超积累植物东南景天热解过程中Cd的迁移转化规律及炭产物安全利用研究

Research on migration and transformation of Cd and safe utilization of carbon products during pyrolysis of hyperaccumulator Sedum alfredii

在管式炉对Cd超积累植物东南景天(Sedum alfredii)进行热解,研究热解过程中Cd的迁移和形态转化,并在最佳温度条件下探究制备的东南景天生物炭对Cd的吸附作用。结果表明,随着温度上升,生物炭产率下降,挥发分增加;温度能影响Cd在气、液、固三相中的分布,温度升高能明显促进重金属由固相向气相迁移;生物炭中Cd形态受温度影响,随温度升高,对环境影响较大的水溶态和酸溶态Cd含量呈现出降低趋势,在700℃以上时,大部分Cd是以稳定的可氧化态、可还原态以及残渣态形式存在;800℃热解得到的东南景天生物炭对Cd具有一定的吸附效果,最高吸附量达到28.7mg/g。通过合理控制热解温度能够实现炭产物的稳定化,并可安全利用到重金属污染水体或者农田污染治理中。

The migration and morphological transformation of Cd at different temperatures during the pyrolysis of Cd hyperaccumulator Sedum alfredii were studied in a tube furnace,and the adsorption effect of prepared Sedum alfredii biochar was studied under the optimal temperature conditions.The results showed that with the increase of the temperature,the yield of biochar decreased and the volatile matter increased.The temperature could affect the distribution of Cd in gas,liquid and solid phases.The increase of temperature could significantly promote the conversion of heavy metals from solid phase to gas phase.The morphology of Cd in biochar was affected by temperature.The content of water-soluble Cd and acid-soluble Cd which were harmful to environment showed a decreasing trend with increasing temperature.When the temperature was above 700 ℃,most of the Cd was stable,mainly existed in oxidizable,reducible and residual forms.Sedum alfredii biochar obtained by pyrolysis at 800℃ had a certain adsorption effect,and the highest adsorption amount reached 28.7 mg/g.By reasonably controlling the pyrolysis temperature,the stabilized carbon product could be safely utilized in heavy metal polluted water bodies and farmland pollution control.