Superior polyethylene based total heat exchange membranes made from sealing polyamide separating layers with in situ grown ZIF-8 particles

ZIF-8 particles (PTs) were effectively in situ grown from a cross substrate counter diffusion (CSCD) process to enhance the performance of polyamide (PA)/polyethylene(PE) based total heat exchange membranes (THEMs). They could effectively block CO 2 leakages by sealing the defects in polyamide layers, and also provide selective water vapor permeating channels and surface area to enhance energy recovery efficiencies. Total heat recovery efficiency reached 82% with a very low CO 2 permeance of 1.15 GPU. A cross substrate counter diffusion (CSCD) process between the solutions of Zn(II) solution and 2-methyl imidazole (2-MIM)-ammonia solution (pH = 10) to in situ grow ZIF-8 particles was developed to enhance the performance of polyamide (PA)/polyethylene(PE) based thin film composite (TFC) total heat exchange membranes (THEMs). In situ grown ZIF particles from CSCD processes had effectively blocked CO 2 leakages across the PA separating layer by sealing the defect points, and provided selective water vapor permeating channels and surface area to enhance energy recovery efficiencies. The effects of Zn(II) loading concentration, CSCD reaction time and ligand type on the structure, CO 2 barrier property and heat exchange efficiencies were systematically investigated. Under optimized conditions, sealing with ZIF-8 particles could decrease the CO 2 permeance from 7.5 GPU to 1.15 GPU, at the same time, increase the sensible heat, latent heat and heat exchange efficiencies from 80 %, 53 %, 68 % to 96 %, 73 % and 82 % respectively.