Abstract
Negatively charged MIL-101(Cr)-Pyz-SO3H nanoparticles (NPs), with several concentrations (0.001–0.02 wt%), were used as a hydrophilic and charge modifier to make a high performance thin-film nanocomposite reverse osmosis membrane (TFC RO) through the interfacial polymerization between 1,3-phenylenediamine (MPD) and trimesoyl chloride (TMC) monomers. Surface analyses revealed smoother surfaces and higher hydrophilicity for the modified membranes. The zeta potential investigation approved rising the negative surface charge of MIL-101(Cr)-Pyz-SO3H NPs embedded RO membranes. The desalination performance displayed that 0.005 wt% MIL/RO indicated the most incredible separation efficiency for NaCl (98.05%). The desalination performance of seawater was also studied. Observations showed that 0.005 wt% MIL/RO means the best separation efficiency for seawater desalination (94.46%). Water flux for the modified membranes improved and reached the maximum value of 41.4 L/m2.h in 0.005 wt% MIL-101(Cr)-Pyz-SO3H TFC RO membrane. The fouling resistance of the membranes was identified by filtration of humic acid (HA)/NaCl solution. The obtained results demonstrated that modified membranes improved fouling resistance, and the highest fouling resistance was recorded for 0.005 wt% MIL-101(Cr)-Pyz-SO3H TFC RO membrane.
| Original language | English |
|---|---|
| Article number | 121066 |
| Journal | Journal of Membrane Science |
| Volume | 664 |
| DOIs | |
| Publication status | Published - 15 Dec 2022 |
Bibliographical note
Publisher Copyright:© 2022 Elsevier B.V.
Funding
The authors would like to thank Kharazmi University (Iran) for the financial support of this project. Population growth, droughts, and pollution caused by the development of industry have led to a shortage of water resources [1–4]. Today, the achievements of membrane technologies in water treatment applications are tremendous and undeniable. Membrane processes consume less energy than other methods but are more efficient. Reverse osmosis (RO) is a membrane process that is often utilized for sea water desalination and saline water purification [5–7]. The RO membranes are often made from thin-film composites (TFC) [8,9]. They are typically composed of three layers: (a) an active polyamide ultra-thin top layer that has vital control on the permeability and selectivity properties, (b) a polysulfone support layer that acts as a support for the active polyamide layer, and (c) a thicker polyester fabric (bottom layer) as a mechanical support [10–12]. The ultra-thin top layer (1,3-phenylenediamine–polyamide (MPD–PA) is formed by the in-situ interfacial polymerization (IP) between MPD and TMC (trimesoyl chloride) on the support surface [13]. Because mixed matrix/nanocomposite membranes usually exhibit remarkable properties and performance, the use of nanoparticles in membrane fabrication has received considerable attention [14,15]. Separation, adsorption, good interaction, and excellent thermo-mechanical properties are properties that have been improved by scientists in mixed matrix/nanocomposite membranes [16–19]. In TFC membranes, nanoparticles must be well dispersed in the ultra-thin layer. Various nanofillers have been used in TFC RO membranes to reach better flux, rejection, and antifouling properties [20–26]. Fabrication of TFC RO membranes by coating method was studied by Ng et al. [27]. They used this method to prevent the deposition of nanofillers and, consequently, to enhance the efficiency of RO membranes. In their study, polyvinyl alcohol (PVA) is used as an adhesive for hydrophilic GO, with different orientations (above PA layer and between PA and substrate), and GO loadings (0–0.02 wt/v%). The optimal GO concentration in both fabricated membranes was reported to be 0.015 wt/v%. The pure water flux increased to 50.94% in the GO-15/PVA-coated PA and 91.93% for the GO-15/PVA-coated PSf. Moreover, high desalination performance (98% NaCl rejection) and excellent fouling resistance (complete FRR) are measured from the membrane containing GO/PVA on the PA layer. Liu et al. [28] studied monodispersed spherical MCM-48 NPs through dispersing in the organic or aqueous solution with several concentrations to make TFC RO membranes. By dispersing into the organic solution, MCM-48 nanofillers were embedded throughout the PA layer. With increasing MCM-48 loading into the organic solution, the water flux almost doubled, while the solute rejection of all membranes remained more than 95%. Metal−organic framework (MOF) due to specific surface areas, narrow porosity, inorganic−organic attributes, and acceptable compatibility with polymers improve the separation properties of TFC membranes [29,30]. MIL-101(Cr) MOF nanoparticles as effective nanofillers used in TFC membranes. Butler et al. [31] investigated poly(piperazine trimesamide) TFC membrane fabrication based on MIL-101. Nitrobenzene was used to fabricate TFC membranes, which well-dispersed MIL-101 and prevented the formation of defects. TFC membranes were made utilizing nitrobenzene through two different reaction situations, which makes two membranes smoother and rougher. With enhancing the load of MIL-101 into the organic phase, no change was occurred in the rejection and permeability of the smoother membranes. In comparison, the permeability in the rougher membranes increased up to 3.6 times and showed a slight decrease in rejection. Fabrication and investigation of high performance hollow fiber (HF) TFC membranes modified by MIL-101(Cr) MOF NPs, which a PA layer is made on the external or internal surface of PSf HF, was performed by Echaide-Górriz et al. [32]. Studies have shown that both TFN-in and TFN-out membranes have MIL-101(Cr) NPs in their thin films. The IP technique fabricating the TFN-out membrane allows more MIL-101(Cr) NPs to be embedded in its thin layer. Therefore, due to the more fabulous existence of MIL-101(Cr) in the thin outer layer than the thin inner layer, a more remarkable improvement in water permeate was observed.To fabricate TFC RO membranes, IP reaction between aqueous and organic phase was applied. An aqueous phase of 3 wt% MPD, 3 wt% camphor, and 3 wt% TEA was arranged, and the wet PSF–UF membrane was dipped in it for 1 min. The components used in the aqueous solution are presented in Table 1. A roller was used to erase the extra aqueous solution. Then, for preparing the PA layer, the support was soaked in the hexane solution containing 0.2 wt% TMC for 10 s. To make a compact and great crosslinked PA layer, the fabricated membranes were located in the oven at 80 °C for 10 min. The TFC RO membranes fabrication was adopted using the MIL-101(Cr)-Pyz-SO3H within the MPD solution.Fig. 6, illustrates the cross-sectional SEM images obtained from the bare and the modified membranes. As seen in the images, the support membranes have asymmetric finger-like bottom-layer and sponge-like porous top-layer structure that a very thin and dense layer of PA is created on it [39]. The very thin PA layer has the most vital role in determining the permeation, rejection, and separation characteristics of the membrane. By increasing the MIL-101(Cr)-Pyz-SO3H NPs concentration in the PA super-thin layer up to 0.005 wt%, with the formation of hydrogen bonds and better crosslinking due to the presence of functional groups (Cr, N, COOH or OH, and SO3H) in the structure of MIL-101(Cr)-Pyz-SO3H, the PA layer becomes denser and the PA layer thickness decreases [40]. The bare RO has the PA thickness of about 600 nm, that addition of 0.005 wt% MIL-101(Cr)-Pyz-SO3H reduce the PA thickness to about 300 nm. However, in 0.01 wt% and 0.02 wt%, the thickness of PA layer increases to about 400 nm and 800 nm, respectively, which can reduce the permeability of these membranes.The authors would like to thank Kharazmi University (Iran) for the financial support of this project.
| Funders | Funder number |
|---|---|
| Thalassemia Foundation of Canada | MIL-101, 10–12, 8,9, 29,30 |
| Kharazmi University | |
| Pacific Salmon Foundation |
Keywords
- Desalination
- Hydrophilicity
- Interfacial polymerization
- MIL-101(Cr)-pyz-SOH NPs
- Metal organic frameworks
- RO membrane
