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为提高花生壳对Cr(Ⅵ)的吸附性能,采用ZnCl2对花生壳进行改性,制得花生壳活性炭。通过批次吸附实验,考察了花生壳活性炭投加量、pH值、吸附时间等因素对Cr(Ⅵ)的吸附性能影响,同时,对吸附动力学、等温吸附特征和热力学进行了系统研究。结果表明,当吸附剂投加量为0.2 g时,在Cr(VI)初始浓度为20 mg/L、pH值为2.0条件下,吸附反应180 min后,花生壳活性炭对Cr(Ⅵ)的吸附率可维持在94.13%以上。吸附过程符合准二级动力学方程和Langmuir等温吸附模型;由吸附热力学方程计算得到吸附焓变(ΔH)>0,吸附自由能变(ΔG)<0,吸附熵变(ΔS)>0,表明花生壳活性炭对Cr(Ⅵ)的吸附过程是吸热和自发的。
In order to improve the adsorption capacity of peanut shell to Cr (Ⅵ), peanut shell was modified with ZnCl2 to produce peanut shell activated carbon. The batch adsorption experiments were carried out to investigate the effect of the amount of activated carbon added on the peanut shell, the pH and the adsorption time on the adsorption of Cr (Ⅵ). At the same time, the adsorption kinetics, isothermal adsorption characteristics and thermodynamics were systematically studied. The results showed that when the adsorbent dosage was 0.2 g, the adsorption of Cr (Ⅵ) by peanut hull activated carbon was 180 min after the initial concentration of Cr (VI) was 20 mg / L and pH was 2.0 Rate can be maintained above 94.13%. Adsorption enthalpy change (ΔH)> 0, adsorption free energy change (ΔG) <0 and adsorption entropy change (ΔS)> 0 indicate that the adsorption process is in accordance with quasi-second order kinetic equation and Langmuir isothermal adsorption model The adsorption of Cr (Ⅵ) by peanut shell activated carbon is endothermic and spontaneous.