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

Abstract

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.

Hollow Polyaniline Microsphere/Fe3O4 Nanocomposite as an Effective Adsorbent for Removal of Arsenic from Water

“…S9 and it shows no significant effects on arsenite uptake in the presence of SO 4 3− and CO 3 2− ion (concentrations ranging from 0 to 100 mg L −1 ), arsenite removal efficiency considerably reduced from ~94 to 59% and ~94 to 63%, respectively. Further, it was noted that arsenite adsorption in the presence of co-existing ions follows the order NO 3 − < SO 4 2− < CO 3 2− < PO 4 3− and in agreement with that reported by many other researchers 20,21,25,44 . XPS analysis of used PNHM/Fe 3 O 4 -40 adsorbent already established the partial oxidation of arsenite to arsenate.…”

“…− ), and phosphate (PO 4 3− ) present in the groundwater could significantly influence the arsenic removal efficiency 20 . Accordingly, investigations have been made to comprehend the interferences of co-existing ions in the adsorption of arsenite on PNHM/Fe 3 O 4 -40.…”

“…These could be ascribed to the interaction of wrapped Fe 3 O 4 nanoparticles at the exterior surface of PNHM with As(III) 42 . However, the band corresponding to surface water molecules (~3400 cm −1 ) and hydrogen-bonded surface −OH groups remain more or less unaltered, which is an all probability due to their non-involvement for adsorption of As(III) 20 . Further, in-plane deformation vibration of −OH bond in Fe−OH (~1375 cm −1 ) almost disappeared in the spent adsorbent.…”

“…Further, in-plane deformation vibration of −OH bond in Fe−OH (~1375 cm −1 ) almost disappeared in the spent adsorbent. These could be attributed to the substitution of −OH groups with adsorbed arsenic species 20 . Additionally, XPS analysis has also been widely utilized in understanding the mechanism of arsenic adsorption on adsorbent (PNHM/Fe 3 O 4 -40).…”

Adsorptive filtration of As(III) from drinking water by CuFe2O4 particles embedded in carbon nanotube membranes

“…Similar decreases in As adsorption in the presence of phosphate also were observed in previous studies using a variety of adsorbents. [35][36][37][38] The inhibitive effect of phosphate on As(III) adsorption is ascribed to the similarity of As(III)and phosphate in chemical structure and capability in forming inner-sphere complexes on metal-oxide surfaces. 39,40 As a result, phosphate ions effectively competed with As(III) for sorption sites on CuFe 2 O 4 particles.…”