Due to its considerable advantages over lower alcohols such as ethanol, in particular with regard to its physical properties like volatility, corrosivity, and hygroscopicity, butanol has attracted considerable interest as a potential biofuel candidate. It has therefore been a target of a series of experimental studies probing its combustion characteristics. Nevertheless, its ignition behaviour at elevated pressures still remains widely unexplored. The present study investigates the oxidation of n-butanol at pressures near 80 bar. Ignition delays were determined experimentally in the temperature range of 795-1200 K between 61 and 92 bar.The time of ignition was determined by recording pressure and CH-emission time histories throughout the course of the experiments. The results display the first evidence of the influence of negative temperature coefficient (NTC) behaviour which was not observed in earlier ignition studies. The high pressure measurements show that NTC behaviour is enhanced as pressures are increased. The experimental results were modelled using an improved chemical kinetic mechanism which includes a simplified submechanism for butylperoxy formation and isomerisation reactions currently absent in n-butanol kinetic models.The detailed mechanism validated with the high pressure ignition results for realistic engine in-cylinder conditions can have significant impact on future advanced low temperature combustion engines.

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Bentazone is a herbicide, which is frequently detected in groundwater due to its mobility and persistence in aquifers. Groundwater is used as a drinking water source all over the world, and sustainable methods to remove pesticides at low concentrations are urgently needed since pesticide contaminations can adversely affect human health. The aim of this study was to investigate whether microbial bentazone degradation was associated with methane oxidation in full-scale drinking water treatment plants.To this end, we investigated bentazone biodegradation in microcosms with water and filter material from rapid sand filters, or biomass from aeration systems, and we investigated the statistical relation between the presence of methane and bentazone in groundwater abstraction wells. An array of evidence supported an association between bentazone degradation and methane oxidation in the biological treatment process. The biodegradation potential of bentazone was associated with the presence of methane in the raw water at 14 different water works. In contrast, no association was observed with any of the other investigated inorganic energy sources, e.g., ammonium. Addition of acetylene inhibited methane oxidation and the bentazone degradation in filter material from two investigated waterworks. Biomass from the aeration tanks degraded bentazone, but only while oxidizing methane. Bentazone removal rates and methane removal rates correlated significantly across all the experiments with biomass or filter material, with an overall transformation yield of 15 ± 1 × 10 −5 mole BTZ /mole CH4 . This demonstrated that the bentazone degradation was conducted by the same type of process in all the investigated communities, governed by methane oxidation. Furthermore, based on more than 10.000 water analyses from waterworks abstraction wells in Denmark, bentazone was detected significantly less frequent in wells with high methane concentrations (>1 mg/L) than in wells without methane. This suggests that biological treatment of bentazone contamination in drinking water may be achieved using methanotrophs.

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