Abstract:The refined carbon obtained by fly ash flotation has the characteristics of low ash content (Ad=17.85%) and high carbon content (Cd=77.53%), it is a cheap carbon source for preparation of activated carbon. High quality activated carbon with iodine adsorption value of 1 140.78 mg/g, methylene blue adsorption value of 140.00 mg/g, and specific surface area of 853.75 m2/g can be obtained by activating flotation refined carbon by KOH activation method. The optimum activation conditions include alkali carbon ratio of 3.0, activation temperature of 800 ℃, and activation time of 60 min. The results of infrared spectroscopic analysis, BET specific surface analysis, and scanning electron microscope analysis show that the activated carbon prepared by flotation refined carbon contains many oxygen-containing active groups, the pores are developed, especially the pores below 2 nm are abundant. The micropores pore volume accounts for 48.30%, and the average pore diameter of activated carbon is only 2.33 nm. The activated carbon has good adsorption performance for Cu2+ in solution. When the dosage is 2.5 g/L, pH=5.0, adsorption temperature is 25 ℃, adsorption equilibrium time is 120 min, and initial concentration is 50, 75, and 100 mg/L respectively, the removal rate of Cu2+ can reach 99.70%, 93.61% and 81.67% respectively. The adsorption mechanism analysis shows that adsorption of Cu2+ on the surface of activated carbon is mainly chemical adsorption, which conforms to the Langmuir monolayer isothermal adsorption model. This study can provide a new technical approach for low-cost preparation of high-quality activated carbon for water treatment.