Stability of β-cyclodextrin interface-modified iron-carbon composite and its migration in porous media

β-cyclodextrin (βCD) can significantly improve the reactivity and long-term remediation performance of nano-zero-valent iron (nZVI), but the stability of composite and the migration performance in porous media have been less studied. In this study, a kind of βCD interface-modified iron-carbon composite (BC-nZVI@βCD) was synthesized, the Zeta potential measurements and sedimentation experiments were conducted to study the stability of materials. Afterwards, the migration behavior of BC-nZVI@βCD in porous media was explored by one-dimensional (1D) sand column experiments and a novel two-dimensional (2D) sand tank simulating the groundwater state. Specifically, in 1D sand column experiments, the primary focus was on investigating the relative effluent concentration ( C/C 0 ) and its distribution patterns within the sand column. In 2D sand tank experiment, the ERT technique was utilized to precisely and real-time monitor the migration behavior of the composite through changes in resistivity. The results showed that the suspensions of BC-nZVI@βCD had the best stability and slowest settling rate. 1D sand column migration experiments showed that the mobility of BC-nZVI@βCD was greatly enhanced, and C/C 0 was increased to 0.60. Moreover, the concentrations of Ca 2 + and SO 4 2- had little effect on migration performance. Humic acid (HA) promoted BC-nZVI@βCD migration at low concentrations (10 mM), while inhibited the migration at high concentrations (20 and 40 mM). In 2D sand tank, BC-nZVI@βCD also showed more excellent migration ability, with the migration distance of BC-nZVI@βCD clearly exceeded 0.40 m. Generally, this study provides a new approach for the study of stability and migration performance of iron-based materials.