Adsorption Mechanisms of Heavy Metal Ions from Drinking Water by Weakly Basic Anion Exchange Resins

IntroductionWastewater of mineral processing industriesnormally contains a variety of hazardous heavymetals and sometimes may be discharged withoutadequate treatment. These heavy metalcontaminants may be transported into drinkingwater sources,such as rivers,lakes,even theground water by natural circulation.Most waterworks can not remove these heavy metals due tothe lack of suitable treatment processes. In China,along the Yangzi River and the Huaihe River,some water sources have micro- pollut…

Adsorption Mechanisms of Heavy Metal Ions from Drinking Water by Weakly Basic Anion Exchange Resins

Heavy metal micro-contaminants can be removed from water sources such as rivers and lakes using variations of conventional treatment technologies. Weakly basic anion exchange resins offer the best ability to remove trace amounts of heavy metals with high selectivity. This paper discusses how weakly basic resins adsorb heavy metals using two different approaches. The removal of mercury, cadmium, and lead ions is based on the fundamental theory of coordination chemistry. The mechanism is not ion exchange but extractive adsorption of heavy metal salts. However, the marked preferential adsorption of chromate by weakly basic anion exchange can be explained using the traditional theory of ion exchange. A lab-scale study produced positive results for the removal of trace amounts of heavy metal ions from drinking water.