ION EXCHANGEION EXCHANGE AND DIALYSIS AND DIALYSIS

THE REMOVAL OF IONS FROM SOLUTION USING RESINS

RESIN PARTICLE AND BEADS

Ion exchange of monovalent cations: (assume = 1)

For most solutions A = B

Ion exchange of mixed-valent cations: (assume = 1)

CROSSLINKING TO MAKE ION EXCHANGE RESINS

Selectivity of Ion Exchange ResinsIn Order of Decreasing Preference

Strong acid cation Strong base anion Barium Iodide

Lead Nitrate Calcium

Bisulfite Nickel Chloride Cadmium Cyanide Copper

Bicarbonate Zinc Hydroxide

Magnesium Fluoride Potassium Sulfate Ammonia Sodium Hydrogen

Chelating Cation Resin Selectivities for Metal

Metal KM/Caa Hg+2........................... 2,800 Cu+2........................... 2,300 Pb+2........................... 1,200 Ni+2 .......................... 57 Zn+2........................... 17 Cd+2........................... 15 Co+2....... .................... 6.7 Fe+2............................ 4.7 Mn+2............................ 1.2 Ca+2............................ 1

Selectivity coefficient for the metal over calcium ions at a pH of 4

Cost of Commercially Available Resins

Resin Cost($/ft3) Strong acid cation.......... 45-130 Weak acid cation............ 120-160 Strong base anion........... 210-270 Weak base anion............. 210-260 Chelating cation............ 350-650

SMALL SCALEION EXCHANGECOLUMNS

SKID-LOADED SMALL SCALE ION EXCHANGE PLANT

LARGE-SCALE ION EXCHANGE COLUMNS

POSITIONING OF RESIN BEADS FOR A MIXED BED JUST AFTER BACKWASHING

Improved Nitrate Removal from Drinking Water by Ion Exchange: Testing a Hydraulic Device for Improved Regeneration

Nitrate and Sulfate Concentrations For Run 4

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Bed Volumes Treated

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Nitrate Influent Nitrate Effluent Sulfate Influent Sulfate Effluent

Salometer Test Comparison

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0 10 20 30 40 50 60 70Regeneration Time, minutes

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IXCalcTM

A powerful computer program

High Performance Liquid Chromatography (DEAE and CM)</

                                                                                                             

   

America's really big sacred cow is fluoridation of drinking water. Fact: Fluoride is so toxic that only one milligram constitutes a prescription dose. In spite of this, the Environmental Protection Agency (EPA) allows up to this amount in a single glass of drinking water. Fact: Virtually every country in Europe has stopped fluoridation. Research shows that fluoride confers little if any real benefit. Fact: Persons who have grown up with fluoridated water have, on the average, only 1/2 of one filling less per lifetime than people who did not drink fluoridated water (Chemical and Engineering News, May 8, 1989).

 

  

Of the 50 largest cities in the United States, 43 have community water fluoridation. Fluoridation reaches 62% of the population on public water supplies—more than 144 million people.

 

  

Water fluoridation costs, on average, 72 cents per person per year in U.S. communities (1999 dollars).

 

  

Fluoride also benefits adults, decreasing the risk of cavities at the root surface as well as the enamel crown. Use of fluoridated water and fluoride dental products will help people maintain oral health and keep more permanent teeth.

http://www.cdc.gov/mmwr/preview/mmwrhtml/rr5014a1.htm

ELECTRODIALYSIS