Flue gas desulfurization with citrate solution is one of the methods to tackle sulfur dioxide pollution.In order to theoretically elucidate the mechanism of absorption and desorption of sulfur dioxide by citrate solution and provide theoretical instruction for experiments and industrial application

the influence of initial pH

distribution coefficient

buffer index and buffer capacity on the properties of the buffer solution were studied in this work.The study was performed through examining the multiple buffer solution system of citric acid - sodium citrate - sulfurous acid formed in the process of desulfurization by applying the theory of multi-buffer solution combined with the method of computer numerical calculation.The results showed that the distribution of various citric acid radical ions in the solution varied with the solution acidity.H2Ci-and HCi2-played the dominant role in the buffer action during the desulfurization process.The transformation of the citric acid radical ions was Ci3-－HCi2-－H2Ci-－H3Ci in the absorption process and H3Ci－H2Ci-－HCi2-－Ci3- in the desorption process.When pH＝2.5—6.5，the sulfur dioxide in the absorption solution existed mainly as HSO-3 which could maximally reach 99% when pH＝3.5—5.5.When pH=4.5—5.5

the buffer capacity of citrate buffer solution reached its maximum.The optimal pH value of citrate solution should be about 4.5 by considering both the absorption and desorption processes.The experimental results were in good agreement with theoretical analysis.