Melamine-based covalent organic framework-incorporated thin film nanocomposite membrane for enhanced osmotic power generation

Abstract

A melamine-based covalent organic framework (COF) nanomaterial, Schiff base network-1 (SNW-1), was incorporated into the polyamide layer of a novel thin film nanocomposite (TFN) pressure retarded osmosis (PRO) membrane. The deposition of SNW-1 was made on an open mesh fabric-reinforced polyamide-imide (PAI) support substrate through interfacial polymerization (IP). SNW-1 loading influence on the water permeability and osmotic power density during PRO operation was investigated. The porous and highly hydrophilic SNW-1 nanomaterial facilitated the flow of water molecules across the membranes, while maintaining satisfactory salt rejection ability of the polyamide selective layer. The membranes exhibited significantly enhanced surface hydrophilicity, water permeability, and power density. The mode of incorporation of SNW-1 during IP was also investigated and it was observed that the secondary amine groups of SNW-1 react with the carbonyl groups of 1,3,5-benzenetricarbonyl trichloride, the acyl halide precursor in polyamide formation; thus, SNW-1 was incorporated through the amine precursor, 1,3-phenylenediamine. Testing with 1.0 M NaCl as the draw solution, the TFN membrane with a loading of 0.02 wt% SNW-1 exhibited the highest water flux of 42.5 Lm -2 h -1 and power density of 12.1 Wm -2 , while withstanding hydraulic pressure over 24 bar. This study suggests that COF-incorporation can be a promising method in PRO membrane fabrication to improve both osmotic performance and energy harvesting capability for the PRO process.

Graphene Oxide Incorporated Polysulfone Substrate for Flat Sheet Thin Film Nanocomposite Pressure Retarded Osmosis Membrane

“…Incorporation of hydrophilic nanomaterials into the polymeric membranes (skin layer or/and substrate layer) led to a new generation of TFC membranes called thin film nanocomposite (TFN) membranes. This includes nanomaterials such as modified carbon nanotubes [ 11 , 12 , 13 ], covalent organic framework [ 14 ], zeolites [ 15 , 16 ] and graphene oxide (GO) [ 17 , 18 ]. Due to the enhanced hydrophilicity, structural parameter, water flux and mechanical properties that lowered the ICP phenomenon, an excellent TFC PRO performance was achieved [ 18 ].…”

Nanocomposite Membranes for Liquid and Gas Separations from the Perspective of Nanostructure Dimensions

“…COF can be formed in eclipsed and staggered 3D structures with tunable pores. Although MOFs have been exploited in more separation applications, with more efforts made in increasing the thermal and solvent stability of COFs [ 92 ], this new class of nanostructures has also been progressively used for nanocomposite membrane preparation [ 93 , 94 ]. Polyhedral oligomeric silsesquioxanes (POSS) belong to the group of silsesquioxanes with a general formula (RSiO 1.5 )n, where R is hydrogen or an organic group such as alkyl, aryl, alkylenes and their derivatives [ 95 ].…”

Generation of Osmotic Power from Membrane Technology

“…Covalent organic framework (COF) nanomaterials are one of the best choices for the development of TFN membranes. Gonzales et al synthesized the melaminebased COF nanomaterials, Schiff base network-1 (SNW-1) added TFN membranes for the PRO process [36]. Their study impact shows that after adding SNW-1 nanoparticles while interfacial polymerization to make a thin selective polyamide layer influence the osmotic power density.…”

“…Nanoparticles-based membranes have the capability to provide a high surface area for the application along with to reduce the fouling and concentration polarization [33][34][35]. Metal-organic framework (MOF)-based TFN membranes are also the best choice for to developed TFN membranes producing high power density as studied by Gonzales et al [36]. Carbon nanotubes incorporated TFN membranes show high hydrophilicity along with chemical etching of the active layer gives 1.7 W/m 2 power density by using 0.5 M NaCl solution as draw and deionized water was used as feed solutions, respectively [37].…”

“…Schematic of melamine-based covalent organic framework SNW-1 nanoparticles incorporated TFN membrane for the enhanced osmotic power generation (adapted with permission from[36])…”