摘要
根据粒径将红壤组分分为4种（〈0.002 mm、0.002~0.05mm、0.05~0.25 mm、0.25~2 mm）,研究了苯系物（邻二甲苯、对二甲苯和乙苯混合物,BTEX）在不同粒径组分上的吸附-解吸行为。结果表明,两区非平衡模型可以很好地拟合红壤不同粒径组分对BTEX的吸附动力学,吸附量随红壤粒径减小而增大。红壤不同粒径组分对BTEX的吸附-解吸过程接近于线性（R2〉0.98）,Kd随粒径减小而增大,表明红壤粒径的差异极大地影响了BTEX的吸附行为。同时,BTEX在红壤不同粒径组分上的解吸存在不同程度的滞后现象,滞后系数HI随粒径减小而增大。BTEX的解吸滞后现象比多环芳烃和石油烃明显,可能是由于BTEX的分子较小,易进入颗粒孔隙内部成为不可逆吸附部分而不容易解吸。通过XRD及FTIR分析了红壤不同粒径组分吸附BTEX前后的特征。XRD的分析结果表明,BTEX主要吸附于高岭石和伊利石表面;FTIR的结果表明,BTEX主要与羧酸酯、酚式羟基等官能团相结合而吸附于土壤颗粒上。
The given article is dedicated to the exploration of the ef- fects of different particle sizes of red soil on BTEX （the mixture of o- xylene, p-xylenc and ethylbenzene） sorption and desorption behaviors through a batch of experiments. The said red soil is here referred to as that made of particle sizes of 〈 0.002 mm, 0.002 - 0.05 mm, 0.05- 0.25 mm, 0.25 -2 ram. Since the sorption kinetics can be made well fitted by the TSNE model （R2 〉 0.98 ）, the sorption amounts of BTEX tend to increase from 265.7 mg/kg to 955.7 mg/kg with the decrease of the soil particle size. As a result, on the condi- tion when the absorption behavior is well fitted with the linear model, the sorption coefficients （Ka） may tend to decrease from 35.8 L/kg to 9.25 L/kg with the increase of the particle-sizes of the red soil, signifying that the sorption of BTEX tends to be significantly affected by the soil＇s particle-size. What is more, since the sorption behavior of different sizes of the particle-fractions are mainly influenced by the soil features, including the pore characteristics, the total organic car- bon and soil surface area, and the desorption hysteresis, can be ob- served due to their sorption irreversibility in different soil particle-size fractions, the hysteresis index （HI） has thus been proved to be in- versely related to the soil particle-size. Besides, since the desorption hysteresis of BTEX was more obvious than that of PAHs and the petroleum hydrocarbon, it is easier for the comparatively smaller molecules of BTEX to penetrate into the inside of the soil to result in irreversible sorption, the X-ray diffraction （XRD） and the Fourier- transform infrared （FFIR） spectrometry analysis of soil particles be- fore and after the BETX sorption were done for us to better understand the sorption and desorption mechanism of the BETX on different soil particles. What is more, since the X-ray diffraction peak of kaolinite and illite before the sorption tended to be minor than that after the sorption, it implies that the BTEX tends to be mainly absorbed onto the surface of kaolinite and illite. Besides, since the FTIR spectra transmittance may decline as long as the adsorption and the transmit- tance tend to decrease with the increase of red soil＇ s particle size, a shift would happen for the peaks of hydroxyl and carboxylate after be- ing adsorbed. Thus, all the aforementioned results demonstrate that the hydroxyl and carboxylate groups have thus turned to be the chief functional sites participating in the said sorption.
出处
《安全与环境学报》
CAS
CSCD
北大核心
2015年第2期210-215,共6页
Journal of Safety and Environment
基金
国家自然科学基金项目(41271476)
关键词
环境学
苯系物
红壤
粒径组分
吸附
解吸
environmentalology
BTEX
red soil
particle-size frac-tions
sorption
desorption
