磷酸改性板蓝根药渣污泥基生物炭的制备及其对含铅废水的处理研究

Preparation of activated sludge based biochar modified with phosphoric acid and its treatment of lead containing wastewater

铅[Pb(Ⅱ)]对水资源的污染越来越严重,寻找高效、低成本的吸附剂一直是一个难题。选用污泥和板蓝根药渣这两种固体废物使用共热解的方式制备了生物炭,为了增强对废水中铅离子的吸附,用磷酸(H_(3)PO_(4))对生物炭进行了改性处理。通过SEM图像可以看出改性生物炭的孔隙结构变得更加发达,比表面积增大。EDS谱图的结果表明改性生物炭在废水中吸附Pb(Ⅱ)的过程可能存在阳离子交换作用。FTIR、XRD和XPS图像分析显示改性生物炭在废水中吸附Pb(Ⅱ)的过程可能存在络合作用和共沉淀作用。吸附动力学试验结果显示,拟一级动力学模型,拟二级动力学模型和Elovich模型的R^(2)均大于0.99,表明物理和化学吸附在改性生物炭去除Pb(Ⅱ)的过程中都起着重要作用。吸附等温线分析表明,吸附容量n大于1,证实改性生物炭对Pb(Ⅱ)具有良好的吸附效果。由此可见,对环境友好的磷酸改性板蓝根药渣污泥基生物炭可以作为一种有效的吸附剂从水系统中去除Pb(Ⅱ)。

The pollution of lead[Pb(Ⅱ)]to water resources is more and more serious.Finding efficient and low-cost adsorbents has been a difficult problem.In this study,two kinds of solid wastes,sludge and Radix isatidis residue,were used to prepare biochar by co-pyrolysis.In order to enhance the adsorption of lead ions in wastewater,the biochar was modified with phosphoric acid(H_(3)PO_(4)).SEM images showed that the pore structure of the modified biochar became more developed and the specific surface area increased.The results of EDS spectra indicate that there may be cation exchange in the process of Pb(Ⅱ)adsorption by modified biochar in wastewater.FTIR,XRD and XPS analysis showed that there may be complexation and co-precipitation during the adsorption of Pb(Ⅱ)from wastewater by modified biochar.The results of adsorption kinetics experiment showed that R²of pseudo-first-order kinetic model,pseudo-second-order kinetic model and Elovich model were all greater than 0.99,indicating that physical and chemical adsorption played an important role in the removal of Pb(Ⅱ)from modified biochar.Adsorption isotherm analysis showed that the adsorption capacity n in this study was greater than 1,which confirmed that modified biochar had a good adsorption effect on Pb(Ⅱ).In conclusion,the environmentally friendly phosphoric acid modified isatidis sludge-based biochar can be used as an effective adsorbent to remove Pb(Ⅱ)from water systems.