Document gEbVQ60w3nndwNrV8Qd8OapoJ

Monsanto MOM IN4MC ft I.OCAT '"'W- W- Richard - BBaenrah nuntgp OATS October 8, 1969 auftjcer ftircMNci TO D. R. Miller Attached are the first of several Internal papers dealing with various aspects of the "Aroclor pollution" problem. The purpose is to stimulate thinking and encourage an Input of Ideas as to what steps should be taken to minimize adverse effects on our business. Anyone wishing to put his oar In Is Invited to do so, either by writing his own white paper or by-commenting on subject matter which has already appeared. Papers may or may not be "in depth" reviews of a specific topic. We anticipate that short concise reports will be of most value, but anything contributing to the stated objective will be satisfactory. W. R. Richard ms iN. 10 *<V It MQNS 09S166 SOME TENTATIVE RULES FOR PREDICTING BIOLOGICAL REFRACTIVITY OF HALOGENATED AROMATICS Q. E. Thompson Evidence to date Indicates that among chlorinated biphenyls those molecules containing 4 or more chlorine atoms per molecule are the chief offenders insofar as biological con tamination Is concerned. The higher Aroclors are thus said to be "refractive" with respect to natural degradative pro cesses. The extent to which lower chlorinated biphenyls are refractive remains to be determined. A considerable literature exists concerning the blodegradablllty of chlorinated hydrocarbon pesticides. Several recent papers (1,2,3) give results which may be of use in predicting biodegradability of Aroclors and some possible Aroclor substitutes. In brief, the findings may be sum marized aB follows. A. Aliphatic Hydrocarbons; Aliphatic materials containing one chlorine atom are not refractive. Additional chlorine substitution markedly Increases refractiveness (Dleldrln, Aldrln, Heptachlor, DDT) although the latter may still be somewhat degradable under anaerobic con ditions. _ B. A Benzene Nucleus 1. When not substituted with at least one C-atom or one O-atom, a benzene ring becomes refractory with only one Cl-atom attached. DDT and DDD seem to be special cases In which refractiveness Is Increased by the high degree of chlorination In the aliphatic portion of the molecule, 1.e. CClaCH # and CHClaCH ^@hCl j g 2. A benzene nucleus substituted by one C-atom or one O-atom generally requires at least two chlorines before it becomes refractive. Examples: HONS 098167 -2- Cl OCHaCOOH not refractory while the 2,4,6 trlchloro analog la. d) Ar-0 substitution alleviates refractlvity more than Ar-C substitution (cf b vs. c_) e) An Isomer with chlorine closest to the point of ' substitution will metabolize slower than one with chlorine substitution farther away (1-chloronapthalene slower than 2-chloro Isomer, o-chlorobenzolc acid slower than p_-chlorobenzolc acid) Applying the preceding observations to the Aroclor situation permits the following predictions. A Aroclors Cl-T >C1 probably not refractory - neither ring has more than two chlorines. -1242 (4l* Cl) .2 ci-^ Cl borderline - probably not completely refractory. ~1248 (48.55 Cl) 3. refractory - B. Bromochlors 1 2 3. Would conform to the same rules. equivalent to Aroclor 1248 would no longer be borderline but should be at least as degradable as the (Cl)s-blphenyl. equivalent to 1254 in physical properties but approximately the same as Aroclor 1248 in refractlvity equivalent to 1242 in physical properties but less refractive. MONS 098168 -3C. OthSI* possible Aroclor replacements less refractory than (Cl)4-blphenyl 2. Diphenyl sulfides - Cl_(/ \s~c\-Cl probably still less refractory than the corresponding oxygen ether since is more electron re leasing than -0-. Undoubtedly, additional factors such as water solubility, hydrolytic stability as well as oxidative and light stability also influence the extent of environmental refractiveness. Thus, for example, highly chlorinated materials which could hydrolyse readily to chlorophenols (pentachlorophenol, etc.) might be expected to be substantially less serious long term contaminants than a material of similar or lesser chlorine oontent which resists the Initial hydrolytic attack. Speolflc data on these points are however lacking at present. October 6, 1969 MONS 098169 REFERENCES: 1. R. W. Olte'y and R. H. Bogan, "The Apparent Involvement of Electronic Mechanisms in Limiting the Microbial Metabolism of Pesticides", J. Water Pollution Control Federation. 37, 692 (1965) ~ " 2. D. W. Hill and P. L. McCarty, "Anaerobic Degradation of Selected Chlorinated Hydrocarbon Pesticides", ibid., 39, 1259 (19<>7). -------- 3. H. 0. Schwartz, "Microbial Degradation of Pesticides in Aqueous Solutions", ibid,. 39, 1701 (1967). MONS 098170 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 DDP 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 organlo 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, aoylated 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 ba 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. MONS 098171 -2- A. Oxidative Degradation The simplest method of disposal one would consider is burning in presenoe 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 oould be recovered as ferric chloride and stannic ohlorlde. B. Pyrolytic Degradation Pyrolysis under reducing condition with HI catalyst and ammonia could lead to progressive dehalogenatlon above 270. Exhaustive chlorination above 300* should produce lower chlorinated olefins, e.g. CaCl.t, C3C10, 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 FeCls, SnCl and the lower perchlorlnated allcanes (l.e.CgClg) 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 sulfidlc ore, possibly in presence of coke; adsorption on clay and burning, adsorption on suitable carriers 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 MONS 098111