STUDY OF HUMIC ACIDS CATALYTIC PROPERTIES IN REACTIONS OF SODIUM SULFITE LIQUID-PHASE OXIDATION

The paper focuses at researching the model reaction of sodium sulfite oxidation in soft conditions (T = 30 – 60o C, PO2 = 1 atm) in water solutions in the presence of copper (II) and iron (III) chlorides modified by humic acids to give sodium sulfate oxygen. The purpose of the research is developing new effective homogeneous catalysts of sodium sulfite liquid-phase oxidation in water solutions for purification of flue gases from sulfur dioxide. Using the methods of kinetics, volumometric, redox-potentiometry, IR-spectroscopy, gravimetry the kinetics, mechanism, intermediate and final products, optimum conditions, kinetic and activation parameters of the reaction of Na2SO3 liquid-phase oxidation in water solutions have been defined. Influence of the concentration of reagents (chloric copper, chloric iron, humic acid, yellow phosphorus) and temperature on the speed of reactions was studied. Catalytic effecty of copper and iron chlorides on the speed of sodium sulfite oxidation with oxygen in water solutions to get sodium sulfate was found. Optimum conditions  for  reaction  and  good  exit  of  sulfate  of  sodium  are  reached  at  60° C  at  the  molar  ratio  of  reagents [FeCl3]:[Na2SO3] = (0,1:1,0) and [CuCl2]:[Na2SO3]: [HHum] = (0,129:1,0:0,005). Kinetic and activation parameters were calculated. The studied processes proceeds were found to follow the oxidation-reduction mechanism and to consist of two key stages: Cu(II) and Fe(III) reduction with sodium sulfite to Cu(0) and Fe(I) with formation of sodium sulfate and Cu(I) oxidation to Cu(II) with Fe(II) oxidation to Fe(III) with oxygen. The results of the research can form a basis for developing effective catalytic systems for purification of flue gases from sulfur dioxide in the oil-processing and petrochemical  industry.  Thus,  sodium  sulfite  was  found  to  be  effectively  oxidized  with  oxygen  in  soft  conditions (T = 30 – 60o C PO2 = 0-1 atm) in water solutions of copper(II) and iron(III) chlorides to sodium sulfate with high yields (90 – 100 %).

sodium sulfite, copper and iron chlorides, humic acid

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