Carbon nanotube-immobilized super-absorbent membrane for harvesting water from the atmosphere

Abstract

This paper describes the development of a carbon nanotube (CNT)-immobilized membrane for harvesting pure water from air. The CNTs were incorporated into a layer of super-absorbing poly(acrylamide-co-acrylic acid) which was cast over a porous hydrophilized polypropylene support. The super-absorbing polymer tended to bind to the water molecules to form water clusters. The incorporation of CNTs led to the interruption of specific water–polymer as well as water–water interactions to generate more free water which permeated more easily through the membrane. The CNTs were functionalized with carboxylic groups to improve the dispersibility into the polymer matrix. The water vapor extraction efficiency reached over 50%, and the presence of CNTs led to an enhancement in water vapor removal by as much as 45% and in the mass transfer coefficient by 44%.