Fig 1 - uploaded by Abdel-hameed Mostafa El-Aassar
Content may be subject to copyright.
The polyamide structure formed from an IP reaction between MPD and TMC has a crosslinked portion (X-fraction) and linear moiety (Y-fraction), which has an un-reacted acid chloride group that subsequently, hydrolyzes to a carboxylic acid group.
Source publication
A variety of polyamide thin film composite (PA-TFC) membranes was synthesized via interfacial polymerization (IP) technique. IP was carried out between aqueous solution of m-phenylene diamine (MPD) and trimesoyl chloride (TMC) in dodecane as organic solvent onto polysulfone (PSf) supporting membrane. The characterization of synthesized membranes wa...
Context in source publication
Context 1
... monomer concentration and the reactant ratio (Morgan 1965;Chai and Krantz 1994). These properties play a pivotal role in membrane performance. For the current studies, PA-TFC membranes were synthesized using m-phenylenediamine (MPD) and trimesoyl chloride (TMC) on a polysulfone support via IP (Rozelle et al., 1977;Cadotte 1981). As indicated in Fig. 1, the polyamide contains a crosslinked portion (X) and a more hydrophilic linear moiety (Y) containing free carboxylic acid groups (Roh et al., 2006). The number of free carboxylic acid groups as well as the thickness and mechanical properties of the thin film are governed by the monomer concentrations and the NH 2 /COCl molar ratio. ...
Similar publications
A new sulfonated diamine monomer, namely 3,3′-(ethane-1,2-diylbis(azanediyl))bis(2,6-dimethylbenzenesulfonic acid) (EDADMBSA), was designed and synthesized in order to fabricate a novel thin-film composite (TFC) reverse osmosis (RO) membrane by using the interfacial polymerization (IP) technique with trimesoyl chloride (TMC). In particular, EDADMBS...
Citations
... ). The -C=O group, amide I and II, and the bending and stretching vibrations of the carbonyl amide groups are represented by the peaks detected at 1745.64, 1672.32, and 1535.39 cm −1 , respectively(Mostafa and El-Aassar 2012;Porubská et al. 2012). Aromatic C-C, symmetric O=S=O, ether C-O-C, andFig. ...
Cesium removal from aqueous solutions of radioactive waste streams is a challenge in the field of radioactive waste management; this is due to the small atomic radii of Cs⁺ metal ions and their high migration ability. So, the development of a withstand system for the removal of Cs⁺ is crucial. In the current study, the removal of radioactive cesium from aqueous solutions using an RO-TLC membrane was studied. Two modifications were conducted; the first is to enlarge the cesium metal ion radii by interacting with mono- and dibasic acids, namely, stearic acid, tartaric acid, citric acid, and EDTA, and the second is the modification of the RO membrane pore size via reaction with the same acids. The modification was confirmed using SEM, FTIR, and EDX analysis techniques. The Cs⁺ and K⁺ rejection capacities and water permeability across the membrane at 1.5 bars were evaluated. Along with using the above-mentioned acids, the Cs⁺ metal ion retention index (RCs) was also obtained. It was found that employing EDTA as a chelating agent in an amount of 1.5 g/L in conjunction with the variation of feed content since it provided the highest value of RCs ~ 98% when used. Moreover, the elution of Cs⁺ using water, EDTA, ammonia, and HCl is also investigated. The optimal value of the eluent concentration was (0.25 M) HCl. Finally, Langmuir and Freundlich isotherm models were applied for a better understanding of the sorption process. The results of the present work more closely match the Langmuir isotherm model to determine the dominance of the chemical sorption mechanism.
... In IP, a SL was first soaked in a 2 wt% MPD solution for 2 min, and then the excess solution was discarded. After that, a frame was employed to assemble the membrane so that only the top layer of the membrane surface was exposed in a 0.1 wt% TMC (in hexane) solution for 1 min, and a defect-free polyamide AL formed [165]. ...
... IP technique (Fig. 9) was used to build the membrane's SL. (d) apply a TMC solution to the membrane surface for 1 min; (e) clean the membrane's surface using n-hexane; and (f) keep the TFC membrane submerged in DI water until required [165]. Reproduce with permission from Xie et al. [167]. ...
Forward osmosis (FO) is a membrane separation technique used to recover water from feed solution (FS) across a semi-permeable membrane, using a concentrated draw solution (DS). The feed solution could be sea/brackish water, wastewater, or other contaminated water. The DS and membrane play important roles in its overall performance. Permeate in FO is not pure water but a diluted DS. So, FO requires an additional step to regenerate DS and to recover freshwater as a product. This additional regeneration process might increase the total capital investment and energy requirement for the FO process. Selecting a proper DS and designing an energy-efficient DS regeneration system are the main challenges to make the FO process energetically viable. The FO process has significant advantages as it operates with very low hydrodynamic pressure, due to which it shows lower membrane fouling propensity. Hence, it helps for saving energy and reducing membrane replacement costs. It has some limitations, such as reverse solute flux, internal and external surface concentration polarization, that need to address before making it commercially more viable. This review focuses on the FO process's recent significant advancements in FO membranes, draw solutions, regeneration processes of draw solutions, overall energy efficiency, membrane fouling and overall performance during the long-term run, and future research directions.
... The first fast reaction generates the dense core layer that is significantly thinner than the extended loose layer formed later as monomer diffuses through the dense core layer. In addition, the PA contains a crosslinked portion (X) and a more hydrophilic linear moiety (Y) containing free carboxylic acid groups [11]. Figure 3 has shown the PA structure formed from an IP reaction between MPD and TMC which has a crosslinked portion (X-fraction) and linear moiety (Y-fraction), which has an unreacted acid chloride group that subsequently, hydrolyzes to a carboxylic acid group. ...
Polyamide thin film composite immobilized with TiO 2 is prepared using M-phenylene diamine and Trimesoyl chloride via interfacial polymerization. To determine the characteristics and performance of the membranes, effect of TiO 2 loading is studied. 2 (w/v) % of MPD solution and 0.2 (w/v) % of TMC/n-hexane solution were used to prepare PA TFC membrane with different amount of TiO 2 loading (0 wt. %, 0.1 wt. %, 0.2 wt. %, 0.3 wt. %, 0.4 wt. % and 0.5 wt. %).PA/TiO 2 composite membranes are characterized by FESEM, EDX, FTIR and water contact angle. The properties of the membranes have improved upon TiO 2 loading. With over 90% of BPA rejection exhibited by all the fabricated membranes, it is proved that the membranes especially PA/TiO 2 TFC membrane with 0.4 wt. % TiO 2 (with the highest rejection and degradation value of 99.9% and 14% respectively) are potentially employed as the hybrid photocatalytic membrane for BPA removal.
... Uygulanan tüm bekletme sürelerinde, PIP monomeri ile üretilen membranların temas açısı değerlerinde düşüş izlenirken, bekletme süreleri arasında bir ilişki izlenmemiştir. Poliamid tabakasının çapraz bağlanma derecesinin artmasıyla, yüksek oranda hidrofilik membranların oluştuğu bilinmektedir [40]. ...
... the -C=O group, amide I and II with bending and stretching vibrations of carbonyl amide groups, respectively (Porubská et al. 2012;El Aassar 2012). The -CH 2 stretching vibration of the peak is seen at 2376 cm −1 with corresponding-NH stretching vibration occurring at 3446.91 cm −1 which are associated with the primary and secondary amines connected with terminal amine groups. ...
Global supply of commercial reverse osmosis (RO) membranes is growing exponentially due to rapid population growth, industrialization, and urbanization. The continuous demand for enormous quantity of drinking water has brought about process improvements and technological advancements in membrane preparation. The transformation of used RO membranes into nanofiltration (NF) and ultrafiltration membranes by opening up the pores using chemical treatment by inexpensive oxidizing agents could be one of the cost-effective options. The present study investigates the chemical oxidation of the indigenously synthesized RO membrane using aqueous sodium hypochlorite (NaOCl). The performance of the membrane was evaluated by conducting experiments under varying operating conditions of operating time, feed pressure, and total dissolved solids (TDS) in raw water for calculation of flux and salt rejection (%). From an initial flux of 25.2 L/m2 h and TDS rejection of 97.5% for original RO membrane, the values reached 80 L/m2 h and 25.5%, which is in NF range, after a reaction time of 780 min with 4000 ppm concentration of NaOCl oxidizing agent. Further extension of treatment time to 900 min enhanced the flux to 130 L/m2 h with salt rejection lowering to 5.67%. Membrane cleaning was performed efficiently using an advanced technique in which chlorine dioxide (ClO2) was used in combination with citric acid. This combination ensured rapid cleaning with restoration of water flux and % salt rejection. The process was scaled up to pilot plant level using RO membranes modified to NF range of pore size. Permeate water enriched with minerals was further packed using an indigenously designed semi-automatic bottling unit. The studies revealed that the indigenously developed RO membranes are easy to alter into high-performance NF membranes. Overall, the process for production of packaged drinking water was cost-effective, easy to operate, and environmentally friendly.
... Therefore, it is common to use a large excess of amine over acid chloride, which drives partitioning and diffusion of the amine into the organic phase [15]. The IP between DAT and TMC involves an incipient fast stage that forms a dense, highly cross-linked and ultrathin core of PA barrier layer followed by a slow growth stage that is DAT diffusion limited "self-limiting" [16]. The result of polymerization at this stage is the formation of a more loose second layer of PA which covers the core layer causing the ridge and valley morphology but having less effect on the membrane performance [17]. ...
... In order to identify the chemical structure of the active skin layer of the TFC-PA-RO membranes, FTIR spectra were recorded for TMC, DAT monomers and the PA layer as shown in Fig. 2. From the TMC spectrum, a peak at 1,755 cm −1 is characteristic of the C=O stretching vibration of the acid chloride moiety and a peak at 705 cm −1 is attributed to the C-Cl stretching vibrations [16][17][18][19]. The coupled doublet peak in the range of 3,410-3,334 cm −1 in the DAT spectrum is due to the N-H hydrogen bonded primary amine asymmetric and symmetrical stretching [20]. ...
Thin-film composite (TFC) membranes with polyamide (PA) as an active layer synthesized via interfacial polymerization (IP) are dominant in reverse osmosis (RO). This work reports the development of a TFC-PA-RO membrane that minimizes the energy consumption while maintaining superior membrane separation properties. The TFC-PA-RO membranes were prepared by IP of 2,6-diamino-toluene (DAT) and trimesoyl chloride (TMC) on polysulfone (PS) support. The conventional monomer, m-phenylenediamine, is replaced by a DAT monomer. These membranes were characterized by infra-red spectroscopy, scanning electron microscope and contact angle measurements. It was found that the optimum preparation conditions for the TFC-PA-RO membranes included soaking DAT (1 wt%) for 2 min, TMC (0.15 wt%) for 0.5 min and curing at 75°C for 5 min. The TFC-PA-RO membrane prepared at these conditions exhibited a salt rejection of 99.54% and a permeate water flux of 11.4 L/m 2 h in 10 g/L NaCl feed solution at 18 bar. Also, the TFC-PA-RO membranes produced a salt rejection of 98.25% and a permeate water flux of 9.3 L/m 2 h at 35 bar in 35 g/L NaCl feed solution. This low operating pressure compared with the commercial membranes that operate at 55 bar for seawater desalination saves the energy consumed by the RO system to 1.29 kWh/m 3 .
... TFC membranes include a dense and thin layer that controls the performance of the membranes (including permeability and selectivity), and a thicker porous moiety which provides mechanical properties to the thin layer. Hence, a thin layer with lower thickness and more hydrophilicity could result in valuable permeability and selectivity [2]. Overall, the performance of the top polyamide thin layer membrane can be significantly influenced by some physiochemical properties such as selectivity, permeability, surface roughness, charge and hydrophilicity. ...
In this work, changes in structure and performance of poly (piperazine amide) thin layer membranes incorporated with Fe2O3/SiO2 nanoparticles to fabricate new modified thin films were investigated. Thin films incorporated with Fe2O3/SiO2 offered enhanced performance and antifouling properties compared with unmodified thin layers. AFM and SEM images clearly illustrated that the morphology and structure of the surface of thin layers varied in the presence of the nanoparticles. Moreover, the rejection capability of the thin films toward NaCl (from 13.2 to 30.1%), Na2SO4 (from 58.5 to 85.0%), PbNO3 (from 33.3 to 64.0%), and CuSO4 (from 57.1 to 80.0%) showed favorable changes, leading to improved performance of the Fe2O3/SiO2-modified poly (piperazine amide) thin film composite membranes. Increasing of the flux recovery ratio (FRR) to about 96% proved that the employed modification procedure was successful. It should be highlighted that a thinner poly (piperazine amide) layer containing more COOH functional groups was obtained at a proper concentration of Fe2O3/SiO2. On the contrary, higher concentrations of the nanoparticles led to undesired properties for the Fe2O3/SiO2-modified thin films.
... Also, the stretching peak of OH group was present at 3384 cm -1 . This result was in agreement with the previous work of [28]. There is no a reasonable difference between the spectra of both neat PA-TFC (Fig. 3B) and PA-TFNC with NF-CNTs (Fig. 3C). ...
... By introducing a bond spring constant (k) between particles, membrane permeation could be readily controlled, with essentially rigid membranes (k > 20) exhibiting 10-fold lower (particle) fluxes compared to flexible models (k < 5). As is the case when synthesizing actual PA thin films [18,22,37], the overall properties of the continuum models, including permeability, pore distribution, surface roughness, density, and diffusion characteristics, could be regulated by manipulating the MPD/TMC residue ratio and particle interaction potentials. ...
Desalination and water reuse are rapidly evolving technologies that have become mainstays of a broad portfolio of water management practices around the globe. Osmotically-driven molecular partitioning processes mediated by functional permselective membranes lay at the heart of each of these technologies. Despite a strong theoretical and empirical framework of knowledge discovered over the past half century that allows engineering of modern reverse osmosis (RO) systems at unprecedented scales, our understanding of water transport and solute rejection at the atomic and molecular scales by the semipermeable membranes is incomplete. One reason for this is a dearth of analytical techniques capable of non-invasively accessing (and visualizing) in real time the exceedingly small spatial and temporal dimensions of atomic interactions underlying membrane transport phenomena. This knowledge gap has been increasingly eroded, however, since the first use of molecular simulations to explore RO membrane structure and dynamics in the late 1990 s. Over the last decade, molecular dynamics (MD) and related simulations techniques have been aggressively pursued to advance understanding of membrane architecture and transport at the atomistic scale. Results emerging from sophisticated computational approaches, especially when coupled with today's powerful new imaging technologies, reveal a rich landscape of physicochemical interactions not only inside the polymer membranes, but also at the water-membrane interface. For example, it is now clear that the discriminating polyamide (PA) layer of modern RO membranes consists of an inhomogeneous tangled polymer network pervaded by tortuous water-filled transmembrane “tunnels” and nanopores whose shapes fluctuate at ambient temperatures over femtosecond to picosecond time scales. Recent modeling efforts indicate that the nanoscale roughness of PA membranes, evident in electron micrographs, is also reflected at the atomic scale, with an ill-defined diffuse interfacial region shared with the bulk water phase. Simulations are also yielding a clearer picture of water and solute (ions and small organics) behaviors inside the membrane matrix resulting from complex intermolecular hydrogen bonding and atomistic solvation processes. The thermodynamic (enthalpy and free-energy) barriers to water and solute entrance into nanopores located at membrane surfaces have been recently elucidated by means of specialized non-equilibrium simulations protocols. Notwithstanding these recent successes, questions nonetheless remain concerning membrane molecular organization and performance, especially with respect to their ability to reject certain small organic compounds and not others. Other questions concern the dynamic interplay between membrane surfaces and foulant molecules as they undergo adsorption. Because of its unique ability to translate atomic-scale interactions and processes into a dynamic visual experience, it is anticipated that computational chemistry will play an ever greater role in the coming years in helping to answer these and related questions about membrane structure and function. It is expected that fundamental advancements in these areas will lead to a new generation of membrane materials with improved durability and reduced energy demands.
... Aromatic polyamides (aramides) explore high thermal stability, good chemical resistance, excellent mechanical properties, and a series of reliable properties that have broad applications in many areas of research and engineering [1][2][3][4]. However, all of these polymers have the main problem of being difficult to process and of fabrication because of their infusibility and poor solubility in common organic solvents. ...
... On the other hand, sulfone units in the aromatic diamines reduce the flexibility and increased close packing and crystallinity. According to the above discussion, therefore, the solubility of polyamides was affected by the several variables and, significantly, the structural variations in diacid monomer (4) and aromatic diamine components can be considered. The surface morphology of polymers has been studied by scanning electron microscopy using their SEM images ( Figures 4, 5, 6, and 7). ...
We report the synthesis of new polyamides containing 2,6-bis(2-thio-2-(4-carboxyphenyl)-1-oxo)pyridine subunit, under microwave irradiation using Yamasaki phosphorylation method. The solubility, thermal behavior, and viscosity of polyamides were evaluated. The structures of polymers have been characterized using IR and 1H NMR spectroscopy. These polyamides showed good solubility, viscosity, high thermal stability, and glass transition temperatures. Their viscosities and glass transition temperatures are in the range of 0.63–0.88 and 223–295°C, respectively. Thermal stabilities for 10% weight loss (T10) are 137–173°C and for 50% weight loss (T50) are in the range of 483–523°C. The study of surface morphology showed particle and amorphous structures.
