Removal of organic contaminants from water using nanosponge cyclodextrin polyurethanes

Abstract

Insoluble nanoporous cyclodextrin (CD) polymers were synthesized using bifunctional isocyanate linkers. The ability of these polymers to remove selected organic pollutants from water at varying concentrations was studied. The investigated pollutants were selected high-priority chlorinated disinfection by-products (DBPs) and a common odour-causing compound in water, 2-methylisoborneol (2-MIB). The unpleasant musty odour imparted by 2-MIB and geosmin in water can be detected by the human nose even at ng L −1 (parts per trillion) levels. Pre-concentration and extraction of water samples containing low levels of pollutants was performed using solid phase extraction (SPE) and subsequently quantified by gas chromatography-mass spectrometry (GC/MS). Here we show that the CD polymers demonstrate excellent absorption efficiency (>99%) with respect to the organic pollutants, considerably better than granular activated carbon (GAC). The recyclability efficiency of these CD polymers is also reported.

γ-Cyclodextrin Cuprate Sandwich-Type Complexes

“…They are (i) an increase in the thermal motion at higher temperatures and (ii) a higher affinity between the assembly and CO 2 molecules. A previous study 16 with a CDbased polymer also showed little N 2 uptake. The activated Li 4 [Li 4 (OH 2 ) 4 Cu 4 (γ-CDH −8 ) 2 ] sample exhibited an uptake of 40 cm 3 /g CO 2 at 1 bar and a NLDFT surface area of 370 m 2 /g, as estimated from the CO 2 gas isotherm data collected.…”

Polymerization of Cyclodextrin-Ionic Liquid Complexes for the Removal of Organic and Inorganic Contaminants from Water

“…In our laboratories the use of cyclodextrin polyurethanes has been studied. These CD polymers have been found to have a high efficiency for the removal of organic pollutants from water, even at ppb levels (Mhlanga et al, 2007). Cyclodextrin polyurethanes are discussed in the following sections.…”

“…Converting them to water insoluble entities is therefore crucial if CDs are to be utilised in the removal of contaminants from water. To attain this property, CD derivatives have been polymerised with suitable bifunctional linkers in our laboratories to produce water insoluble polymers (Mhlanga et al, 2007;Mamba et al, 2007;Salipira et al, 2007). The presence of the OH groups in the CDs or CD-derivatives allows a reaction in which the monomers react with linkers to produce insoluble polymers.…”

“…The CD polyurethanes have demonstrated a high efficiency for the absorption of organic pollutants in water (Mhlanga et al, 2007;Mamba et al, 2007;Salipira et al, 2007). However, in real water systems organic and inorganic contaminants co-exist; the challenge is to craft a water treatment system that is capable of simultaneously removing these contaminants from water.…”

Application of Cyclodextrins in Textile Dyeing

“…The amount of aromatic organic pollutants (phenols, aniline, formaldehyde and others) can be reduced from dyeing wastewater by using cyclodextrins which can be immobilized on a water insoluble organic support. The new concept for modification of textile substrates is based on permanent fixation of supramolecular compounds -cyclodextrins on the material surface and thus imparts new functionality to the fabric Mhlanga et al, 2007). The guest molecules could be various organic molecules and some metal ions as well.…”