Sorption Of Ethylene Dibromide Research Articles

Sorption of Selected Organic Compounds from Water to a Peat Soil and Its Humic-Acid and Humin Fractions: Potential Sources of the Sorption Nonlinearity

The sorption isotherms of ethylene dibromide (EDB), diuron (DUN), and 3,5-dichlorophenol (DCP) from water on the humic acid and humin fractions of a peat soil and on the humic-acid of a muck soil have been measured. The data were compared with those of the solutes with the whole peat from which the humic-acid (HA) and humin (HM) fractions were derived and on which the sorption of the solutes exhibited varying extents of nonlinear capacities at low relative concentrations (Ce/Sw). The HA fraction as prepared by the density-fractionated method is relatively pure and presumably free of high-surface-area carbonaceous material (HSACM) that is considered to be responsible for the observed nonlinear sorption for nonpolar solutes (e.g., EDB) on the peat; conversely, the base-insoluble HM fraction as prepared is presumed to be enriched with HSACM, as manifested by the greatly higher BET-(N2) surface area than that of the whole peat. The sorption of EDB on HA exhibits no visible nonlinear effect, whereas the sorption on HM shows an enhanced nonlinearity over that on the whole peat. The sorption of polar DUN and DCP on HA and HM display nonlinear effects comparable with those on the whole peat; the effects are much more significant than those with nonpolar EDB. These results conform to the hypothesis that adsorption onto a small amount of strongly adsorbing HSACM is largely responsible for the nonlinear sorption of nonpolar solutes on soils and that additional specific interactions with the active groups of soil organic matter are responsible for the generally higher nonlinear sorption of the polar solutes.

Removal of Ethylene Dibromide from Citrus Fumigation Chambers

ABSTRACT ALL fresh Florida citrus which is exported to other United States citrus producing areas and Japan must be fumigated with ethylene dibromide (EDB). The fumigant can cause an air pollution hazard. De-sign parameters related to the recovery and contain-ment of the fumigant were investigated. Initial EDB vapor concentration of 5.1 to 17.5 g/m3 were reduced by 1.4 to 6.0 g/m3 through sorption of EDB by cartons and fruit. Over 70 percent of the EDB reduction was attributed to sorption by the cartons. Activated carbon was utilized for recovery of the remaining EDB in fumigation chambers. The adsorption relationship between activated carbon and EDB followed the Freundlich power law relationship. Field work was undertaken to validate laboratory results. A portable filter unit that could recover a minimum of 60 percent of the EDB vapor in 1 hr was developed.

Cereal Sorption of Grain Fumigants, Sorption of Ethylene Dibromide, Ethylene Dichloride, and Carbon Tetrachloride by Cereal Products

Cereal Sorption of Grain Fumigants, Sorption of Ethylene Dibromide, Ethylene Dichloride, and Carbon Tetrachloride by Cereal Products

Soil fumigation. IV.—Sorption of ethylene dibromide on soils at field capacity

AbstractSorption of ethylene dibromide was studied in the presence of air on twenty different soils at moisture contents corresponding to field capacity. The soils ranged from coarse sands through silts and clays to heavy peats. All isotherms were linear and the sorption coefficient (slope of the isotherm) could be correlated with surface area, with organic matter content, with moisture content and less closely with clay content. The latter three soil properties also correlated with each other. It was found possible to predict the sorption coefficient with reasonable accuracy from moisture content alone.

Problems connected with ethylene dibromide fumigation of cereals. I.—sorption of ethylene dibromide by grain

AbstractIn this paper experiments on ethylene dibromide fumigation of different cereal species are described in which the influence of various fumigation conditions on the content of bromine is studied. Two bromine forms were found to be present in fumigated grain: a volatile bromide (unchanged ethylene dibromide), and a non‐volatile, water‐soluble bromide. Differences in sorption of ethylene dibromide by various cereals seemed to result from differences in seed structures.By airing of fumigated grain free ethylene dibromide is removed gradually, but the content of bound bromine is not markedly changed. Under usual conditions of fumigation of whole grain in silos, the volatile bromide disappears after airing for 6‐7 weeks.

Soil fumigation. III —The sorption of ethylene dibromide by soils at low moisture contents

AbstractIsotherms of ethylene dibromide sorbed on two soils have been plotted at relative humidities between o and 98% of saturation. The sorptive capacities of the soils (an organic soil and a clay) decreased with increasing humidity, and the shape of the isotherms obtained changed from Type II (Brunauer, Deming, Deming & Teller1 classification of isotherms) on the dry soils, becoming similar to Type III isotherms at humidities above 50%. The measurements were made with the aid of a helical spring balance, the construction of which is described.

Soil fumigation. I.—the sorption of ethylene dibromide by soils

AbstractSorption of ethylene dibromide by soils is rapid, the greater part of the total amount sorbed being taken up within half an hour. Equilibrium was established by the end of 24 hours. Sorption isotherms on the air‐dried and moist soils have been plotted. Over the usual field range of moisture content the amount of ethylene dibromide held by the soil remains constant; the total amount sorbed increases slightly with increasing moisture content owing to solution of the fumigant in the soil water. In this range of moisture content the amount sorbed is proportional to the content of organic carbon of the soils. Very little evidence for any irreversible sorption or decomposition of ethylene dibromide by the soils has been found over the range 10‐25°.