| 牛粪生物炭对水中氨氮的吸附特性 |
| 摘要点击 3837 全文点击 1932 投稿时间：2014-09-12 修订日期：2014-12-18 |
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| 中文关键词 生物炭 牛粪 吸附 氨氮 动力学 |
| 英文关键词 biochar dairy manure adsorption ammonium kinetics |
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| 中文摘要 |
| 以牛粪生物炭为吸附剂,研究了pH、粒径、投加量、温度和共存阳离子等因素对牛粪生物炭吸附氨氮的影响及吸附特性. 结果表明,共存阳离子Na+、Ca2+的存在对牛粪生物炭吸附氨氮有抑制作用,在Na+、Ca2+浓度相同条件下对氨氮吸附影响大小顺序为Na+>Ca2+; 牛粪生物炭吸附氨氮的最佳初始pH值应在5~8范围; 通过对动力学数据进行分析,发现准二级动力学方程(R2=0.9673)比准一级动力学方程(R2=0.7659)和Elovich方程(R2=0.7249)能更好地拟合动力学数据,颗粒内扩散方程拟合结果发现牛粪生物炭对氨氮的吸附包括表面吸附和颗粒内扩散两个过程. 吸附等温线拟合发现Freundlich方程(R2=0.9762)能很好地描述氨氮在牛粪生物炭上的吸附行为. 吉布斯自由能变化(ΔGθ)、焓变(ΔHθ)和熵变(ΔSθ)的计算结果表明,牛粪生物炭对氨氮的吸附是自发的吸热过程. |
| 英文摘要 |
| The adsorption characteristics of ammonium from aqueous solution onto biochar derived from dairy manure were investigated as a function of parameters such as solution pH, particle size, adsorbent dosage, temperature and competitive cations. The results indicated that the effects of other cations on the adsorption of ammonium followed the order of preference Na+>Ca2+ at identical mass concentrations. It was observed that pH played an important role in the ammonium adsorption and the optimal pH values ranged between 5 and 8. The kinetic data fitted the pseudo-second-order model (R2=0.9673) but showed very poor fits for the pseudo-first-order model (R2=0.7659) and the Elovich model (R2=0.7249). The results from the Intra-particle model also showed that there were two separate stages in sorption process, which were external diffusion and the diffusion of inter-particle. Adsorption isotherms for dairy manure biochar were fitted the Freundlich model (R2=0.9762) more effectively than other models. Thermodynamics parameters such as free energy (ΔGθ), enthalpy (ΔHθ), and entropy (ΔSθ) were also determined, which indicated that the adsorption was a spontaneous and endothermic process. |
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