Estudo da adsorção de saxitoxina e geosmina em carbono ativado através de simulação molecular

Abstract

Human activities have been causing negative impacts towards the available water for human consumption regarding both its quality and quantity, being important to mention eutrophication of water sources and the occurrence of cyanobacterial blooms. Such microorganisms, in addition to producing substances that cause the odor and taste of mold and earth to water (2-methylisoborneol and geosmin), also produce metabolites, associated with various intoxications in animals and man, called cyanotoxins (cyanobacterial toxins) and which include hepatoxins acting on the liver, neurotoxins acting on the nervous system and dermatoxinscausing skin irritation. Sinceconventional water treatment plants (coagulation, flocculation, sedimentation and filtration) are not able to remove cyanotoxins and other dissolved extracellular metabolites, the two main forms of removal are the use of activated carbons (GAC) and post-chlorination. Aiming to establish a theoretical approachregarding the selection of suitable activated carbon for cyanobacteria metabolite removal, in particular saxitoxin (STX), a number of molecular simulations targeting to study both STX and GSM adsorptionin activated carbon pores and graphitic surfaces were performed. Before, however, simulation parameters (force field type, force field parameters, molecular loads) were validated based on experimental studies with biphenyl (BPH), phenylcyclohexane (PCH) and bicyclohexyl (BCH)