| 不同热解及来源生物炭对西北黄土吸附敌草隆的影响 |
| 摘要点击 2156 全文点击 962 投稿时间：2016-06-25 修订日期：2016-07-20 |
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| 中文关键词 生物炭 黄土 吸附动力学 吸附热力学 敌草隆 |
| 英文关键词 biochar loess soil adsorption kinetics adsorption thermodynamics diuron |
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| 中文摘要 |
| 以西北黄土为研究对象，采用批量法研究不同温度下制得的生物炭对西北黄土吸附敌草隆的影响. 结果表明，敌草隆在添加不同质生物炭黄土上的动力学吸附过程较好地符合准二级吸附动力学模型，且吸附过程主要分为快吸附（0~8 h）和慢吸附（8~12 h）两个阶段，在12 h左右达到平衡；热力学较好地符合Freundlich等温吸附模型；添加生物炭的黄土对敌草隆的吸附量随着温度的升高而增大，且吸附过程中ΔGθ小于0，ΔHθ和ΔSθ大于0；不加生物炭的黄土对敌草隆吸附量则随着温度的升高而降低，且吸附过程中ΔGθ和 ΔHθ小于0，ΔSθ大于0；在体系温度范围内，E（吸附平均自由能）为1.29~5.00 kJ·mol-1，表明无论是否添加生物炭，黄土对敌草隆的吸附都以物理吸附为主. 其影响因素分析结果显示，随着生物炭热解温度的升高，溶液中敌草隆的平衡浓度降低，平衡吸附量增大；添加生物炭的黄土对敌草隆吸附量在0.5~6 mg·L-1浓度范围内快速上升，之后吸附量随初始浓度的升高缓慢增加并逐渐趋于平衡；溶液pH对黄土吸附敌草隆有一定影响，但影响不大. |
| 英文摘要 |
| The primary objective of this study was to investigate the effect of biochar, produced from maize and pine needles residue at different temperatures, on the adsorption of diuron onto loess soil. Meanwhile, the effect of the systemic temperature, pH values and the initial concentration of diuron were also investigated for the adsorption of diuron onto losses soil. And Kinetic parameters, such as rate constants, equilibrium adsorption capacities and related correlation coefficients were also calculated and discussed. The results showed that the adsorption of diuron onto loess soil by adding biochar could be described by the pseudo-second-order kinetic model, and followed the intraparticle diffusion model, but diffusion was not only the rate-controlling step. The adsorption process was divided into fast (0-8 h) and slow (8-12 h) adsorption stages, and equilibrium was reached at around 12 h. The adsorption thermodynamics of diuron onto loess soil was nonlinear by nature, and well fitted with the Freundlich isothermal model. Thermodynamic parameter analysis of diuron onto loess soil by adding biochar showed that Gibbs free energy (ΔGθ) was less than zero, while Enthalpy (ΔSθ) and Entropy (ΔHθ) were greater than zero, indicating a spontaneous endothermic adsorption, which increased the degree of disorder during the process. And Thermodynamic parameter analysis of diuron onto loess soil without adding biochar showed that Gibbs free energy (ΔGθ) and Entropy (ΔHθ) were less than zero, while Enthalpy (ΔSθ) was greater than zero. The average adsorption free energy E was in range of 1.29-5.00 kJ·mol-1 when the temperatures increased from 25 to 45℃, indicated that adsorption of diuron onto loess was a physical adsorption. The results also suggested that the influencing factors of diuron had significant effects on the adsorptive behaviors of diuron on loess soil. With increasing pyrolysis temperature of biochar, the equilibrium concentration of diuron in water decreased, while the amount of adsorption on loess soil increased. When the initial concentration of diuron increased from 0.5 mg·L-1 to 6 mg·L-1, the adsorption capacity of diuron onto loess soil by adding biochar showed a rapidly increasing trend. When the initial concentration increased. the adsorption capacity showed a slow increasing trend and gradually tended to be stable. In the pH range of 3 to 10, the adsorption capacity of diuron onto loess soil by adding biochar changed a little. |
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