Chlorine[2]

Updated: 2026-09-19

Overview

Chlorine is a halogen element discovered in 1774 by Carl Wilhelm Scheele. It ranks among the top 10 industrial chemicals globally due to its extensive applications in sanitation and manufacturing. As a diatomic gas (Cl₂), it exhibits high reactivity and is rarely found in its free form in nature. Industrial production primarily involves electrolysis of sodium chloride brine. Chlorine's electronegativity and oxidizing properties make it indispensable in chemical synthesis, though its toxicity requires careful handling.

Physical and Chemical Properties

Chlorine gas has a pungent, irritating odor detectable at low concentrations (0.2-3.5 ppm). It is 2.5 times denser than air, causing it to accumulate in low-lying areas. The gas liquefies under pressure at room temperature, facilitating transport in steel cylinders or tankers. Chemically, chlorine readily forms compounds with nearly all elements. Notable reactions include halogenation of hydrocarbons and displacement of less reactive halides. Its aqueous solution forms hydrochloric and hypochlorous acids, the basis for its disinfectant properties.

Main Applications

Over 60% of chlorine production serves water treatment and sanitation. It effectively kills pathogens in drinking water and swimming pools at 1-4 ppm concentrations. In manufacturing, chlorine is crucial for PVC production (accounting for ~30% of use) through ethylene dichloride intermediates. The chemical industry utilizes chlorine in producing solvents (e.g., chloroform), pesticides, and pharmaceuticals like antibiotics. Bleaching agents for paper and textiles also rely on chlorine derivatives such as sodium hypochlorite.

Safety and Storage

Chlorine exposure above 1 ppm causes respiratory irritation, while concentrations over 30 ppm are immediately dangerous. Storage requires corrosion-resistant containers (steel or nickel alloys) with pressure relief devices. Facilities must have gas detection systems and emergency scrubbers. Leak control measures include using alkaline solutions (e.g., sodium hydroxide) to neutralize released gas. Personnel require NIOSH-approved respirators, chemical goggles, and impervious protective clothing when handling chlorine.

B2B Procurement Guide

Industrial buyers should specify required purity (typically 99.5-99.9% for most applications) and delivery format (cylinders, ton containers, or bulk liquid). Verify supplier compliance with transportation regulations (e.g., DOT Hazard Class 2.3 in the US). Long-term contracts often provide price stability. Consider on-site sodium hypochlorite generation as an alternative for water treatment applications to reduce transportation risks. Audit suppliers for ISO 9001 certification and safety performance records.