DOWEX Resins for Separation of Silica from Liquid Media

Silica - Si Silica is second only to oxygen in weight percentage of the earth's crust. It is found in an enormous diversity of silicate minerals. The water soluble ionic forms of silicate are the sodium salts of the general form [SiO2(OH)2]2- but, depending on the pH and concentration, can form other polymerized species.

Applications

Water / Wastewater: Sodium silicate can be removed from water with DOWEX™ 21K XLT strong base anion exchange resin. For streams that have a high organic content and are prone to surface fouling DOWEX MARATHON™ MSA anion exchange resin is recommended. Unfortunately, silicate is very weakly ionic, so it is not selectively removed and resin capacity will be limited in the presence of most other anions. See table of selectivity data (24K PDF) . Removal is complicated by the polymeric forms that often occur.

Selective Silica Removal from salt solutions has been described using a metal hydroxide loaded ion exchange resin. DOWEX G-26 (H) resin is a tough and versatile cation resin for this application. See reference below.

Catalysis: Information on catalysts for the inter-conversion of different silica compounds can be found at Silane Inter-Conversion and Processing.

DOWEX Ion Exchange Resins

Product	Description	Type	Matrix	Total Exchange Capacity* eq/l (kgr/ft3)	Available Forms
DOWEX G-26 (H)	Uniform particle size strong acid cation exchange resin for specialty demineralization and catalyst applications.	Strong Acid Cation	Styrene-DVB, Gel	2.0	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-

References "Method of purification of salt solution for electrolysis", Oohara, C.; Matsuoka, T.; Kishi, T. and Okuno, T. of Chlorine Engineers Corp., Ltd. European Patent Application EP 0 987 221 A1 (1999).