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New materials may vacuum up CO2, culprit in global warming

March 30, 2005
Courtesy 
and World Science staff

Sci­en­tists say they have found an im­proved way to re­move car­bon diox­ide—the chief gas blamed for glob­al warm­ing—from sources such as smokestacks, tailpipes and even the air around us.

Car­bon di­ox­ide is gen­er­at­ed in many in­dus­t­ri­al pro­cesses, as well as dur­ing com­mon ac­ti­vi­ties such as driv­ing and burn­ing things. But now re­search­ers say a grow­ing glut of car­bon di­ox­ide in the air may be kill­ing us by caus­ing glob­al warm­ing, be­cause car­bon di­ox­ide traps heat.

In the new re­search, though, sci­en­tists are re­port­ing the ex­ist­ence of ma­te­ri­als that achieve some of the high­est car­bon di­ox­ide re­mov­al ca­pa­ci­ties ev­er re­ported for real-world, hu­mid-a­ir con­di­tions. G. K. Surya Prakash of the Un­ivers­ity of South­ern Cal­i­for­nia, who worked with col­leagues in­clud­ing chem­is­try No­bel Lau­re­ate George A. Olah, re­port the find­ings in the Jour­nal of the Amer­i­can Chem­i­cal So­ci­e­ty.

Ex­ist­ing meth­ods for re­mov­ing car­bon di­ox­ide from smokestacks and oth­er sources, in­clud­ing the at­mos­phere, are energy-intensive, don’t work well and have oth­er draw­backs, the group said. In an ef­fort to over­come such ob­sta­cles, they turned to sol­id ma­te­ri­als based on polyethylen­imine, a readily avail­a­ble and in­ex­pen­sive pol­y­mer­ic ma­te­ri­al. A pol­y­mer­ic ma­te­ri­al is one whose mo­le­cules are made up of many re­peat­ing sub­units, a struc­ture char­ac­ter­is­tic of many plas­tics and bi­o­log­i­cal tis­sues.

Tests by the group showed the polyethylen­imine-based ma­te­ri­als achieved some of the high­est car­bon di­ox­ide re­mov­al rates ev­er re­ported for hu­mid air, un­der con­di­tions that sty­mie oth­er re­lat­ed ma­te­ri­als, they said. Af­ter cap­tur­ing car­bon di­ox­ide, they added, the ma­te­ri­als give it up easily so that the the gas can be used in mak­ing oth­er sub­stances. Or, it can be per­ma­nently locked away. The cap­tur­ing ma­te­ri­al can be re­cy­cled and re­used many times.

The group sug­gests the ma­te­ri­als may be use­ful in smokestacks, on sub­marines or in the open at­mos­phere. There, they could clean up car­bon di­ox­ide pol­lu­tion that comes from small sources like cars or home heaters, rep­re­sent­ing about half of the to­tal car­bon di­ox­ide emis­sions re­lat­ed to hu­man ac­ti­vity.

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Scientists say they have found an improved way to remove carbon dioxide—the chief gas blamed for global warming—from sources such as smokestacks, tailpipes and even the air around us. Carbon dioxide is generated in many industrial processes, as well as during common activities such as driving and burning things. But now researchers say a growing glut of carbon dioxide in the air may be killing us by causing global warming, because carbon dioxide traps heat. In the new research, though, scientists are reporting the existence of materials that achieve some of the highest carbon dioxide removal capacities ever reported for real-world, humid-air conditions. G. K. Surya Prakash of the University of Southern California, who worked with colleagues including chemistry Nobel Laureate George A. Olah, report the findings in the Journal of the American Chemical Society. Existing methods for removing carbon dioxide from smokestacks and other sources, including the atmosphere, are energy-intensive, don’t work well and have other drawbacks, the group said. In an effort to overcome such obstacles, they turned to solid materials based on polyethylenimine, a readily available and inexpensive polymeric material. A polymeric material is one whose molecules are made up of many repeating subunits, a structure characteristic of many plastics and biological tissues. Tests by the group showed the polyethylenimine-based materials achieved some of the highest carbon dioxide removal rates ever reported for humid air, under conditions that stymie other related materials, they said. After capturing carbon dioxide, they added, the materials give it up easily so that the the gas can be used in making other substances, or permanently locked away; the capturing material can be recycled and reused many times. The group suggests the materials may be useful in smokestacks, on submarines or in the open atmosphere. There, they could clean up carbon dioxide pollution that comes from small point sources like cars or home heaters, representing about half of the total carbon dioxide emissions related to human activity.