Adsorption characteristics of nano-carbon on heavy metal cadmium and copper and its effects on tobacco absorption of the two heavy metals

In order to clarify the adsorption characteristics of nano-carbon on heavy metals, the adsorption characteristics of nano-carbon on Cd and Cu were investigated in a liquid-liquid system. The effects of nano-carbon on the available Cd content in soil and the Cd absorption of tobacco cultured in soil were discussed. The results showed that the Cd and Cu isothermal adsorption curves of nano-carbon could be fitted by Freundlich and Langmuir equations. The Cd and Cu adsorption by nano-carbon agreed with a quasi-two stage kinetic equation, and its adsorption rate was fast. At the initial solution concentration of 2 000 mg/L, the Cd adsorption amount was more than 80% of the equilibrium adsorption amount after 10 min, while it only took 3 min to reach that level for Cu adsorption. With the rise of temperature, the adsorption amounts decreased, which indicated that the adsorption by nano-carbon was an exothermic reaction. With the increase of pH, the adsorption amount by nano-carbon raised. Under the condition of this experiment, both the available Cd content in soil and the Cd content in tobacco leaves decreased with the increase amount of nano-carbon, and the optimal nano-carbon addition rate was 4.0 gram/pot.