Anatoxin-a adsorption by virgin and preloaded granular activated carbon

Adsorption of the cyanotoxin anatoxin-a (ANTX) in ultrapure water by five virgin and preloaded granular activated carbons (GACs) was examined using the bottlepoint technique; this article presents baseline adsorption data for ANTX not yet available in the literature. Of the virgin carbons, the two wood-based carbons adsorbed ANTX more rapidly than the one coconut-based or two coal-based carbons. Virgin coal-based carbons had the greatest equilibrium capacity (1.8-6.9 mu g/ mg at 1 mu g/L aqueous ANTX) compared with their virgin coconut- and woodbased counterparts (1.2 and 0.9-1.0 mu g/mg, respectively). GAC preloading via exposure to surface water resulted in kinetic changes and reduced capacity. Pre-loaded coal-based carbons adsorbed ANTX faster than the virgin equivalents. At environmentally relevant ANTX concentrations, coal-based preloaded carbons retained higher equilibrium capacity (1.2 mu g/mg) compared with coconut- and wood-based carbons (1.0 and 0.6 mu g/mg, respectively). Natural organic matter competition will affect adsorption performance and should be investigated.