Remove Sulfur Dioxide from Flue Gases to Obtain Sulfuric Acid through Electrodialysis Enrichment

Abstract

This article illustrates the experimental research which disposes low concentration SO 2 flue gases through liquid absorption and electrodialysis enrichment. It introduces the technology and devices to produce sulfuric acid by liquid absorption and oxidation of low concentration SO 2 in aqueous solutions as well as electrodialysis enrichment in the same reactor. Numerous experiments have been carried out in order to observe the performance of the reactor under the operating conditions: the current density, temperature, volume flow rate of the electrolyte, the sulfuric acid concentration, volume flow rate of the gas, the components of gas mixture, and initial SO 2 concentration. When the removal rate of SO 2 reaches 83.64%, we eventually get sulfuric acid with the concentration of 28.56%. Sulfur dioxide in flue gas generated from the combustion of fossil fuel, such as metal smelting factory, thermal power plants, etc. It is the main cause of air pollution and acid rain. Many countries have therefore adopted strict regulations to SO 2 emissions from coal and oil-fired boilers, which are one of the primary sources of SO 2 emissions. The increasing importance of sulfur dioxide pollution control stimulated the improvement of technology for the removal of sulfur dioxide from flue and waste gases.The electrochemical processes which do not require the continuous use of chemical reagents, possess advantages and bring a helpful contribution in the proposal or development of depollution processes. 1 Sulfur dioxide can be oxidized electrochemically to species such as sulfuric acid and dithionite, the electrochemical oxidation of SO 2 has been investigated both as a pollution control method and as part of recycling and utilization of resources.2,3 The electrochemical oxidation of sulfur dioxide can be achieved either through a direct process at an anode surface or using a redox mediator through a chemical process, which has to be regenerated at the electrode. 4 In the electrolysis of the sulfur dioxide absorbed in aqueous solution, the process involves a chemical oxidation of SO 2 by adsorbed oxygen species.5 It is also possible that SO 2 is oxidized at the anode while hydrogen is produced at the cathode.6 Furthermore, the removal of SO 2 from the copper ions containing wastes provides electrowinning of copper simultaneously. 7The main products of electrochemical oxidation and reduction of SO 2 in acid solution are sulfuric acid and sulfur, respectively. The formation of sulfur may come with a significant solids handling problem and can lead to problems in cell operation.8 In many applications, for example, in the chemical process industries, sulfuric acid is a desirable product as it can be used in chemical manufacture and is readily transported.The overall reaction for the oxidation of SO 2 can be written as:Where hydrogen is formed at the cathode. Dissolved sulfur dioxide is converted to sulfuric acid at the anode and hydrogen is formed at the cathode. 9 The mechanism of SO 2 oxidation in water is complex, the absorption ...

Treatment of complex sulfur-containing solutions in ammonia desulfurization ammonium sulfate production by ultrasonic-assisted ozone technology

“…In some metal smelters, ammonia desulfurization to prepare ammonium sulfate ((NH 4 ) 2 SO 4 ) is an effective way to realize flue gas desulfurization. The obtained product (NH 4 ) 2 SO 4 is a necessary chemical by-product with enormous application demand in many fields, such as agriculture, textiles, leather, and medicine [2] . The specific steps involved in this process are as follows: (i) passing the cooled and purified sulfur dioxide flue gas through the absorption tower to produce a mixed solution of (NH 4 ) 2 SO 4 and sulfites ((NH 4 ) 2 SO 3 and NH 4 HSO 3 ), called the mother liquor, (ii) adding an excess of H 2 SO 4 to oxidize all the sulfites in the mother liquor, (iii) adding NH 3 ·H 2 O to neutralize excess concentrated sulfuric acid, and (iv) obtaining the ammonium sulfate product through evaporation and crystallization [3] .…”

Treatment of complex sulfur-containing solutions in ammonia desulfurization ammonium sulfate production by ultrasonic-assisted ozone technology

“…In some metal smelters, ammonia desulfurization to prepare ammonium sulfate ((NH 4 ) 2 SO 4 ) is an effective way to realize flue gas desulfurization. The obtained product (NH 4 ) 2 SO 4 is a necessary chemical by-product with enormous application demand in many fields, such as agriculture, textiles, leather, and medicine [2] . The specific steps involved in this process are as follows: (i) passing the cooled and purified sulfur dioxide flue gas through the absorption tower to produce a mixed solution of (NH 4 ) 2 SO 4 and sulfites ((NH 4 ) 2 SO 3 and NH 4 HSO 3 ), called the mother liquor, (ii) adding an excess of H 2 SO 4 to oxidize all the sulfites in the mother liquor, (iii) adding NH 3 ·H 2 O to neutralize excess concentrated sulfuric acid, and (iv) obtaining the ammonium sulfate product through evaporation and crystallization [3] .…”

Preparation of proton block and highly conductive AEM by creating PANI dominated and hydrophobicity ion channels for sulfuric acid enrichment

“…There is an excessive quantity of waste acid with low concentration produced during industrial production, such as titanium production, rare earth refining, steel picking, metal refining, and other industries 1‐3 . In addition, enormous wastewater containing acids would generate from industrial off‐gas treatment process 4,5 . The recovering of high‐concentration acid from such wastewaters will create enormous economic and environmental benefits.…”

Treatment of complex sulfur-containing solutions in ammonia desulfurization ammonium sulfate production by ultrasonic-assisted ozone technology

“…In some metal smelters, ammonia desulfurization to prepare ammonium sulfate ((NH 4 ) 2 SO 4 ) is an effective way to realize flue gas desulfurization. The obtained product (NH 4 ) 2 SO 4 is a necessary chemical by-product with enormous application demand in many fields, such as agriculture, textiles, leather, and medicine [2] . The specific steps involved in this process are as follows: (i) passing the cooled and purified sulfur dioxide flue gas through the absorption tower to produce a mixed solution of (NH 4 ) 2 SO 4 and sulfites ((NH 4 ) 2 SO 3 and NH 4 HSO 3 ), called the mother liquor, (ii) adding an excess of H 2 SO 4 to oxidize all the sulfites in the mother liquor, (iii) adding NH 3 ·H 2 O to neutralize excess concentrated sulfuric acid, and (iv) obtaining the ammonium sulfate product through evaporation and crystallization [3] .…”

Preparation of proton block and highly conductive AEM by creating PANI dominated and hydrophobicity ion channels for sulfuric acid enrichment

“…There is an excessive quantity of waste acid with low concentration produced during industrial production, such as titanium production, rare earth refining, steel picking, metal refining, and other industries 1‐3 . In addition, enormous wastewater containing acids would generate from industrial off‐gas treatment process 4,5 . The recovering of high‐concentration acid from such wastewaters will create enormous economic and environmental benefits.…”

Treatment of complex sulfur-containing solutions in ammonia desulfurization ammonium sulfate production by ultrasonic-assisted ozone technology

“…In some metal smelters, ammonia desulfurization to prepare ammonium sulfate ((NH 4 ) 2 SO 4 ) is an effective way to realize flue gas desulfurization. The obtained product (NH 4 ) 2 SO 4 is a necessary chemical by-product with enormous application demand in many fields, such as agriculture, textiles, leather, and medicine [2] . The specific steps involved in this process are as follows: (i) passing the cooled and purified sulfur dioxide flue gas through the absorption tower to produce a mixed solution of (NH 4 ) 2 SO 4 and sulfites ((NH 4 ) 2 SO 3 and NH 4 HSO 3 ), called the mother liquor, (ii) adding an excess of H 2 SO 4 to oxidize all the sulfites in the mother liquor, (iii) adding NH 3 ·H 2 O to neutralize excess concentrated sulfuric acid, and (iv) obtaining the ammonium sulfate product through evaporation and crystallization [3] .…”

Preparation of proton block and highly conductive AEM by creating PANI dominated and hydrophobicity ion channels for sulfuric acid enrichment

“…There is an excessive quantity of waste acid with low concentration produced during industrial production, such as titanium production, rare earth refining, steel picking, metal refining, and other industries 1‐3 . In addition, enormous wastewater containing acids would generate from industrial off‐gas treatment process 4,5 . The recovering of high‐concentration acid from such wastewaters will create enormous economic and environmental benefits.…”