Supporting Information

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1 Electronic Supplementary Material (ESI) for RSC Advances. This journal is The Royal Society of Chemistry 2014 Supportg Information Built-up Superhydrophobic Composite Membrane with Carbon Nanotubes for Water Desalation Bowu ZHANG a, Lixia LIU b,c, Siyuan XIE a,c, Fei SHEN* b, Hui YAN b, Huanhuan WU b,c, Yhua WAN b, Mg YU a, Hongjuan LI a, Lfan LI a and Jgye LI* a a TMSR Research Center and CAS Key Lab of Nuclear Radiation and Nuclear Energy Techniques, Shanghai Institute of Applied Physics, Chese Academy of Sciences. Shanghai , P. R. Cha. Fax: (+) ; jgyeli@sap.ac.cn b The National Key Laboratory of Biochemical Engeerg, Institute of Process Engeerg, Chese Academy of Sciences, Beijg , P.R. Cha. Tel: (+) ; fshen@home.ipe.ac.cn c University of the Chese Academy of Sciences, Beijg , P.R. Cha. Dr. B.W. Zhang and Miss L.X. Liu contributed equally to this work. 1

2 Experimental Part Materials Multi-walled carbon nanotube (L-MWNT-4060, 95%) were purchased from Shenzhen Nanotech Port Co., Ltd., (Shenzhen, Cha); Nitric acid (65 wt%), vyl acetate (99%) and other chemical reagents (AR) were purchased from Sopharm Chemical Reagent Co., Ltd (Shanghai, Cha); All chemicals were used as received without any purification process. Double distilled water was used for all experiments unless stated. Graft Polymerization of Vyl Acetate onto CNT 30 mg of dry priste CNT were dispersed 30 ml of vyl acetate/acetone by 30 mutes ultrasonication. Followg dry nitrogen-bubblg and second ultrasonication (10 mutes), the black dispersion was irradiated by γ-ray the field of 60 Co source for presettg doses at the given dose rate. After irradiation, glue or gel-like mixtures were obtaed. The mixtures were diluted respectively with excessive acetone and then sonicated for 15 mutes. For the sake of separatg dissoluble black sediment, the mixtures were subjected to centrifugation at 1000 rpm for 10 mutes. After removal of the homogeneous black supernatant, the black sediment was redispersed acetone by sonication and centrifuged for 10 m aga. This operation cycle was repeated 3 times, and the black supernatant was collected every time. The collected black supernatant was vacuum-filtered with 0.45 μm PVDF microfiltration, and the collected black solids were thoroughly washed 5 times with fresh acetone. The black filter-cake was then redispersed fresh acetone by sonication for 15 m, filtered, and washed with superabundant fresh acetone aga. After 3 times repeated operation, the obtaed black solids, i.e. poly (vyl acetate) functionalized CNT (F-CNT) were scraped off from PVDF and dried overnight a vacuum oven at 60 C. The amount of poly (vyl acetate) on CNT (degree of graftg, DG) was determed by thermogravimetric analysis (TGA), and we can control the DG by alterg the feed ratio of vyl acetate acetone. 2

3 Build-up of superhydrophobic F-CNT/PVDF composite 15 mg F-CNT powder was dispersed 100mL acetone and after sonication 10 mutes, a stable black dispersion was obtaed. The stable black dispersion was filtered through a PVDF (0.45 μm) to produce an F-CNT coatg. After washed with acetone several times, the coatg was dried overnight vacuum oven at 60 C. Contact angle measurements Static contact angle (CA) was measured for water drops placed on the sample surface usg a KSV ATTENSION Theta Optical Tensiometer. A 4 μl liquid drop from a staless steel needle was stroked onto the surface. Shape of the droplet was recorded by a digital camera and static contact angle was calculated accordg to the image taken by evaluation software provided from the strument manufacturer. 5 different pots of every sample and 3 samples for every were measured and the CA was the average of these 15 measurements. All measurements were carried out at room temperature (25 C) and the relative humidity of air was 30~60%. Characterization and method The FT-IR spectra of samples were collected the form of potassium bromide (KBr) tablets usg a Thermo Nicolet Avatar 370 FTIR Spectrometer at a re of 4 cm - 1 and 32 scanng. A Renishaw Via plus laser Raman spectrometer was used to vestigate the structural changes of powder samples usg an excitation wavelength of nm. XPS analysis was carried out on a SHIMADZU Kratos AXIS Ultra DLD XPS strument equipped with a monochromated Al K α X-ray source. The TGA curves were recorded usg a PerkElmer Pyris 1 Thermogravimetric Analyzer at a heatg rate of 10 C/m under a nitrogen atmosphere (20 ml/m). The surface feature of F-CNT coatg was observed through a JEOL JSM-6700F Field-Emission Scanng Electron Microscope. The Testg of DCMD 3

4 The DCMD set-up used to evaluate the flat-sheet F-CNT/PVDF composite s was presented Figure S1. The module was composted by two staless steel cyldrical chambers. One of the chambers was connected to a heatg system while the other chamber was connected to a coolg system. The was placed between the two chambers. The hot feed was brought to contact with the hydrophobic CNTs layer of the and the cold permeate is contact with the supportg (PVDF). Pure water, sodium chloride s with 3.5 wt% and 10.0 wt% were employed as feed sequentially. Deionized water was used at cold side. The effective area of the DCMD system is m 2. The feed and cold water were circulated counter-current operation. The flow rates on both sides were set to be 500 ml/m. The let and outlet temperatures of the feed and permeate were measured by sensors connected to a digital meter. The permeate flux was collected an overflow tank located on one digital balance. The DCMD flux was calculated accordg to J w m At (1) Where J, m, A, t representg the water flux (kg/m 2 h), amount of permeate (kg), w effective area (m 2 ), and the time duration (h), respectively. The sodium chloride concentration of both permeates and feed was determed by a conductivity meter. The salt rejection rate R was calculated usg the followg expression: C p R (1 ) 100% C f (2) C p C f Where and are the sodium chloride concentration of permeate and bulk feed, respectively. 4

5 Table S1 DCMD performances of the reported flat-sheet MD s for desalation: feed temperature (T f ), permeate temperature (T p ), feed flow rate and permeate flow rate are the same. Membrane PVDF-HFP electrospun PVDF electrospun PVDF-clay nanofiber CF4 plasmamodified PVDF PVDF electrospun CNT Bucky- Paper Silanefunctionalise d CNT Bucky-Paper PTFE coated CNT Bucky- Paper CNT Bucky- Paper F-CNT-2M Permeate Flux (Kg/m 2 h) Salt rejection (%) ~9 95~ Feed 10g/L NaCl 12 g/l NaCl 3.5 wt% NaCl 4.0 wt% NaCl 3.5 wt% NaCl 35 g/l NaCl 35 g/l NaCl 35 g/l NaCl 35g/L NaCl 3.5 wt% NaCl process operatg property T f ( C) T p ( C) Flow rate Ref L/s [1] rpm [2] 65 17±2 1.8L/m [3] ml/m [4] m/s [5] ml/m 300ml/m 300ml/m 300ml/m 500ml/m [6] [7] [8] [9] Curre nt 5

6 Figure S1 Schematic diagram of the experimental DCMD set-up. Figure S2 (a) the water contact angle stability of PVDF with 0.45 μm pore size before and after 1 hour DCMD testg by 3.5% NaCl ; (b) the relationships of permeate flux and salt rejection of PVDF with 0.45 μm pore size to testg time of DCMD by 3.5% NaCl. 6

7 Figure S3 the TGA curves of priste CNT and F-CNT with different DG. Figure S4 The dispersibility of CNT before and after graftg with PVAc. Figure S5 (a) the photo of CNT/PVDF composite ; (b) the photo of F- CNT/PVDF composite. 7

8 Figure S6 (a) the relationships of permeate flux and salt rejection of F-CNT-1M to testg time of DCMD by 3.5% NaCl ; (b) the relationships of permeate flux and salt rejection of F-CNT-3M to testg time of DCMD by 3.5 wt% NaCl. (Temperature of feed : 70 C; temperature of permeate : 20 C) Figure S7 the surface micro-morphology of (a) F-CNT-1M; (b) F-CNT-2M and (c) F- CNT-3M. 8

9 Figure S8 the water contact angle stability of F-CNT-1M, F-CNT-2M and F-CNT- 3M before and after 2 hour DCMD testg by 3.5% NaCl at 70 C. Figure S9 the contact angle of water droplet on the surface of PVAc film which prepared by castg the PVAc on class slide. 9

10 Video S1 The water drop on the F-CNT-1M surface with a slope of 1.6 Video S2 The water drop on the F-CNT-1M surface with a slope of 2 Video S3 The water drop on the F-CNT-1M was completely taken by syrge needle Video S4 The water drop on the F-CNT-1M was completely sopped up with drkg paper Video S5 strokg water drop on syrge needle onto the surface of F-CNT-1M References 1. Lalia, B.S., et al., Fabrication and characterization of polyvylidenefluoride-cohexafluoropropylene (PVDF-HFP) electrospun s for direct contact distillation. Journal of Membrane Science, : p Essalhi, M. and M. Khayet, Self-sustaed webs of polyvylidene fluoride electrospun nanofibers at different electrospng times: 1. Desalation by direct contact distillation. Journal of Membrane Science, : p Prce, J.A., et al., Preparation and characterization of highly hydrophobic poly(vylidene fluoride) Clay nanocomposite nanofiber s (PVDF clay NNMs) for desalation usg direct contact distillation. Journal of Membrane Science, : p Yang, C., et al., CF4 plasma-modified superhydrophobic PVDF s for direct contact distillation. Journal of Membrane Science, : p Liao, Y., et al., Fabrication of polyvylidene fluoride (PVDF) nanofiber s by electro-spng for direct contact distillation. Journal of Membrane Science, : p Dumée, L.F., et al., Characterization and evaluation of carbon nanotube Bucky- Paper s for direct contact distillation. Journal of Membrane Science, (1-2): p

11 7. Dumée, L., et al., Enhanced durability and hydrophobicity of carbon nanotube bucky paper s distillation. Journal of Membrane Science, (1-2): p Dumée, L., et al., The impact of hydrophobic coatg on the performance of carbon nanotube bucky-paper s distillation. Desalation, : p Dumée, L., et al., Carbon nanotube based composite s for water desalation by distillation. Desalation and Water Treatment, (1-3): p