Improvements in our knowledge of materials science aspects of nanocomposite formation and of fundamental processes governing transport through reactive nanostructures are likely to guide the development of nanoparticle-enabled multifunctional membranes. Better understanding of the mechanisms of reactions at the nanostructured surface and within the confi nes of membrane nanopores is needed to describe the reactive transport
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in membranes. The progress in membrane materials could be expected in directions of increased structural and functional complexity (e.g., evolving, adaptive, or programmable structures), leveraging structure–function coupling (e.g., nanoparticle-directed healing of structural defects, or, conversely, removal of compromised or even sacrifi cial portions of the membrane matrix) and process intensifi cation (e.g., use of membrane asymmetry to establish and separate in space a hierarchical sequence of membrane functions). Of immediate interest is elucidating the roles of key variables that are unique for nanocomposite membranes: (i) nanoparticle dispersion and distribution within host matrices such as polymers, multilayer polyelectrolyte fi lms, grafted polymeric fi lms, and so on, (ii) nanoparticle–
matrix adhesion, (iii) changes in the structure (porosity, connectivity) and properties (permeability, hydrophilicity, tensile strength, compressibility) of the host matrix, especially if nanoparticles were introduced into the forming matrix, (iv) changes in the nanoparticle properties, especially if nanoparticles were synthesized in preformed or forming porous matrix.
Acknowledgment
This material is based upon work supported by the National Science Foundation under grant nos. 0530174 and 0506828.
Figure 5.6 Eff ect of transmembrane pressure on permeate fl ux at an ozone concentration of 5.5 g/m 3 and a cross-fl ow velocity of 0.47 m/s.
1 1.5 0 0.5
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1
2 Permeate volume [L]
0.68 bar 1.36 bar 2.03 bar
2.03 bar−9.5 g/m3
Normalized permeate flux
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Membranes: Applications for Water Purifi cation and Desalination
Olgica Bakajin, 1 Aleksandr Noy, 1 Francesco Fornasiero, 1 Costas P. Grigoropoulos ,2 Jason K. Holt ,1 Jung Bin In ,1 ,2 Sangil Kim ,1 and Hyung Gyu Park 1 1 Molecular Biophysics and Functional Nanostructures Group, Chemistry, Materials, Earth, and Life Sciences Directorate, Lawrence Livermore National Laboratory, Livermore, CA, USA
2
Department of Mechanical Engineering, University of California at Berkeley, Berkeley, CA, USA