2. ENVIRONMENTAL ChEMISTRy & TEChNOLOGy 2.1. Lectures

Chem. Listy, 102, s265–s1311 (2008) Environmental Chemistry & Technology
P27 REPROCESSING OF DANGEROuS PuT-OuT
ChEMICALS AND wASTES
JURAJ KIZLInK
Faculty of Chemistry, Brno University of Technology, Purkyňova
118, 612 00 Brno,
kizlink@fch.vutbr.cz
Introduction
The possibilities of reprocessing of some dangerous put-
out chemicals and wastes are described. The usual way for
the disposal of these compounds and wastes is the effective
combustion in the suitable incinerator. However, this facility
must be equipped with effective furnace, vigorous supplier
for air-oxygen, hold-up of waste gases for at least six seconds
and also with effective cleaning of emissions 1–4 . Procedure is
relatively simple, however too expensive. Some of these chemicals
and wastes can be disposed by total decomposition by
means of strong reactive chemical agents 5–10 . We suggested
and also elaborated the chemical reprocessing of these chemicals
or their wastes into some non-toxic chemicals, suitable
for technical praxis.
Proposed Procedures
B e n z i d i n e ( 4 , 4 ’ - d i a m i n o d i p h e n y l )
( 9 2 - 8 7 - 5 )
Benzidine as dangerous proved chemical cancerogen is
already put out from chemical praxis and usually its diposal is
due to combustion in suitable mixtures of more combustible
materials 1–4 . This compoun is possible to change by reprocessing
into aromatic etherical compound. The base of this
reprocessing is diazotation of benzidine (base, hydrochlorine,
sulfate) in the methanolic solution by dry hydrochlorine and
then with addition of concentrated water solution or finelly
powdered alkaline nitrite in the ice bath. When diazotization
is over, another methanol is added and the reaction
mixture is very slowly heated (simmered) in the large flask
under reflux water-cooled condenser. The diazonium salt is
slowly decomposed, the nitrogen gas escape and in the methanol
solution after heating up to boiling is converted into
the 4,4’-dimethoxydiphenyl compound (fragrance). nOTE:
The volume in the flask must be at least twice larger than
volume of reaction mixture because the escape of nitrogen
gas is vigorous and it is possible to reach explosion hazard
of the flask. This compound often contains 4,4’-dihydroxydiphenyl
as impurity, especially if this reaction is carried out in
the presence of water.
When we need the pure compound, it is possible to
apply alkalization by means of alkaline lye and then to use
some methylating agent, such as methyl iodide or dimethyl
sulfate 11,12 . In the case we use ethanol as solvent, after boiling
the diphenyl compound is obtained.
The similar procedure is possible to use for other aromatic
amines and diamines, such as 1,4-diaminobenzene known
as p-phenylene diamine (Ursol S, alergen, harmful substance)
and other aromatic diamines as 1-aminonaphtalene
s390
(alfa-naphtyl amine) and 2-aminonaphtalene (beta-naphtyl
amine, Feba, Fenyl-beta, PBn), which is also very potent
carcinogen!
H y d r a z i n e ( D i a z a n e ) / 3 0 2 - 0 1 -
2 / a n d A l s o H y d r a z i n e - H y d r a t e
( 1 0 2 1 7 - 5 2 - 4 )
Hydrazine in the salts (hydrochloride, sulphate) is relatively
stable substance and its disposal is quite safe 5–10 . Hydrazine
in the form of base or hydrate is also effective carcinogen
and its disposal is usually realized by the means of
combustion 1–4 .This substance is possible to convert to prosperous
compound by boiling with benzaldehyde resulting
into substituted hydrazone, known in the cosmetic industry
under trade name Benzalazine (cheap UV-absorber for suncreams).
H y d r o g e n C y a n i d e ( F o r m o n i t r i l e ,
Z y k l o n B ) ( 7 4 - 9 0 - 0 8 ) a n d A l k a l i n e
C y a n i d e s K C n ( 1 5 1 - 5 0 - 8 ) a n d
n a C n ( 1 4 3 - 3 3 - 9 )
Hydrogen cyanide and alkaline cyanides are very toxic
substances. They could be totally decomposed under influence
of strong oxidative agents, such as alkaline hypochlorites,
hydrogen peroxide and fumic nitric acid, even to nitrogen,
carbon dioxide and water 13–15 . However all concentrated
alkaline cyanides could be converted by heating of their ethanolic
solution together with benzyl chloride and the benzyl
cyanide (phenylacetonitrile). After addition of toluene into
reaction mixture, followed by azeotropical distillation and
removal of reaction water the phenylacetic acid ethyl ester
is obtained. This compound is possible to obtain as pure substance
(fragrance) after suitable drying (calcium chloride or
sodium sulphate) and distillation. After reduction by hydrides
it is possible to obtain 2-phenylethanol (fragrance) as the chemical
substitute of natural rose oil.
REFEREnCES
1. Brunner C. D.: Incineration Systems, Selection and
Design, Van nostrand - Reinhold, new York 1984.
2. Dawson G. W., Mercer B. W.: Hazardous Waste Management,
Wiley, new York 1986.
3. Bilitewski B., Hardtle G., Marek K.: Abfallwirtschaft,
Springer Verlag, Berlin 1991.
4. LaGrega M. D., Buckingham P. L., Evans J. C.: Hazardous
Waste Management, McGraw-Hill, new York
2001.
5. Lunn G., Sansone B.: Destruction of Hazardous Chemicals
in the Laboratory, Wiley, new York 1990.
6. Luxon S. G.: Hazards in the Chemical Laboratory,
Royal Society of Chemistry, London 1992.
7. Richardson M. L.: Risk Management of Chemicals,
Royal Society of Chemistry, London 1992.
8. Stricoff R. S., Walters D. B.: Handbook of Laboratory
Health and Safety, Wiley, new York 1995.