PET-modified red mud as catalysts for oxidative desulfurization reactions

This work describes the synthesis of catalysts based on red mud/polyethylene terephthalate(PET) composites and their subsequent heat treatment under N2 atmosphere.The materials were characterized by scanning electron microscopy(SEM),temperature programmed reduction(TPR),Fourier transform infrared spectroscopy(FT–IR),X-ray diffraction(XRD),thermogravimetric(TG) analysis and N2adsorption/desorption.The catalysts were evaluated in the oxidative desulfurization reaction of dibenzothiophene(DBT) in a biphasic system.The results indicated that the PET impregnation on red mud increased the affinity of the catalyst with the nonpolar phase(fuel),in which the contaminant was dissolved,allowing a higher conversion(up to 80%) and selectivity to the corresponding dibenzothiophene sulfone.The sulfone compound is more polar than DBT and diffused into the polar solvent as indicated by the data obtained via gas chromatography–mass spectrometry(GC–MS).     

Effects of reduced nitrogen and sulphur deposition on the water chemistry of moorland pools

To assess changes as a result of reduced acidifying deposition, water chemistry data from 68 Dutch moorland pools were collected during the periods 1983-1984 and 2000-2006. Partial recovery was observed: nitrate- and ammonium-N, sulphur and aluminium concentrations decreased, while pH and alkalinity increased. Calcium and magnesium concentrations decreased. These trends were supported by long term monitoring data (1978-2006) of four pools. Increased pH correlated with increases in ortho-phosphate and turbidity, the latter due to stronger coloration by organic acids. Increased ortho-phosphate and turbidity are probably the result of stronger decomposition of organic sediments due to decreased acidification and may hamper full recovery of moorland pool communities. In addition to meeting emission targets for NO_x, NH_x and SO_x, restoration measures are still required to facilitate and accelerate recovery of acidified moorland pools.     

The effect of turbation on zinc relocation in a vertical floodplain soil profile

Turbation is hypothesized to affect the redistribution of heavy metals in polluted floodplain soils by effects on mobility. This hypothesis was tested in microcosms by turbation of zinc-spiked sediment top layers. Manual turbation caused a fast decrease of the zinc content in the upper 15 cm of the soil, even though turbation was only applied to the upper two centimetres. It was especially zinc attached to colloid and organic matter particles that was redistributed from the top layer. Percolation processes resulted in the attached zinc being drained to depths of more than 15 cm. The decrease in zinc content of the topsoil was even stronger in combination with inundation. No indications were found for the redistribution of zinc as a result of an increase of the extractability with 0.01 M CaCl2 or changes in pH. The findings suggest that mechanical turbation and bioturbation may redistribute heavy metals from topsoils in polluted floodplains just after inundation as observed in these turbation experiments.