Article

A review on nanofiltration membrane fabrication and modification using polyelectrolytes: Effective ways to develop membrane selective barriers and rejection capability

Department of Chemical and Process Engineering, Faculty of Engineering and Built Environment, Universiti Kebangsaan Malaysia, 43600 UKM Bangi, Selangor, Malaysia.
Advances in Colloid and Interface Science (Impact Factor: 8.64). 05/2013; 197–198. DOI: 10.1016/j.cis.2013.04.004
Source: PubMed

ABSTRACT The performance of nanofiltration (NF) processes is mainly governed by factors such as the sieving effect (also known as size exclusion) and the Donnan effect (which depends on membrane surface charges). This has encouraged the development of new types of NF membranes using various kinds of polyelectrolytes as they have good pore-sealing effects and are able to improve the membrane surface charge density. Manipulation of the pH, supporting electrolyte concentration, type and concentration of polyelectrolyte solutions can significantly vary the characteristics of polyelectrolyte molecules thus improving their electrostatic interactions with the surrounding compounds. This is highly desired and useful when polyelectrolytes are to be incorporated in membrane surface modification as the charges formed can increase the membrane surface charge density, membrane surface coating stability and membrane selectivity. Most of the research discussed in this paper employed the special features of polyelectrolyte molecules to improve the performance of NF membranes in various applications. Various methods have been used to incorporate polyelectrolytes in order to improve NF membrane performance, such as static deposition, dynamic deposition, single layer coating, layer-by-layer (LbL) coating, and so forth. Some of the suitable devices or instruments used for polyelectrolyte-modified membranes are recommended and evaluated. In conclusion, polyelectrolyte-modified membranes offer significant improvements, can be produced in a short period of time, require less energy during membrane modification or fabrication and incur lower production costs. Thus, a full understanding of the factors affecting polyelectrolyte-modified membranes is very much desired and worth further detailed investigation in the near future.

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    • "Agglomeration is a common phenomenon at higher concentrations of nanoparticles. This may lead to unwanted membrane characteristic such as weak polymer structure and pore blockage [10]. Therefore, there is a need for a new approach to improve homogenisation and reduce the agglomeration of nanoparticles in order to synthesise a high-performance membrane. "
    The Chemical Engineering Journal 04/2015; DOI:10.1016/j.cej.2015.04.107
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    • "Agglomeration is a common phenomenon at higher concentrations of nanoparticles. This may lead to unwanted membrane characteristic such as weak polymer structure and pore blockage [10]. Therefore, there is a need for a new approach to improve homogenisation and reduce the agglomeration of nanoparticles in order to synthesise a high-performance membrane. "
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    • "Previously, we have verified that NF membranes prepared by a domestic polyacrylonitrile (PAN) exhibited excellent retention for bivalent calcium ions [14]. However, some other problems, including short lifetime and low efficiency, have strictly restricted the development of NF, which is commonly caused by concentration polarization and membrane fouling in daily operation [15] [16]. In order to circumvent those problems, modification of membrane materials is usually adopted to improve the membrane performance, apart from the optimization of operation conditions [17] [18]. "
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