花生壳吸附Pb^(2+)、Cu^(2+)、Cr^(3+)、Cd^(2+)、Ni^(2+)的动力学和热力学研究

Study on the kinetics and thermodynamics of Pb^(2+),Cu^(2+),Cr^(3+),Cd^(2+),Ni^(2+) adsorption onto peanut hull

以花生壳为生物吸附剂,通过序批式实验研究了吸附剂投量、吸附时间、金属离子初始质量浓度、吸附温度对吸附金属离子的影响,探讨了花生壳吸附的动力学及热力学特性。结果表明,准二级动力学方程能很好地描述花生壳对Pb2+、Cu2+、Cr3+、Cd2+、Ni2+的吸附过程。Langmuir模型和Freundlich模型均能较好地描述花生壳对5种重金属离子的等温吸附过程,而Langmuir模型拟合的线性更好。Pb2+、Cu2+、Cr3+、Cd2+、Ni2+5种金属离子的最大吸附量分别是32.25、7.09、3.82、2.95、2.22 mg.g-1,花生壳可用于处理低质量浓度多种重金属混合的废水。热力学研究表明,花生壳对5种金属离子的吸附具有自发、吸热和熵增的特性。

Peanut hull was used to remove Pb2＋,Cu2＋,Cr3＋,Cd2＋,Ni2＋ from aqueous solutions as an adsorbent by bath adsorption experiments.The effects of adsorbent dosage,contact time,initial heavy metals concentration and temperature on the removal of heavy metals were investigated.The kinetics and thermodynamics was also discussed.The results showed that the adsorption kinetics of heavy metal ions could be described by the pseudo-second order model.The adsorption data followed well the Langmuir model and the Freundlich model and the adsorption equilibrium was described better by the Langmuir isotherm model with maximum adsorption capacity of 32.25 mg g-1 of Pb2＋,7.09 mg·g-1 of Cu2＋,3.82 mg·g-1 of Cr3＋,2.95 mg·g-1 of Cd2＋,2.22 mg·g-1 of Ni2＋ onto peanut hull respectively.Peanut hull was showed to be effective for removal of heavy metals from the multi-metallic mixture.Thermodynamic analysis showed that adsorption process was spontaneous,endothermic and entropy increased.