The aim of this study was to generate and characterize pyrolysis bio-oil from dried coffee grounds for the purpose of testing its pesticide characteristics towards selected microorganisms and the Colorado Potato Beetle. Dried coffee grounds were pyrolyzed to produce bio-oil. Pyrolysis was carried out at five different temperatures from 400 degrees C to 600 degrees C and at a vapor residence time of 5 s, to study the effect of temperature on the yield of the pyrolysis products. The trends clearly indicated a strong effect of temperature on the bio-oil yield. The highest bio-oil yield was found to be 43.8% at 500 degrees C. Gases were analyzed using gas chromatography-mass spectrometry (GC-MS). Gas yield increased from 17.6% at 400 degrees C to 32.1% at 600 degrees C. Char yield decreased from 35.2% at 400 degrees C to 19.6% at 600 degrees C.Each of the bio-oils produced between 400 and 600 degrees C were tested for bactericidal and insecticidal activities against pests found on plants in Canada that currently require improved control options. The dried coffee grounds bio-oil showed significant activity towards two bacteria (Streptomyces scabies and Clavibacter michiganensis subsp. michiganensis) and the Colorado Potato Beetle (Leptinotarsa decemlineata Say). The bio-oil was fractionated and tested for bactericidal and insecticidal activity. The most active fractions were analyzed using GC-MS. While some compounds in the bio-oil were active against both the insect and bacteria, the coffee grounds bio-oil also contained chemicals that provided additional insecticidal activity with no bactericidal activity. (C) 2011 Elsevier B.V. All rights reserved.

Tobacco bio-oil, gases, and char were produced through pyrolysis of tobacco leaves using a fluidized bed pilot plant under varying temperature (350, 400, 450, 500, 550, and 600 degrees C) and residence time (5, 10, and 17 s) conditions. The optimized condition for the production of bio-oil was found to be at 500 degrees C at a vapor residence time of 5 s, giving a bio-oil yield of 43.4%. The Colorado Potato Beetle (CPB) Leptinotarsa decemlineata L. (Coleoptera: Chrysomelidae), a destructive pest toward potato crops, and three microorganisms (Streptomyces scabies, Clavibacter michiganensis, and Pythium ultimum), all problematic in Canadian agriculture, were strongly affected by tobacco bio-oil generated at all pyrolysis temperatures. Nicotine-free fractions of the tobacco bio-oil were prepared through liquid liquid extraction, and high mortality rates for the CPB and inhibited growth for the microorganisms were still observed. A potential pesticide from tobacco bio-oil adds value to the biomass as well as the pyrolysis process.

Pyrolysis converts biomass such as agricultural and forestry waste into bio-oil, preserving some chemicals while creating other, new ones. Nicotine, a chemical present in tobacco leaves and a known pesticide, was found to remain intact during pyrolysis. As expected, insecticidal properties were observed for tobacco bio-oil. Pesticide characteristics of tobacco bio-oil have been observed on the Colorado potato beetle (CPB), a pest currently resistant to all major insecticides, as well as a few bacteria and fungi that do not currently respond well to chemical treatment. Unexpectedly, nicotine-free fractions of the bio-oil were also found to be highly lethal to the beetles and successful at inhibiting the growth of select microorganisms. Through GC-MS, it was found that the active, nicotine-free fractions were rich in phenolics, chemicals likely created from lignin during pyrolysis. While bio-oils in general are known to contain phenolic chemicals, such as cresols, to our best knowledge, quantitative analysis has not been performed to determine if these chemicals are solely responsible for the observed pesticide activities. Based on GC-MS results, ten of the most abundant chemicals, eight of which were phenolic chemicals, were identified and examined through bio-assays. A mixture of these chemicals at the concentration levels found in the bio-oil did not account for the bio-oil activity towards the microorganisms. Tobacco bio-oil may have potential as a pesticide, however, further analyses using liquid chromatography is necessary to identify the remaining active chemicals.

Single-stage and two-stage tubular electrostatic precipitators were designed. A nitrogen stream containing very fine droplets of fogging oil was forced through the electrostatic precipitator chamber. It was found that 98.6wt% of the oil droplets present in the turbulent jet were mechanically collected on the inner walls of the test chamber. When the electrode was energized at 13kV, 92.37wt% of the droplets that had not been mechanically separated were collected in single-stage mode. The collection efficiency was increased to 93.18wt%, when the electrostatic precipitator was operated in two-stage mode.Voltage–current (V–I) characteristics of the single-stage and two-stage electrostatic precipitators were studied in detail for different test conditions. Nitrogen impurities played a major role in determining the V–I characteristics. They became less relevant with the introduction of mist in the nitrogen stream, presumably due to the presence of water vapor in the gas.The two-stage tubular electrostatic precipitator was scaled up and tested on a fluidized bed pilot plant used for the pyrolysis of biomass. A droplet collection efficiency of 95wt% was observed. Such demisters will extend, to the product recovery train, the process intensification gains of short residence time processes such as fast pyrolysis.