Encapsulated hybrid deep eutectic solvents to overcome high viscosity barrier for NH3 capture and established mass transfer resistance model

Although deep eutectic solvents (DESs) are green ammonia capture solvents with simple synthesis and easy availability of raw materials, their absorption rate is limited due to inherent high viscosity barrier. Herein, a high-viscosity hybrid DES (choline chloride/resorcinol/glycerol = 1:3:5, CRG) was encapsulated in a highly permeable shell of polydimethylsiloxane (PDMS) by microfluidics. The absorption capacity and absorption rate of the 550 μm Microcapsule were found to be 1.45 and 6.01 times higher than that of unpacked CRG respectively for the increased mass transfer area of CRG. Additionally, the 550 μm Microcapsule maintained 93 % of its initial maximum absorption capacity after 8 cycles. Moreover, a model of mass transfer resistance 1 / k μ based on chemical potential into the ammonia absorption rate formula was established. Then 1 / k μ related to the sizes of microcapsules was proposed based on the observation that there is a certain linear relationship between d m NH 3 / d t and l n ( x NH 3 , e / x NH 3 , t ) , based on which, mass transfer enhancement mechanism was analyzed. This study is the first to extend the concept of microencapsulation to the field of ammonia capture, which has a certain guiding role for other gases capture research.