Antimony in water: sources, speciation and treatment

Antimony (Sb) can enter water through natural weathering and from activities such as mining, ore processing, smelting, and the use or disposal of antimony-containing materials. In water, its behaviour depends strongly on oxidation state, pH, redox conditions, mineral surfaces, and other dissolved constituents.

Read more about antimony and its chemical properties.

For common antimony salts and compounds in water, their solubility and treatment options, see common antimony salts and compounds in water: solubility and treatment.

Sources and occurrence

Antimony occurs naturally in minerals such as stibnite (Sb₂S₃) and may be released when antimony-bearing rocks and mine wastes weather. Mining and metallurgical waters can also contain suspended mineral particles, acidity or alkalinity, sulfate, iron, and other metals. Antimony trioxide is used in flame-retardant applications and may enter the environment through industrial releases and waste handling.

Drinking-water occurrence is generally much lower than concentrations possible in mine-affected or process waters. Results should specify whether they represent dissolved antimony or total antimony, which includes particulate material.

Aqueous forms

The most common inorganic oxidation states in natural waters are antimony(III) and antimony(V). Near neutral pH, Sb(III) commonly occurs as the largely neutral hydrolysis species Sb(OH)₃, while Sb(V) commonly occurs as the anion Sb(OH)₆⁻. Their proportions and interactions with solids vary with pH, redox conditions, dissolved organic matter, sulfide, and mineral surfaces. Oxic or reducing conditions can influence speciation, but do not alone determine it in every water.

Sb(V) can associate with iron and manganese (oxyhydr)oxides; Sb(III) may also be retained by mineral surfaces. Antimony may remain dissolved or move with particles depending on water chemistry. Measuring only total concentration does not identify which species controls treatment.

Removal and treatment

Choose treatment from a representative water analysis and, where important, antimony speciation. The target may be drinking-water treatment, mine-water discharge, process-water reuse, or recovery from a concentrated stream.

Solids separation: settling, coagulation, and filtration remove antimony-bearing particles. Microfiltration and ultrafiltration alone do not remove dissolved antimony species.
Ferric coagulation and co-precipitation: iron-based coagulants can capture dissolved antimony, especially Sb(V), by adsorption and incorporation into floc. Performance depends on pH, dose, oxidation state, and competing constituents; the resulting sludge requires suitable handling.
Adsorptive media: iron-, titanium-, or other reactive media can remove antimony in suitable waters. Capacity and breakthrough depend on pH, speciation, competing anions, and natural organic matter.
Ion exchange: anion exchange can be considered for anionic Sb(V) species and selected process streams. Neutral Sb(III) at near-neutral pH may behave differently, and competing anions can reduce performance.
Nanofiltration and reverse osmosis: pressure-driven membranes can separate dissolved antimony along with other constituents in suitable feed waters. They transfer antimony to a concentrate stream, which must be managed; they do not recover antimony selectively by default.
Oxidation or reduction: redox adjustment can condition speciation before a capture step, but is not a complete removal process on its own.

Antimony treatment is matrix-dependent. Confirm removal, residuals, and operating conditions with representative samples before selecting or scaling a process.

Discuss an antimony-bearing water stream

Share the water composition and treatment objective with Lenntech to discuss suitable separation and purification options. Discuss a water-treatment challenge.

Contact Lenntech at info@lenntech.com.

Last reviewed: 8 November 2026 by Lenntech.