β-FeOOH Nanorods/Carbon Foam-Based Hierarchically Porous Monolith for Highly Effective Arsenic Removal

Arsenic pollution in waters has become a worldwide issue, constituting a severe hazard to whole ecosystems and public health worldwide. Accordingly, it is highly desirable to design high-performance adsorbents for arsenic decontamination. Herein, a feasible strategy is developed for in situ growth of β-FeOOH nanorods (NRs) on a three-dimensional (3D) carbon foam (CF) skeleton via a simple calcination process and subsequent hydrothermal treatment. The as-fabricated 3D β-FeOOH NRs/CF monolith can be innovatively utilized for arsenic remediation from contaminated aqueous systems, accompanied by remarkably high uptake capacity of 103.4 mg/g for arsenite and 172.9 mg/g for arsenate. The superior arsenic uptake performance can be ascribed to abundant active sites and hydroxyl functional groups available as well as efficient mass transfer associated with interconnected hierarchical porous networks. In addition, the as-obtained material exhibits exceptional sorption selectivity toward arsenic over other coexisting anions at high levels, which can be ascribed to strong affinity between active sites and arsenic. More importantly, the free-standing 3D porous monolith not only makes it easy for separation and collection after treatment but also efficiently prevents the undesirable potential release of nanoparticles into aquatic environments while maintaining the outstanding properties of nanometer-scale building blocks. Furthermore, the monolith absorbent is able to be effectively regenerated and reused for five cycles with negligible decrease in arsenic removal. In view of extremely high adsorption capacities, preferable sorption selectivity, satisfactory recyclability, as well as facile separation nature, the obtained 3D β-FeOOH NRs/CF monolith holds a great potential for arsenic decontamination in practical applications.