摘要
采用野生型水稻(WT,高硅)和硅缺失突变体水稻(lsi1,低硅)秸秆为原材料制备成300、500、700℃3种温度生物炭,探究高低硅秸秆生物炭对Cd^(2+)的吸附特性及作用机制。野生型和突变型水稻秸秆原料总硅含量分别为17.88%和7.42%,制备出的高硅生物炭相对于低硅生物炭具有较高的硅含量、较大的比表面积和孔径。通过元素分析、电镜能谱扫描分析(SEM-EDS)、傅里叶红外光谱分析(FTIR)以及比表面积分析(BET-N2)等对两种生物炭进行分析,结果表明随温度上升两类生物炭均表现出产率下降、pH增大、比表面积上升,高低硅生物炭均能在471、788、1090 cm^(-1)波峰处观察到Si-O-Si键。吸附实验表明,高低硅生物炭均在pH为6、固液比为1 g·L^(-1)时对水溶液中Cd^(2+)吸附效果最佳。吸附动力学模型结果表明,高低硅生物炭的吸附动力学过程均符合准二级动力学模型(R2>0.9),说明该过程以化学吸附为主。通过Langmuir和Freundlich模型进行等温吸附拟合,均能较好反映出高低硅生物炭的吸附行为与特性。结合高低硅生物炭的基本理化性质、FTIR分析和SEM-EDS观察的结果表明生物炭吸附机制主要为离子交换、沉淀和官能团络合作用。研究表明,热解温度较高的高硅生物炭吸附效果更好,这可能与其具有较高的硅含量、较大的比表面积与孔体积、较多的阳离子及较为丰富的官能团有关。
Materials from wild type(WT,high-Si)and silicon(Si)-defective mutant material(lsi1,low-Si)were pyrolyzed to prepare biochar at 300,500℃,and 700℃.The adsorption characteristics and mechanisms of high-and low-silicon biochar for Cd^(2+)were investigated.The total Si concentration of WT and lsi1 were 17.88%and 7.42%,respectively;WT biochar showed higher Si concentration and larger specific surface area and porosity compared with lsi1 biochar.Elemental analysis,electron microscope energy spectrum scanning analysis(SEM-EDS),fourier infrared spectral analysis(FTIR),specific surface area analysis(BET-N2),and other characterization methods showed that,as pyrolysis temperature increased,the yield of biochar decreased,the pH value and specific surface area increased,and the Si O Si bond was observed at the 471,788 cm^(-1),and 1090 cm^(-1)peaks for both high and low silicon biochar.Adsorption experiments showed that both WT and lsi1 biochars had the best effect on Cd^(2+)adsorption in an aqueous solution at pH 6 and solid-liquid ratio 1 g·L^(-1).The adsorption kinetic model demonstrated that the dynamics adsorption process of WT and lsi1 biochars were more in line with the quasi-secondary kinetic model(R2>0.9),chemical adsorption played an important role in the absorption of Cd.Furthermore,the isothermal adsorption fitting by Langmuir and Freundlich models could better reflect the adsorption behavior and characteristics of biochar.Combined with the basic physicochemical properties,FTIR and SEM-EDS analysis showed that the Cd adsorption mechanisms of both types of biochar included ion exchange,precipitation,and functional group networking.High temperature and WT biochar had better effects on Cd^(2+)adsorption,possibly due to their higher Si concentration,large specific surface area and pore volume,higher cation density,and richer functional groups.
作者
谭丹
王衡
梅闯
郜礼阳
蔡昆争
TAN Dan;WANG Heng;MEI Chuang;GAO Liyang;CAI Kunzheng(College of Natural Resources and Environment,South China Agricultural University,Guangzhou 510642,China;South China Key Laboratory of Tropical Agricultural Environment,Ministry of Agriculture and Rural Affairs,Guangzhou 510642,China;Guangdong Provincial Key Laboratory of Ecological Circulation Agriculture,Guangzhou 510642,China)
出处
《农业环境科学学报》
CAS
CSCD
北大核心
2023年第2期339-351,共13页
Journal of Agro-Environment Science
基金
国家自然科学基金项目(31870420)。
