Membrane micro-porous carbon

Sircar, S. and Rao, M.B. (2000). Nano-porous carbon membranes for gas separation. In Recent Advances on Gas Separation by Micro-Porous Membranes (N. KaneUopoulos, ed.). Elsevier, pp. 473-6. 

Carbon dioxide in acidified blood samples is transferred through a hydrophobic micro-porous membrane and dissolved in an acceptor stream of basic buffer solution containing an acid-base indicator. The absorbance change is measured by spectrophotometry. 

A simple but effective macroscopic manipulation of carbon nanotube arrays called domino pushing has been developed to make thicker aligned carbon nanotube papers. The schematic of the domino pushing method is shown in Fig. 4.6. First, the nanotube array is covered with a piece of micro-porous membrane. The nanotubes in the array are then... 

The novel GPE mentioned above was adopted as an electrolyte for Sony s IPB. A schematic drawing of the Sony LPB is illustrated in Figure 7. LiCoOg and a small amount of carbon were coated on aluminum foil to prepare a positive electrode. Graphite for a negative electrode material was designed elaborately to be compatible with PC and was coated on copper foil. In addition to GPE membrane, very thin separator, micro-porous polyethylene film with thickness around 10 jxn. was used to prevent mechanical short circuits between positive and negative electrodes. 

A general template method for preparing nanomaterials has been investigated by Martin and others for the formation of micro- and nanoelectrode arrays (140). The method entails synthesis of the desired metal (or polymer, protein, semiconductor, carbon nanowire) within the cylindrical and monodisperse pores of a membrane or another porous material (Figure 10.9) (see also Section 16.2 in Chapter 16). 

Esquivel et al. (2010) present an all-polymer micro-DMFC fabricated with a SU-8 photoresistor. This development exploits the capability of SU-8 components to bond to each other by a hot-pressing process and obtain a compact device. The device is formed by a MEA sandwiched between two current collectors. The MEA consists of a porous SU-8 membrane filled with a proton-exchange polymer and covered by a thin layer of carbon-based electrodes with a low catalyst loading (1.0 mg/cm ). The current collectors consist of two metalhzed SU-8 plates provided with a grid of through-holes that make it possible to deliver the reactants to the MEA by diffusion. The components were then bonded to obtain a compact micro-DMFC. With this assembly, using a 4 M methanol concentration at a temperature of 40°C, a maximum power density of 4.15 mW/cm was obtained. 

To explore the difficulties in practical implementation of the above concepts, mixed matrix membranes, with 20% molecular sieves (by volume), were prepared by solution deposition on top of a porous ceramic support. The ceramic supports used were Anodise membrane filters which had 200 A pores that open into 2000 A pores and offer negligible resistance to gas flow. Initially the molecular sieve media, zeolites (4A crystals) or carbon molecular sieves, was dispersed in the solvent, dichloromethane, to remove entrapped air. After two hours, Matrimid was added to the mixture, and the solution was stirred for four hours. The solutions used varied in polymer content from 1-5 wt %. The solution was then deposited on top of the ceramic support, and the solvent was evaporated in a controlled manner. The membranes were then dried overnight at 90°C under vacuum. This was followed by a reactive intercalation post treatment technique 15) to eliminate defects. This technique involves imbibing a reactive monomer (e.g. diamine) from an inert solvent (e.g. heptane) into any micro defects. Next, a second reactive monomer (e.g. acid chloride) was introduced to reactively close defects by forming a low permeability polymer. The membranes were dried again to remove the inert solvent. Individual membrane thickness was determined by weight gain and varied from 5 to 25 Jim. 

Next, I turn to work on water confined in porous media of carbon-based materials. Bardenhagen and co-workers studied fluid distribution and pore wettability for water and dimethylsufoxide in carbon xerogels. They used H relaxation measurements and related the results to the liquid exchange between micro- and mesopores. Wakai et reported a study of the hydration process of a nafion membrane by H... 

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