苏云金芽胞杆菌杀虫原粉对铬离子吸附热力学研究

Thermodynamics of Adsorption of Chromium(VI) on the Insecticidal Powder of Bacillus thuringiensis

通过静态吸附试验,研究了苏云金芽胞杆菌原粉对水溶液中铬离子(Cr6+)的吸附热力学特性。铬离子初浓度依次为50、100、150、200、250、300、400、500mg·L^(-1),菌体浓度固定为1g·L^(-1),pH值为2,分别在5℃、20℃、35℃、50℃条件下进行等温吸附,采用Freundlich方程和Langmuir方程进行拟合。结果显示,苏云金芽胞杆菌原粉对铬离子的吸附符合Langmuir(r>0.979)方程和Freundlich(r>0.977)方程。吸附焓△H为1.39￣2.33kJ·mol^(-1),吸附自由能ΔG为-3.75￣-2.84kJ·mol-1,吸附熵ΔS为15.2￣18.8J·mol^(-1)。苏云金芽胞杆菌原粉对铬离子的吸附是吸热过程,吸附能够自发进行。

The adsorption thermodynamics of chromium （VI） ions on Bacillus thuringiensis powder under static conditions was studied. The initial concentration of Cr^6＋ was 50, 100, 150, 200, 250, 300, 400 and 500 mg· L^1, respectively, the concentration of B. thuringiensis powder was 1 g·L^-1,pH was adjusted to 2. The adsorption of Cr^6＋ on B. thuringiensis powder was carried out at 5℃, 20℃, 35 ℃ and 50 ℃, respectively. The adsorption data were simulated with Langmuir equation and Freundlich equation, and the results showed that the adsorption isotherms followed Langmuir equation （0.979） and Freundlich equation （0.977）. The adsorption enthalpy AH ranged from 1.39 to 2.33 kJ· mol^-1 the adsorption free energy AG ranged from -3.75 kJ·mol^-1to -2.84 kJ·mol^1- and the adsorption entropy AS ranged from 15.2 to 18.8 J ·mol^1, suggesting that the adsorption of Cr^6＋on B. thuringiensis was an endothermic process and belonged to spontaneous process.