Mercury Reduction in Sulfuric Acid: Cleaner Industrial Chemicals

Sulfuric acid stands as one of the globe’s most essential chemicals, driving production lines in sectors like paper, pharmaceuticals, cosmetics, batteries, detergents, and fertilizers. A persistent hurdle has been mercury as a toxic contaminant in certain sulfuric acid streams, which poses health risks when absorbed. Researchers at Sweden’s Chalmers University of Technology have demonstrated a method that reduces mercury levels in sulfuric acid by more than ninety percent.

The team notes that purification of finished sulfuric acid has long been challenging. Their breakthrough yields high-purity sulfuric acid that satisfies strict safety standards and is in strong demand for industrial use. The work is led by an associate professor in the Department of Physics at Chalmers, who emphasizes environmental benefits and the broader value of cleaner industrial chemicals in the supply chain.

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Sulfuric acid can be produced from sulfur in the petroleum industry or arise as a byproduct of mining smelting. In some instances, mercury can become part of the final products, and recycled smelter streams may carry mercury as well.

Toxic emissions affecting all life on Earth

Mercury released into the environment is a worldwide concern. Being volatile, it travels with air currents and settles into streams and lakes after rainfall. It moves through ecosystems, accumulating in soil, water, and living organisms, and can affect the brain and central nervous system of both humans and wildlife.

A United Nations Environment Programme (UNEP) assessment notes that atmospheric mercury emissions rose by roughly twenty percent between 2010 and 2015. In 2015 alone, human activities emitted about 2,200 tons of mercury as air pollutants from cement production, small-scale gold mining, coal combustion, metal production, and other manufacturing processes. The same year, around 1,800 tons of mercury were released to soil and water. Data suggest atmospheric mercury levels may have surged by as much as 450 percent over the past century.

“Mercury pollution in the environment remains a long-lasting health threat”

Reducing mercury emissions is essential, as released mercury accumulates and continues to pose risks for thousands of years, according to the study’s lead researchers. The team stresses that lowering emissions helps protect health and ecosystems.

Mercury pollution in South America agencies

Five years ago, Chalmers researchers introduced an electrochemical approach to remove mercury from water. The method uses a metal electrode that absorbs toxic metal and forms an alloy, enabling safe disposal and reuse of the electrode. The latest work extends this technology to concentrated sulfuric acid, showing how mercury can be removed from such streams.

The sulfuric acid experiments were conducted in collaboration with Boliden, a mineral and metal refining company, and Atium, a spin-off of the Chalmers School of Entrepreneurship. The goal is to develop a reactor design where sulfuric acid can flow and be purified simultaneously.

Potential to reduce costs and environmental impact

Mercury removal typically occurs earlier in the supply chain, from concentrates and recycled smelter materials, before sulfuric acid production. Yet traces of mercury can still linger in the final products.

Mercury is eventually introduced into animals for human consumption agencies

Purifying sulfuric acid also lowers additional mercury emissions, helping the industry maintain profitability while delivering a high-purity, non-toxic product. The researchers aim to scale the method to handle thousands of tons, aligning with real-world industrial volumes. The study’s lead author notes that the work demonstrates practical applications and real-world feasibility.

With the new method, mercury content dropped to 0.02 milligrams per kilogram of sulfuric acid

Market data indicate the global sulfuric acid market runs around 260 million tons annually, with expectations to exceed 300 million tons in the near term. Lower mercury content increases the value and safety of sulfuric acid in commercial use. Current quality thresholds consider sulfuric acid acceptable when mercury is below 0.30 milligrams per kilogram, and high purity when below 0.08 milligrams per kilogram. In pilot studies, the team achieved 0.02 milligrams per kilogram.

Researchers note that existing limit values depend on current technology. The new purification approach may tighten these standards further, as improvements in measurement and control enable stricter limits.

HOW THE PROCESS WORKS

The purification method eliminates mercury by forming an alloy with another metal. Mercury ions are ionized, and a platinum-surfaced electrode binds the mercury electrochemically. The mercury is absorbed, an alloy forms, and the electrode can be regenerated and reused. The process is energy efficient and supports safe disposal of the toxic substance.

Reference article: ScienceDaily, 2023 update on mercury removal technologies.

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Note: This article is a consolidated summary of the latest research into mercury removal from sulfuric acid and related streams.