Cyclodextrin-ionic liquid polyurethanes for application in drinking water treatment

The prevalence of toxic contaminants in water remains a huge challenge for water-supplying companies and municipalities. Both organic and inorganic (especially heavy metals) pollutants are often present in water distribution networks. The presence of these contaminants in drinking water poses a major risk to human health. Organic and inorganic pollutants often co-occur in drinking water networks. However, at present there is no water treatment intervention that simultaneously removes both organic and inorganic pollutants from water to desirable levels. In our laboratories, recent studies have shown that both functionalised and un-functionalised cyclodextrin (CD) polymers are capable of removing organic pollutants from water, with the functionalised CD polymers showing an enhanced absorption capability. Ionic liquids (ILs), on the other hand, have been reported to absorb heavy metals from aqueous media. In this paper, we report on the synthesis of several cyclodextrin-ionic liquid (CD-IL) polymers, a dual system capable of removing both organic and inorganic pollutants from water. This system has been tested and has proved to possess excellent capabilities for the removal of model pollutants such as p-nitrophenol (PNP), 2,4,6-trichlorophenol (TCP) and chromium (Cr6+) from aqueous media.Keywords: organic and inorganic pollutants, CD polymers, ionic liquids, CD-IL polymer

Synthesis and characterisation of ultrafiltration membranes functionalised with C18 as a modifier for adsorption capabilities of polyaromatic hydrocarbons

The disposal of wastewater containing polyaromatic hydrocarbons (PAHs) has been observed to be a very costly process, hence mitigation for many industrial plants continues to be a challenge. The purpose of this study was to examine the potential use of C18 as a modifier in membrane technology; thus, C18 was incorporated into poly (vinylidene fluoride) (PVDF) membranes. According to the specific composition ratios, the phase inversion process was used for dispersion of the C18 into PVDF, which was subsequently dispersed in 1-methyl-2-pyrrolidone (NMP). The resulting membranes were characterised with Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The mechanical properties of the membranes were analysed using dynamic mechanical analysis (DMA), whereas the thermal behaviour was studied with a thermogravimetric analyser (TGA). Furthermore, the functionality of the synthesised membrane was further evaluated by its adsorption potentials using high performance liquid chromatography equipped with an ultraviolet detector. The SEM micrographs showed successful incorporation of the C18 within the polymeric membrane (PVDF) backbone. The TGA showed that the thermal decomposition of the synthesised membranes was observed at 495 and 610°C for PVDF bare and PVDF/C18, respectively. In addition, the HPLC results obtained indicated that the C18 modified membrane was more effective in adsorbing PAHs when compared to the bare PVDF membrane. The salient features of this study therefore suggest that C18 could be used as a potential modifier for the development of PVDF membranes