浮床植物收割策略及资源化制取生物炭吸附重金属

Harvesting Strategy of Ecological Floating Bed Plants and Its Utilization to Prepare Biochar for Heavy Metals Adsorption

为了准确制定生态浮床植物收割策略并寻求收割后植物的资源化途径,首先监测浮床中不同植物的茎叶和根系中氮、磷含量的历时变化,然后将收割植物组织在高温限氧环境下裂解制备生物炭,用于废水中重金属的去除并解析其机理。结果表明,浮床植物中菖蒲和千屈菜的茎叶应在每年10月下旬—11月上旬进行收割,而鸢尾和铜钱草无需收割。另外,优选出菖蒲茎叶在400℃下裂解制取的生物炭用于去除废水中的重金属,其对Pb^(2+)、Cu^(2+)、Ni^(2+)和Mn^(2+)的饱和吸附量分别可以达到256.189、52.538、49.141和43.463 mg/g,而且吸附过程符合单分子层吸附的Langmuir模型;除了吸附作用外,生物炭和重金属之间的阳离子π作用以及碱性条件下重金属的沉淀作用也有助于废水中重金属的去除。

To accurately formulate the harvesting strategy of ecological floating bed plants and seek for the resource utilization method of the harvested plants,the changes of nitrogen and phosphorus contents in stems,leaves and roots of different plants in ecological floating bed were monitored first,and then the harvested plant tissues were pyrolyzed in high temperature and oxygen‑limited environment to prepare biochar for removing heavy metals from wastewater,and the adsorption mechanism was eventually analyzed.The stems and leaves of Calamus and Lythrum should be harvested from late October to early November each year,while Iris and Hydrocotyle vulgaris did not need to be harvested.In addition,the biochar prepared by stems and leaves of Calamus pyrolyzed at 400℃was selected to remove heavy metals from wastewater.The saturated adsorption capacities of Pb^(2+),Cu^(2+),Ni^(2+)and Mn^(2+)reached 256.189 mg/g,52.538 mg/g,49.141 mg/g and 43.463 mg/g,respectively,which conformed to the monolayer adsorption of Langmuir model.Except adsorption,the cationicπinteraction between biochar and heavy metals and precipitation of heavy metals under alkaline conditions also contributed to the removal of heavy metals from wastewater.