生物沥浸改性后污泥基生物炭对Pb^2+和Cd^2+的吸附

Adsorption of Pb^2+and Cd^2+by Bioleaching Modified Sludge-based Biochar

为探索利用生物沥浸改性后污泥基生物炭去除废水中Pb^2+和Cd^2+的可行性,以生物沥浸改性后污泥为原料制备生物炭,并测定了该材料的性能和吸附特性。通过单因素试验研究了pH值、生物炭投加量对吸附Pb^2+、Cd^2+性能的影响,并利用吸附动力学和热力学来揭示吸附机制。试验结果表明,经生物沥浸改性后污泥基生物炭的重金属含量降低;吸附Pb^2+和Cd^2+的最佳pH值分别为5、6,最佳生物炭投加量均为2 g/L;其对Pb^2+和Cd^2+的吸附均能较好地符合准二级动力学方程和Langmuir等温线模型,在25、35、45℃三种温度下对Pb^2+、Cd^2+的饱和吸附量分别为30.68、39.95、43.93 mg/g和19.82、28.58、32.29 mg/g,吸附过程均主要以物理吸附为主,且为吸热过程。

Biochar was prepared from sludge modified by bioleaching in order to explore the feasibility of removing Pb^2+and Cd^2+from wastewater,and the material characteristics and adsorption properties were measured.The effects of p H and biochar dosage on the adsorption properties of Pb^2+and Cd^2+were studied by single-factor experiments,and the adsorption mechanism was revealed by adsorption kinetics and thermodynamics experiments.The results showed that the heavy metal content of sludge-based biochar decreased after modified by bioleaching.The optimal pH of Pb^2+and Cd^2+adsorbed by biochar was 5 and 6,respectively,and the optimal dosage of biochar was 2 g/L for both heavy metal ions.The adsorption of Pb^2+and Cd^2+was in good agreement with the quasi-second order kinetic equation and Langmuir isotherm model.The saturated adsorption capacities of Pb^2+were 30.68 mg/g(25℃),39.95 mg/g(35℃)and 43.93 mg/g(45℃),and the saturated adsorption capacities of Cd^2+were 19.82 mg/g(25℃),28.58 mg/g(35℃)and 32.29 mg/g(45℃),respectively.The adsorption process was mainly physical adsorption and endothermic process.