花椰菜基生物炭对水中Pb(Ⅱ)的吸附性能

Adsorption characteristics of Pb(Ⅱ) by biochars derived from cauliflower(Brassica oleracea L.) from aqueous solution

以农业废弃物花椰菜的根和叶为原材料,采用限氧裂解法在500℃条件下制备花椰菜根基生物炭(BCR)和叶基生物炭(BCL),探究了吸附时间、温度、Pb(Ⅱ)初始浓度、pH及不同共存离子对2种生物炭吸附性能的影响,并通过扫描电镜(SEM)、能谱分析(EDS)、红外光谱(FTIR)及比表面积测定(BET)等手段对生物炭的结构和性质进行了表征,初步探讨了吸附机理.结果表明,2种生物炭对Pb(Ⅱ)的吸附符合准二级动力学和颗粒内扩散模型,BCR和BCL对Pb(Ⅱ)的吸附分别在3 h和6 h达到吸附平衡;2种生物炭对不同浓度下Pb(Ⅱ)的吸附符合Langmuir和Freundlich等温吸附模型;在25℃条件下,BCR和BCL对Pb(Ⅱ)的最大吸附量分别达到454.55和434.78 mg·g^(-1),BCR和BCL具有良好的吸附效果,可作为优良的生物质基吸附材料.

Two types of biochars derived from cauliflower roots（BCR） and cauliflower leaves（BCL） were prepared by pyrolyzing at a temperature of 500℃ under an oxygen-limited condition.The effects of contact time,temperature,initial Pb（Ⅱ） concentration and initial pH in batch experiments were investigated and discussed.The structure and properties of biochars were characterized by using scanning electron microcopy（SEM）,energy dispersive spectroscopy（EDS）,fourier transform infrared spectroscopy（FTIR） and Brunauer-Emmett-Teller（BET） surface area measurements,which were used to preliminarily analyze adsorption mechanism.The results show that the two adsorption kinetics of Pb（Ⅱ） onto biochars followed the pseudo-second-order kinetics and well fitted by intra-particle diffusion model;the adsorption of Pb（Ⅱ） onto BCR and BCL could reach equilibrium after 3 h and 6 h of reaction,respectively;the adsorption isotherm experimental data of BCR and BCL were fitted well with the Langmuir isotherm model and Freundlich isotherm model;the maximum adsorption capacities of BCR and BCL at 25 ℃ were 454.55 mg·g-1 and 434.78 mg·g-1,respectively.This indicates that biochars can be used as an excellent adsorbent material to effectively remove Pb（Ⅱ） because of the extraordinary absorption ability.