Sodium Dichromate[2]

Updated: 2026-09-15

Overview

Sodium dichromate is a critical industrial chemical primarily produced from chromite ore. It serves as a precursor for chromium compounds and finds extensive use in metal finishing, leather tanning, and corrosion inhibition. The compound’s strong oxidizing properties make it valuable in organic synthesis and wastewater treatment. As a hexavalent chromium compound, it is subject to strict environmental regulations. Modern production focuses on closed-loop systems to minimize chromium(VI) emissions. Alternatives like trivalent chromium are increasingly adopted where feasible.

Physical and Chemical Properties

The compound crystallizes as orange-red dihydrate (Na2Cr2O7·2H2O), converting to anhydrous form at 100°C. It exhibits high thermal stability but decomposes above 400°C to form chromium(III) oxide. Its aqueous solutions are strongly acidic (pH ~4 for 10% solution). Notably hygroscopic, sodium dichromate readily absorbs moisture from air. It reacts violently with reducing agents, organic materials, and metals like aluminum. These reactions may generate heat, flammable hydrogen gas, or explosive mixtures.

Main Applications

Over 60% of global production is used in chrome plating baths, where it provides the chromium(VI) source for electrodeposition. In pigments, it yields chrome yellows and oranges for ceramics and coatings. The textile industry employs it as a mordant for dye fixation. Other uses include wood preservatives (against fungi/insects), drilling mud additives, and photographic screen printing. Emerging applications include flow battery electrolytes, though environmental concerns limit adoption.

Safety and Storage

Classified as a Category 1 carcinogen (EU CLP), sodium dichromate requires hazard pictograms GHS06 (toxic) and GHS08 (health hazard). Storage areas must have secondary containment and avoid contact with acids or combustibles. Spills require neutralization with reducing agents like sodium bisulfite. Personnel need chemical-resistant gloves (e.g., nitrile), face shields, and respiratory protection when handling powders. Facilities must implement exposure monitoring and provide emergency eyewash stations.

B2B Procurement Guide

Industrial buyers should prioritize suppliers with ISO 14001 certification, reflecting environmental compliance. Technical specifications should confirm heavy metal limits (e.g., ≤50 ppm Pb) and crystal size uniformity for consistent dissolution rates. Bulk shipments typically use UN-approved steel drums with polyethylene liners. Just-in-time procurement is recommended due to shelf-life concerns (typically 2 years). Always audit supplier waste disposal practices to avoid liability risks.