Department of Chemistry and Environmental Science, New Jersey Institute of Technology, Newark, New Jersey 07102, USA. Md. Rabiul Islam 26-03-2016
Background:
(a) Schematic illustration of the homemade fog-harvesting system. (b) Water collection (a) Water collection rates as a function of mesh number; (b) the comparison of the water collection rates of the different samples. efficiency by the samples prepared at different thermal treatment temperatures. Yuchao Wang,Lianbin Zhang,Jinbo Wu,Mohamed Nejib Hedhilib and Peng Wang, A facile strategy for the fabrication of a bioinspired hydrophilic–superhydrophobic patterned surface for highly efficient fog-harvesting, J. Mater. Chem. A, 2015, 3, 18963–18969
(a) Schematic diagram of the inkjet printing method for the micropatterning of superhydrophilicity on superhydrophobic surfaces. (b) Wenzel's wetting behavior of the deposited microdroplets of dopamine solution on the superhydrophobic surface. (c) Formation of polydopamine by the oxidative self polymerization of dopamine.
Lianbin Zhang, Jinbo Wu, Mohamed Nejib Hedhili, Xiulin Yanga and Peng Wang; Inkjet printing for direct micropatterning of a superhydrophobic surface: toward biomimetic fog harvesting surfaces J. Mater. Chem. A, 2015 , 3, 2844
Water collection processes on various kinds of surfaces. (a) On the superhydrophilic surface, water droplets spread over the surface and quickly form a thin water film (arrow). (b) On the superhydrophobic surface, the tiny captured droplets coalesce randomly (dashed circles). As the sizes of these droplets grow beyond a certain threshold, the droplets roll off the superhydrophobic surface. The tiny droplets spontaneously move and coalesce into the superhydrophilic polydopamine micropatterns (dashed circles and arrows) on (c) the superhydrophobic surface with 500 µm polydopamine patterns and 1000 µm separation, (d) the superhydrophobic surface with 200 µm polydopamine patterns and 400 µm separation and (e) the superhydrophobic surface with 200 µm polydopamine patterns and 1000 µm separation. Some of the polydopamine micropatterns are outlined with black dashes. All scale bars ¼ 500 µm . Lianbin Zhang, Jinbo Wu, Mohamed Nejib Hedhili, Xiulin Yanga and Peng Wang; Inkjet printing for direct micropatterning of a superhydrophobic surface: toward biomimetic fog harvesting surfaces J. Mater. Chem. A, 2015, 3, 2844
Adv. Mater. 2011 , 23 , 3718–3722 Isolated Droplets Hydrophilic Layer Annealing Silicon Substrate Hydrophobic Layer Proposed formation of micropatterned surfaces via the dewetting of polymer bilayer fi lms. The top layer is an unstable P4VP(. poly(4-vinylpyridine) film, which spontaneously dewets on the bottom PS layer.
Stuart C. Thickett , Chiara Neto , * and Andrew T. Harris; Biomimetic Surface Coatings for Atmospheric Water Capture Prepared by Dewetting of Polymer Films; Adv. Mater. 2011 , 23 , 3718–3722
In this Paper Introduction: • The supply of potable water all over the world is a growing challenge. • Water treatment methods such as distillation, reverse osmosis (RO) and waste water recycling systems are being developed. • Typical methods of water extraction include cooling and refrigeration, use of liquid and solid desiccants, and compression. • These conventional techniques possess inherent disadvantages; for example, the condensed water can be contaminated, and desiccant systems involve energy-inefficient regeneration steps and may have to be discarded after several uses. • Selective water vapor transport through polymeric membrane is an attractive approach because it provides continuous operation, has a relatively small footprint, is easy to operate and reduces energy costs. • The overall performance in terms of flux as well as water removal is still relatively poor and such processes are not competitive at this time. • While CNTs are potentially good sorbents that can allow rapid mass transfer to increase the yield of water during extraction from air, they need to be incorporated into a mechanically stable, highly hydrophilic environment. • The introduction of functionalized CNTs into a super-absorbent polymer (SAP) membrane provides the dual benefits of high water sorption along with nano-structured sorption–desorption sites for rapid mass transport. • A highly hydrophilic carbon nanotube immobilized SAP membrane for generation of water from the atmosphere. Sagar Roy, Chaudhery Mustansar Hussain and Somenath Mitra, Carbon nanotube-immobilized super-absorbent membrane for harvesting water from the atmosphere, Environ. Sci.: Water Res. Technol., 2015, 1, 753
Experiment: 1. Stirring 3hr. CNTs + SAP CNIM-SAP 2. Porous polypropylene Stirring support 0.1 wt% overnight. 3. 60 °C overnight sonication 3 hr. annealing. Sagar Roy, Chaudhery Mustansar Hussain and Somenath Mitra, Carbon nanotube-immobilized super-absorbent membrane for harvesting water from the atmosphere, Environ. Sci.: Water Res. Technol., 2015, 1, 753
Experiment: poly(acrylamide-co-acrylic acid) Sagar Roy, Chaudhery Mustansar Hussain and Somenath Mitra, Carbon nanotube-immobilized super-absorbent membrane for harvesting water from the atmosphere, Environ. Sci.: Water Res. Technol., 2015, 1, 753
Result and Discussion: Fig. 2 The contact angle and the photograph of the water drop on (a) unmodified PP Fig. 3 The variation of water sorption in CNIM-SAP at different water vapor membrane, (b) hydrophilized PP membrane, (c) SAP membrane over the modified PP concentrations and temperatures. support and (d) CNIM-SAP membrane over the modified PP support. Sagar Roy, Chaudhery Mustansar Hussain and Somenath Mitra, Carbon nanotube-immobilized super-absorbent membrane for harvesting water from the atmosphere, Environ. Sci.: Water Res. Technol., 2015, 1, 753
Result and Discussion: Fig. 5 (a) Water vapor flux, (b) water vapor removal and (c) enhancement in Fig. 4 (a) Water vapor removal, (b) water vapor flux and (c) enhancement in water vapor removal (at 68% RH) as a function of the inlet flow rate at water vapor removal (at 1 mL min−1) as a function of the inlet feed different temperatures. concentration. Sagar Roy, Chaudhery Mustansar Hussain and Somenath Mitra, Carbon nanotube-immobilized super-absorbent membrane for harvesting water from the atmosphere, Environ. Sci.: Water Res. Technol., 2015, 1, 753
Result and Discussion: The membrane performance in terms of water vapor flux and % water vapor removal with time (at 25 °C and 68% RH). Sagar Roy, Chaudhery Mustansar Hussain and Somenath Mitra, Carbon nanotube-immobilized super-absorbent membrane for harvesting water from the atmosphere, Environ. Sci.: Water Res. Technol., 2015, 1, 753
Mechanism of water permeation in CNIM-SAP: Schematic representation of the permeation of water molecules through CNIM-SAP. Sagar Roy, Chaudhery Mustansar Hussain and Somenath Mitra, Carbon nanotube-immobilized super-absorbent membrane for harvesting water from the atmosphere, Environ. Sci.: Water Res. Technol., 2015, 1, 753
Conclusion: The highly hydrophilic CNIM-SAP was successfully employed to harvest water vapor from air. The presence of CNTs led to higher amounts of water vapor being extracted which increased with relative humidity. Advantages over a membrane without CNTs including enhancement in water vapor removal by as much as 52%, and 44% enhancement in mass transfer coefficients. The water vapor flux and the mass transfer coefficient of the membrane reached as high as 28.31 × 10 −9 gm mol cm −2 min −1 and 8.14 × 10 −7 m s −1 , respectively. CNIM-SAP an excellent membrane for harvesting pure water from air.
Possible work: We can use SAP+ Graphene composite for AWC(atmospheric water capture) because water transfer rate will be increase through the composite. SAP+ Graphene SAP
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