Because of the important contributions of electrochemical redox reactions to biochemical cycles and their potential application for the in-situ remediation of contaminated sediment, the mechanisms of long-distance electron transport coupling spatially separated redox half reactions in sediment have drawn much attention. To explore a preliminary mechanism of long-distance electron transport in sediment, in the current study, two simplified composite systems are constructed consisting of spherical ferroferric oxide (Fe₃O₄) nanoparticles and rod-like carbon nanotubes (CNTs) as conductive fillers and silica (SiO₂) particles as the matrix. Two different constructed composite systems (e.g., SiO₂/Fe₃O₄ and SiO₂/Fe₃O₄/CNTs) were used to model a three-dimensional sediment framework instead of sediment with quite complex components. The effects of the loading of conductive fillers (e.g., Fe₃O₄, CNTs) and the particle size of SiO₂ matrix on the conductive behavior of the composite system were investigated. The results showed that both of the electrical properties of SiO₂/Fe₃O₄ and SiO₂/Fe₃O₄/CNTs composite systems typically exhibited a non-linear conductive behavior that the electrical conductivity increased with the increasing of filler loading and showed an abrupt increase at critical filler loading. The conductivity of the SiO₂/Fe₃O₄ and SiO₂/Fe₃O₄/CNTs composite systems with micro-sized SiO₂ as the matrix was higher than that of the composite systems with nano-sized SiO₂ as the matrix. Compared with the SiO₂/Fe₃O₄ composite system, the electrical conductivity of the SiO₂/Fe₃O₄/CNTs composite system was enhanced by several orders of magnitude and only a small loading of CNTs could make the conductivity of the SiO₂/Fe₃O₄/CNTs composite system reach a higher level. The electrical conductivity predicted by the electrical conductivity model of a two-phase composite system showed a similar trend as the experimental results and the two-dimensional (2D) percolation-based model filled with rods gave a good estimation of percolation probability.

由于电化学氧化还原反应对生化循环的重要贡献及其在污染底泥原位修复中的潜在应用，长距离电子输运耦合空间分离的氧化还原半反应机理引起了人们的广泛关注。为了探索沉积物中长距离电子传输的初步机理，在本研究中，构建了两个简化的复合系统，包括球形的三氧化二铁（Fe ₃ O ₄）纳米颗粒和作为导电填料的棒状碳纳米管（CNT）以及二氧化硅（SiO ₂）颗粒作为基质。两种不同的复合材料体系（例如SiO ₂ / Fe ₃ O ₄（SiO ₂ / Fe ₃ O ₄ / CNTs）和SiO ₂ / Fe ₃ O ₄ / CNTs）用来模拟三维沉积物骨架，而不是组成复杂的沉积物。研究了导电填料（例如Fe ₃ O ₄，CNT）的负载量和SiO ₂基体的粒径对复合体系导电性能的影响。结果表明，SiO ₂ / Fe ₃ O ₄和SiO ₂ / Fe ₃ O ₄的电性能均/ CNTs复合系统通常表现出非线性的导电性能，其电导率随填料载荷的增加而增加，并在临界填料载荷下突然增加。以微米级SiO ₂为基体的SiO ₂ / Fe ₃ O ₄和SiO ₂ / Fe ₃ O ₄ / CNTs复合体系的电导率高于以纳米级SiO ₂为基体的复合体系。了SiO相比₂ / Fe的₃ ö ₄复合体系中，SiO的电导率₂ / Fe的₃ ö₄ / CNTs复合体系提高了几个数量级，只有少量的CNT才能使SiO ₂ / Fe ₃ O ₄ / CNTs复合体系的电导率达到较高水平。由两相复合系统的电导率模型预测的电导率显示出与实验结果相似的趋势，并且填充了棒的二维（2D）基于渗流的模型给出了良好的渗流概率估计。