Abstract:

With the rapid development of large-scale breeding， the production of poultry manure increases accordingly， how to treat and recycle it has increasingly become a research hotspot. The performance of chicken manure-derived biochar （CMBC-400， pyrolysis temperature of 400 ℃） was investigated to remove Pb²⁺ in wastewater. The sorption kinetics， isotherms and thermodynamics of Pb²⁺ adsorption on CMBC-400 were investigated by batch experiments. The experimental data fitted well with the pseudo-second order model， which indicated chemisorption was the rate-limiting step of sorption process. Equilibrium sorption of CMBC-400 on Pb²⁺ fitted best with the Langmuir model， indicating a fixed number of identical and energetically equivalent active sites on the homogeneous surface of CMBC-400. The thermodynamic investigation confirmed that the sorption of CMBC-400 on Pb²⁺ could carry out spontaneously， and the higher temperature favored the processes. The SEM and XRD analysis indicated that CMBC-400 could intensely adsorb solution Pb²⁺ via precipitation of Pb-containing microcrystals. Moreover， soil experiments indicated that addition of CMBC-400 could effectively enhanced the conversion of the available Pb to the stable forms， thereby decreasing the bioavailability of soil Pb.

Key words: chicken manure-derived biochar, Pb, adsorption, immobilization

摘要：

随着规模化养殖的快速发展，畜禽粪便的产量随之增加，如何对其进行有效处理与资源化利用已成为研究热点。选取鸡粪为原料，在400 ℃下限氧热解制备生物炭（CMBC-400），探究其对水体中铅离子（Pb²⁺）的吸附性能。通过批处理试验考察吸附时间、Pb²⁺初始含量、吸附温度等因素对CMBC-400吸附Pb²⁺性能的影响，并利用吸附动力学、等温线和热力学计算模型对吸附数据进行拟合，进一步阐述吸附过程。结果表明，CMBC-400吸附Pb²⁺的过程更符合准二级动力学模型，表明该吸附过程的吸附速率主要受化学吸附控制；相比Freundlich和Dubinin-Radushkevich （D-R）模型，Langmuir等温线模型具有更高的拟合相关系数，表明CMBC-400表面均一，Pb²⁺吸附位点的吸附能大致相同；吸附热力学数据表明CMBC-400对Pb²⁺的吸附过程是自发的吸热反应。扫描电镜和X-射线衍射表征结果表明，CMBC-400主要通过在表面形成含Pb微晶的形式固定水体中的Pb²⁺。此外，向土壤中添加CMBC-400还可促进有效态Pb转化为稳定态，降低Pb的生物有效性。

关键词: 鸡粪生物炭, 铅, 吸附, 固定