Effect of Petroleum Carrier on Rate of Loss of Pentachlorophenol from Treated Stakes

After 12-year exposure in the soil, residual pentachlorophenol was determined in stakes treated originally with 4-lb. retentions of 5 percent penta in various types of petroleum oil. The amount of pentachlorophenol remaining in the stakes represented over 60 percent of the initial amount in all but two cases, and for most heavy oil solutions, it exceeded 75 percent. The loss of pentachlorophenol was proportionately greater from stakes treated to 8- and 12-pound retentions of two solutions, possibly because of greater bleeding of whole solution from the more heavily treated stakes. The finding of greater losses from heavily treated specimens is not in line with results that have been obtained in studies of the loss of creosote from treated wood. The residuals of pentachlorophenol found for the different oils do not vary so widely as might be expected in view of the wide range in such properties as distillation range and viscosity. With the light oils, the above-groundline portion showed more pentachlorophenol than did the below-groundline portion. This trend was reversed in the three heaviest oils. A possible explanation for this reversal may be in the smaller loss by evaporation of the heavier oils with less deposition of solid chemical in the upper parts of the stakes. There was no consistent relation between the effect that an oil had on, the permanence of pentachlorophenol and the effectiveness of the solution in preventing decay. This relation is complicated by differences in the toxicities of the oils themselves; as mentioned previously, several of the solvents, notably the two heaviest oils and the catalytic gas-base oil, gave considerable protection when used without the addition of pentachlorophenol. The conclusion is drawn that it is the permanence of the oil itself along with its toxicity that appears to be the main source of differences in the preservative effectiveness of various solutions of pentachlorophenol.

You must be logged in to download any documents. Please login (login accounts are free) or learn how to Become a Member