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Title:UČINKOVITOST KEMIJSKO MODIFICIRANIH NF MEMBRAN PRI ZADRŽEVANJU IONOV TEŽKIH KOVIN
Authors:ID Pečovnik, Kristina (Author)
ID Lobnik, Aleksandra (Mentor) More about this mentor... New window
ID Poberžnik, Mojca (Comentor)
Files:.pdf UNI_Pecovnik_Kristina_2012.pdf (3,35 MB)
MD5: 6D9820F4324B6FE165E24F114F609FAB
PID: 20.500.12556/dkum/58fa395b-8aa1-4319-aaee-241da3689ac1
 
Language:Slovenian
Work type:Undergraduate thesis
Typology:2.11 - Undergraduate Thesis
Organization:FS - Faculty of Mechanical Engineering
Abstract:Polimerne membrane se pogosto pojavljajo v različnih separacijskih procesih, kot npr. pri nanofiltraciji. Tankoplastne nanofiltracijske membrane (TFC NF) imajo sposobnost zadrževanja večvalentnih kationov, med njimi tudi ionov težkih kovin, vendar je njihova slabost ta, da se zaradi pojava koncentracijske polarizacije in mašenja (fouling) občutno zmanjša pretok skozi membrano. Namen modifikacije površine membrane je izboljšati njihovo selektivnost, ohraniti in povečati pretok skozi membrano (fluks), ohraniti stabilno strukturo, minimizirati nagnjenost k mašenju in s tem ugodno vplivati na separacijske lastnosti membran. V okviru raziskav za diplomsko delo je bila izvedena modifikacija komercialno dostopne tankoslojne kompozitne NF membrane (NF2, Sepro Inc.) ter njena karakterizacija pred in po modifikaciji. Modifikacijo smo izvedli v kislem in bazičnem mediju (s pomočjo citronske kisline in natrijevega hidroksida). Namen raziskav je bil primerjati učinek zadrževanja ionov težkih kovin (cink, kadmij, svinec) v kombinaciji z različnima anionoma (- NO3- oz. Cl-) pri filtraciji skozi modificirano in nemodificirano NF2 membrano. Filtracija je bil izvedena pri različnih delovnih pogojih (pH 4; in tlaku 5; 20 in 44 bar). Na osnovi rezultatov filtracije, kot tudi iz analiz lastnosti (selektivnost, hidrofilnost, navidezna velikost por-NMWCO) osnovne in modificirane TFC NF2 membrane je razvidno, da lahko s preprosto kemijsko modifikacijo vplivamo na lastnosti membran v smislu površinskih karakteristik in morfološke strukture samega kompozita ter izboljšamo zadrževanje ionov težkih kovin, npr. pri delovnem tlaku 20 bar Pb2+ za 19% oz. 9% (iz raztopine PbNO3- oz. PbCl2), Cd2+ za 17% oz. 8% (iz raztopine CdNO3- oz. CdCl2) ter za Zn2+ za 4% oz. 8% (iz raztopine ZnNO3- oz. ZnCl2) glede na enako NF2 nemodificirano membrano.
Keywords:Nanofiltracija, tankoplastne kompozitne membrane, površinska modifikacija, ioni težkih kovin, cink, kadmij, svinec
Place of publishing:Maribor
Publisher:[K. Pečovnik]
Year of publishing:2012
PID:20.500.12556/DKUM-24449-cc8c7eef-1308-0452-e0b6-c0f594cd3dd9 New window
UDC:542.816(043.2)
COBISS.SI-ID:16301590 New window
NUK URN:URN:SI:UM:DK:ZAIP8WBM
Publication date in DKUM:29.06.2012
Views:3585
Downloads:307
Metadata:XML DC-XML DC-RDF
Categories:KTFMB - FS
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Secondary language

Language:English
Title:EFFICIENCY OF CHEMICALLY MODIFIED NF MEMBRAN BY HEAVY METAL IONS REJECTION
Abstract:Polymeric membranes often appear in different separation processes, for instance in nanofiltration. Thin film composite membranes (TFC NF) have the ability to reject multivalent cations, including heavy metal ions. However its weakness is that because of concentration polarization the flux through the membrane considerably decreases. The purpose of membrane surface modification is to improve their selectivity, preserve and increase the flux, preserve the stable structure, minimize the fouling phenomena and in that way have a positive influence on separation characteristics of membranes. Within the research of my diploma thesis a modification of a basic commercially accessible thin composite NF membrane (NF2, Sepro Inc.) was carried out and its characterization before and after the modification. The modification was carried out in an acid and basic medium (using citric acid and sodium hydroxide). The purpose of the research was to compare effectiveness of heavy metal ions rejection (zinc, cadmium, lead) in the combination with different anions (- NO3- or Cl-) during the filtration process using the modified (6h KM NF2) and non-modified NF2 membrane. The model filtration solutions were prepared as clear solutions of metal salts. The filtration was carried out under different operating conditions (pH 4; pressure 5; 20 and 44 bar). Based on the filtration efficiency results as well as from the characteristics (selectivity, hydrophilicity, molecular weight cut off-NMWCO) of basic and modified TFC NF2 membranes it can be stated that the membrane quality in the sense of surface characteristics and morphological structure of a composite can be influenced by a simple chemical modification. The filtration show that the surface modification of NF membranes can be effective in terms of heavy metal ions retention, e.g. at 20 bar Pb2+ retention from Pb(NO3)2 and PbCl2 solution is improved for 19% and 9%, respectively in comparison to non-modified membrane. Similarly the retention of Cd2+ from Cd(NO3)2 and CdCl2 solution is improved for 17% and 8% respectively and the retention of Zn2+ from Zn(NO3)2 and ZnCl2 for 4% and 9% respectively in comparison to the some NF2 non-modified membrane.
Keywords:Thin film composite membranes, nanofiltration, Surface modification, Heavy metal ions, Zinc, Cadmium, Lead


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