李星燃,梁媛.生物炭的13C标记方法及对镉、铜的吸附性能探究[J].环境科学学报,2020,40(9):3389-3396
生物炭的13C标记方法及对镉、铜的吸附性能探究
- 13C labeled biochar and its adsorption performance on cadmium and copper
- 基金项目："十三五"国家水体污染控制与治理科技重大专项（No.2017ZX07205002）；国家自然科学基金青年基金（No.21507097）；苏州市科技发展计划项目（民生科技）（No.SS2019027）；苏州科技大学研究生科研创新计划（No.SKCX18-004）
- 李星燃
- 苏州科技大学环境科学与工程学院, 苏州 215009
- 梁媛
- 苏州科技大学环境科学与工程学院, 苏州 215009
- 摘要：生物炭施入土壤后很难分离和检测，因而难以直观研究生物炭在土壤中的环境行为.本文采用稳定同位素标记法制备13C标记的生物炭，研究了13C标记生物炭的制备方法，以及标记前后生物炭的基本理化性质及其对Cd2+和Cu2+的吸附效果和吸附机理.结果表明，脉冲标记法可有效提高玉米植株的δ13C值，经过550℃限氧热解法制备的13C玉米秸秆生物炭（13C BC）的δ13C值为249.3‰，显著高于土壤（-23.5‰）及未标记的玉米秸秆生物炭（-25.7‰），具有显著的生物炭示踪效果.13C标记的生物炭的pH、CEC、比表面积、表面官能团种类及数量等理化性质与未标记生物炭相似，说明脉冲标记法制备的13C标记生物炭不改变生物炭的基本理化性质.吸附动力学和吸附热力学实验结果表明，13C标记生物炭与未标记生物炭对Cu2+、Cd2+的吸附均符合准二级动力学方程和Langmuir等温吸附方程，且吸附平衡时间、最大吸附量基本相同，表明13C标记生物炭不改变生物炭对Cd2+、Cu2+的吸附效果和吸附特征.XRD、FT-IR结果表明，13C标记生物炭和未标记生物炭具有相同的吸附机理，均为离子交换作用、静电吸附作用和阳离子-π键作用.因此，脉冲标记法制备的13C标记生物炭具有与生物炭相同的基本理化性质和对镉、铜的吸附行为，同时具有显著高于土壤背景的δ13C值，可为土壤中生物炭迁移、生物炭与重金属相互作用行为的研究提供一条途径.
- Abstract：It is challenging to study the transportation and behavior of biochar in the soil environment due to technical difficulties in separation and detection. In this study, 13C-labeled biochar was prepared by stable isotope labeling method to examine the impact of preparation method, and the physicochemical properties of the biochar both before and after labelling on the absorption performance and mechanism for Cd2+ and Cu2+. The results showed that the pulse labelling technique could significantly improve δ13C value of maize plants. The δ13C of 13C labeled biochar (13C BC) produced by 550℃ oxygen-limited pyrolysis from 13C labeled corn straw was 249.3‰, which was higher than that of soil (-23.5‰) and the unlabeled corn straw derived biochar (-25.7‰). The properties of 13C BC such as pH, CEC, specific surface area, surface functional group were similar to that in the unlabeled biochar, indicating that the 13C-labeled biochar produced by pulse labeling technique had not changed the physicochemical properties of the biochar. Adsorption kinetics and thermodynamic experiments showed that both 13C-labeled biochar and unlabeled biochar conformed to the quasi second order kinetics and Langmuir isotherm adsorption equation. The absorption equilibrium time of the two kinds of biochars for cadmium and copper was very similar. The maximum RSD of Cd2+ and Cu2+ were 0.26% and 4.49%, respectively, suggesting that 13C-labeled biochar had not changed the adsorption performance and mechanism of biochar on Cd2+ and Cu2+. XRD and FTIR analysis also revealed that 13C-labeled biochar and unlabeled biochar had the same adsorption mechanism, namely the ion exchange, electrostatic adsorption and cation-π bonding. Therefore, the 13C-labeled biochar prepared by pulse labeling method had the same basic physicochemical properties and adsorption mechanism for Cd2+ and Cu2+as that of biochar. The δ13C of the 13C-labeled biochar was significantly higher than the soil, which can provide an approach for carrying out research on biochar migration and its interaction with heavy metals in soil environment.
