Para-Aminobenzoic Acid (PABA) Storage & Tank Compatibility

Storing Para-Aminobenzoic Acid (PABA)? Start Here

Para-aminobenzoic acid (PABA, 4-aminobenzoic acid, _C7H7NO2) is a white-to-beige crystalline aromatic acid that carries both an amine and a carboxylic-acid group on a benzene ring. It is a folate-related growth factor and a building block for dyes, the local-anesthetic ester family, and historic sunscreen actives. In handling it usually arrives as a powder that is dissolved into water or dilute alkali to form mild, weakly acidic process solutions for batching and dosing. Because PABA is only slightly water-soluble (about 4.7 grams per liter), those streams stay dilute, and dilute aqueous weak-acid solutions are exactly the class polyethylene resists well - making HDPE and crosslinked polyethylene (XLPE) the practical default tanks. The solid darkens in light and air, so keep it shaded and the tank closed. This page summarizes verified hazard ratings, physical properties, and an honest material-of-construction read.

Is Para-Aminobenzoic Acid Compatible with Polyethylene (HDPE / XLPE) Tanks?

Yes. PABA in solution is a weak aromatic carboxylic acid carried in water or dilute alkali, and that places it in the salts-and-aqueous-solutions class that polyethylene handles well. Published plastic chemical-resistance guidance is consistent that PE is not attacked by aqueous solutions of salts, weak acids, and alkalis, with no swelling, stress-cracking, or oxidative degradation expected from PABA itself; its low water solubility keeps practical solutions dilute, which only eases the duty. That makes a polyethylene tank the sensible default for dissolving the powder, holding solution, and feeding it downstream. Two cautions apply: polyethylene loses strength as temperature rises, so hot solutions are better served by polypropylene, CPVC, or Type 316 stainless; and because PABA discolors in light and air, keep the tank closed and shaded to protect product quality. Confirm gasket and fitting elastomers (EPDM is a strong default) and check the resistance chart for your exact concentration, carrier, and temperature before committing.

Material compatibility at a glance

Para-aminobenzoic acid is handled almost entirely as a dilute aqueous solution of a weak aromatic acid, and HDPE and XLPE polyethylene tanks store, dissolve, batch, and dose it reliably at ambient temperature. For hot solutions step up to polypropylene, CPVC, or Type 316 stainless. Avoid bare carbon steel, keep the solid out of direct light, and control fine dust during charging.

Ratings: S suitable · C conditional / limited · U unsuitable. Verify against the cited resistance charts and your concentration/temperature before specifying.

The safety that actually matters

• Wear chemical splash goggles - PABA causes serious eye irritation (H319). Eye protection is mandatory when charging powder or handling solution.
• Wear impervious gloves and protective clothing; the material irritates skin (H315) and may cause an allergic skin reaction (H317), so minimize repeated and prolonged contact.
• Control dust and use local exhaust or a NIOSH-approved respirator where airborne dust or mist can occur; inhalation may irritate the respiratory tract (H335).
• Provide eyewash and a safety shower at fill and handling points; flush exposed eyes with running water for at least 15 minutes and seek medical attention if irritation persists.
• Store the solid in a closed container away from light and air, which cause it to discolor; keep the storage tank closed and shaded to protect product quality.
• Contain spills and prevent release to waterways - the material is harmful to aquatic life with long-lasting effects (H412). Collect without raising dust and follow local disposal rules.

Common questions

Can I store para-aminobenzoic acid solution in an HDPE or XLPE tank?

Yes. Aqueous PABA solutions are a mild weak-acid stream, and polyethylene resists aqueous solutions of salts, weak acids, and alkalis. HDPE and XLPE are the usual default for dissolving, holding, and dosing the solution at ambient temperature. For hot solution, step up to polypropylene, CPVC, or Type 316 stainless.

Is PABA corrosive to metal tanks?

As a weak organic acid in solution it will slowly corrode bare carbon steel and can discolor the product, and it can locally attack Type 304 stainless when hot or concentrated. Type 316 stainless is preferred for hot process solutions. For most water-based duty a polyethylene tank avoids the metal-corrosion question entirely.

How soluble is para-aminobenzoic acid in water?

It is only slightly soluble - about 4.7 grams per liter (0.47 g per 100 mL) at room temperature, rising in hot water and dissolving far more readily in dilute alkali as the aminobenzoate salt. Practical process solutions stay dilute, which keeps the duty gentle on polyethylene.

What are the main hazards when handling PABA?

PABA causes serious eye irritation, irritates the skin and may trigger an allergic skin reaction, and can irritate the respiratory tract as a dust or mist. It is also harmful to aquatic life with long-lasting effects. Use goggles, gloves, dust control, and spill containment; its NFPA fire and reactivity ratings are both zero.