SORPTION OF MICROCYSTIN-LR BY NATURAL AND MODIFIED CLAY MINERALS
James Beer1, Javier Gonzalez, PhD2, Janae Bos2.
1Northeastern Illinois University, Chicago, IL, 2United States Department of Agriculture, Agricultural Research Service, National Soil Erosion Research Lab, West Lafayette, IN.
Microcystins are toxins produced by cyanobacteria that are associated with harmful algal blooms and eutrophic surface water. Microcystin contamination in drinking water is a problem worldwide and has been linked to various health problems. Microcystin-LR is the most common and among the most acutely poisonous cyanotoxins. Commonly used water treatment methods are ineffective or impractical for the removal of microcystins. The goal of this project is to investigate the efficacy of several materials for the removal of microcystin-LR from water. Microcystin-LR sorption isotherms will be constructed using several media including clay minerals, organoclays, and organoclays modified with tannins. After the sorption procedure, microcystin-LR in solution will be measured using liquid chromatography coupled with a mass detector. The Freundlich isotherm equation will be used to obtain the sorption coefficient of the microcystin-LR in the media used. We hypothesize that the sorption coefficient of microcystin-LR will vary with the type of material used. Organoclays are expected to be the least effective sorbents followed by the natural clays. The organoclays modified with tannins are expected to be the most effective material for sorbing microcystin-LR because microcystins are polypeptides, and tannins have the ability to precipitate proteins. Many conventional methods for removing microcystins from water are considered impractical; thus, it is imperative to find new ways to accomplish this goal. Tannins and organoclays are promising materials to consider. Treatment facilities utilizing these materials could potentially eliminate the risk of health problems associated with microcystin contamination and reduce the cost of public water supplies.