Facile synthesis of flower-like CoFeO particles for efficient sorption of aromatic organoarsenicals from aqueous solution.

HYPOTHESIS

Aromatic organoarsenicals are heavily used as poultry feed additives, and the application of manure containing these compounds could release toxic inorganic arsenic into the environment. Bimetal ferrites are recognized as promising sorbents in removal of organoarsenicals with formation of FeOAs complexes, and their high saturation magnetization also allows easy sorbent separation.

EXPERIMENTS

Herein, a flower-like CoFeO sorbent was synthesized through an environmental-friendly process.

FINDINGS

The flower-like CoFeO particles have abundant mesopores and a large specific surface area of 48.4 m/g. At an equilibrium concentration of 80 μmol/L, the sorption capacities towards p-arsanilic acid (p-ASA), roxarsone (ROX), 4-hydroxyphenylarsonic acid (4-HPAA), 2-aminophenylarsonic acid (2-APAA), phenylarsonic acid (PAA), and 2-nitrophenylarsonic acid (2-NPAA) were 38.1, 45.7, 38.7, 39.3, 33.0, and 32.8 mg/g, respectively. Langmuir model and pseudo-second-order kinetics could well fit the sorption isotherms and rates. The sorption performance was better under acidic conditions due to enhanced electrostatic attraction. Humic acid (HA) and PO inhibited the sorption through competing for sorption sites, while Fe promoted sorption due to formation of additional FeOAs complexes on sorbent surface. The experimental observations, spectroscopic insights, and density functional theory (DFT) calculations consistently indicate that the sorption of aromatic organoarsenicals on the flower-like CoFeO particles occurs mainly through formation of inner-sphere complexes. The flower-like CoFeO could be regenerated and reused over multiple cycles. The high sorption capacities, together with its magnetic property, make the flower-like CoFeO an attractive sorbent for removing aromatic organoarsenicals from wastewater.