农林废弃物吸附废水中重金属Pb2+的性能及机理研究进展

Research Progress of the Properties and Mechanism of Heavy Metal Pb2+Absorbed by Agricultural and Forestry Waste in Wastewater

人体Pb 2+超标会造成贫血、肾功能衰竭、内分泌系统和中枢神经系统紊乱等症状。Pb 2+可通过含Pb 2+废水、废渣等形式对环境造成污染,其中含Pb 2+废水不仅对水源造成直接污染,同时也会在流经区域土壤形成Pb 2+富积而造成土壤重金属污染,因此对含Pb 2+废水的无害化处理刻不容缓。废水中Pb 2+的去除方法主要包括离子交换法、化学沉淀法、电化学法、膜过滤法和吸附法等,其中,吸附法因具有效率高、方便操作和成本低等优点而被广泛应用。商业活性炭吸附废水中Pb 2+的效果很好,但是高成本限制其使用,因此寻找活性炭替代吸附剂是吸附法处理含Pb 2+废水技术发展的关键。农林废弃物(AFW)因其来源广泛、种类繁多、成本低廉、吸附效果好、吸附材料可再生等诸多优势,被广泛应用于废水中Pb 2+的去除。可通过酸碱盐改性、结构改性、炭化改性、有机溶剂改性和复合改性等对AFW进行处理,以提高其吸附效率。同时,Pb 2+初始浓度、吸附剂量、pH值、温度和时间等因素对AFW吸附Pb 2+的效率有较大的影响。AFW可通过离子交换、络合作用、物理吸附、化学沉淀等多重作用机制实现Pb 2+的高效吸附,其吸附动力学一般符合准二级动力学模型,吸附热力学一般符合Langmuir热力学模型或Freundlich热力学模型。本文综述了AFW吸附废水中Pb 2+的研究现状与进展,从AFW改性、Pb 2+吸附影响因素及其作用机制等方面进行了讨论。最后,对AFW吸附Pb 2+研究中存在的问题进行了分析,并对其未来的研究方向进行了展望,以期为制备稳定可循环的AFW提供参考。

Excessive Pb 2+in human body can cause some diseases such as anemia,renal failure,endocrine system and central nervous system disorders.Pb 2+pollution may exist in the form of waste water and solid waste.Among them,the Pb 2+containing waste water can not only directly cause the water source pollution,but also contaminate the soil in the related area.So the treatment of Pb 2+containing waste water is urgent.Pb 2+can be removed from water by means of ion exchange,chemical precipitation,electrochemical method,membrane filtration and adsorption method.Adsorption method has been extensively used for the treatment of waste water due to its high efficiency,easy operation and low cost.Commercial activated carbon has better adsorption effect to treat waste water,but the high cost limits its utilization as an adsorbent.Hence,it is a key point to develop an alternative of activated carbon for the technology of wastewater treatment.Agricultural and forestry waste(AFW)has been widely used to remove the Pb 2+in wastewater due to the advantages such as wealth sources,great varieties,low cost,good adsorption effect and renewability.Moreover,the adsorption efficiency of AFW can be improved by means of acid-base salt modification,structure modification,carbonization modification,organic solvent modification and compound modification.Meanwhile the factors such as the initial concentration of Pb 2+,amount of adsorbent,pH value,adsorption temperature and time have great influences on the adsorption efficiency of AFW.AFW can efficiently adsorb the Pb 2+in wastewater through ion exchange,coordination action,physical adsorption and chemical precipitation.The adsorption kinetics can be described by pseudo second order,and the thermodynamics can be calculated by Langmuir isotherm model and Freundlich thermodynamic model.This paper reviewes the research progress on the adsorption of Pb 2+in wastewater by AFW.The modification of AFW,the influence factors of Pb 2+adsorption and adsorption mechanism are discuss in this paper.We also discuss the directions of future research on the adsorption of Pb 2+by AFW,thus to provide a reference for the development of stable and renewable AFW adsorbents.