Composite cellulose membranes

Commercial interest in RO began with the first high-flux, high-NaCl-retention Loeb-Sourirajan anisotropic cellulose acetate membrane. Practical application began with the thin film composite (TFC) membrane and implementation for seawater desalination at Jeddah, Saudi Arabia [Muhurji et ak. Desalination, 76, 75 (1975)]. 

Bonfante et al. (73) used monoclonal antibodies and enzyme-gold complexes to reveal pectins and cellulose at the interface between the fungal wall and the host plasma membrane in AM roots (Fig. 6), and additional wall components have been investigated with other molecular probes (74-76). These studies indicate that the interface is an apoplastic space of high molecular complexity where the boundaries of the partners are defined. The examination of other endomycorrhizal systems has demonstrated that their interface is morphologically similar but different in composition. Cellulose and pectins are present at the interface... 

The effect of casting solution composition on flux and rejection of formamide-modified cellulose acetate membranes is shown in Figure 1, illustrating the general capability of this membrane type as function of solvent concentration. Membranes of casting solution composition cellulose diacetate/acetone/ formamide 23/52/25 (solvent-to-polymer ratio 2.26) were used as reference membranes in this work. 

This technique has also been employed for the preparation of a catalytic imprinted membrane by coating a cellulose membrane with a polymer incorporating particles imprinted with the transition-state analogue of a dehydrofluorination reaction [264]. The application of such an MIP composite membrane as the recognition element in an optical sensor has been reported for digitoxin analysis in serum samples by embedding digitoxin-MIP particles in polyvinyl chloride film in presence of plasticizer by the dry inversion process [265],... 

Cellulose acetate and linear aromatic polyamide membranes were the industry standard until 1972, when John Cadotte, then at North Star Research, prepared the first interfacial composite polyamide membrane.8 This new membrane exhibited both higher throughput and rejection of solutes at lower operating pressure than the here-to-date cellulose acetate and linear aromatic polyamide membranes. Later, Cadotte developed a fully aromatic interfacial composite membrane based on the reaction of phenylene diamine and trimesoyl chloride. This membrane became the new industry standard and is known today as FT30, and it is the basis for the majority... 

Membrane material. During the early days, membranes were usually made of cellulose acetate. At present, membranes can also be made from aromatic polyamide and thin-filmed polymer composites. Different membrane materials have their own distinctive characteristics, such as hydraulic resistance, pH range, temperature range, chlorine tolerance, and biodegradation tolerance. 

During the period of 1965 to 1972, the best data on flux and salt rejection for cellulose acetate membranes were exhibited by the composite membranes. However, these membranes never reached commercial viability efforts on them died out completely by 1975. Reasons for this appear to be threefold. First, composite cellulose acetate membranes were technically difficult to scale up. Second, the advent of noncellulosic composite membranes in 1972 (the NS-100 membrane) offered much more promise for high performance (salt rejection and water flux), especially for seawater desalination. Third, continual improvements in asymmetric cellulose acetate membrane casting technology (such as the development of swelling agents and of blend membranes) brought the performance of asymmetric membranes to full equality with composite cellulose acetate membranes. 

Zhang and Qi synthesized hybrid bacterial cellulose/titania. They obtained mesoporous Titania networks consisting of nanowires, using as a template bacterial cellulose membrane. The network obtained shows Titania photocatalytic activity [46]. Composites of cellulose acetate/silica were obtained by sol-gel method [47]. Tanaka and Kozuka precipitated silica by acid catalysis of tetraethyl orthosilicate (TEOS). The composites of cellulose acetate/silica showed... 

Bhattacharyya, A., Mohapatra, P. K., Ghanty, T. K., and Manchanda, V. K. 2008. A pH dependent transport and back transport of americium(III) through the cellulose triacetate composite polymer membrane of Cyanex-301 and TBP Role of H-bonding interactions. Physical Chemistry Chemical Physics 10 6274-6280. 

Poly(vinylidene fluoride) (PVDF) porous supports coated with cellulose [92] were commercialized by Dow (ETNA membranes). PVDF is soluble only in a few organic solvents such as dimethyl acetamide. Cellulose is very stable in organic and aqueous solvents. However, because of its low solubility, preparing cellulose membranes is not a trivial task. Stengaard [72] proposed the preparation of composite membranes by coating chlorotrifluoroethylene/vinylidene fluoride (CTFE/VF) or PVDF supports with hydroxyethylcellulose and hydroxypropylcel-... 

Cheng and Wiersma (1982, 1983) patented the composite MD membranes consisting of a hydrophobic top layer made of PTFE or PVDF and a hydrophilic sublayer made of cellulose acetate, polysulfone (PS), cellulose nitrate, or polyallylamine. 

Referring to microbial cellulose applications, bacterial nanocellulose has proven to be a remarkably versatile biomaterial with use in paper products, electronics, acoustic membranes, reinforcement of composite materials, membrane filters, hydraulic fracturing fluids, edible food packaging films, and due to its unique nanostructure and properties, in numerous medical and tissue-engineered applications (tissue-engineered constructs, wound healing devices, etc). 

Taha AA, Yn W, Wang H, Li F (2012) Preparation and application of functionalized cellulose acetate/silica composite nanofibrous membrane via electrospinning for Cr(VI) ion removal from aqueous solution. J Environ Manag 112 10-16... 

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