title: The influence of cosolvent and heat on the solubility and reactivity of organophosphorous pesticide DNAPL alkaline hydrolysis.
abstract: The presented research concerned the compatibility of cosolvents with in situ alkaline hydrolysis (ISAH) for treatment of organophosphorous (OPP) pesticide contaminated sites. In addition, the influence of moderate temperature heat increments was studied as a possible enhancement method. A complex dense non-aqueous phase liquid (DNAPL) of primarily parathion (~50 %) and methyl parathion (~15 %) obtained from the Danish Groyne 42 site was used as a contaminant source, and ethanol and propan-2-ol (0, 25, and 50 v/v%) was used as cosolvents in tap water and 0.34 M NaOH. Both cosolvents showed OPP solubility enhancement at 50 v/v% cosolvent content, with slightly higher OPP concentrations reached with propan-2-ol. Data on hydrolysis products did not show a clear trend with respect to alkaline hydrolysis reactivity in the presence of cosolvents. Results indicated that the hydrolysis rate of methyl-parathion (MP3) decreased with addition of cosolvent, whereas the hydrolysis rate of ethyl-parathion (EP3) remained constant, and overall indications were that the hydrolysis reactions were limited by the rate of hydrolysis rather than NAPL dissolution. In addition to cosolvents, the influence of low-temperature heating on ISAH was studied. Increasing reaction temperature from 10 to 30 °C provided an average rate of hydrolysis enhancement by a factor of 1.4-4.8 dependent on the base of calculation. When combining 50 v/v% cosolvent addition and heating to 30 °C, EP3 solubility was significantly enhanced and results for O,O-diethyl-thiophosphoric acid (EP2 acid) showed a significant enhancement of hydrolysis as well. However, this could not be supported by para-nitrophenol (PNP) data indicating the instability of this product in the presence of cosolvent.
authors: Department of Chemistry and Bioscience, Section of Chemical Engineering, Aalborg University, Niels Bohrs Vej 8, DK-6700, Esbjerg, Denmark. jm@bio.aau.dk.
authors: Jens
authors: http://orcid.org/0000-0003-1082-3409
authors: J
authors: Muff
authors: Geosyntec Consultants Inc., 130 Research Lane, Suite 2, Guelph, Ontario, Canada.
authors: Leah
authors: L
authors: MacKinnon
authors: Geosyntec Consultants Inc., 10220 Old Columbia Road, Suite A, Columbia, USA.
authors: Neal D
authors: ND
authors: Durant
authors: Rambøll, Forurenet jord og grundvand, Lysholt Allé 6, DK-7100, Vejle, Denmark.
authors: Lars Frausing
authors: LF
authors: Bennedsen
authors: COWI A/S, Jord og Grundvand, Parallelvej 2, DK-2800, Kongens Lyngby, Denmark.
authors: Kirsten
authors: K
authors: Rügge
authors: Central Denmark Region, Environment, Lægårdvej 12, DK-7500, Holstebro, Denmark.
authors: Morten
authors: M
authors: Bondgaard
authors: Department of Civil and Environmental Engineering, Tufts University, 200 College Avenue, Medford, MA, 02155, USA.
authors: Kurt
authors: K
authors: Pennell
mesh_terms: D000468:Alkalies / Q000737:chemistry; D006358:Hot Temperature; D006868:Hydrolysis; D009943:Organophosphorus Compounds / Q000737:chemistry*; D010278:Parathion; D010575:Pesticides / Q000737:chemistry*; D012995:Solubility; D013696:Temperature; D014874:Water Pollutants, Chemical / Q000737:chemistry
chemical_list: D000468:Alkalies; D009943:Organophosphorus Compounds; D010575:Pesticides; D014874:Water Pollutants, Chemical; D010278:Parathion
keywords: Cosolvent; DNAPL; In-situ alkaline hydrolysis (ISAH); Organophosphorous pesticides; Parathion