Liquid Chlorine Bleach

Ingredients

Ingredient	Function	% w/w
Sodium hypochlorite solution (12–15% av. Cl₂)	Active bleaching agent	40.0–50.0
Sodium hydroxide (50% NaOH)	pH stabilizer	0.25–0.50
Sodium silicate (37–40% SiO₂)	Metal ion sequestrant	0.10–0.30
Deionized water	Diluent	qs to 100.0
Final specifications: av. Cl₂ = 5.0–6.0%; pH = 11.5–13.0

Expected Parameters

The HOCl/OCl⁻ equilibrium has pKₐ ≈ 7.5, so at pH 11.5–13.0 the equilibrium lies overwhelmingly toward the stable hypochlorite anion . Below pH 10.8, decomposition accelerates sharply . Excess NaOH at 0.025–0.35% by weight achieves the target pH, with sodium silicate chelating trace metal ions. Fabric safety requires that available chlorine in the wash liquor remain below 0.5%; higher concentrations cause oxidative cellulose chain scission. The product must never be mixed with acids (toxic Cl₂ gas), ammonia (chloramine formation), or hydrogen peroxide.

Formulation Notes

Liquid chlorine bleach employs sodium hypochlorite (NaOCl, CAS 7681-52-9) as its active species, with the hypochlorite anion (OCl⁻) acting as the primary oxidant at alkaline pH.

Formulation Card FC-12.1-M: Liquid Chlorine Bleach

Sodium hypochlorite stability is governed by two competing decomposition pathways. The dominant route at elevated temperature is chlorate-forming disproportionation: 3 NaOCl → 2 NaCl + NaClO₃ . The alternative oxygen-producing pathway (2 OCl⁻ → 2 Cl⁻ + O₂) becomes significant in the presence of transition metal catalysts (Cu²⁺, Ni²⁺, Fe³⁺, Co²⁺) . Both reactions exhibit second-order kinetics, with activation energy for a 15.89% NaOCl solution reported at 96.43 kJ/mol . The decomposition rate increases by a factor of ~3.5 for every 10 °C rise in temperature ; storage at 15 °C versus 25 °C extends shelf life 3.5-fold.