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On February 6, 1978, two maintenance workers employed by a chemical company in Atlanta, Georgia, became ill after cleaning a clogged drain. Both were hospitalized with acute fulminant hemolytic anemia and renal failure. While the clinical picture suggested arsine or stibine poisoning, preliminary investigation of the plant revealed no obvious source of arsenic, antimony, or hydrogen gas. During the cleaning operation, the men drained a mixing tank that 5 yr before had been used to store arsenical herbicides. To unclog the drain, they added a standard drain cleaner containing sodium hydroxide and aluminum chips, a combination that reacted to release hydrogen gas. This gas combined with the arsenic residue to form toxic quantities of arsine gas (arsenic trihydride). Arsenic was found in the liquid and gas from the drain and in blood and urine of both patients, and of two other workers who worked in the vicinity of the drain. This investigation suggests that drain cleaners which react to release hydrogen should not be used in situations where arsenic or antimony may be present. Furthermore, maintenance men, who may be exposed to the chemicals used in a plant, should be educated, supervised, and screened so that their risk for occupational hazards may be reduced.

Calorimetric heats of adsorption have been determined at coverages up to one-tenth of a monolayer for hydrogen sulfide, methanethiol, ethanethiol, and dimethyl sulfide, adsorbed at 423°K on silica gels of varying surface hydroxyl group concentrations. Adsorption isotherms have been determined and entropies of adsorption calculated to provide additional data on the nature of the adsorbed species. The high values of the initial heats of adsorption of up to 30 kcal mol-1 are associated with surface heterogeneity. Subsequently, at coverages greater than 0.020 /¿mol m-2 a similar type of adsorbed species is probably formed by all gases through interactions involving the formation of hydrogen bonds between surface hydroxyl hydrogen atoms and the sulfur atoms of the adsorbate. The differences in heats, entropies, and adsorption capacities for these gases are believed to be related to the magnitude of the inductive effect on the sulfur atom. A decrease in the heat of adsorption and adsorption capacity and an increase in the entropy of the adsorbed species occurred with all gases as the surface hydroxyl group concentration of the silica gels was decreased.

Calorimetric beats of adsorption for sulfur dioxide at low surface coverages from 0.004 to 0.600 μmol m−2 on a number of supported transition metal catalysts have been measured between 273 and 423 °K mainly by an adiabatic technique. The catalysts included Fe2O3, Mn2O3, V2O5, MnSO4, and "NiS" ail supported on silica gel.Sulfur dioxide adsorption/desorption isotherms, nitrogen adsorption data, and chemical and infrared analyses were also determined to provide further ancillary information.Heats of adsorption at 423 °K for adsorbed amounts of 0.004 μmol m−2 varied with the adsorbent from nearly 39.0 for Mn2O3 on silica gel to 23.0 kcal mol−1 for the silica gel support medium. With increase in surface coverage to 0.600 μmol m−2 the heat values begin to steady at 6 to 7, 7 to 8, and 8 to 9 kcal mol−1 at 423, 373, and 323 °K, respectively, and less discrimination is observed among the various materials. Preadsorption of small amounts of sulfur dioxide on the supported oxides followed by oxygen admission caused sharp initial falls of as much as 7 to 8 kcal mol−1 in the heat values whereas preadsorption of oxygen followed by sulfur dioxide gave only slight heat increases of around 1 kcal mol−1.It is proposed that sulfur dioxide is chemisorbed on all surfaces with the strongest interactions occurring at the lowest coverages. Sulfates are formed on the oxides as confirmed by chemical analysis, and it is postulated that multiple hydrogen bond formation occurs on silica gel through the interaction of sulfur dioxide oxygen atoms with surface hydroxy groups.

Heats and entropies of adsorption have been determined for sulfur dioxide on commercial grades of activated charcoal and carbon black from 323 to 423 K by calorimetry. The pore structures, physical forms, and surface oxygen contents of the adsorbents were also studied. The results can be of general value in the development and applications of carbon adsorbents in the removal of sulfur dioxide from waste gases and similar effluents. It is concluded that the variation in the amount of surface oxygen present on the carbon surfaces has greater influence on adsorption heats and capacities than the physical characteristics of the adsorbents.