Chlorine

Chlorine (Cl) — 10-Year Trends

As of 2026-09-25 · the last 10 years

Chlorine’s research intensity is currently at about 99% of its all-time peak, a level reached within this specific window.

Research intensity ran from about 83% of the element's own all-time peak in 2016 to about 99% in 2026 — a steady climb, and the all-time peak (2024) falls inside this window. Over the same span its share of research attention across all elements rose. Among the 118 elements, chlorine has a larger-than-average research literature.

The number of papers involving the element rose from about 86,373 in 2016 to about 183,700 in 2025 (2.13x). That matches the growth of the literature as a whole over the same years: the general tide of scientific output, not a surge specific to the element.

Chlorine’s recent research is anchored by four distinct communities, each representing a different application of the element. The largest is Chlorine Disinfection and By-Products in Water Distribution, which accounts for about 13% of the element's recent research. This community focuses on chlorine and hypochlorite dosing, residual decay, and disinfection by-product formation in municipal distribution systems, with distinctive work on free chlorine and residual chlorine. Chlorine is one strand of a broader community, appearing in about 14% of its papers. The share has remained steady over the last decade. A key paper in this area, "Assessing the Use of Probes and Quenchers for Understanding the Reactive Species in Advanced Oxidation Processes" (2023), has been cited over 620 times.

The second major community is PVC Microplastic Formation and Thermal Degradation, holding about 13% of chlorine’s recent research. This field studies the thermal degradation of polyvinyl chloride and the resulting formation of chloride microplastics and gel particles. Chlorine is one strand of a broader community, appearing in about 13% of its papers. This community has seen a steady share, growing slightly from 10% to 13% over the window. A notable recent contribution is "Microplastics and Nanoplastics in Atheromas and Cardiovascular Events" (2024), cited over 1,100 times.

Chloride Corrosion and Transport in Concrete represents about 9% of the element's research. These papers model chloride ingress, binding, and diffusion mechanisms that drive steel corrosion in reinforced concrete structures. Chlorine is a minor presence in this much larger community, appearing in about 4% of its papers. The share has been steady, rising slightly from 6% to 9%. A foundational review, "Durability Performance of Geopolymer Concrete: A Review" (2022), has been cited over 370 times.

Finally, Chlorine as a Corrosive Medium in Steel Inhibition accounts for about 5% of recent research, though it is a declining area, dropping from 10% to 5% over the window. This community examines how chloride ions in hydrochloric acid accelerate steel corrosion and tests organic compounds to inhibit that damage. Chlorine is one strand of a broader community, appearing in about 20% of its papers. Recent work includes "Methods of corrosion prevention for steel in marine environments: A review" (2025), cited about 54 times.

The overall composition shows a consolidation: while the steel inhibition share declined, the other three communities held or slightly increased their relative weight, with the remainder of the literature (about 61%) remaining steady.

For a deeper look at the current state of chlorine research, see the Last 12 Months and Executive Brief reports.