Improvement of thin-film nanocomposite (TFN) membrane performance by CAU-1 with low charge and small size

Thermally stable thin film composite polymeric membranes for water treatment: A review

MXenes and other 2D nanosheets for modification of polyamide thin film nanocomposite membranes for desalination

Removal of polar organic micropollutants by mixed-matrix reverse osmosis membranes

The membrane technology is still considered a costly method to produce potable water. In view of this, RO membrane with enhanced water permeability without trade-off in salt rejection is desirable as it could further reduce the cost for water desalination. In this study, thin film nanocomposite (TFN) membranes containing 0.05 or 0.10 w/v% hydrophilic nanofillers in polyamide layer were synthesized via interfacial polymerization of piperazine and trimesoyl chloride monomers. The resultant TFN membranes were characterized and compared with a control thin film composite (TFC) membrane. Results from the filtration experiments showed that TFN membranes exhibited higher water permeability, salt rejection and fouling resistance compared to that of the TFC membrane. Excessive amount of nanofillers incorporated in the membrane PA layer however negatively affected the cross-linking in the polymer matrix, thus deteriorating the membrane salt rejection. TFN membrane containing 0.05 w/v% of nanofillers showed better performances than the TFC membrane, recording a pure water flux of 11.2 L/m2∙h, and salt rejection of 95.4%, 97.3% and 97.5% against NaCl, Na2SO4 and MgSO4, respectively.

Thin-film nanocomposite membranes incorporated with water stable metal-organic framework CuBTTri for mitigating biofouling

Water vapor dehumidification using thin-film nanocomposite membranes by the in situ formation of ultrasmall size iron-chelated nanoparticles

Development of high water permeability and chemically stable thin film nanocomposite (TFN) forward osmosis (FO) membrane with poly(sodium 4-styrenesulfonate) (PSS)-coated zeolitic imidazolate framework-8 (ZIF-8) for produced water treatment

Polyethylenimine modified silica nanoparticles enhance interfacial interactions and desalination performance of thin film nanocomposite membranes

Zeolite-polyamide thin film nanocomposite membranes: Towards enhanced performance for forward osmosis

Thin-film composite (TFC) membranes still suffer from fouling and biofouling. In this work, by incorporating a graphene oxide (GO)-silver-based metal-organic framework (Ag-MOF) into the TFC selective layer, we synthesized a thin-film nanocomposite (TFN) membrane that has notably improved anti-biofouling and antifouling properties. The TFN membrane has a more negative surface charge, higher hydrophilicity, and higher water permeability compared with the TFC membrane. Fluorescence imaging revealed that the GO-Ag-MOF TFN membrane kills Escherichia (E.) coli more than the Ag-MOF TFN, GO TFN, and pristine TFC membranes by 16, 30, and 92%, respectively. Forward osmosis experiments with E. coli and sodium alginate suspensions showed that the GO-Ag-MOF TFN membrane by far has the lowest water flux reduction among the four membranes, proving the exceptional anti-biofouling and antifouling properties of the GO-Ag-MOF TFN membrane.

Catalytic TFN membranes containing MOF loaded Ag NPs prepared by interfacial polymerization

Improved performance and antifouling properties of thin-film composite polyamide membranes modified with nano-sized bactericidal graphene quantum dots for forward osmosis

Forward osmosis application of modified TiO2-polyamide thin film nanocomposite membranes

Thin film nanocomposite (TFN) membranes contain nanoparticles in the thin polyamide (PA) top layer, resulting in a remarkable increase in water permeability without compromising the salt rejection. Mesoporous silica nanoparticles (MSN) have gained much attention as nanofillers for improved performance PA TFN membranes. However, aggregation of MSN inside the PA layer and their tendency to fast dissolution in aqueous solutions are serious challenges which strongly affect the separation performance of MSN-based TFN membranes. In this work, these challenges were addressed by controlling the functionalization of MSN with hydrophobic organo-silane, such as octadecyltrichlorosilane (OTS) or methyltrichlorosilane (MTS), before incorporating in the PA layer. MSN were synthesized first by sol-gel process and then functionalized using post-grafting method during silanization reaction. The functionalization was tuned in order to allow the hydrophobic alkyl group of the silane molecule to graft both the external surface of MSN as well as their interior pores or to modify only their external surface depending on the functionalization procedure and the silane concentration. The model of functionalization and the amount of OTS or MTS grafted on the surface were estimated through the nitrogen adsorption measurement and thermogravimetric analysis. The functionalized MSN with a particle diameter of ≈ 80 nm were thereafter easily dispersed in the organic solvent during the TFN membrane preparation via interfacial polymerization method. The membrane performance was then assessed based on water permeability and salt rejection measurements. Several parameters were found to have a strong influence on the membrane performance such as concentration of grafted OTS or MTS and the NPs loading inside the PA layer. The low aggregation and good integration of the functionalized nanofillers inside the PA layer produced TFN membranes with superior initial water permeability. The results revealed that the initial water permeability of the TFN membranes with OTS functionalized MSN achieved ≈ 65% higher initial permeability than the reference TFC membrane at the optimum OTS amount and NPs loading, without sacrificing the membrane selectivity. Whereas the corresponding TFN membranes with MTS functionalized MSN achieved ≈ 130% higher permeance but with 2% less salt rejection than the reference TFC membrane at the same conditions. The controlled functionalization of MSN nanofillers not only can improve membrane performance but also can provide a deeper understanding of the role of porous structure of MSN on the separation mechanism. This work clearly emphasizes the direct relationship between the internal pores of MSN inside the PA barrier layer and increasing or decreasing the water permeability of resulting TFN membranes. Furthermore, it was investigated, how hydrophobic functionalization of MSN can improve the stability of MSN in aqueous solutions and improve the stability of the respective TFN membranes over prolonged filtration time at different pH values. The results showed that TFN membranes containing the OTS-functionalized MSN had only ≈ 6% (or 7.5% for MTS-functionalized MSN) decline in salt rejection compared to 34.5% decline for the membrane containing unfunctionalized nanofillers accompanied by increasing in water permeability after 240 h filtration time (120 h at pH 5 then 120 h at pH 9). According to these results, it was concluded that the functionalized MSN have low dissolution tendency due to the formation of a protective organic layer leading to enhanced long-time stability of the TFN membranes. Finally, the durability of the barrier layer after a prolonged use for desalination performance of PA TFN membranes was also investigated.

Influential effects of nanoparticles, solvent and surfactant treatments on thin film nanocomposite (TFN) membranes for seawater desalination