Ethanolamine Purification by Nanofiltration through PIM-1 and Carbon Membranes: A Molecular Simulation Study

Economical purification of high-value chemicals after biomass conversion is highly desirable. Herein, we report a molecular simulation study to investigate ethanolamine (ETA) purification from its mixture with water and ammonia by nanofiltration. Two different classes of membranes are considered including a polymer of intrinsic microporosity (PIM-1) and two activated carbons, namely, curved corannulene (CRNL) and functionalized CRNL with OH (CRNL-(OH)2). Water flux and permeability through the membranes are found to decrease in the order CRNL-(OH)2 > PIM-1 > CRNL. As attributed to its hydrophilic nature, CRNL-(OH)2 exhibits the highest flux and permeability. Ammonia is also observed to permeate through the three membranes. Nevertheless, 100% ETA retention is achieved by CRNL-(OH)2, indicating the suitability of CRNL-(OH)2 for optimal ETA purification. Due to strong affinity, water near CRNL-(OH)2 exhibits a substantially longer residence time than near PIM-1 and CRNL. Furthermore, the lifetime of hydrogen bonds for water in the membranes follows the reverse trend of water flux. The simulation study provides microscopic insights into the dynamic and structural properties of water, ETA, as well as ammonia in the three membranes, and suggests that CNRL-(OH)2 might be an interesting candidate for ETA purification.