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[Display omitted] • Three-dimensional porous MIL-88A-Fe/gelatin aerogel (PMGA) was prepared. • The PMGA/H 2 O 2 system has dual functions of oxidation and adsorption. • Surface •OH and surface •OOH are the main oxide species of As(III). • The Fenton-like catalytic activity of PMGA originates from the exposed (1 0 0) facet. • PMGA can effectively repair the arsenic pollution in different real water samples. Metal-organic frameworks (MOFs) are considered a reliable adsorbent for controlling arsenic contamination. However, developing rapid and efficient MOF adsorbents with the capability of easy recovery is still challenging. Herein, we prepared a three-dimensional porous MIL-88A-Fe/gelatin aerogel (PMGA) with macroscopic size and coupled it with H 2 O 2 to fabricate a heterogeneous catalytic oxidation adsorption system to remove As(III) in water. The green synthesis strategy of this catalyst by foaming and low-temperature carbonization not only avoided the use of toxic chemical crosslinkers but also endowed PMGA with a rich hierarchical porous structure and exposed more active sites. Thus, the PMGA/H 2 O 2 system was able to reduce the concentration of As(III) from 1106 to below 10 µg/L and simultaneously realize the complete oxidation of As(III) to As(V) in only 120 min. Meanwhile, the system exhibited an excellent saturation adsorption capacity (24.863 mg/g) for As(III), superior to most similar bio-based or iron-based materials. Quenching experiments, EPR and DFT calculations showed that the active species (surface •OOH and surface •OH) generated by the Fenton-like interaction between the exposed (1 0 0) facet of MIL-88A-Fe in PMGA and H 2 O 2 played an essential role in promoting the oxidative removal of As(III). Moreover, the reaction system could work efficiently for As(III) in a wide pH range and was hardly affected by other substances such as chlorides, sulfates, carbonates, silicates, and humic acids. Simultaneously, the fixed bed column filled with PMGA could stably and continuously treat As(III) in groundwater. Therefore, this study not only broadens the horizon for the development and design of 3D functional materials but also provides a new strategy in water purification to eliminate arsenic pollutants using Fe-MOF aerogels. [ABSTRACT FROM AUTHOR]

• The FeMnO x /S(IV) system has faster removal speed and higher adsorption capacity for As(III) compared to FeMnO x alone. • The As(III) (1079 µg/L) could be decreased to less than 10 µg/L within 10 min. • The SO 5 •− radicals generated by S(IV) acting as the driving force for the redox cycle between As(III) and Mn(II/III/IV). • The possible mechanism of As(III) oxidation and removal for the FeMnO x /S(IV) system was proposed. • The FeMnO x nanocellulose aerogel broadened the scope of FeMnO x /S(IV) system in engineering applications. Manganese (Mn)-containing composite metal adsorbents are very effective at removing arsenite (As(III)) from contaminated water, however, the low removal speed and oxidation efficiency have limited their further application. In this study, a nonhomogeneous catalytic oxidation–adsorption system was constructed by coupling iron–manganese composite oxide (FeMnO x) with sulfite (S(IV)) to enhance the recovery of oxidative capacity and accelerate the removal of As(III). Experimental results showed that the FeMnO x /S(IV) system decreased the As(III) concentration from 1079 to <10 µg/L within 10 min and almost completely oxidized As(III) to As(V). In contrast, FeMnO x alone removed only 82.4% of As(III) within 30 min, and 60.0% of the adsorbed As(III) was not oxidized. Meanwhile, the adsorption capacity of FeMnO x /S(IV) system for As(III) was considerably higher than that of the only-FeMnO x system (76.5 > 46.3 mg/g). The efficient and fast As(III) removal was attributed to the SO 5 •− radical generated by S(IV) acting as the driving force for the redox cycle between As(III) and Mn(II/III/IV). Several environmental factors (e.g., solution pH and inorganic anions) and the reusability and practicality of FeMnO x were systematically investigated, and the results further confirmed the superiority of the FeMnO x /S(IV) system in As(III) removal. In particular, the proposed FeMnO x nanocellulose aerogel effectively purified arsenic-contaminated groundwater using a fixed-bed column. Thus, FeMnO x –S(IV) coupling is very promising for the purification of arsenic-contaminated water bodies. [Display omitted] [ABSTRACT FROM AUTHOR]