Cation Resin Overview
Urbans Aqua stocks Purolite, Thermax & ResinTech cation resin for quick shipment.
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Cation resin is a negatively charged matrix with exchangeable positive ions (cations). Negatively charged ions are fixed and permanently attached – part of the resin structure. Because the bead is negatively charged only positive ions are attracted or exchanged. For water treatment purposes the cation resin is sold in the sodium form (Na+) or hydrogen form (H+).
Visit our PDF Library for technical specifications and product manuals on cation resins.
Visit our SDS Library for safety data sheets on cation resins.
Cation Resin Applications
Water Softeners – Hardness Reduction
Strong base cation resin in the sodium (Na+) is commonly used for household, commercial and industrial water softening applications. According to the Water Quality Association, the hardness of water supplies in the United States ranges from 1 to 350 grains (gpg) per gallon or 17.1 to 5,985 ppm. However, most waters range between 3 and 50 gpg. USGS Water Quality Information
Softening with cation resin is a simple exchange function. The resin bead is negatively charged and attracts positive ions. When supplied in the sodium form (Na+) the resin will exchange sodium ions for hardness ions – calcium and magnesium. The bead is more strongly attracted to these ions and readily exchanges with the sodium. Once the resin is exhausted it is regenerated with a brine solution (NaCl). The brine overwhelms and releases the calcium and magnesium from the bead. The resin is converted back to the sodium form and ready for re-use.
- Free chlorine levels above 0.5ppm or any oxidant decrosslink and shorten cation resin life. Dow Resins Recommended maximum free chlorine levels
- In applications with high chlorine levels and temperature use a 10% crosslinked gel or macroporous resin.
Urbans Aqua stocks:
- Purolite C-100Na C100 Cation Resin Product Data Sheet
- Thermax Tulsion T42NaBC Resin Cation TULSION T-42 Na BC N & Tulsion T52NaBC Resin Cation TULSION T-52 Na BC N
- ResinTech CG8 CG8 CATION and CG10HPCG10 CATION.
- These cation resins are suitable for residential, commercial and industrial applications. They are either NSF or WQA Gold Seal Certified.
Water Softeners – Iron & Manganese Removal
The hard water problem is often compounded by contaminants like iron (rust stains) and manganese (black stains). Iron water has a distinctive taste.
- Softening resin removes ferrous, or soluble iron, in water.
- The USEPA Secondary Drinking Water Regulations require less than 0.3 ppm for iron.
- Ferrous iron is often referred to as “clear water iron” and commonly found in ground or well water.
- When sizing a softener compensate for ferrous iron –> for every part per million (ppm) of iron add 1 grain of hardness. For example – if the water sample shows 5 grains hardness and 2 ppm of iron, you would size up the softener for 7, not 5 grains.
- Ferrous Fe++ not Ferric Fe+++
- Ferrous iron sticks to the cation resin and isn’t easily exchanged. Regular use of resin cleaners or salt with resin cleaner additives is recommended.
- When ferrous iron meets oxygen (air) it changes to ferric iron. Ferric iron is insoluble and leaves the classic rust stains people are familiar with and often mistakenly refer to as hardness. Ferric iron is best removed through mechanical filtration not cation resin.
- Specialty cation resins such as Purolite SSTC60Na are well suited to remove iron. Purolite’s Shallow Shell Technology, SST resin has a solid center. When in service hardness molecules and ferrous iron cannot penetrate deeply into the bead. Regeneration is far more efficient and doesn’t require the same concentration of brine. Read more about SST60 – SSTC-60 Resin for Softening.
- Manganese can be reduced with cation resin.
- Manganese is often a companion to iron and is similarly removed. The black or dark brown stain occurs when the soluble manganese ions are oxidized and converted to manganese dioxide.
- The USEPA Secondary Drinking Water Regulations require less than 0.05 ppm – it is an aesthetic problem and not harmful.
- Softener sizing is not affected by the presence of manganese. Like iron, it is not easily exchanged, will stick to the resin and require regular resin maintenance as noted above.
- Softening resin has a strong affinity for lead – Pb++.
- Contact your water professional or Urbans Aqua for further information on this application.
- WQA 2016 Lead Fact Sheet
Strong Acid Cation in the hydrogen form (H+) in combination with strong base anion (SBA) in the hydroxide form (OH), is most often used for demineralization processes such as portable exchange tank (PEDI) operations. In this case, the hydrogen is exchanged for calcium, magnesium and sodium. (For more information please refer to section on demineralization for portable DI exchange operations.)
Links to Specifications & Engineering Bulletins:
Urbans Aqua is a stocking wholesaler of Residential & Commercial Water Treatment Equipment and supplies including Ion Exchange Resin; Calgon & Jacobi Activated Carbon; Filterag Plus; GreensandPlus; Pyrolox Advantage; KDF; Birm; Sand/Gravel; Clack, Fleck & AqMatic valves; Stenner Pumps & Parts.
We work exclusively with water treatment dealers.