Solubility measurements and determination of Setschenow constants for the pesticide carbaryl in seawater and other electrolyte solutions

Abstract

Accurate solubility measurements covering the range 278–318 K were obtained for the carbamate pesticide carbaryl (1-naphthyl-N-methylcarbamate) in water, natural and artificial seawater, and NaCl, Na2SO4, CaCl2, and (CH3)4NBr electrolyte solutions. Carbaryl solubilities were determined using a combination of a generator column method and spectrophotometric techniques. In all cases the solubility of carbaryl in water and in the electrolyte solutions increased with an increase in temperature. The salt effect on the pesticide solubility as a function of temperature was obtained by calculating the Setschenow constants for each one of the electrolyte solutions. Salting-out was observed in solutions prepared with NaCl, Na2SO4, and CaCl2 as well as in natural and artificial seawater, whereas salting-in was observed with (CH3)4NBr solutions.