ammonium persulfate help yellow ammonium sulfate to white
“Improving the quality of ammonium sulfate produced from the flue gas desulfurization process by using ammonium persulfate” explores the issue of yellow ammonium sulfate produced as a by-product of the flue gas desulfurization process.
The lower product quality is attributed to the chromaticity of the ammonium sulfate not meeting the requirements for ammonium sulfate fertilizer. The study investigates the role of various impurities, including organic pollutants, metal impurities, and sulfur-containing impurities, on the chromaticity of the ammonium sulfate products.
The research identifies sulfur impurity as the main cause of the yellowing of ammonium sulfate products. This impurity is generated when ammonium thiosulfate in the absorption mother liquor reacts with concentrated sulfuric acid, which serves as an oxidant in the ammonia desulfurization process. To address this issue, the authors propose using ammonium persulfate as an alternative oxidant to replace concentrated sulfuric acid. The experimental results demonstrate that under optimized process conditions, ammonium persulfate effectively removes thiosulfate and sulfite impurities from the desulfurization mother liquor, achieving removal rates as high as 90.1% and 93.4%, respectively. As a result, the obtained ammonium sulfate product appears white with uniform particles.
The study also examines the oxidation process of ammonium persulfate and identifies different oxidation components, including S2O82-, SO4radical dot-, and radical dotOH. The authors find that ammonium persulfate offers several advantages over the conventional ammonia acid process, such as increased oxidation efficiency, reduced sulfur generation, and improved ammonium sulfate product quality.
The article begins with an introduction to the significance of sulfur dioxide (SO2) emissions and the desulfurization methods employed in the metallurgy and chemical industries. Among these methods, the ammonia acid desulfurization process is highlighted for its high desulfurization efficiency and the production of ammonium sulfate as a valuable by-product. The production process of ammonium sulfate from flue gas desulfurization is explained, involving absorption, oxidation, and evaporation crystallization steps.
The authors address the problem of yellow ammonium sulfate products, which do not meet the chromaticity requirements. Previous studies have suggested that impurities such as organics, metal impurities, and ferric salts contribute to the abnormal coloration. However, despite attempts to remove these impurities, the yellow color persists in some ammonium sulfate products. Therefore, the research aims to determine the cause of yellowing and develop effective methods to remove color pollutants and enhance product quality.
The study utilizes samples from a lead-zinc smelting company in Yunnan province, China, which uses the ammonia acid method for flue gas desulfurization. The authors analyze the yellow ammonium sulfate product and the unqualified absorption mother liquor using various analytical techniques, including ICP, XRD, XPS, and GC/MS, to identify the sulfur impurity responsible for the yellow coloration.
Based on their findings, the authors propose the use of ammonium persulfate as an oxidant to remove chromogenic impurities from the absorption mother liquor. They investigate different factors such as reaction time, amount of ammonium persulfate, reaction temperature, and pH value of the solution to optimize the process conditions. The resulting ammonium sulfate product is characterized for its microstructure and phase composition.
The study concludes that sulfur impurities generated from the reaction of thiosulfate with concentrated sulfuric acid are the main cause of yellow ammonium sulfate products. The use of ammonium persulfate as an alternative oxidant effectively removes these impurities, resulting in high-quality white ammonium sulfate products.
