James G. Leesch

Methyl bromide adsorption on activated carbon to control emissions from commodity fumigations.

A process to control emissions of methyl bromide (MB) into the atmosphere following the fumigation of commodities has been developed. The process consists of adsorbing the MB in the vent-stream from a fumigation process onto activated carbon (carbon). Research was undertaken to observe the eAects of (1) temperature, (2) relative humidity (r.h.), (3) the concentration of MB in the vent-stream, and (4) carbon type on the amount of MB that could be adsorbed (loaded) on the activated carbon. Temperature had the most eAect on the loading, followed by r.h., for a given type of carbon. The loading decreased as temperature and r.h. increased. For a given temperature and r.h., the loading varied significantly for diAerent carbon types. These diAerences were consistent with the type of pore structures of the carbons, which in turn is determined by the raw materials and by the activation procedures used during the carbon manufacturing process. Temperatures in the carbon column rose in response to the adsorption of MB. By monitoring the temperatures, the adsorption zone could be followed throughout the column from the inlet at the start of an adsorption run to column exhaustion, or breakthrough at the end of the trial. Breakthrough was reached when the MB concentration in the column exhaust stream reached 500 ppm (2 mg/l) MB. Relative humidity of the vent-stream was less critical than first anticipated because of the heating of the column. The temperature increase due to the heat of adsorption lowered the r.h. at the adsorption zone which led to the increased adsorption capacity normally associated with low humidities. Published by Elsevier Science Ltd.

Large-Scale, On-Site Confirmatory, and Varietal Testing of a Methyl Bromide Quarantine Treatment to Control Codling Moth (Lepidoptera: Tortricidae) in Nectarines Exported to Japan

Abstract In total, 30,491 codling moth, Cydia pomonella (L.), 1-d-old eggs on May Grand nectarines in two large-scale tests, and 17,410 eggs on Royal Giant nectarines in four on-site confirmatory tests were controlled with 100% mortality after fumigation with a methyl bromide quarantine treatment (48 g3 for 2 h at ≥21°C and 50% volume chamber load) on fruit in shipping containers for export to Japan. Ranges (mean ± SEM) were for percentage sorption 34.7 ± 6.2 to 46.5 ± 2.5, and for concentration multiplied by time products 54.3 ± 0.9 to 74.5 ± 0.6 g · h/m3 in all tests. In large-scale tests with May Grand nectarines, inorganic bromide residues 48 h after fumigation ranged from 6.8 ± 0.7 to 6.9 ± 0.5 ppm, which were below the U.S. Environmental Protection Agency tolerance of 20 ppm; and, organic bromide residues were <0.01 ppm after 1 d and <0.001 ppm after 3 d in storage at 0–1°C. After completion of large-scale and on-site confirmatory test requirements, fumigation of 10 nectarine cultivars in shipping containers for export to Japan was approved in 1995. Comparison of LD50s developed for methyl bromide on 1-d-old codling moth eggs on May Grand and Summer Grand nectarines in 1997 versus those developed for nine cultivars in the previous 11 yr showed no significant differences in codling moth response among the cultivars.