Abstract
In this paper, we used an octadecylamine functionalized graphene oxide (ODA@GO) to induce the confined growth of a polyamide nanofilm in the organic and aqueous phase during interfacial polymerization (IP). The ODA@GO, fully dispersed in the organic phase, was applied as a physical barrier to confine the amine diffusion and therefore limiting the IP reaction close to the interface. The morphology and crosslinking degree of the PA nanofilm could be controlled by doping different amounts of ODA@GO (therefore adjusting the diffusion resistance). At standard seawater desalination conditions (32,000 ppm NaCl, ~55 bar), the flux of the resultant thin film nanocomposite (TFN) membrane reached 59.6 L m−2 h−1, which was approximately 17% more than the virgin TFC membrane. Meanwhile, the optimal salt rejection at seawater conditions (i.e., 32,000 ppm NaCl) achieved 99.6%. Concurrently, the boron rejection rate was also elevated by 13.3% compared with the TFC membrane without confined growth.
Highlights
Polyamide thin-film-composite (TFC) reverse osmosis (RO) membranes have been widely used in desalination because of their low energy consumption and high separation efficiency [1,2]
The selective layers in TFC-RO membranes are fabricated by the interfacial polymerization (IP) process, in which a polyamide (PA) film is formed at the interface of aqueous amine solution and organic acyl chloride solution
To further explore the barrier effect of nanomaterials, we have modified single-layer graphene oxide (GO) nanosheets with octadecylamine (ODA) to disperse the octadecylamine functionalized graphene oxide (ODA@GO) nanosheets into the organic phase
Summary
Polyamide thin-film-composite (TFC) reverse osmosis (RO) membranes have been widely used in desalination because of their low energy consumption and high separation efficiency [1,2]. The design and preparation of TFN membranes by combining new inorganic or organic nanomaterials with a traditional polyamide layer is a new research direction in the membrane separation field [13,14]. To further explore the barrier effect of nanomaterials, we have modified single-layer graphene oxide (GO) nanosheets with octadecylamine (ODA) to disperse the ODA@GO nanosheets into the organic phase In this design, the MPD diffusion is largely confined to the molecular level because of the large lateral dimension of the ODA@GO nanosheets, which should enrich the MPD concentration at the organic/aqueous interface. We carried out the seawater desalination tests to reveal how these impacts are related to the performance of the resultant ODA@GO TFN membrane
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