Recycling application of waste long-root Eichhornia crassipes in the heavy metal removal using oxidized biochar derived as adsorbents

An oxidized biochar was prepared using long-root Eichhornia crassipes through an aerobic/anaerobic hybrid calcination to recycle its waste plants after eutrophic treatments. The adsorption performances of the biochar were investigated and the results showed that the adsorption equilibrium could arrive in 30 min and the adsorption capacities for Pb2+, Cu2+, Cd2+ and Zn2+ at 30 degrees C were 0.57, 0.41, 0.44 and 0.48 mmol/g, respectively. The adsorption could be promoted at higher pH and temperature and the adsorption tolerance for different heavy metal ions to the existence of competing ions and organic matters was hierarchical. The adsorption was deduced to be heterozygous courses and mainly controlled by complexation of oxygen-containing groups with these heavy metal ions. It was confirmed that the biochar could be regenerated with HCl solution and the adsorption performance kept consistent in 10 adsorption-desorption cycles.