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Substance Identification
Published in Philip H. Howard, Edward M. Michalenko, William F. Jarvis, Dipak K. Basu, Gloria W. Sage, William M. Meylan, Julie A. Beauman, D. Anthony Gray, Handbook of Environmental FATE and EXPOSURE DATA, 2017
Philip H. Howard, Edward M. Michalenko, William F. Jarvis, Dipak K. Basu, Gloria W. Sage, William M. Meylan, Julie A. Beauman, D. Anthony Gray
Summary: Pentachloronitrobenzene (PCNB) is used as an intermediate, herbicide, fungicide for seed and soil treatment, and as a slime inhibitor in industrial waters. PCNB released to soil is not expected to leach extensively. Field and laboratory half-lives for PCNB in soil vary from several weeks to almost 2 years. Volatilization may be the most significant loss mechanism for PCNB from aerobic soils, followed by biodegradation. In a anaerobic soil, PCNB loss was principally by conversion to pentachloroaniline (PCA). PCNB released to water will sorb to sediments, suspended solids, and biota. The Henry’s Law constant for PCNB indicates that volatilization from water may be significant; however, sorption of PCNB to organic particulate matter in water will decrease the significance of volatilization. PCNB will have a low to moderate tendency to bioconcentrate (BCF in fish 200-1200). Photolysis and hydrolysis of PCNB are probably not significant degradative processes. biodegradation appears to be relatively slow; however, it may be a significant degradative process for PCNB in water. No information was found on the fate of PCNB in the atmosphere; however, it will probably adsorb to particulate matter and thus may be removed from the atmosphere by wet and dry deposition. PCNB has been found in drinking water, well water, crop land and nursery soils, spinach leaves, cheese, fruits, ground grains, leaf and stem vegetables, nuts, and oilseed byproducts. The most probable route of human exposure to PCNB will probably be through the ingestion of contaminated food.
Reduction
Published in Richard A. Larson, Eric J. Weber, Reaction Mechanisms in Environmental Organic Chemistry, 2018
Richard A. Larson, Eric J. Weber
Pentachloronitrobenzene (PCNB) is another example of a nitroaromatic agrochemical that is known to undergo facile reduction in anaerobic systems. PCNB has been identified as a pollutant in river water and groundwater (Fushiwaki et al., 1990). Reduction of PCNB results in the formation of pentachloroaniline, which is fairly resistant to further transformation pathways (Wang and Broadbent, 1973; Kuhn and Suflita, 1989a) (Equation 3.23). ()
Novel drying and pretreatment methods for control of pesticide residues in fruits and vegetables: A review
Published in Drying Technology, 2023
Tiantian Tang, Min Zhang, Ronghua Ju, Arun S. Mujumdar, Dongxing Yu
Microwave drying generates heat by directly converting electromagnetic energy into kinetic energy of molecules, which makes the liquid moisture evaporate and transport to the material surface.[66] Compared with traditional hot air drying, microwave is faster and more energy-saving, but there is a problem of uneven drying. Several studies have reported that microwave drying can effectively reduce pesticide residues, which is mainly attributed to the thermal effect.[37] Zhao et al.[37] reported that microwave drying had the best degradation effect on pesticide residues in jujube compared with sun-, freeze-, and oven-drying, with the degradation rate of 66.9–93.2%. Zhang et al.[67] investigated the effects of microwave drying on pesticide residues in ginseng. The results showed that the degradation rate increased with the increase of drying temperature, and the highest pesticide removal rate was obtained after microwave drying for 32 min, which was 58.51% for fluazinam, 51.39% for BHC, 58.26% for PCNB, 16.54% for chlorpyrifos, and 18.14% for DDT. Acoglu and Yolci Omeroglu[65] also found that microwave pretreatment of orange slices before hot air and vacuum drying could effectively increase the degradation rate of pesticide, and the highest degradation rate of buprofezin and thiophanate-methyl was observed in microwave-hot air drying.