Degradation Studies of β-Cyclodextrin Polyurethane Polymers using Soil Burial Experiments

Degradation studies of β-cyclodextrin polymers cross-linked with toluene-2,4-diisocyanate (TDI) and hexamethylene diisocyanate (HMDI) were carried out by exposing the polymers to different soil types for up to 120 days. The aim of the study was to determine the fate of these novel polymers in the environment. The polymers were either digested with sulphuric acid prior to performing a soil burial test or buried undigested. Results from the study indicate that the β-CD/TDI polymers with aromatic links underwent a greater mass loss during soil burial when first digested in sulphuric acid (ca. 50 % maximum mass loss). The β-CD/HMDIpolymers, on the other hand, underwent the same mass loss for both the digested and undigested polymers (ca. 30 % maximum mass loss). Although the Fourier transform infrared (FTIR) spectroscopy data suggested no changes in the overall polymer structures, the scanning electron microscopy (SEM) micrographs revealed changes in the surface morphology of the polymers. Moreover, results of thermogravimetric analysis (TGA) point to polymer degradation under all conditions tested.Keywords: Degradation, cyclodextrin polyurethanes, scanning electron microscopy, soil burial test, microorganism

Humic acid as a model for natural organic matter (NOM) in the removal of odorants from water by cyclodextrin polyurethanes

Current practices in some water-treatment facilities have reported that natural organic matter (NOM) blocks the adsorption sites of activated carbon resulting in lower geosmin and 2-methylisoborneol (2-MIB) removal. Humic acid has been reported to compete with geosmin and 2-MIB removal in the same way. The removal of odour chemicals such as geosmin and 2-MIB is important for potable-water treatment by water supply companies and municipalities. We have previously demonstrated that cyclodextrin polyurethanes are capable of removing a number of organic pollutants from water, but are not able to reduce the levels of NOM significantly. We wished to determine if the polymers would selectively remove geosmin and 2-MIB, despite the presence of NOM. Humic acid was chosen as a model for NOM since NOM constitutes about 70% of humic acid. Results obtained from this study indicate that the presence of humic acids at different concentrations could not affect the removal of geosmin and 2-MIB when cyclodextrin polymers were used since 90% removal was achieved. However the UV-Vis analysis showed a low removal of humic acids (3 to 20%)

Removal of geosmin and 2-methylisorboneol (2-MIB) in water from Zuikerbosch Treatment Plant (Rand Water) using â-cyclodextrin polyurethanes

Geosmin and 2-methylisorboneol (2-MIB) are major organic pollutants responsible for undesirable taste and odour in water. These compounds impact greatly on the aesthetic quality and general consumer acceptability of drinking water. The use of granular activated carbon (GAC) in the removal of geosmin and 2-MIB is generally ineffective since these compounds are present at very low concentrations (ngE.-1). Water treatment technologies that can remove geosmin and 2-MIB from water below human detection threshold (<10 ngE.-1) are highly sought by drinking water supplies, e.g. Rand Water. The removal of these odour-causing compounds from water samples using cyclodextrin- based nanoporous polyurethanes was investigated in our laboratory. Geosmin and 2-MIB were extracted from water samples by solid phase micro-extraction (SPME) and analysis was carried out using gas chromatography-mass spectrometry (GC-MS). Results from the analysis demonstrated that thesepolymers were highly effective in removing geosmin and 2-MIB

Sample preparation techniques for GC

Sample preparation is still considered the most time-consuming and error-prone step within the analytical process in many research fields. This is particularly true in food and environmental analysis where the complexity of many of the investigated matrices and the low concentration levels at which the target compounds should be accurately determined made necessary the use of tedious and highly manipulative multistep sample preparation protocols. This chapter reviews current state of the art in the field of sample preparation for combined use with gas chromatographic-based techniques. The most relevant developments achieved in the last two decades in this active research area have been reviewed and discussed on the basis of representative application studies primarily taken from the environmental and food fields. As in other research areas, miniaturisation and increased integration of the several treatment steps typically required for the preparation of these matrices are revealed as the most relevant trends within this step of the analytical process.Author thanks MINECO (CTQ2010-32957) and CM and FEDER program (project S2009/AGR-1464, ANALISYC-II) for financial support.Peer reviewe