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In this study, nanoporous titanate (NT) nanoparticle synthesized by the solvothermal method was used to modify polyamide layer of thin film composite membranes with the aim of improving membrane resistances against organic and inorganic fouling. Thin film nanocomposite membranes (NMs) were synthesized by adding mNTs (modified nanoparticles) into polyamide selective layer followed by characterization using different analytical instruments. The results of XPS and XRD confirmed the presence of mNTs in the polyamide layer of NMs, while FESEM, AFM, zeta potential and contact angle measurement further supported the changes in physical and chemical properties of the membrane surface upon mNTs incorporation. Results of fouling showed that NM1 (the membrane incorporated with 0.01 w/v% mNTs) always demonstrated lower degree of flux decline compared to the control membrane when membranes were tested with organic, inorganic and multicomponent synthesized water, brackish water or seawater. Besides showing greater antifouling resistance, the NM also displayed significantly higher water flux compared to the control M membrane. The findings of this work confirmed the positive impact of mNTs in improving the properties of NM with respect to fouling mitigation and flux improvement. [ABSTRACT FROM AUTHOR]

Novel forward osmosis (FO) is a membrane-based separation process with significant potentials for low energy desalination. While this technology offers various benefits, overcoming its low water flux performance caused by internal concentration polarization (ICP) of solutes in porous substrates remains a challenge. This study aims at addressing this issue by introducing hydrophilic halloysite nanotubes (HNTs) into substrate made of polysulfone (PSF). The thin film nanocomposite (TFN) membranes suitable for FO applications were prepared via interfacial polymerization on the top surface of PSF-HNT nanocomposite substrates. The results obtained from filtration experiments showed that the TFN membrane prepared with 0.5 wt% HNTs (TFN0.5 membrane) demonstrated the most satisfactory results by exhibiting high water permeability and low reverse solute flux. Furthermore, TFN0.5 membrane exhibited remarkably higher water flux than that of control TFC membrane in both FO (27.7 vs 13.3 L/m 2 h) and PRO (42.3 vs 26.0 L/m 2 h) configurations when they were tested with 10 mM NaCl as feed solution and 2 M NaCl as draw solution. This improvement can be ascribed to the fact that the structural parameter of TFN0.5 is much lower compared to control TFC membrane (0.37 vs 0.95 mm), leading to reduced ICP effect. [ABSTRACT FROM AUTHOR]

In the present study, the self-synthesized thin film nanocomposite (TFN) membrane incorporated with hydrophilic functionalized titanate nanotubes (TNTs) has been fabricated and tested for forward osmosis (FO) desalination. The ATR-FTIR results showed that NH 2 -TNT S were successfully modified by AATPS and while TEM and XRD revealed the tubular morphology and crystal structure of NH 2 -TNTs nanotubes, respectively. The presence of the chemical bondings between NH 2 -TNTs and polyamide (PA) selective top layer of TFN is corroborated with the FTIR results. The existence of NH 2 -TNTs in PA top layer was further confirmed by XPS analysis on the control and TFN membranes. The effect of NH 2 -TNTs on the PA layer was investigated and discussed in terms of surface morphology and separation performance. The morphology of the PA layer was investigated through FESEM and AFM micrographs and the outgrowth of the “leaf-like” structure was observed following the increase in NH 2 -TNTs content. Compared to the thin film composite (TFC) control membrane, the TFN membrane embedded with 0.05 wt% NH 2 -TNTs (designated as TFN0.05) exhibited two times improvement in water flux without sacrificing salt rejection. [ABSTRACT FROM AUTHOR]

In this work, titanium dioxide (TiO 2 ) nanoparticles/halloysite nanotube (HNT) nanocomposites synthesized via one-step solvothermal method were used as nanofillers in the preparation of thin film nanocomposite (TFN) membranes for forward osmosis (FO) application. With respect to separation performance, it was reported that the TFN membrane incorporated with 0.05%(w/v) TiO 2 /HNTs (denoted as TFN0.05) exhibited the best performance due to its high water permeability and low reverse solute flux when tested using 10 mM NaCl feed solution and 2.0 M NaCl draw solution under two different membrane configurations. Moreover, compared to control membrane, the fabricated TFN0.05 membrane showed significantly better antifouling affinity against bovine serum albumin (BSA) as well as complete recovery of water flux after a simple water cleaning process. The results revealed that fouling in the TFN0.05 membrane is fully reversible. Overall, it can be concluded that the unique tubular structure of HNTs coupled with the excellent anti-fouling features of TiO 2 have madeTiO 2 /HNTs a reliable material with a bright perspective in improving the antifouling affinity of conventional thin film composite membranes for FO applications. To the best of the authors' knowledge, this is the first study dedicated to the application of composite nanomaterials for the development of TFN FO membranes. [ABSTRACT FROM AUTHOR]

In this work, titanate nanotubes (TNTs) were self-synthesized and amino functionalized to produce titanate nanotubes (NH 2 -TNTs) for thin film nanocomposite (TFN) reverse osmosis (RO) membrane fabrication. The novel RO membranes were fabricated by embedding NH 2 -TNTs of different quantities into polyamide (PA) layer. The nanotubular morphology of NH 2 -TNTs was studied using TEM while FTIR was employed to confirm the reaction of TNTs with [1-(2-amino-ethyl)-3-aminopropyl] trimethoxysilane. The effect of NH 2 -TNTs on the PA layer of TFN with respect to surface morphology, separation performance and antifouling properties was thoroughly investigated and discussed. The presence of NH 2 -TNTs in PA layer was verified using XPS while the “leaf-like” outgrowth morphology of PA layer was observed using FESEM. Results showed that the TFN membrane with 0.05% NH 2 -TNTs embedded was the most promising membrane as it exhibited 93% higher water flux than the control thin film composite (TFC) membrane, without compensating NaCl rejection. In terms of organic fouling tendency, the TFN0.05 membrane also showed higher tolerance compared to the control membrane during RO process. Furthermore, as high as 94% of the water flux of TFN0.05 was able to retrieve by a simple water rinse process, which suggests that organic fouling in TFN0.05 is highly reversible. [ABSTRACT FROM AUTHOR]

Antifouling properties of the polysulfone (PSf) and titanium nanotube (TNT) mixed matrix ultrafiltration membrane were investigated. The membrane was prepared by phase separation process using different concentrations of TNT and PSf. The pure water flux, protein removal and fouling parameters were studied to analyze the performance of the membrane. Morphology of the membrane was characterized by using scanning electron microscopy and atomic force microscopy. The most prominent observation was the significant improvement in water flux which attributed to improved hydrophilicity. The improvement of hydrophilicity was confirmed by water contact angle measurement and porosity measurements. This improvement in hydrophilicity is because of hydroxyl group present on TNT as determined by ATR-IR spectra. Fouling resistance of the membranes assessed by BSA solution filtration showed that 0.3 and 0.5 wt.% TNT loading membrane exhibited the best antifouling property that resulted in 100% flux recovery. The results also showed that 0.3 wt.% TNT loading membrane possessed the highest mean pore radius, porosity, and water flux. The effect of different washing directions in fouling experiment was reported. The perpendicular washing and parallel washing were carried out during fouling experiment and effects were discussed. The TNT nanocomposite membrane with parallel washing showed significant reusability during filtration. [ABSTRACT FROM AUTHOR]

In this study, a new type of thin film nanocomposite (TFN) forward osmosis (FO) membranes was prepared by incorporating different quantities of halloysite nanotubes (HNTs) into the polyamide layer via interfacial polymerization. The FO performance of all fabricated TFN membranes in terms of water permeability and reverse solute flux was compared and the best performing membrane which showed good balance between permeability and solute flux, among all, was selected for further organic fouling investigation. Using 10 mM NaCl concentration in feed solution and draw solution of 2 M NaCl, the TFN membrane that was embedded with 0.05% HNTs (i.e. TFN0.05) was identified as the best performing membrane due to its high water permeability and low reverse solute flux. Confirmed by the results of BSA removal in the presence of Ca 2 + , the TFN0.05 membrane also exhibited significantly higher fouling resistance compared to a typical TFC membrane. As an indication to the TFN0.05 fouling reversibility, it was found that > 96% permeate flux could be recovered after a simple water rinse process. Overall, it can be concluded that the addition of an appropriate amount of HNTs into the polyamide layer can remarkably improve the antifouling affinity of conventional TFC membranes for FO applications. [ABSTRACT FROM AUTHOR]

A major limiting factor of forward osmosis (FO) membrane, particularly in pressure retarded osmosis (PRO) mode, is fouling by natural organic matters. In this work, we investigated the effect of the nanocomposite substrate on the fouling of a thin film nanocomposite (TFN) membrane due to organic foulants in PRO mode. The TFN membrane was synthesized by coating a polyamide film over the surface of substrate made of polysulfone-titanium dioxide. The TFN membrane always showed much higher FO water flux than the typical thin film composite TFC membrane prepared from the pristine polysulfone substrate. Reduced internal concentration polarization following a significant decrease of the structural parameter in the nanocomposite substrate causes the mass transfer coefficient of the substrate to increase. In the PRO mode, BSA removal in the presence of Ca2+ confirmed that the TFN FO membrane could significantly mitigate fouling tendency compared to a typical TFC membrane. Results also showed that fouling in TFN FO is highly reversible, recovering >92% permeate flux after a simple water rinse process. A complete study of the membrane fouling was reported with detailed scientific discussion. To the best of our knowledge, this is the first report on the effect of the nanocomposite membrane on membrane fouling in PRO mode. [ABSTRACT FROM AUTHOR]

Highlights: [•] Modifications on PSf substrate of TFC membrane using TiO2 nanoparticles. [•] Performances of PSf substrate were improved upon addition of TiO2 nanoparticles. [•] TFN FO membrane with small S value and minimum ICP was able to produce. [ABSTRACT FROM AUTHOR]

Abstract: Realizing that one of the most important challenges in the forward osmosis (FO) membrane is internal concentration polarization (ICP), thin film nanocomposite (TFN) membranes were prepared by incorporating different loadings of titanium dioxide (TiO2) nanoparticles (ranging from 0 to 0.90wt%) into the polysulfone (PSf) substrate in order to reduce ICP. The nanocomposite substrates prepared were characterized with respect to hydrophilicity, overall porosity, surface roughness and cross-sectional morphology by different methods. Results revealed that both hydrophilicity and porosity of the substrate were increased upon addition of TiO2 nanoparticles. Moreover, a large number of finger-like macrovoids were developed by increasing the loading of TiO2 nanoparticles, leading to enhancement in water permeability. As for the FO performance tested at AL-FS orientation and with DI water as feed and 0.5M NaCl as draw solution, the TFN membrane prepared using PSf substrate embedded with 0.60wt% TiO2 nanoparticles (designated as TFN0.60) exhibited the most promising result by showing water flux of 18.81L/m2 h, i.e. 97% higher than the control TFC membrane prepared by substrate without TiO2 incorporation (designated as TFC), with no significant change in reverse solute flux. Compared to the control TFC membrane, the FO water flux of TFN0.60 was also reported to increase significantly from 4.2 to 8.1L/m2 h (AL-FS orientation) and from 6.9 to 13.8L/m2 h (AL-DS orientation) when seawater was used as feed solution and 2M NaCl was used as draw solution. The increase in water flux can be attributed to the decrease in structural parameter (S value=0.39mm), mainly due to the formation of finger-liked macrovoids that connect the top and bottom layer of the substrate and reduce the tortuosity, resulting in decreased ICP. Although further increasing TiO2 nanoparticles loading to 0.90wt% could increase membrane water permeability, the FO performance was compromised by a significant increase in reverse solute flux. To the best knowledge of the authors, this is the first report on TFN membrane using PSf-TiO2 nanocomposite substrate for FO applications. [Copyright &y& Elsevier]

Abstract: In this study, thin film nanocomposite (TFN) membrane was developed using novel polysulfone–titanium dioxide (PSf–TiO2) nanocomposite substrate. The effects of TiO2 on the PSf substrate morphologies, hydrophilicity and water permeability were investigated and discussed. The results revealed that the hydrophilicity and the porosity of the substrate were improved upon the TiO2 addition, leading to significant enhancement in water flux. TFN membrane was then fabricated by establishing a polyamide layer made of 1,3-phenylendiamine and 1,3,5-benzenetricarbonyl trichloride monomers over the surface of the modified substrate. Compared with the typical TFC and commercial CTA membranes, the TFN membrane prepared always demonstrated much higher FO water flux without showing a significant increase in reverse solute flux when tested under same conditions. When tested in AL–FS orientation using 0.5M NaCl as a draw solution and 10mM NaCl as feed solution, the water flux of the TFN membrane was ∼120% and ∼87% higher than that of the commercial membrane and typical TFC membrane, respectively. The water flux of the TFN membrane was also reported to be much higher under prolonged filtration time, mainly due to the improved properties of substrate upon addition of TiO2. [Copyright &y& Elsevier]

• CFD simulation of FO and PRO processes with loading TiO 2 nanoparticles conducted. • Addition of TiO 2 NPs to the polymers produced a cross-linking membrane. • Loading of TiO 2 NPs to the membranes caused to increase the water flux. • Hydrophilic properties of TiO 2 NPs improved the water permeation. • Good coincidence of the results obtained with 0.3% error in a PRO process. Forward osmosis (FO) has made significant progress in recent years as an emerging membrane technology for the treatment of water and wastewater. Differential osmotic pressure is used to extract pure water across a semi-permeable membrane in this process. CFD simulations were used to investigate the performance of flux changes in membrane systems in this study. This paper simulates the performance of a thin film composite (TFC) membrane with a titanium dioxide (TiO 2) modified substrate in terms of FO and pressure retarded osmosis (PRO). The results showed how the simulation results (CFD) can be used to detect flux changes with additive particles. It was discovered that even a small amount of TiO 2 nanoparticles can alter water flux. In the FO and PRO systems, adding 1 wt% TiO 2 to the membrane matrix increased water flux by about 15% and 14%, respectively. Nevertheless, the increased solute flux was insignificant in simulation, which indicates the positive effect of adding TiO 2 nanoparticles. Finally, a comparison of the results for different membranes indicated the best correlation between the simulation and experimental results, when 0.75 wt% TiO 2 was used, and a relative error of 0.3% has been recorded in PRO process. Also, the maximum pure water flux rate (8 · 974 × 10 − 4 m o l m 2 · s) obtained in the simulation of thin film nanocomposite (TFN) 1 and PRO process. [Display omitted] [ABSTRACT FROM AUTHOR]

In this work, a new type of mixed matrix membranes (MMMs) composed of dual-nanofillers at different ratios of hydrous manganese oxide (HMO) and titanium dioxide (TiO 2 ) was fabricated with the objective of improving properties of polyethersulfone (PSF)-based membrane for oil-water separation process. The morphology and surface chemistry of the resultant MMMs were characterized by several analytical instruments, i.e., SEM-EDX, contact angle goniometer and FTIR spectrometer prior to separation performance evaluation using oily solution composed of 500 or 2000 ppm. The results showed that the membrane surface hydrophilicity was greatly improved upon addition of hydrophilic nanofillers and HMO in particular showed greater extent of hydrophilicity enhancement owing to the fact that it is associated with higher amount of OH functional groups compared to TiO 2 . The improved surface hydrophilicity coupled with formation of long finger-like voids in the membrane structure are the main factors leading to greater water flux of MMMs in comparison to control PES membrane. MMM2 (membrane made of HMO:TiO 2 ratio of 0.75:0.25) and MMM4 (HMO:TiO 2 ratio of 0.25:0.75) in particular were the best two performing nanofillers-incorporated membranes owing to their good balance between water flux and oil removal rate. They achieved 31.73% and 26.41% higher water flux than that of the control membrane without sacrificing oil removal rate. Most importantly, these nanofillers-incorporated membranes showed significantly lower degree of flux decline as a result of improved surface resistance against oil fouling and are of potential for long-term operation with extended lifespan. [ABSTRACT FROM AUTHOR]

This review focuses on the development of polyamide (PA) thin film nanocomposite (TFN) membranes for various aqueous media-based separation processes such as nanofiltration, reverse osmosis and forward osmosis since the concept of TFN was introduced in year 2007. Although the total number of published TFN articles falls far short of the articles of the well-known thin film composite (TFC) membranes, its growth rate is significant, particularly since 2012. Generally, by incorporating an appropriate amount of nanofiller into a thin selective PA layer of a composite membrane, one could produce TFN membranes with enhanced separation characteristics as compared to the conventional TFC membrane. For certain cases, the resulting TFN membranes demonstrate not only excellent antifouling resistance and/or greater antibacterial effect, but also possibly overcome the trade-off effect between water permeability and solute selectivity. Furthermore, this review attempts to give the readers insights into the difficulties of incorporating inorganic nanomaterials into the organic PA layer whose thickness usually falls in a range of several-hundred nanometers. It is also intended to show new possible approaches to overcome these challenges in TFN membrane fabrication. [ABSTRACT FROM AUTHOR]

Highlights: [•] Different amounts of SMM were used to improve the surface hydrophobicity of PVDF HFM. [•] The PVDF HFMs were used in contactor application for CO2 stripping from water. [•] The CO2 stripping flux and efficiency increased by increasing SMM concentration. [•] The gas flow rate has no significant effect on the CO2 desorption flux. [ABSTRACT FROM AUTHOR]

Highlights: [•] Different amount of SMM were used to improve the surface hydrophobicity of PVDF HFM. [•] Average pore size and contact angle increased by increasing SMM concentration. [•] The fabricated PVDF HFMs were used in contactor application for CO2 absorption. [•] The CO2 flux of the hollow fiber increased by increasing SMM concentration. [•] The membrane mass transfer resistance decreased by enhancement of SMM concentration. [Copyright &y& Elsevier]

Abstract: Carbon dioxide (CO2) stripping from water was conducted through the porous asymmetric polysulfone (PSf) hollow fiber membrane contactor. The effect of the liquid and gas flow rates on the stripping performance, the liquid phase CO2 concentration and the CO2 stripping efficiency of the membrane module and the effect of liquid phase temperature on CO2 stripping flux were studied. The experimental results showed that the stripping gas velocity had a minor effect on the CO2 desorption flux while the increase in the liquid velocity could enhance CO2 desorption flux in the gas stripping membrane contactor. By increasing liquid flow rate to 200ml/min, the maximum CO2 stripping efficiency of almost 66% was achieved. Enhancement of liquid flow rate from 50 to 200ml/min increased the CO2 flux around 482%. It was found that the CO2 stripping flux was significantly affected by the liquid phase temperature. By increasing liquid temperature from 80 to 90°C, the CO2 stripping flux increased from 1.3×10−4 to 4.9×10−4 molm−2 s−1 at liquid velocity of 200mlmin−1. Hence, the higher stripping efficiency can be achieved by applying the higher liquid flow rate in the membrane contactor module. As well, the liquid phase temperature is a key parameter that needs to be controlled. [Copyright &y& Elsevier]