Direct Chemical Oxidation of Mixed or Toxic Wastes

Abstract

Direct chem. oxidn. (DCO) is an ambient-pressure, low-temp. (<100 Deg), and aq.-based process for general-purpose destruction of the org. fraction of hazardous or mixed waste. It uses the peroxydisulfate anion (S2O82-) in acid or base solns. The byproduct of the oxidn. reaction, typically Na or NH4H sulfate, may be recycled electrolytically to produce the oxidant. The oxidn. kinetic reaction is 1st order with respect to the peroxydisulfate concn., expressed in equiv. The rate const. is const. for nearly all dissolved org. compds.: ka = 0.01 +- 0.005 min-1. This reflects a common rate-detg. step, which is the decompn. of the peroxydisulfate anion into the chem. active deriv., the sulfate radical anion, SO4-. This decompn. is promoted in DCO by raising the operating temp. into the range of 80-100 Deg. Rates are given for .apprx.30 substances with diverse functional groups at low concns., and for a no. of solid and liq. wastes typical of nuclear and chem. industries. The process was scale up for treatment studies on chlorinated hydrocarbons, in which the hydrolysis of solvent mixts. was followed by oxidn. of products in a series of stirred tank reactors.