生物炭对土壤中释放的石油类污染物的吸附

Adsorption of Petroleum Pollutants Released From Soil by Biochar

为探究不同来源生物炭对土壤释放到水中石油烃的吸附性能,选取麦秆炭、椰壳炭、稻壳炭和棉秆炭作为吸附剂。通过批量吸附实验,分别考察反应时间、生物炭投加量、pH值和溶液初始浓度对生物炭吸附石油烃性能的影响,并进行动力学和等温吸附拟合。结果表明:4种生物炭均有较高的比表面积,麦秆炭最大,达到729.12 m ^2/g。当溶液pH值为5、溶液初始质量浓度125.64 mg/L、稻壳炭投加量40 mg、其他生物炭投加量20 mg、反应5 h时,生物炭对石油烃的吸附效果达到最佳状态。4种生物炭对石油烃的吸附能力大小依次为麦秆炭、椰壳炭、稻壳炭、棉秆炭。准二级动力学模型能更好地描述4种生物炭的动力学过程,结果表明生物炭对石油烃的吸附为表面吸附和内部扩散等多种方式;Freundlich模型能够更好地反映等温吸附过程,结果表明生物炭对石油烃为多分子层吸附。

Different sources of biochar, including wheat straw biochar (WSB), coconut shell biochar (CCB), rice husk biochar (RHB) and cotton straw biochar (CSB) were used as adsorbents to study the adsorption properties of petroleum hydrocarbons. Batch adsorption experiments were conducted to investigate the effects of reaction time, biochar dosage, pH value and initial concentration on the petroleum hydrocarbons adsorption capacity by biochars, and then kinetic and isothermal adsorption fitting were performed. The experiment results indicated that all biochars have high surface areas, and the highest value is found for WSB which is 729.12 m ^2/g. When the pH value of the solution is 5, the initial mass concentration of solutions is 125.64 mg/L, the dosage of RHB is 40 mg, the dosages of other biochars are 20 mg, and the reaction time is 5 h, the adsorption capacity reached the optimal state. The adsorption capacity of the four biochars decreased in the order of WSB, CCB, RHB and CSB. The Pseudo-second order kinetics model is found having a better description of the dynamic processes, indicating that the adsorption of petroleum hydrocarbons by biochar contains both surface adsorption and internal diffusion. It is found that the Freundlich model reflects better the isothermal adsorption process, indicating that adsorption of petroleum hydrocarbons by biochars belongs to the multilayer molecular adsorption.