Optimization of water flux and salt rejection properties of polyamide thin film composite membranes

Abstract

Optimizing synthesis factors of polyamide top layers is an important requirement in the design of thin film composite (TFC) membranes. In this research, the top layer fabrication method (conventional, heat curing, and spin coating), type of acid acceptor (sodium carbonate, sodium hydroxide, and triethylamine), type of organic phase solvent (hexane, heptane, and mixed hexane/heptane), and concentration of surfactant sodium dodecyl sulfate (0, 0.5, and 1 wt %) are selected as the control parameters of this synthesis and optimized using the Taguchi approach. The analysis of variance shows that the layer fabrication method is the most influential parameter on water flux and salt (NaCl) rejection of TFCs. Furthermore, although the type of organic solvent has not a significant contribution to the water flux, it is another significant factor affecting the rejection. The optimized membrane is then used to construct structureproperty relationships and to understand the influence of each individual factor on the desalination performance. Accordingly, a TFC membrane with the top layer fabricated by the heat curing method, in the presence of Na 2 CO 3 as the acid acceptor, hexane as the organic phase solvent and 0.5 wt % of the surfactant is prepared that shows water permeance of 2.73 L m −2 h −1 bar −1 and NaCl rejection of 98.1%. centration demonstrated the importance of these parameters in the preparation process of TFCs. The same group recently studied the synergistic effects of different additives on desalination properties of PA-TFC membranes. 23 The additives, which Additional Supporting Information may be found in the online version of this article.

A systematic study on the effects of synthesis conditions of polyamide selective layer on the CO2/N2 separation of thin film composite polyamide membranes

“…Recently, Azizi and Sharif 15 and Khorshidi et al 12,13 have shown that a simple linear model which interpolates between the control factors levels of a Taguchi L9 orthogonal array can predict permeation properties of IP‐TFC membranes for water desalination rather accurately. In order to access the predictability of the above model in the case of IP‐TFCs for gas separation, four new confirmation TFCs (C1–C4, Table 3) were prepared at the synthesis levels that differ from those given in the Taguchi design (Table 1).…”

“…Furthermore, as revealed by the AFM images (Figure 9) and listed in Table 4, TFC membranes with smoother PA surfaces were obtained when SDS was added in the aqueous phase of the IP reaction. It seems that the uniform coatings on the surfaces of the PSf sublayers of membranes C3 and C4 created as the result of the addition of SDS, 29 weakened the upward forces of the spin coating process which are responsible for increasing the roughness of PA layers 15 . It is important to note that the above roles of the surfactant SDS in the PA layer formation through the spin coating process is different from the simple behavior of SDS during PA film formation by conventional IP method, where the PA layer cross‐linking density and thickness are increased by increasing the SDS concentration 38,39 …”

“…It was found that concentration of polysulfone (PSf) and immersion time in the aqueous phase were the most influential factors on the water permeation and salt rejection, respectively. In addition, recently, Azizi and Sharif 15 employed the Taguchi approach to optimize synthesis parameters of PA top layers of TFC membranes for desalination applications. The PA layer fabrication method, acid acceptor type, organic phase solvent type and SDS concentration were considered as the controlling parameters.…”

Cross-Flow Treatment of PFAS in Water: Materials Challenges and Potential Solutions

“…A wide operating range of pH allows treatment of various types of feed water (e.g., drinking water, landfill leachate, wastewater). More importantly, the polyamide barrier layer is highly modifiable (via grafting, cross-linking), allowing optimization of the membrane’s surface properties to enhance PFAS selectivity. − Therefore, CFF using polyamide barrier layer is considered promising preconcentration technology, whose effluent can further be treated by destruction methods (e.g., catalytic redox degradation). However, there remain several challenges that need to be addressed.…”

Alleviation of Reverse Salt Leakage across Nanofiber Supported Thin-Film Composite Forward Osmosis Membrane via Heat-Curing in Hot Water

“…Currently, there are two typical heat-curing methods applied to prepare PA active layers, hot-air-curing (oven-curing) and hot-water-curing. For example, Azizi et al reported using an oven to heat-cured the PA layer at 80 °C for 10 min after interfacial polymerization, and the salt rejection of the resulting membrane possessing higher crosslinking was superior to that without heat treatment [ 39 ]. Zhan et al Ghosh et al, and Han et al respectively investigated the effects of curing conditions (temperature, time) on the morphologies and performances of the as-prepared PA-TFC membranes in nanofiltration (oven-curing), reverse osmosis (oven-curing) and FO (specific hot-water-curing) [ 40 , 41 , 42 ].…”