Methyl Bromide Recovery on Activated Carbon with Repeated Adsorption and Electrothermal Regeneration

Abstract

Methyl bromide is commonly used as a postharvest fumigant. Because it has been identified as an ozone-depleting substance, production of methyl bromide has been targeted for phaseout. Methyl bromide readily adsorbs onto activated carbon. In situ carbon regeneration is being investigated as a means of decreasing the expense of methyl bromide recovery. Heating by passing an electrical current through an adsorbent bed is an efficient means of regenerating carbon and can be performed in the same vessel in which adsorption occurs. Carbon adsorbs roughly 10% of its weight in methyl bromide and can be repeatedly regenerated using electrothermal desorption. Methyl bromide desorbed in this manner is easily condensed at moderate temperatures. Carbon was submitted to 12 adsorption/regeneration cycles and then compared with virgin samples in terms of adsorption equilibria and adsorption rate. The regenerated carbon experienced no loss of mass and exhibited nearly the same capacity as the fresh samples.