PHOSPHATE SORPTION ON KYANITE: PROGRESS TOWARDS A GEOENVIRONMENTAL TECHNOLOGY TO COMBAT NON-POINT SOURCE POLLUTION

Phosphate non-point source pollution is a global environmental problem that largely impacts freshwater ecosystems causing extensive eutrophication and has negative impacts on marine ecosystems nearshore. Phosphate dominantly is derived from agricultural activities as well as human and animal sewage which is introduced to ecosystems primarily via overland flow or in the case of sewage direct or indirect discharge. This large scale phosphate pollution could be remediated if inexpensive technologies could remove or retard phosphate in drainage systems. The present study is centered on utilizing the mineral kyanite as a reactive sorption media for sequestering phosphate in freshwater systems. Kyanite is an aluminosilicate mineral that is used extensively in the ceramics industry but has not been investigated for environmental technologies. For this project three grain sizes of kyanite from Kyanite Mining Corporation in Virginia were investigated to determine sorption properties and utility as an environmental technology to control phosphate pollution. Materials were characterized by scanning electron micrscopy, transmission electron microscopy, and powder X-ray diffraction. Batch experiments were conducted using three different sizes of kyanite: K48 (48 mesh), K200 (200 mesh), and micronized kyanite (~5-7 micrometers). The concentrations for batch experiments were 2.5 ppm, 5.00 ppm, 10 ppm, 15 ppm, 20 ppm, 25 ppm, 30 ppm, 35 ppm, 40 ppm, 50 ppm, 60 ppm, 70 ppm and 80 ppm at pH values of 5.4, 6.2, and 7.0 which are appropriate for freshwater systems globally. Thirteen phosphate solutions were made from a stock solution using KH2PO4. Each solution was combined with one gram of each grain size and left to mix on a shake table for 24 hours. Then triplicate samples from each bottle were run through an ion chromatograph to determine the phosphate concentration. All isotherm plots show linear adsorption and preliminary analysis shows potential for utilizing kyanite as a reactive media. The 200 mesh kyanite material performed as well and sometimes better than the micronized kyanite. The results suggest kyanite is a viable geomaterial to remove phosphate from freshwater.