脱水污泥-松木共热解生物炭的制备及吸附性能

摘要

以脱水污泥(含水率80％)和松木的混合物为原料共热解制备生物炭.研究了松木掺混比、热解温度对生物炭产率和BET比表面积(SBET)的影响,采用元素分析、工业分析和扫描电镜比较了单独热解及共热解生物炭的元素组成和表面形貌.结果表明,生物炭产率随着松木掺混比的增加而提高,随着热解温度的升高而下降.2种原料共热解存在明显的协同效果:松木提高了生物炭的碳元素含量,污泥的水分具有一定的活化作用,生物炭表面粗糙程度增加、SBET扩大.当松木掺混比为60％、热解温度为750℃时,生物炭 SBET达到最高的213.4 m2/g.此外,生物炭对水中苯酚的吸附符合准二级动力学,等温吸附过程能用Freundlich模型描述.%Blends of dewatered sewage sludge(moisture content was 80％) and pine sawdust were used as feed stocks for biochar preparation from co-pyrolysis.The effects of blending ratio of pine sawdust and pyrolysis temperature on yield and SBET of biochar were studied; furthermore,the element composition and surface topography of biochars prepared from pyrolysis and co-pyrolysis were compared through ultimate analysis,proximate analysis and SEM.The results showed that,biochar yield increased with the increasing of pine sawdust while decreased with the increasing of pyrolysis temperature.A synergetic effect was found during the co-pyrolysis of the two feed stocks.As the addition of pine sawdust increased the carbon content of the biochar and the activating ability of the water in the sludge,the surface roughness and SBET of the biochar were increased.The maximal SBET reached 213.4 m2/g,which was obtained under the condition that the blending ratio of pine sawdust was 60％ and the pyrolysis temperature was 750 ℃.Moreover,the adsorption of phenol by the biochar followed the pseudo second-order kinetics model and the adsorption isotherm could be described by Freundlich model.