Document 6RKgKzQwQRx0waxvXEMew38a3

SCHEMES FOR THE RECOVERY AND DISPOSAL OF AROCLORS R. W. Weiss Improvement of analytical techniques has arrived at a point where parts per billion of stable chlorinated hydrocarbons can be identified. This led to discovery of DDT and more recently of PCB (polychlorinated biphenyl) in the environment, and whereas the harmful effects of DDT are known, PCB's are quite naturally suspected. This and the current emphasis on pollution prompts the question: what can and should be done to reduce the amount of Aroclor that now finds its way into the environ ment. Two obvious ways will be dealt with in the follow ing sections: Recovery of Aroclor from the environment by absorption of an organic phase or solute from the medium, air or water. Secondly, the innocuous disposal- of spent Aroclor containing fluids will be considered. I. Recovery of Aroclor dissolved or dispersed In wastewater. Recovery of Aroclors from water or air can be achieved by means of adsorbents or absorbents. Highly selective ad sorbents are desirable for an economic process. Active adsorbents are expected to be found under activated clays or earths, zeolites, alumina, dlcallte, active carbon, acylated cellulose or other polymers. Aroclor can also be preferentially absorbed on materials like tar, paraffins or waxes. The adsorbing or absorbing agents will be ad mixed with waste water and allowed to settle In tanks and lagoons. An alternative are suitably packed towers or pipes. The techniques involved are now commonly applied in the treating of industrial or household wastes. From expensive adsorbents Aroclor will have to be recovered by solvent extraction; cheaper material can be disposed . of like any other solid waste after removal from tanks and towers, drying or pressing. A screening program for the most suitable absorbers will he greatly facilitated by the excellent and sensitive analytical techniques available to identify Aroclors. II. Disposal of Aroclors . Large amounts of Aroclors will have to be disposed of In the foreseeable future at a rate of 10 million pounds a year. A considerable fraction of this will be contaminated with mineral oil and phosphate esters from our industrial hydraulic business. The following methods for disposal have been suggested. HONS 03003? -2- A. Oxidative Degradation The simplest method of disposal one would consider Is burning In presence of a combustible carrier In a hot furnace. There evolve considerable quantities of highly corrosive hydrochloric acid and chlorine which have to be scrubbed. Hydrochloric acid could In principle be recovered. The combustion can be carried out In presence of chlorine binders. The use of lime for this purpose requires a suitable setup for cleaning the furnace. Also feasible is the use of scrap iron or tin cans as binders. The chlorine from Aroclor pre sumably could be recovered as ferric chloride and stannic chloride, * B. Pyrolytic Degradation Pyrolysis under reduolng condition with N1 catalyst and ammonia could lead to progressive dehalogenatlon above 270*. Exhaustive chlorination above 300* should produce lower chlorinated olefins, e.g. CaCU, cCla, etc. The destructive chlorination technique might also be promoted by and oarrled out In conjunction with a tin recovery operation using tinned cans. Thus pyrolytic overchlorination of waste Aroclor in the presence of scrap Pe* and Sn* would afford Feds, SnCL* and the lower perchlorlnated alkanes (l.e.cCl) all of which are volatile, separable and have recovery value. C. Other Miscellaneous Methods Other methods suggested for disposal of Aroclor In clude roasting with sulfldlc ore, possibly In presence of coke; adsorption on clay and burning, adsorption on suitable oarrlers and burying and partial condensation on an acidic catalyst Increasing the molecular weight to render the material Innocuous. The methods under A. are suitable for contaminated Aroclor whereas the processes under B. and C. are probably only practical with material having a high content of Aroclor. October 8, 1969 03038