Tip and inner walls modification of single-walled carbon nanotubes (3.5 nm diameter) and preparation of polyamide/modified CNT nanocomposite reverse osmosis membrane

Abstract

(2018) Tip and inner walls modification of single-walled carbon nanotubes (3.5 nm diameter) and preparation of polyamide/modified CNT nanocomposite reverse osmosis membrane, Journal of Experimental Nanoscience, 13:1, 11-26, DOI: 10.1080/17458080.2017 ABSTRACTTo enhance the water flux and salt rejection of reverse osmosis membranes, thin film nanocomposite reverse osmosis membranes were prepared by incorporating functionalised single-walled carbon nanotubes (SWNTs). The functionalised SWNTs were obtained by chemical process such as mixed acid oxidation and substitution reaction. The SWNTs were characterised by HRTEM, FTIR, TGA, Raman spectra, UV-Vis and XPS, etc. The surface morphology and structure of membrane were characterised by SEM and contact angle measurement, respectively. The results showed that carboxyl, acyl, amide and amine were successfully grafted on the tip and inner wall of the single-walled carbon nanotubes. The dispersity of the functionalised SWNTs in water was tested, indicating a good hydrophilic property. The polyamide/modified CNT nanocomposite reverse osmosis membrane was prepared. Compared with the bare polyamide membrane, the SWNT-polyamide thin film nanocomposite membranes showed higher property in hydrophilic surface and its water flux, as along with salt rejection, improved dramatically. The experimental results revealed that the modified SWNTs (especially those containing hydrophilic groups such as carboxyl groups and amino groups) well dispersed in the polyamide thin film layer, and hence improved the water permeation, and the salt rejection. KEYWORDSSingle-walled carbon nanotubes; inner/surface modification; SWNTpolyamide nanocomposite membranes; water flux and salt rejection ABBREVIATION CNTs: carbon nanotubes

Hyperbranched Polyethylenimine-Tethered Multiple Emulsion-Templated Hierarchically Macroporous Poly(acrylic acid)–Al2O3 Nanocomposite Beads for Water Purification

“…After deconvolution, high-resolution Al 2p spectra of AO (Figure S1A), PAA–AO (Figure S1B), and PAA–AO–PEI (Figure A) NC afford signals at 72.65 ± 1.11 and 74.25 ± 0.14 eV, which are indicative of Al and Al–O (Al 3+ /Al 2 O 3 ) species, respectively. , The deconvoluted high-resolution O 1s spectra of AO (Figure S1C), PAA–AO (Figure S1D), and PAA–AO–PEI NC (Figure B) show bands at 529.54 ± 0.36 and 531.3 ± 0.34 eV that may be attributed to the chemical bond of Al–O and overlapping of Al–O–Al, respectively. , The peaks of C 1s orbitals at binding energies of 283.04 ± 0.79, 285.67 ± 0.27, and 289.07 ± 0.83 eV can be assigned to C–C, C–N, and OC–OH groups, respectively, in PAA–AO (Figure S1E) and PAA–AO–PEI NC (Figure C). − Furthermore, the high-resolution deconvoluted peak at 399.70 eV for N 1s orbitals in PAA–AO (Figure S1F) is the characteristic of amide (OC–N) in BAM cross-linker. However, the N 1s spectrum of PAA–AO–PEI (Figure D) was resolved into four peaks at the binding energies of 398.08, 398.69, 399.29, and 400.08 eV, which typically correspond to secondary amino, primary amino, tertiary amino, and amide, respectively. − …”

Improved Water Flux and Separation of Polyamide Reverse Osmosis Membranes by Trace Loading of Biomimetic Modified Carbon Nanotubes

“…After 1 h, most CNTs had settled, and all CNTs had sunk to the bottom after 2 h. Besides, Figure S3 shows the dispersion of raw CNTs (without sonication–centrifugation treatment), which aggregated in a shorter time. These changes directly suggest that DOPC lipid modification enhances the dispersion and stability of CNTs in aqueous solution, which benefits the formation of a defect-free PA layer . Additionally, CNTPs exhibited a less negative charge (−15.8 mV) compared to CNTs (−28.5 mV) owing to the masking effect of the lipid modification, as shown in Figure c.…”

“…These changes directly suggest that DOPC lipid modification enhances the dispersion and stability of CNTs in aqueous solution, which benefits the formation of a defect-free PA layer. 35 Additionally, CNTPs exhibited a less negative charge (−15.8 mV) compared to CNTs (−28.5 mV) owing to the masking effect of the lipid modification, as shown in Figure 2c.…”

Unexpected spontaneous dynamic oxygen migration on carbon nanotubes

“…Understanding the behavior of functional groups at interfaces is of fundamental importance in physical, chemical, and biological processes such as the ions adsorption, 1-3 catalysis, [4][5][6][7] ligand recognition/binding, 8,9 and protein folding, [10][11][12] as well as the focus of various potential applications ranging from functional material fabrication, [13][14][15][16][17][18] water purification 3,19 /desalination [20][21][22][23] to drug synthesis and delivery, 24,25 biosensor. 16,26 In particular, oxygen functional groups such as epoxy, hydroxyl and carboxylic acid, covalently bond with the carbon skeleton of organic molecules and widely exist on the surface of carbon-based materials.…”