Can common liquid polymers and surfactants capture CO2?

Search for effective, inexpensive, benign, and recyclable liquid media for CO2 capture and sequestration has attained utmost importance in recent times. Common and popular liquid surfactants and polymers are explored for their CO2 absorption and retention under ambient conditions. Specifically, three Tween (Tween 20, Tween 40, Tween 80), two Triton (TX-100, TX-114), and one Pluronic (P84) series liquid surfactants, and three poly(ethyleneglycol) (PEG200, PEG400, PEG600) and two poly(ethyleneimine) (PEI800, PEI25000) family liquid polymers are found to absorb appreciable amount of CO2 in the presence of superbase. The reaction of electron-rich centers of hydroxyl/amine functionality of the liquid surfactant/polymer with electron-deficient center of CO2 is facilitated by the superbase. 1,5-diazabicydo[4.3.0]-non-5-ene (DBN) superbase is found to afford more effective absorption of CO2 within the liquid surfactants/polymers investigated as compared to 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) and 1,5,7-triazabicydo[4.4.0]-dec-5-ene (TBD). Except for PEGs, the efficiency of CO2 absorption is directly correlated to the number of moles of hydroxyl/amine groups present; inter-PEG H-bonding in PEG200 having relatively smaller polymer chain results in partial unavailability of hydroxyl groups to interact with added CO2. Presence of water within the liquid surfactant/polymer renders the CO2 uptake by the media faster due to decreased viscosity, the efficiency of CO2 absorption is decreased due to favorable back reaction and H-bonding between added water and hydroxyl of surfactant/polymer. The superbase-added liquid surfactants/polymers exhibit excellent CO2 absorption expulsion reversibility with alternate CO2-N-2 addition. Recovery of absorbed CO2 by heating the superbase-added liquid surfactant/polymer to 60 degrees C is ca. 45% by weight, which increases to ca. 75% by weight when the temperature is increased to 100 degrees C. Inexpensive, benign, and readily-available common and popular liquid surfactants/polymers are shown to have potential for effective and easy storage and release of CO2. (C) 2018 Elsevier B.V. All rights reserved.