Phenanthrene and pyrene sorption and intraparticle diffusion in polyoxymethylene, coke, and activated carbon
Phenanthrene and pyrene sorption and intraparticle diffusion in polyoxymethylene, coke, and activated carbon
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DOI：
10.1021/es050113o
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发表时间：
2005-09-01
影响因子：
11.4
通讯作者：
Luthy, RG
中科院分区：
文献类型：
--
作者：
Ahn, S;Werner, D;Luthy, RG
我们报告了三种有机模型吸附剂：聚甲醛（POM）、焦炭和活性炭对菲和芘的吸附等温线和吸收动力学。我们利用探针激光解吸激光电离质谱（mu(LMS)-M-2）对菲和芘在横截面颗粒内的长期扩散进行了直接观察，并结合了批平衡和动力学实验。对于POM颗粒，通过动力学批实验和具有球形几何的聚合物扩散模型预测的颗粒内浓度分布与独立mu(LMS)-M-2测量结果一致。焦炭颗粒的表观扩散系数随粒径的减小而减小。扩散率的这些趋势是用吸附延迟孔隙扩散模型来描述的，该模型具有依赖于颗粒的固体-水分配系数，该系数是从动力学批研究中观察到的表观平衡中得到的。对于活性炭，μ (LMS)-M-2测量结果表明，菲和芘向颗粒内部的径向扩散速度比基于单一吸附域和扩散率的扩散模型预测的要快。多环芳烃（PAH）大孔扩散与大孔和微孔域间动力学交换的支孔动力学模型与实验结果吻合较好。由于平行的宏观和微观扩散过程，非线性吸附等温线和浓度依赖的扩散率，使用我们目前的程序不可能对活性炭中的颗粒内扩散进行独立的参数估计。
We report sorption isotherms and uptake kinetics for phenanthrene and pyrene with three organic model sorbents: polyoxymethylene (POM), coke, and activated carbon. We combine batch equilibration and kinetic experiments with the direct observation of the long-term diffusion of phenanthrene and pyrene as measured within cross-sectioned particles using microprobe laserdesorption laser-ionization mass spectroscopy (mu(LMS)-M-2). For POM pellets, the intraparticle concentration profiles predicted from kinetic batch experiments and a polymer diffusion model with spherical geometry are in agreement with the independent mu(LMS)-M-2 measurements. For coke particles, the apparent diffusivities decreased with smaller particle size. These trends in diffusivities were described by a sorption-retarded pore diffusion model with a particlesize-dependent solid-water partitioning coefficient obtained from apparent equilibrium observed in the kinetic batch studies. For activated carbon, the mu(LMS)-M-2 measurements showed faster radial diffusion of phenanthrene and pyrene into the particle interior than predicted from diffusion models based on a single sorption domain and diffusivity. A branched pore kinetic model, comprising polycyclic aromatic hydrocarbon (PAH) macropore diffusion with kinetic exchange of PAH between macroporous and microporous domains, fits the experimental observations better. Because of parallel macro- and microdiffusion processes, nonlinear sorption isotherms,and a concentration dependent diffusivity, it is not possible to make independent parameter estimations for intraparticle diffusion in activated carbon using our present procedures.