Nanofiltration membranes separation technology

Kosutic, K., Furac, L., Sipos, L. and Kunst, B. (2005) Removal of arsenic and pesticides from drinking water by nanofiltration membranes. Separation and Purification Technology, 42(2), 137-44. 

J. Cadotte, R. Forester, M. Kim, R. Petersen and T. Stocker, Nanofiltration Membranes Broaden the Use of Membrane Separation Technology, p. 77, Copyright 1988, with permission from Elsevier... 

Nanofiltration (NF) is a pressure-driven membrane separation technology used to separate ions from solution. Nanofiltration membranes were widely available beginning in the 1980 s. This technology uses microporous membranes with pore sizes ranging from about 0.001 to 0.01 microns. Nanofiltration is closely related to RO in that both technologies are used to separate ions from solution. Both NF and RO primarily use thin-film composite, polyamide membranes with a thin polyamide skin atop a polysulfone support (see Chapter 4.2.2). 

Cadotte, J. et al.. Nanofiltration membranes broaden the use of membrane separation technology. Desalination, 70, 77, 1988. 

Maiti, S. K., Lukka Thuyavan, Y., Singh, S., Obetoi, H. S., Agarwal, G. P. (2012). Modeling of the separation of inhibitory components horn pretreated rice straw hydrolysate by nanofiltration membranes. Bioresource Technology, 114, 419—427. 

Nanofiltration (NF) is a pressure-driven membrane separation technology used to separate ions from solution. Nanofiltration membranes were widely available beginning in the 1980 s. This technology uses micropo-rous membranes with pore sizes ranging from about 0.001 to 0.01 microns. 

J. Liu, Z. Xu, X. Li, Y. Zhang, Y. Zhou, Z. Wang, X. Wang, An improved process to prepare high separation performance PA/PVDF hollow fiber composite nanofiltration membranes. Separation arulPurification Technology, 58 (2007) 53-60. 

N. Stafle, D.F. Stamatialis, M. Wessling, Effect ofPDMS cross-linking degree on the permeation performance of PAN/PDMS composite nanofiltration membranes. Separation and Purification Technology, 45 (2005) 220-231. 

This book was planned to commemorate the announcement of the first cellulose acetate membrane for reverse osmosis by Loeb and Sourirajan in 1960, which triggered R D activities for seawater desalination by membrane and eventually resulted in emergence of a novel industrial separation process. Membrane separation technologies that include reverse osmosis, nanofiltration, ultrafiltarion, membrane gas and vapor separation, pervaporation, membrane extraction, membrane distillation, bipolar membrane and others, touch nowadays all aspects of human life since they are applied in various branches of industries such as chemical process, petrochemical and petroleum, pharmaceutical, environmental and food processing industries. 

Membrane technology may become essential if zero-discharge mills become a requirement or legislation on water use becomes very restrictive. The type of membrane fractionation required varies according to the use that is to be made of the treated water. This issue is addressed in Chapter 35, which describes the apphcation of membrane processes in the pulp and paper industry for treatment of the effluent generated. Chapter 36 focuses on the apphcation of membrane bioreactors in wastewater treatment. Chapter 37 describes the apphcations of hollow fiber contactors in membrane-assisted solvent extraction for the recovery of metallic pollutants. The apphcations of membrane contactors in the treatment of gaseous waste streams are presented in Chapter 38. Chapter 39 deals with an important development in the strip dispersion technique for actinide recovery/metal separation. Chapter 40 focuses on electrically enhanced membrane separation and catalysis. Chapter 41 contains important case studies on the treatment of effluent in the leather industry. The case studies cover the work carried out at pilot plant level with membrane bioreactors and reverse osmosis. Development in nanofiltration and a case study on the recovery of impurity-free sodium thiocyanate in the acrylic industry are described in Chapter 42. 

Nanofiltration is a rapidly advancing membrane separation technique for concentration/separation of important fine chemicals as well as treatment of effluents in pharmaceutical industry due to its unique charge-based repulsion property [5]. Nanofiltration, also termed as loose reverse osmosis, is capable of solving a wide variety of separation problems associated with bulk drug industry. It is a pressure-driven membrane process and indicates a specific domain of membrane technology that hes between ultrafiltration and reverse osmosis [6]. The process uses a membrane that selectively restricts flow of solutes while permitting flow of the solvent. It is closely related to reverse osmosis and is called loose RO as the pores in NF are more open than those in RO and compounds with molecular weight 150-300 Da are rejected. NF is a kinetic process and not equilibrium driven [7]. 

Therefore, the need of the hour was to develop an economical alternate separation technology capable of replacing the GFC system by providing rejection of all impurities in a single step with permeation of NaSCN and water. The membrane-based nanofiltration technique appeared to be a suitable alternative based on some of the aspects discussed in the scope of the work [180-184]. 

This chapter focuses on the chemical processing of ceramic membranes, which has to date constituted the major part of inorganic membrane development. Before going further into the ceramic aspect, it is important to understand the requirements for ceramic membrane materials in terms of porous structure, chemical composition, and shape. In separation technologies based on permselective membranes, the difference in filtered species ranges from micrometer-sized particles to nanometer-sized species, such as molecular solutes or gas molecules. One can see that the connected porosity of the membrane must be adapted to the class of products to be separated. For this reason, ceramic membrane manufacture is concerned with macropores above 0.1 pm in diameter for microfiltration, mesopores ranging from 0.1 pm to 2 nm for ultrafiltration, and nanopores less than 2 nm in diameter for nanofiltration, per-vaporation, or gas separation. Dense membranes are also of interest for gas... 

Focusing on the recent advances and updates, this section addresses new development in chemical and pharmaceutical industries and in the conservation of natural resources. Included in this edition are newer practices and technologies and their applications or trends for future applications with relevant references that have appeared in the literature since the first edition was published. Several new chapters on emerging areas such as membrane separation in petrochemical oil refinery, chitosan as new material for membrane preparation, new membrane material for ultrafiltration (UF) and nanofiltration (NF), and potential application of reverse osmosis (RO) in chemical industry have been added in the second edition. 

The membrane separation process was initially conducted in degumming vegetable oil and then was adapted for the recovery of carotenoids. Dense polymeric membranes are employed in this system and are very effective in the separatirm of xanthophylls, phospholipids, and chlorophyll, with retention of 80-100 %, producing an oil rich in carotenes [72,73]. This process, however, requires an additional step of hydrolysis or transesterification. Chiu, Coutinho, and Gruigalves examined the membrane technology as an alternative to concentrate carotenoids from crude palm oil in detriment of ethyl esters. A flat sheet polymeric membrane constituted by polyethersulfone was used and obtained a retention rate of 78.5 % [74]. Damoko and Cheryan obtained similar results using nanofiltration with 2.76 MPa and 40 °C in red palm methyl esters [75]. Whereas Tsui and Cheryan combined ultraiiltration with nanofiltration to separate zein and xanthophylls from ethanolic com extract [76]. 

R. Hnang, G. Chen, B. Yang, C. Gao, Positively charged composite nanofiltration membrane from qnatemized chitosan by toluene diisocyanate cross-linking. Separation and Purification Technology, 61 (2008) 424-429. 

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