engleski

Comparison of Chemical and Physical-chemical Discoloring Methods

Today’ s chemical and physical-chemical wastewater discoloration methods do not completely meet demands regarding degree of discoloration. In this paper discoloration was performed using Fenton (FeSO4• 7H2O+H2O2+H2SO4) and Fenton-like (FeCl3• 6H2O+H2O2+HCOOH) chemical methods and physical-chemical method of coagulation/flocculation (using poly– electrolyte (POEL) combining anion active coagulant (modified poly-acrylamides) and cationic flocculant (product of nitrogen compounds) in combination with adsorption on activated carbon. Suitability of afore-said methods was investigated on reactive and acid dyes, regarding their most common use in textile industry. Also, investigations on dyes of different chromogen (anthracinone, phtalocyanine, azo and xanthene) were carried out in order of determining importance of molecular spatial structure. Oxidative effect of Fenton and Fenton-like reagents resulted in decomposition of colored chromogen and high degree of discoloration. However, the problem is the inability of adding POEL in stechiometrical ratio (also present in physical-chemical methods), when phenomenon of overdosing coagulants occurs in order of obtaining higher degree of discoloration, creating potential danger of burdening water with POEL. Input and output water quality was controlled through spectrophotometric measurements and standard biological parameters. In the addition, a part of the investigations concerned industrial wastewaters obtained from dyeing cotton materials using reactive dye (C.I. Reactive Blue 19), process which demands use of vast amounts of electrolytes. Also, investigations of industrial wastewaters was labeled as a crucial step carried out in order of avoiding serious of misassumptions and false conclusions, which may arise if dyeing processes are only laboratory simulated.

discoloration; reactive dyes; Fenton reagent; coagulation/flocculation; poly-electrolyte; water quality

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