不同生物炭对废水中镉离子的吸附特性

Adsorption Characteristics of Cd^(2+)in Wastewater by Different Biochar

为研究不同生物炭对废水中镉离子的吸附特性,以玉米秸秆、枯树枝、花生壳、核桃壳为生物质材料,在650℃下,对不同农林废弃物材料进行厌氧热解,最终得到4种不同生物炭,并对其进行了扫描电子显微镜(SEM)、X射线衍射(XRD)、傅里叶红外光谱(FT-IR)以及比表面积(BET)表征。研究不同生物炭对溶液中的二价镉离子(Cd^(2+))吸附特性,并分析了其吸附作用机理。探究了溶液中Cd^(2+)初始浓度、体系pH值、生物炭含量和反应时间对吸附的影响。结果表明:不同种类生物炭均对废水中Cd^(2+)有一定的吸附作用,其吸附过程符合Langmuir吸附模型和准一级动力学模型。其中花生壳生物炭(H)对镉离子的吸附效果最好,最大吸附量可达19.52mg·g^(-1)。吸附速率最快,在相同条件下30min内即可达到吸附平衡。生物炭对Cd^(2+)的吸附作用受溶液pH值、生物炭投加量等影响。当pH值为6,H对Cd^(2+)的吸附率最大为95.15%;当溶液体积为20mL,生物炭含量为100mg时,H对Cd^(2+)的吸附率可达98.1%。因此,H可作为良好的吸附剂来修复水体镉污染。

In order to study the adsorption characteristics of Cd^(2+)in wastewater by different biochar,four kinds of biochar were obtained by the anaerobic pyrolysis of four kinds of biomass materials,including corn straw,maple poplar branch,peanut shell and walnut shell,at 650℃.Four kinds of biochar were characterized by scanning electron microscopy(SEM),X-ray diffraction(XRD),infrared spectroscopy(FT-IR),and specific surface area(BET).The adsorption test of divalent Cd^(2+)in solution was carried out,and the adsorption mechanism was analyzed.The effects of initial concentration of Cd^(2+),pH,biochar content and reaction time on adsorption were investigated,the results showed that different kinds of biochar could adsorb Cd^(2+)from wastewater,and the adsorption process was in accordance with Langmuir adsorption model and quasi-first-order kinetic model.The peanut shell biochar(H)had the best adsorption effect on cadmium ion,and the maximum adsorption amount was 19.52mg·g^(-1).The adsorption rate is the fastest,the adsorption equilibrium can be reached within 30min.The adsorption of Cd^(2+)on biochar was affected by pH of solution and the dosage of biochar.The adsorption rate of Cd^(2+)on H reached 95.15% when pH was 6,and 98.1% when the volume of solution was 20ml and the dosage of biochar was 100mg.Therefore,peanut shell biochar can be used as a good adsorbent for remediation of cadmium pollution in water.