Copper and cadmium adsorption by humic acids extracted from compost of municipal waste (AH-CRU) and sewage sludge (AH-LETE) was studied by adsorption isoterms at pH 5,5. High adsorption capacity by humic substances was verified and copper adsortion followed the Langmuir’s model. The maximum copper adsorption was 55.5g of Cu2+kg-1 of AH-LETE and 45,9g Cu2+kg-1 of AH-CRU. The best model for cadmium adsorption was the Freundlich’s model, and different sites of adsorption were observed by infrared spectroscopy. The main adsorption sites observed were COO-, OH and N-H.
heavy metals; adsorption; compost; sewage sludge
