小麦秸秆生物质炭吸附Cr(Ⅵ)的研究

Study on Adsorption of Hexavalent Chromium Using Biochar which Prepared by Wheat Straw

以农业废弃物小麦秸秆制备生物质活性炭,分别用HNO_3、Na OH和KMn O_4进行改性,通过Boehm法对不同改性活性炭进行表征,考察了吸附时间、p H及Cr(Ⅵ)初始浓度对吸附效果的影响。结果表明,经硝酸改性的活性炭,官能团总量提高,吸附Cr(Ⅵ)的效果和吸附速率最高,受p H变化的影响更小。Langmuir和Freundlich吸附等温线均能反映未改性和硝酸改性活性炭的吸附情况,二者的吸附过程均可用Lagergen二级动力学模型描述。

Biochar was prepared by wheat straw and modified by HNO3, NaOH and KMnO4, respectively. The different modified biochar was measured with Boehm titration. The effects of adsorption time, pH and initial concentration of Cr （ V[ ） on adsorption capacities were studied. The amount of surface functional groups of the HNO3 modified activated carbon was increased, and the rate of adsorption was the highest at various pH value. The adsorption onto activated carbon was well reflected by Langmuir and Freundlich adsorption isotherm. The process can be well described by pseudo-second-order kinetic model as sugges- ted by Lagergen.