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ARS Home » Pacific West Area » Parlier, California » San Joaquin Valley Agricultural Sciences Center » Commodity Protection and Quality Research » Research » Publications at this Location » Publication #300683
Title: Activated carbons from end-products of tree nut and tree fruit production as sorbents for removing methyl bromide in ventilation effluent from postharvest chamber fumigation

Author
item Hall Iv, Wiley
item Bellamy, David
item Walse, Spencer

Submitted to: Journal of Agricultural and Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/11/2015
Publication Date: 3/11/2015
Citation: Hall IV, W.A., Bellamy, D.E., Walse, S.S. 2015. Activated carbons from end-products of tree nut and tree fruit production as sorbents for removing methyl bromide in ventilation effluent from postharvest chamber fumigation. Journal of Agricultural and Food Chemistry. 63(12):3094-3103.

Interpretive Summary: Methyl bromide (MB) is a postharvest fumigant that is highly effective against insect and microorganism pests. MB is also an atmospheric source of reactive bromine gases, which deplete stratospheric ozone. Anthropogenic utilization of MB is regulated by international agreement under the Montreal Protocol. In instances where postharvest chamber fumigations are permitted, contribution(s) to ozone depletion can be minimized, or eliminated, by removing MB from the ventilation effluent via activated carbon sorbent. As part of a larger research project to develop the most cost-effective activated carbons for this use, we conducted experiments to determine if end-products of tree fruits and tree nuts produced in California, USA, respectively pits and shells, yield activated carbons capable of trapping MB in chamber effluent. Activated carbons from prune pits were more effective at trapping MB compared to commercially-marketed activated carbon derived from coconut shells that is imported into the United States. Peach pits and walnut shells were nearly as effective. Producing activated carbons from sources in close proximity to the fumigation facilities could serve to keep MB out of the stratosphere as well as reduce costs associated with transporting activated carbons via seaways and roadways from remote manufacturers to the fumigation facility.

Technical Abstract: End-products of tree nuts and tree fruits grown in California, USA were evaluated for the ability to remove methyl bromide from the ventilation effluent of postharvest chamber fumigations. Activated carbon sorbents from walnut and almond shells as well as peach and prune pits were prepared using different methods of pyrolysis, activation, and quenching. The relative performance of each preparation and each source was evaluated as a function of yield from starting material (%, m/m), the number of doses needed to first observe the breakthrough of methyl bromide (MB) through a column bed, and the corresponding capacity (%, m/m). Activated carbons from prune pits prepared by steam activation and carbon dioxide activation with water quenching required the greatest number of doses prior to the breakthrough of MB and had the highest capacity, ~12 to 14 %, outperforming a commercially-marketed activated carbon derived from coconut shells. Experimental evidence is presented that links performance discrepancy between sources of activated carbon to the preferential sorption of water vapor to methyl bromide.