ultraviolet light irradiated from the sun.

Researchers have now demonstrated that the 'selectivity' of these newly modified membranes could be enhanced to a remarkable level for practical applications, with the permeability potentially increasing between anywhere from a hundred to a thousand times greater than the current commercially-used polymer membranes.

Scientists believe such research is an important step towards more energy efficient and environmentally friendly gas-separation applications in major global energy processes -- ranging from purification of natural gases and hydrogen for sustainable energy production, the production of enriched oxygen from air for cleaner combustion of fossil fuels and more-efficient power generation, and the capture of carbon dioxide and other harmful greenhouse gases.

"Our discoveries lead to better understandings of physics of the novel materials, so we will be able to develop better membranes in the future" said Qilei Song, a researcher in Dr Easan Sivaniah's group and the paper's lead author.

In collaboration with groups at the Department of Materials Science and Metallurgy (Professor Tony Cheetham), University of Cambridge, and at the Chemical Engineering department of Qatar University (Prof. Shaheen Al-Muhtaseb), the researchers confirmed that the size and distribution of free volume accessible to gas molecules within these porous polymeric molecular sieves could be tuned by controlling the kinetics of the ultraviolet light-driven reactions.

Conventional separation technologies, such as cryogenic distillation and amine absorption, are significantly energy-intensive processes. Membrane separation technology is highly attractive to industry, as it has the potential to replace conventional technologies with higher energy efficiency and lower environmental impacts.

But gas separation performance of current commercially-available polymer membranes are subject to what scientists describe as "a poor trade-off" between low permeability levels and high degree of selective molecular separation. The next generation membranes -- such as polymers of intrinsic microporosity (PIMs) -- being studied at the Cavendish are based on tuning the pore size and interaction with specific molecules to achieve both high permeability and, critically, high selectivity.

Currently, these flat-sheet membranes show great separation performance and are mechanically robust for clean cylinder gases. "We are working on ways to further improve these membranes and our next step is to develop large scale and more practical industrial modules such as thin film composite membranes or hollow fibers with selective layer as thin as possible," said Dr Easan Sivaniah.

"We are also exploring many other applications of these fascinating polymer materials, such as liquid and vapour separation, water treatment by desalination, sensor devices and photolithography technology, and energy storage applications."


Story Source:

The above story is based on materials provided by University of Cambridge. The original story is licensed under a Creative Commons Licence. Note: Materials may be edited for content and length.


Journal Reference:

  1. Qilei Song, Shuai Cao, Paul Zavala-Rivera, Li Ping Lu, Wei Li, Yan Ji, Shaheen A. Al-Muhtaseb, Anthony K. Cheetham, and Easan Sivaniah. Photo-oxidative enhancement of polymeric molecular sieve membranes. Nature Communications, 2013 DOI: 10.1038/ncomms2942

Cite This Page:

University of Cambridge. "Molecular 'sieves' harness ultraviolet irradiation for greener power generation." ScienceDaily. ScienceDaily, 12 June 2013. <www.sciencedaily.com/releases/2013/06/130612093641.htm>.
University of Cambridge. (2013, June 12). Molecular 'sieves' harness ultraviolet irradiation for greener power generation. ScienceDaily. Retrieved August 27, 2014 from www.sciencedaily.com/releases/2013/06/130612093641.htm
University of Cambridge. "Molecular 'sieves' harness ultraviolet irradiation for greener power generation." ScienceDaily. www.sciencedaily.com/releases/2013/06/130612093641.htm (accessed August 27, 2014).

Share This




More Matter & Energy News

Wednesday, August 27, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Australian Airlines Relax Phone Ban Too

Australian Airlines Relax Phone Ban Too

Reuters - Business Video Online (Aug. 26, 2014) Qantas and Virgin say passengers can use their smartphones and tablets throughout flights after a regulator relaxed a ban on electronic devices during take-off and landing. As Hayley Platt reports the move comes as the two domestic rivals are expected to post annual net losses later this week. Video provided by Reuters
Powered by NewsLook.com
Hurricane Marie Brings Big Waves to California Coast

Hurricane Marie Brings Big Waves to California Coast

Reuters - US Online Video (Aug. 26, 2014) Huge waves generated by Hurricane Marie hit the Southern California coast. Rough Cut (no reporter narration). Video provided by Reuters
Powered by NewsLook.com
Chinese Researchers Might Be Creating Supersonic Submarine

Chinese Researchers Might Be Creating Supersonic Submarine

Newsy (Aug. 26, 2014) Chinese researchers have expanded on Cold War-era tech and are closer to building a submarine that could reach the speed of sound. Video provided by Newsy
Powered by NewsLook.com
Breakingviews: India Coal Strained by Supreme Court Ruling

Breakingviews: India Coal Strained by Supreme Court Ruling

Reuters - Business Video Online (Aug. 26, 2014) An acute coal shortage is likely to be aggravated as India's supreme court declared government coal allocations illegal, says Breakingviews' Peter Thal Larsen. Video provided by Reuters
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins