In a porous fractal medium, the transport dynamics is sometimes anomalous as well as the crossover between numerous transport regimes occurs. In this paper, we experimentally investigate the mass transfer of the diffusing agents of various classes in the composite porous particle with fractal geometry. It is shown that transport mechanisms differ at short and long times. At the beginning, pure advection is observed, whereas the longtime transport follows a convective mechanism. Moreover, the longtime transport experiences either Fickian or non-Fickian kinetics depending on the diffusing agent. The non-Fickian transport is justified for the diffusing agent with higher adsorption energy. Therefore, we speculate that non-Fickian transport arises due to the strong irreversible adsorption sticking of the diffusing molecules on the surface of the porous particle. For the distinguishing of the transport regimes, an approach admitting the transformations of the experimental data and the relevant analytic solutions in either semi-logarithmic or logarithmic coordinates is developed. The time-fractional advection–diffusion equation is used on a phenomenological basis to describe the experimental data exhibiting non-Fickian kinetics. The obtained anomalous diffusion exponent corresponds to the superdiffusive transport.

在多孔的分形介质中，运输动力学有时会异常，并且会发生多种运输方式之间的交叉。在本文中，我们通过实验研究了具有分形几何形状的复合多孔颗粒中各种类别的扩散剂的传质。结果表明，运输机制在短时间和长时间内是不同的。最初，观察到纯对流，而长时间的运输遵循对流机制。此外，取决于扩散剂，长时间运输经历菲克动力学或非菲克动力学。对于吸附剂具有较高吸附能的扩散剂，非菲克安输运是合理的。所以，我们推测，由于扩散分子在多孔粒子表面上强烈的不可逆吸附，从而产生了非菲克式传输。为了区分运输方式，开发了一种允许以半对数或对数坐标表示的实验数据和相关解析解的转换方法。时间-分数对流-扩散方程基于现象学原理，用于描述表现出非菲克动力学的实验数据。所获得的异常扩散指数对应于超扩散输运。时间-分数对流-扩散方程基于现象学原理，用于描述表现出非菲克动力学的实验数据。所获得的异常扩散指数对应于超扩散输运。时间-分数对流-扩散方程基于现象学原理，用于描述表现出非菲克动力学的实验数据。所获得的异常扩散指数对应于超扩散输运。