ADSORPTIONISOTHERM MODELS KINETICS STUDY AND THERMODYNAMIC PARAMETERS OF Hg (II)ADSORPTION BYBIOCHAR PREPARED AT DIFFERENT PYROLYSIS TEMPERATURES

摘要

Biochars were prepared at three different pyrol-ysis temperatures 300 (BC300), 500(BC500),and 650℃C(BC650)using tortoiseshells as raw materials, respectively, and the properties of biochar adsorption of heavy metal Hg2+ were studied. The effects of isothermal adsorption, adsorption kinetics, solution pH and biochar addition dosage on adsorption char-acteristics were analyzed. The results showed that the isothermal adsorption process could be well fit-ted with the Freundich and Langmuir models, and the adsorption kinetics process can be well fitted by the secondary kinetic equation.The best dosage bio-char addition were 2g/L,0.8 g/L,1.2 g/L,and the bestsolution pH was5,6,6 forBC300.BC500.and BC650, respectively.Biochar with high pyrolysis temperature has better adsorption effect than biochar with low pyrolysis temperature, and the adsorption properties of Hg2+ in the solution were obviously different with the preparation temperature.