Modelling the kinetics of ethyl formate sorption by wheat using batch experiments

• Published in: Pest management science 2009-09, Vol.65 (9), p.982-990
• Main Authors: Darby, James, Willis, Tracy, Damcevski, Katherine
• Format: Article
• Language: English
• Subjects: Adsorption; chemical concentration; diffusion; disinfestation; Enzyme kinetics; equilibrium partition; Experiments; food contamination; food safety; foods; formates; Formic Acid Esters - chemistry; fumigants; fumigation; Fumigation - methods; gaseous ethyl formate reaction; grain; Kinetics; mass transfer; methyl bromide; Models, Statistical; pesticide; pesticide residues; phosphine; postharvest treatment; reaction kinetics; simulation models; Sorption; Triticum - chemistry; Triticum aestivum; Wheat
• ISSN: 1526-498X; 1526-4998; 1526-4998
• DOI: 10.1002/ps.1783

BACKGROUND: Ethyl formate formulations are being considered to replace methyl bromide for fast grain disinfestation. Grain adsorbs ethyl formate rapidly, which can result in inadequate fumigation concentrations and unacceptable grain residues. A model of ethyl formate sorption kinetics will enable fumigation approaches to be determined that meet disinfestation and food safety requirements.RESULTS: This paper identifies all mass transport processes involved in ethyl formate sorption by wheat from published and experimental evidence. The model accounts for reaction losses of ethyl formate in air and grain using first-order kinetics, transport in the gas and solid phases with linear mass transfer coefficients and uses a linear partition relationship representation of sorption equilibrium. Batch experimental data were measured to determine model coefficients. Novel gaseous breakdown data for ethyl formate in air were measured, and first-order kinetics was demonstrated, although the specific reactions involved were not identified.CONCLUSION: The model predicts air and grain fumigant concentrations relevant for grain disinfestation and food residue contamination successfully. The form of the model should be applicable to all fumigant-grain systems, as it accounts for the diffusion and reaction influences known to occur with all modern fumigants under concentration and exposure conditions relevant to industry.