Fe_(3)O_(4)/HA复合吸附剂对Ni(Ⅱ)的吸附性能研究

Study on the adsorption performance of Fe_(3)O_(4)/HA composite adsorbent for Ni(Ⅱ)ion

采用碱溶酸析法提取腐植酸(HA),通过CaCl_(2)对其改性后与Fe_(3)O_(4)进行复合,制备出不同配比的Fe_(3)O_(4)/HA复合吸附剂。利用SEM、BET、FT-IR、XRD分析方法对HA、钙改性HA、Fe_(3)O_(4)/HA复合吸附剂进行了表征,考察了物料配比及吸附时间、pH值、温度、投加量和初始浓度对Ni(Ⅱ)吸附率的影响。结果表明:质量复合比mHA:mFe_(3)O_(4):mCaCl_(2)为3∶2∶2的Fe_(3)O_(4)/HA复合吸附剂(HA2)对Ni(Ⅱ)吸附效果最佳。当加入0.8 g吸附剂,Ni(Ⅱ)初始浓度为0.1 g·L^(-1),吸附5 h,pH=5,温度40℃,吸附剂对Ni(Ⅱ)的吸附率为92.57%。复合吸附剂在4次吸附脱附后,对Ni(Ⅱ)的吸附率仍达到52%。吸附过程符合准二级动力学方程和Freundlich吸附等温式。在20℃~40℃条件下,热力学参数ΔG<0、ΔS=37.57 J/(mol·K)、ΔH=11.07 kJ·mol^(-1),表明该吸附是自发、熵增、吸热的过程。

Humic acid(HA)was extracted by alkali-dissolved acid precipitation method,and modified by CaCl_(2) to compound with Fe_(3)O_(4) to prepare Fe_(3)O_(4)/HA composite adsorbents with different ratios.SEM、BET、FT-IR、XRD analysis methods were used to characterize HA,calcium modified HA,Fe_(3)O_(4)/HA composite adsorbent,and the material ratio and adsorption time,pH value,temperature,dosage and initial concentration were investigated.Influence on Ni(Ⅱ)adsorption efficiency.The results show that the Fe_(3)O_(4)/HA composite adsorbent(HA2)with a mass composite ratio of mHA:mFe_(3)O_(4):mCaCl_(2) of 3∶2∶2 has the best adsorption effect on Ni(Ⅱ).When 0.8g adsorbent is added,the initial concentration of Ni(Ⅱ)is 0.1g·L^(-1),the adsorption is 5h,the pH is 5,the temperature is 40℃,and the adsorption rate of the adsorbent to Ni(Ⅱ)is 92.57%.After four times of adsorption and desorption of the composite adsorbent,the adsorption efficiency of Ni(Ⅱ)still reached 52%.The adsorption process conforms to the quasi-second-order kinetic equation and Freundlich adsorption isotherm.Under the conditions of 20℃~40℃,the thermodynamic parametersΔG<0,ΔS=37.57J/(mol·K),andΔH=11.07kJ·mol^(-1),indicating that the adsorption is a process of spontaneous,entropy increase and endothermic.