Experimental Study On Oxidation And Removal Of Nitric Oxide In Potassium Persulphate Solution

Stricter control laws, standards and regulations for NOx emissions by govenment and regulatory agencies justifies the urgent need for efficient and inexpensive NOx removal technologies that can be easily retrofitted to existing coal-fired boilers, and wet scrubbing process is becoming a reseach hotspot. Oxidation process is regarded as one of the effective methods of nitrous oxides emission control from small and medium sized coal-fired boiler flue gas. An experimental study of the method of removing nitric oxide by potassium persulphate has been studied in this paper. On the basis of chemical reaction principle, dynamicsanalysis, thermodynamics analysis, and the principle of gas-liquid mass transfer, removal experiment of NO in simulated flue gas by persulphate wet process was studied in a lab-scale bubbling reactor. The effects of several process parameters such as persulphate concentration, reaction temperature, solution p H on NO removal were investigated. In order to improve the efficiency of denitration, suitable additives were determined by the experiment, appropriate process parameterswere determined, and the reaction mechanism was studied. The following results are obtained.(1) By the standard electrode potential analysis, NO can be removed effectively by persulfate, the chemical reaction in the process of denitration is proposed.(2) The thermodynamic analysis shows that denitration reaction by potassium persulfate is spontaneous. The relationship between NO partial pressure and the reaction temperature in equilibrium state was deduced, temperature rise is against the NO removal. The gas–liquid reaction between NO and persulfate solution is liquid-film controlled.(3) Denitration experiments by potassium persulfate separatelyin bubbling reactor were done, the results showed when the concentration of potassium persulfate was below 0.03 mol/L, removal rate of NO increased with the increasing concentration of potassium persulfate, otherwise, the NO removal efficiency change little; The curve of denitration efficiency changing with temperature was inverted u-shaped curve, the optimal removal efficiency was achieved at 60 ?. Alkaline conditions under the condition of NO removal rate is higher when persulfate solution was under alkaline conditionsthan acid, the optimal removal efficiency was achieved at 13.0; The NO removal efficiency decreases when the flue gas flow rate increased.(4) Fe(II)EDTA was found to be a suitable additive. The removal efficiency of NO change a little when urea, ferrous sulfate or ammonia were added into solution. The optimum operating conditions were obtained in denitration process by potassium persulfate with Fe(II)EDTA aqueous solution concentration of potassium persulphate was 0.02 mol/L, concentration of Fe(II)EDTA was 0.03 mol/L, reaction temperature was 80 ?, the initial p H value was 9.0. At this time 93% of the NO removal rate was observed.(5) Persulfate can be effectively activated by Fe(II)EDTA to form sulfate free radicals. The process of removing NO by potassium persulfate with Fe(II)EDTA aqueous solution actually is the process that complexing absorption of NO by Fe(II)EDTA and sulfate free radicals remove NO activated by ferrous ion simultaneously.