玉米秸秆生物炭对铅离子的等温吸附特征研究

摘要

The use of corn straw in Shenyang,using thermal decomposition method at 400 ℃ for preparing biological carbon.In different temperature (298.15,308.15,318.15 K and 328.15 K),different condition of pH (3,4,5 and 6),different concentration of Ca2+ (0.002 5,0.005,0.01,0.02 mmol/L),using the Langmuir,Freundlich and D-R isotherm equation respectively on isothermal adsorption experimental data fitting,and discussed on the adsorption mechanism.The results showed that the corn straw biomass carbon under different temperature better conforms to Langmuir model (R2=0.989 1~0.995 6) by a Langmuir mode numerical value can be obtained.With the increase of temperature,the adsorption amount increases;in different pH value of corn straw biochar to lead from the adsorption isotherm can also use the Langmuir model (R2=0.989 9~0.999 6) were used to characterize.It shows that,with the decrease of pH,the adsorption capacity decreased;in different concentrations of Ca2+,available Langmuir adsorption isotherm fitting (R2=0.986 6~0.996 0).The maximum adsorption capacity increased by Langmuir adsorption isotherm calculated with Ca2+ concentrations decreased.%选用采自沈阳的玉米秸秆,采用控温热分解法,在400 ℃下制备生物炭.在不同温度(298.15,308.15,318.15,328.15 K)、不同pH(3,4,5,6)、不同浓度的Ca2+ 离子(0.002 5,0.005,0.01,0.02 mmol/L)的条件下进行实验,使用Langmuir、 Freundlich和D-R 等温方程分别对等温吸附实验数据进行拟合,并讨论吸附机理.结果表明,玉米秸秆生物质炭在不同温度下更好地符合Langmuir 模式(R2=0.989 1~0.995 6).由Langmuir模式中的a值可以得出,随温度的升高,吸附量增加;在不同pH 值下玉米秸秆生物质炭对铅离子的吸附等温式同样可以使用Langmuir 模式(R2=0.989 9~0.999 6)进行表征.而且,随pH的降低,吸附量减少;在不同Ca2+ 离子浓度下,可用Langmuir 等温吸附式拟合(R2=0.986 6~0.996 0).通过Langmuir 等温吸附式推算出的最大吸附量随Ca2+离子浓度的增加而减少.