废毛发生物炭的特性及其对Ni(Ⅱ)和Zn(Ⅱ)的吸附研究

Characteristics of waste hair biochar and its adsorption to Ni(Ⅱ) and Zn(Ⅱ)

对利用废毛发制备得到的生物炭进行元素组成、扫描电子显微镜(SEM电镜)等特性的分析,考察其对水中重金属的吸附作用。采用Lagergren模型对Ni(Ⅱ)和Zn(Ⅱ)吸附动力学过程进行拟合,采用Langmuir和Freundlich模型对Ni(Ⅱ)和Zn(Ⅱ)的吸附等温过程进行拟合,以研究生物炭对水中重金属Ni(Ⅱ)和Zn(Ⅱ)的吸附特征。结果表明:生物炭含碳量较高,p H呈碱性,表面结构呈多孔性,具有较强的吸附能力;碳化温度为300、350℃时制备的生物炭,对Ni(Ⅱ)的实际最大平衡吸附量分别为5. 48、6. 25 mg/g,对Zn(Ⅱ)的实际最大平衡吸附量分别为3. 02、3. 78 mg/g;生物炭的吸附以化学吸附为主,碳化温度越高,吸附速率越快,Lagergren模型能较好地描述生物炭对Ni(Ⅱ)和Zn(Ⅱ)的吸附过程; Langmuir和Freundlich模型拟合曲线能较好地描述生物炭对Ni(Ⅱ)和Zn(Ⅱ)的等温吸附,吸附温度升高,生物炭吸附量增加,在温度为20、30和40℃时,对Ni(Ⅱ)的最大吸附量分别为5. 59、7. 16和7. 23 mg/g,对Zn(Ⅱ)的最大吸附量分别为1. 28、1. 29和1. 32 mg/g。

The properties of biochar prepared from waste hair were analyzed by element composition and SEM,and the adsorption ability to heavy metals from domestic wastewater observed.The adsorption kinetics processes of Ni(Ⅱ)and Zn(Ⅱ)were fitted by Lagergren model,and the adsorption isotherm of Ni(Ⅱ)and Zn(Ⅱ)fitted by Langmuir and Freundlich models to investigate the adsorption characteristics of biochar on heavy metals Ni(Ⅱ)and Zn(Ⅱ)in water.The results showed that the carbon content of biochar was high,being alkaline,and the surface structure had porosity with strong adsorption ability.At carbonization temperatures of 300 and 350°C,the actual maximum equilibrium adsorption for Ni(Ⅱ)was 5.48 and 6.25 mg g,and the actual maximum equilibrium adsorption for Zn(Ⅱ)was 3.02 and 3.78 mg g,respectively.The Lagergren model can well describe the adsorption process of Ni(Ⅱ)and Zn(Ⅱ),mainly with chemical adsorption;and the higher the carbonization temperature,the faster the adsorption rate.Langmuir and Freundlich model fitting curves can better describe the isothermal adsorption of Ni(Ⅱ)and Zn(Ⅱ);and the higher the adsorption temperature,the more the adsorption capacity.At the temperature of 20,30 and 40℃,the saturated adsorbents of Ni(Ⅱ)were 5.59,7.16 and 7.23 mg g,and the saturated adsorbents of Zn(Ⅱ)were 1.28,1.29 and 1.32 mg g,respectively.