Polyamide Thin Film Nanocomposite Research Articles

Fabrication and characterization of polyamide thin film nanocomposite (TFN) nanofiltration membrane impregnated with TiO2 nanoparticles

A novel thin-film nanocomposite (TFN) nanofiltration membrane has been developed via interfacial incorporation of aminosilanized TiO2 nanoparticles. Polyethersulfone (PES) barrier coating on a porous α-Al2O3 ceramic hollow fibre membrane was employed as the substrate layer. TiO2 nanoparticles were incorporated in pure and functionalized forms into trimesoyl chloride (TMC) organic phase and m-phenylenediamine (m-PDA) aqueous phase, respectively. The surface functionalization of TiO2 nanoparticle was confirmed by XRD, FTIR and UV-vis reflectance spectral analysis. Surface properties of the fabricated composite membranes were investigated using SEM, EDX, AFM and contact angle goniometry. Heat resistibility of polyamide layers were examined using thermo-gravimetric analysis (TGA). Membranes intrinsic properties such as: the permeability, selectivity and pore size determination were also elucidated. The silane coupling agent containing amino-functional groups reinforced TiO2 nano fillers for the good dispersion inside the polyamide skin layer by reducing their surface energy. At ultra-low concentration (0.005wt.%), the functionalized TiO2 nanoparticles improved the salt rejection to 54% as well as water flux to 12.3l/m2h. By incorporating a higher concentration of TiO2 nanoparticles, water flux was increased up to 2-fold compared with the pure polyamide membrane with negligible rejection loss. These results demonstrated competency of using functionalized inorganic nanoparticles to increase the product flux and the separation efficiency.

Role of NaA zeolites in the interfacial polymerization process towards a polyamide nanocomposite reverse osmosis membrane

This paper explores the behaviour and role of NaA nanozeolites during an interfacial polymerization process towards a polyamide thin film nanocomposite (TFN) reverse osmosis membrane by incorporating nanozeolites into two different reactive phases. In the two cases, the different interactions occurring between the zeolites and polyamide were investigated by FT-IR spectra, XPS analysis, and examining the membrane morphology and the desalination performance. The polyamide TFN membrane with an increased degree of cross-linking was obtained with nanozeolites in the organic phase, as the NaA zeolite reacted with the acyl chloride monomer in the organic phase. Additionally, the membrane with nanozeolites added to the organic phase had a superior reverse osmosis performance, since the porous zeolite appeared in the top layer as a water channel.

Optimizing polyamide thin film composite membrane covalently bonded with modified mesoporous silica nanoparticles

Novel modified mesoporous silica nanoparticles (mMSN)/polyamide (PA) thin film nanocomposite (TFN) membranes were prepared via interfacial polymerization of trimesoyl chloride (TMC) and piperazine (PIP). Mesoporous silica nanoparticles were functionalized with amino groups and introduced into PIP aqueous phase. Therefore, reaction between mMSN and TMC would occur during interfacial polymerization, giving rise to a covalent bonding between silica nanoparticles and active layer of TFN membrane. By adding an appropriate concentration of mMSN into aqueous phase (0.03wt%), the pure water flux of the mMSN/PA TFN membrane reaches to a maximum of 32.4L/m2h which is almost 1.5 times as high as that of TFC membrane, while the rejection to Na2SO4 of TFN membrane keeps at a relative high level (>80%). Two unique properties of mMSN were favorable for the membrane performance: mesoporous structure for water transport and functional groups for better interaction with polymer matrix. The obtained membrane exhibited a promoted anti-fouling ability as well as a good long-term stability. The effect of the mesopore structures of silica nanoparticles on the membrane performance was also investigated. Modified mesoporous silica nanopraticles with proper pore size was more suitable for the optimization of PA TFN membrane.

Fabrication of polyamide thin-film nano-composite (PA-TFN) membrane with hydrophilized ordered mesoporous carbon (H-OMC) for water purifications

To enhance the performance of thin-film composite (TFC) membranes, nano-fillers are often used as additives in the polymerization process. Nano-fillers have to be hydrophilic to be dispersed in the aqueous phase to make thin-film nano-composite membrane (TFN) by interfacial polymerization. In this study, hydrophilized ordered mesoporous carbons (H-OMCs) were explored for TFN preparation. H-OMC was prepared from silica template, and argon atmospheric pressure plasma (APP) was applied to enhance surface hydrophilicity. m-Phenylenediamine (MPD) with trimesoyl chloride (TMC) was polymerized to make polyamide (PA) thin-film layer. The results indicated that 5% loading of H-OMCs increased membrane surface hydrophilicity, wettability and pure water permeability. Measurement of bovine serum albumin (BSA) adsorption on the membranes showed that with increasing H-OMCs loading, BSA adsorption was decreased. The enhanced membrane surface hydrophilicity might have contributed to the decreased BSA adsorption. With increasing amounts of H-OMCs up to 6%, rejection of monovalent ion (NaCl) was reduced from 68% to approximately 50%, but the rejection of divalent ions (Na 2SO 4) decreased only slightly from 94% to around 90%. Incorporation of the H-OMCs into the thin-film layer of the membrane did not change solution permeability in NaCl solution and slightly increased the solution permeability with Na 2SO 4. Overall, surface hydrophilicity, electrical properties and porous structure of the thin-films are significant factors limiting protein adsorption and enhancing membrane performances.