Porous silicate cement membrane: Unraveling the effect of triethanolamine on ice crystal changing, pore structure, and performance

Abstract

Triethanolamine (TEA) has been broadly used as the organic amine conditioning agent to modify the workability of cement-based materials. However, the effect of TEA on the structure and property of porous silicate cement membranes has not been reported. In this paper, TEA was applied to study its effect on parameters of porous silicate cement membranes based on the preparation method combining freeze casting and heat-dry curing, because it is easy to form complexes with cement particles. The effect and acting mechanism of TEA on porous silicate cement membranes were researched using a series of characterizations and molecular dynamics (MD) simulation. Results showed that TEA significantly improved the performance of porous silicate cement membranes. The addition of TEA changed the pore morphology of porous silicate cement membranes from lamellar structures to cellular structures, with mesoporous size distribution focusing on 2.5–4.5 nm at TEA doping ratio of 0.16 wt%. The oil-water separation performance could reach up to 99.6 %. Through comprehensive comparison, the porous silicate cement membrane with 1.0 wt% TEA showed better holistic preponderance of oil-water separation and permeation flux. Quantum chemistry calculation and MD simulation were used to briefly explain the influence of TEA on phase transformation. MD showed that adding TEA changed the morphology and structure of ice crystals. The percentage of the Ih structure significantly increased from 53 % to 86 % after adding TEA. This study might expand the application of TEA in other aspects and enlighten relevant workers in new experimental designs.