Sulfuric acid is the most used chemical in the world.. It is an important reagent used in many industries and is used in the manufacture of almost everything from paper, pharmaceuticals and cosmetics to batteries, detergents and fertilizers. However, sulfuric acid often contains one of the most toxic substances: mercury, causing serious illness when it enters the human body. Now, researchers at Sweden’s Chalmers University of Technology, reduce mercury levels in sulfuric acid by more than 90 percent.
“Until now, there was no viable method to purify finished sulfuric acid. With this radical reduction in mercury content, we are well below current limit values. This high-quality, pure sulfuric acid is in great demand in industrial applications and is an Associate Professor in the Department of Physics at Chalmers. “It’s an important step in reducing environmental impact,” says research leader Björn Wickman.
Sulfuric acid is produced from sulfur in the petroleum industry or as a byproduct in smelters in the mining industry. In the latter case, mercury can form part of the final products. In addition, streams recycled from smelters may contain mercury.
Toxic emissions affecting all life on Earth
The discharge of mercury into the natural environment is a global problem.Because it is a substance, it is volatile and can spread over large areas in the air. This toxic heavy metal gets into streams and lakes when it rains. It affects the entire food chain by being stored in soil, water and living organisms. May damage the brain and central nervous system of humans and animals.
According to the United Nations Environment Program (UNEP) report, mercury emissions into the atmosphere increased by about 20% between 2010 and 2015. In 2015, about 2,200 tons of mercury was released into the air as a result of human activities.such as cement production, small-scale gold mining, coal burning, metal production and other manufacturing industries. In addition, an estimated 1,800 tons of mercury were released into soil and water that same year. According to the report, mercury concentrations in the atmosphere may have increased by 450 percent in the last century.
“Mercury released in the environment continues to be a health threat for thousands of years by accumulating in the environment”
“Any way we can reduce mercury emissions is good, because Released mercury accumulates in the environment and continues to pose a health threat for thousands of years.Wickman says.
Five years ago, the research team at Chalmers presented a pioneering method for removing mercury from water using electrochemical processes. The method is a metal electrode that absorbs toxic metal and forms an alloy. The mercury can then be safely disposed of and the electrode reused. Now, researchers have taken this technology one step further. and in a new study, they show how mercury can be removed from concentrated sulfuric acid.
The sulfuric acid experiments were carried out in collaboration with the mineral and metal refining company Boliden and the company Atium, a spin-off of the Chalmers School of Entrepreneurship, to extract mercury from water and products. The researchers now hope they can move forward with their partners and develop a kind of reactor in which sulfuric acid can flow and be purified at the same time.
Potential to reduce costs and environmental impact
Today, mercury is often removed at an earlier stage: from concentrates and recycled smelters before sulfuric acid is produced. However, this process leaves traces of mercury in the final products.
“Sulfuric acid purification also avoids additional mercury emissions, allowing the industry to operate more profitably and produce a high-purity, non-toxic product. The next step will be to scale the method to a process close to volumes of thousands of tons. “It’s more typical of the real world,” says its first author, Vera Roth.
With the new method, the researchers reduced the mercury level to 0.02 milligrams per kilogram of sulfuric acid.
According to the Statista database, The volume of the world market for sulfuric acid is about 260 million tons per year.. In 2029, this figure is expected to increase to 314 million tons. The lower the mercury content of sulfuric acid, the more valuable it is.
For commercial purposes, sulfuric acid is considered of acceptable quality when the mercury content is less than 0.30 milligrams per kilogram. Sulfuric acid is considered to be of high purity if its content is less than 0.08 milligrams per kilogram. Using the new method, the researchers reduced the mercury level to 0.02 milligrams per kilogram of sulfuric acid in their pilot study.
“The limit values for the amount of mercury that sulfuric acid can contain are based on currently available technology. With the new method for purifying this element, we hope to tighten the legislation on limit values,” says Wickman. . , referring to the requirement that their indices be lower.
HOW THE PROCESS WORKS
The purification method removes mercury from sulfuric acid by forming an alloy with another metal, ionizing the mercury and its ions. A platinum-surfaced electrode electrochemically binds the mercury to itself. It then absorbs the poisonous mercury and forms an alloy of the two metals. It is then possible to remove the mercury and regenerate the electrode in a controlled manner. This means that the electrode can be reused and the toxic substance can be safely disposed of. The process is also highly energy efficient.
Reference article: https://www.sciencedaily.com/releases/2023/07/230704110915.htm
……
Contact details of the environment department: [email protected]