Sulfonic acids, including lignosulfonic acid (the parent compound of sodium lignosulfonate), are generally considered to have a relatively low level of toxicity to humans when handled and used properly.
Here are some key points about the potential hazards of sulfonic acids:
- Corrosivity:
- Sulfonic acids are moderately acidic in nature and can be corrosive to the skin, eyes, and respiratory system if exposed in high concentrations.
- Proper personal protective equipment (PPE) and engineering controls are recommended when handling concentrated sulfonic acid solutions to prevent skin and eye contact, as well as inhalation exposure.
- Ingestion toxicity:
- If ingested, sulfonic acids can cause irritation and damage to the gastrointestinal tract, potentially leading to nausea, vomiting, and abdominal pain.
- However, the acute oral toxicity of most sulfonic acids is considered low to moderate, with LD50 values (lethal dose for 50% of test animals) typically in the range of 500-5000 mg/kg body weight.
- Inhalation toxicity:
- Exposure to aerosolized or vaporous sulfonic acids can irritate the nose, throat, and lungs, potentially causing coughing, wheezing, and shortness of breath.
- Prolonged or repeated inhalation exposure may lead to more serious respiratory effects.
- Skin and eye irritation:
- Direct contact with concentrated sulfonic acids can cause skin and eye irritation, redness, and pain.
- However, the severity of the effects may depend on the specific sulfonic acid compound and its concentration.
It is important to note that the actual risk and severity of the effects will depend on the specific sulfonic acid compound, its concentration, the route and duration of exposure, and the individual’s sensitivity.
What Is a Sulfonic Acid?
A sulfonic acid has the general formula R–SO3H: an organic group (R) attached to a sulfonic acid group. Sulfonic acids are strong acids. When they are neutralised, they form sulfonate salts (R–SO3Na, for example), which are much milder and are the form used in most products.
| Substance | Form | Typical use | Main hazard |
|---|---|---|---|
| Linear alkylbenzene sulfonic acid (LABSA) | Acid | Raw material for detergents | Corrosive to skin and eyes |
| Methanesulfonic acid, p-toluenesulfonic acid | Acid | Catalysts, chemical synthesis | Corrosive |
| Sodium alkylbenzene sulfonate (LAS) | Salt | Active ingredient in detergents | Irritant at high concentration |
| Sodium or calcium lignosulfonate | Salt | Concrete plasticizer, binder, dispersant | Low hazard; dust may irritate eyes |
| Sodium naphthalene sulfonate condensate (SNF) | Salt | Concrete superplasticizer | Low hazard; dust may irritate |
Acid vs Salt: Why the Hazard Differs
- Concentrated sulfonic acids are strong acids and can burn skin and eyes. Handle them with gloves, goggles and ventilation, as the SDS requires.
- Sulfonate salts such as lignosulfonates are neutralised. They are not corrosive in normal use; the main precautions are to avoid breathing dust and to rinse eyes if powder gets in them.
- Always read the SDS of the exact product. Hazard depends on the compound, its concentration and how you are exposed.
First Aid (General)
- Skin or eyes: rinse with plenty of water for at least 15 minutes; remove contaminated clothing.
- Swallowed: rinse the mouth; do not induce vomiting; get medical advice.
- Inhaled: move to fresh air.
- Follow section 4 of the product SDS, which overrides this general guidance.
Our lignosulfonates and naphthalene sulfonates are supplied with SDS, TDS and COA. See sodium lignosulfonate. For detergent acids such as LABSA, see the group’s surfactant division: LABSA.
Frequently Asked Questions
What is sulfonic acid?
An organic acid with the formula R–SO3H. It is a strong acid; neutralised, it forms sulfonate salts used in detergents, concrete admixtures and dispersants.
Is sulfonic acid dangerous?
Concentrated sulfonic acids are corrosive and can burn skin and eyes. Their salts, such as lignosulfonates, are low hazard in normal handling. Check the SDS of the specific product.
What is sulfonic acid used for?
Mainly as a raw material for detergents (LABSA neutralised to LAS), as an acid catalyst, and as the basis of sulfonate surfactants, dyes and dispersants.
