Tetrasodium Iminodisuccinate: A Biodegradable Hydrogen Peroxide Stabilizer for Pulp Mills

The Bleaching Challenge in Pulp Production

Hydrogen peroxide is the preferred bleaching agent for mechanical pulps and recycled fibres. It is effective, chlorine-free, and environmentally favourable compared to elemental chlorine or chlorine dioxide. But it has a well-known weakness.

Trace metal ions—iron, manganese, and copper—are always present in pulp and process water. These metals catalyse the decomposition of hydrogen peroxide into oxygen and water . The bleach breaks down before it can do its job. Mills end up using more peroxide, chasing brightness targets, and dealing with higher chemical costs.

Traditional chelating agents like EDTA and DTPA solve the problem. They sequester those metal ions and keep the bleach stable. The trouble is, EDTA and DTPA do not break down in the environment . They persist. And with tightening regulations across Europe, pulp mills are under pressure to find alternatives that actually work.

Tetrasodium iminodisuccinate (IDS-Na4) offers a way forward. It stabilises peroxide, chelates transition metals, and biodegrades completely .

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What Is Tetrasodium Iminodisuccinate?

IDS-Na4 is a biodegradable chelating agent based on iminodisuccinic acid. It belongs to the same family as MGDA and GLDA—chelates designed to replace persistent alternatives .

The key difference from EDTA is structural. IDS has a different molecular backbone that allows microorganisms to break it down quickly. But it still chelates calcium, magnesium, iron, and copper effectively .

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The Stabilisation Mechanism

In peroxide bleaching, the problem is catalytic decomposition. Metal ions like Fe³⁺ and Mn²⁺ accelerate peroxide breakdown into oxygen and water. That is oxygen you do not want—it does not bleach pulp . IDS prevents this by forming stable complexes with those metal ions, rendering them inactive .

The pulp industry calls this the "Q stage"—a chelation step before the peroxide stage . Pulp is mixed with the chelating agent at 60–80°C for about an hour. Then the peroxide is added . The difference is measurable.

What IDS delivers in practice:

• Higher brightness. Studies on bagasse pulp show IDS achieves equivalent or better brightness than EDTA, with whiteness improvements of 2–4% .

• Better fibre strength. The same research found tensile index improvements of 5–6% and burst index improvements of 20–23% when IDS replaced EDTA .

• Improved peroxide utilisation. By controlling metal ions, IDS reduces peroxide consumption and improves bleaching efficiency .

• Less yellowing over time. IDS prevents iron from reacting with phenolic groups in the pulp, which would otherwise form dark-coloured compounds .

• Scale prevention. IDS controls calcium and magnesium ions that would otherwise form deposits on equipment .

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IDS vs EDTA: Performance Comparison

A comparative study on bagasse pulp put IDS side by side with EDTA :

The performance is essentially identical. The environmental profile is not .

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Why European Pulp Mills Are Switching

European pulp mills face increasing scrutiny under the EU Industrial Emissions Directive, water framework directives, and retailer sustainability standards. EDTA and DTPA are under review. Non-biodegradable chelates are increasingly restricted .

IDS-Na4 is compliant with EU Ecolabel criteria and meets REACH requirements for biodegradability . It is readily biodegradable under OECD 301 standards, breaking down into harmless natural products within 28 days . It also contains no phosphorus, reducing the burden on effluent treatment systems .

For mills supplying paper products to eco-conscious brands or markets with strict environmental procurement policies, that difference is decisive.

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Practical Application

Typical use levels in bleaching: 0.8–1.2% of dry pulp mass in the chelation stage .

Process conditions: Chelation temperature 60–80°C, reaction time 50–70 minutes .

Form: Available as a liquid (34–40% solution) or solid granules . The liquid form is easier to dose in continuous bleaching lines.

Compatibility: IDS works with hydrogen peroxide and other bleaching chemicals. It is compatible with enzymes and shows good stability across pH and temperature ranges .

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The Role of Yuanlian Chemical

Shandong Yuanlian Chemical is one manufacturer that has positioned IDS-Na4 as a core product for the European pulp and paper market. Their IDS-Na4 is described as a "readily biodegradable chelating agent" with "good peroxide stabilisation properties" . The product is REACH-compliant and meets ISO 9001 and ISO 14001 standards, with batch-specific Certificates of Analysis available .

Yuanlian's annual IDS production capacity is reported to be in the range of 15,000 tonnes, and they supply over 30 countries, including Europe . For European buyers, this scale offers supply chain reliability combined with the documentation required for EU compliance—OECD 301 biodegradability data, REACH registration confirmation, and NTA-free certification.

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The Bottom Line

Tetrasodium iminodisuccinate does what EDTA does—just without the persistence . It stabilises peroxide, controls metal ions, prevents deposits, and delivers comparable brightness and fibre strength. And it biodegrades.

For European pulp mills facing regulatory pressure and sustainability targets, IDS is a practical, proven alternative. It is available at scale, works in existing processes, and removes a compliance headache that is only going to get worse.