DOWEX Resins for Separation of Heavy Metals from Water, Wastewater and Acids

Heavy Metals Cadmium - Cd Lead - Pb Tin - Sn Gallium - Ga Germanium - Ge Indium - In Antimony - Sb Thallium - Tl Bismuth - Bi These metals, cadmium, lead, tin, gallium, germanium, indium, antimony, thallium, and bismuth, are grouped together as heavy metals due to common chemistry. The most common economic metals are cadmium, lead and tin. Gallium, germanium, indium, antimony, bismuth and thallium are of less commercial interest and occurrence. These metals will form a wide variety of compounds that are cationic and anionic so a variety of different resins can be applied to their separation.

Applications

Potable Water: Heavy metals can be removed from neutral pH water as cations. A weak acid cation exchange resin like DOWEX™ MAC-3 is a good choice due to its high capacity and ease of regeneration.  A second option is a strong acid cation exchange resin like DOWEX MARATHON™ C (Na). Both resins can be brine regenerated or disposed of once they are loaded with metals.

These resins meet NSF / ANSI Standard 61 for contact with drinking water. For more information see our regulatory information.

Acid and Wastewater: In HCl, all of these metals can form anions that can be removed with anion exchange resins. Ga, Ge, Sn (II), and Sb (III) form stronger anionic complexes (43KB PDF) with higher acid concentrations. Cd (II), Ir (II), Sn (IV), Sb (V), Tl (III), Pb (II), and Bi (III) form their strongest anionic complexes under mildly acidic conditions and in some cases can be eluted with strong HCl. Anions are effectively removed from solution with a strong base resin like DOWEX 21K XLT resin. For streams that have a high organic content and are prone to surface fouling, DOWEX MARATHON MSA resin is recommended. A weak base anion exchange resin like DOWEX M-43 resin should also be evaluated to take advantage of this resins higher capacity and ease of regeneration.

In HCl, few of these metals will form cations that can be captured with a cation exchange resin. Most will form very weak cations in very dilute acid. In these cases, a weak acid cation exchange resin like DOWEX MAC-3 resin should be considered. Ga (III) is the exception, forming a cation in acid that can be removed with DOWEX M-31 and DOWEX MONOSPHERE™ M-31 catalysts.

Many of these metals can be more selectively removed from solution with chelating resins like the iminodiacetic acid resin.

DOWEX Ion Exchange Resins

Product	Description	Type	Matrix	Total Exchange Capacity* eq/l (kgr/ft3)	Available Forms
DOWEX MAC-3	A macroporous weak acid cation exchange resin used for water softening, dealkalization, and demineralization applications.	Weak Acid Cation	Polyacrylic, Macroporous	3.8 (83.0)	H+
DOWEX MARATHON C	A uniform particle size, high capacity cation exchange resin for industrial and residential softening and demineralization applications.	Strong Acid Cation	Styrene-DVB, Gel	2.0 (43.7) 1.8 (39.3)	Na+ and H+
DOWEX 21K XLT	Uniform particle size, high capacity, strong base anion exchange resin for mineral processing applications.	Type I Strong Base Anion	Styrene-DVB, Gel	1.4	Cl-
DOWEX MARATHON MSA	Uniform particle size, high capacity, macroporous strong base anion exchange resin for water demineralization applications.	Type I Strong Base Anion	Styrene-DVB, Macroporous	1.1 (24.0)	Cl-
DOWEX M-43	Corrosion control with DOWEX M-43 ion exchange resin.	Weak Base Anion	Styrene-DVB, Macroporous	1.55	FB (Free Base) form
DOWEX M-31	Standard grade product for general catalytic applications. This catalyst has unmatched durability and dependability within the MTBE/TAME industry.	Strong Acid Cation	Styrene-DVB, Macroporous	1.7	H+
DOWEX MONOSPHERE M-31	A uniform bead size strong acid catalyst. This is our highest performance catalyst for MTBE/TAME.	Strong Acid Cation	Styrene-DVB, Macroporous	1.85	H+

References "Uptake of Heavy Metals by Chelating Resins from Acidic Manganese Chloride Solution" by Claudia Villa Diniz, Afonso Henriques Martins, and Fiona M. Doyle, Minerals and Metallurgical Processing, 17 (4) (2000) pp. 217-222. "Resin Selectivity in Dilute to concentrated Aqueous Solutions" by R.M. Diamond and D.C. Whitney, Chapter 8 of Ion Exchange – A Series of Advances Edited by J.A. Marinsky, Published by Marcel Dekker, Inc., New York (1966).