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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]

Here, we prepared a novel nanostructured Fe–Cu–Mn composite oxide (FCMO x) adsorbent using an ultrasonic coprecipitation method. The maximum adsorption capacity of As(III) and As(V) reached 158.5 and 115.2 mg/g under neutral conditions, respectively. The effects of several environmental factors (coexisting ions, solution pH, etc.) on the removal of inorganic arsenic using FCMO x were studied through batch experiments. The results showed that except for PO 4 3– and high initial pH, it was not significantly affected by ionic strength and other existing anions, implying a higher selectivity and adaptability. Combined with EPR, FTIR, and XPS analysis, we concluded that the Cu component and the reactive oxygen species (ROS) it generates played a decisive role in maintaining the stability of the redox cycle between Mn(IV)/Mn(III)/Mn(II) and enhancing the oxidation efficiency of As(III). Meanwhile, the adsorption mechanism of As(V) was mainly through the replacement of the FCMO x surface –OH to form stable inner-sphere arsenic complexes, while the removal mechanism of As(III) may involve the process of synergistic oxidation and chemisorption coupling. Additionally, the effective removal of As from the simulated As-contaminated water and its satisfactory reuse performance make FCMO x adsorbents favorable candidates for the removal of As-contaminated water in the future. [Display omitted] ● A novel FCMO x adsorbent was employed to remove As(III) and As(V) from aqueous solutions. ● The FCMO x exhibited excellent photocatalytic activity under visible-light irradiation. ● The redox cycle between Mn(II)/Mn(III)/Mn(IV) was mainly driven by the Cu component in FCMO x. ● The coupling effect of photocatalytic oxidation, chemical oxidation and adsorption enhanced the removal of As(III). [ABSTRACT FROM AUTHOR]

The over-reliance on tetracycline antibiotics (TC) in the animal husbandry and medical field has seriously affected the safety of the ecological environment. Therefore, how to effectively treat tetracycline wastewater has always been a long-term global challenge. Here, we developed a novel polyethyleneimine (PEI)/Zn-La layered double hydroxides (LDH)/cellulose acetate (CA) beads with cellular interconnected channels to strengthen the TC removal. The results of the exploration on its adsorption properties illustrated that the adsorption process exhibited a favorable correlation with the Langmuir model and the pseudo-second-order kinetic model, namely monolayer chemisorption. Among the many candidates, the maximum adsorption capacity of TC by 10 %PEI-0.8LDH/CA beads was 316.76 mg/g. Apart from that, the effects of pH, interfering species, actual water matrix and recycling on the adsorption of TC by PEI-LDH/CA beads were also analyzed to verify their superior removal capability. The potential for industrial-scale applications was expanded through fixed-bed column experiments. The proven adsorption mechanisms mainly included electrostatic interaction, complexation, hydrogen bonding, n-π EDA effect and cation-π interaction. The self-floating high-performance PEI-LDH/CA beads exploited in this work provided fundamental support for the practical application of antibiotic-based wastewater treatment. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • SA/PEI-0.25 aerogel showed high elastic, stability and adsorption performance. • The maximum adsorption capacities of Cr(VI) and Cd(II) were 678.67 and 464.23 mg/g. • The fixed-bed continuous filtration of Cr(VI) and Cd(II) wastewater was realized. • SA/PEI-0.25 aerogel reduced the toxicity of heavy metal ions to rice. • The adsorption mechanisms of Cr(VI) and Cd(II) were investigated. Herein, an elastic polyethyleneimine/sodium alginate aerogel was designed by a one-step freeze-drying method. The 3D honeycomb-like structure endowed it excellent compressibility and plentiful exposed adsorption sites to accelerate Cr(VI) and Cd(II) adsorption. The adsorption processes matched the pseudo-second-order and Langmuir models, and the saturated adsorption capacity for Cr(VI) and Cd(II) was 678.67 and 464.23 mg/g, respectively. The obtained aerogel still expressed superior removal performance for Cr(VI) and Cd(II) even in the coexistent of multiple interfering factors and maintained stable adsorption capacity at least after 5 cycles. Importantly, the elastic cylindrical aerogel (∼0.59 g) could achieve dynamic filtration of industrial wastewater containing Cr(VI) and Cd(II) in fix-bed column system with corresponding effective treatment volume of 4.47 and 3.25 L, respectively. The reasonable mechanisms for the adsorption behaviors of heavy metals on the as-prepared aerogel was investigated via FTIR, XPS and Density functional theory (DFT), which could be attributed to the surface electrostatic adsorption, chelation and reduction effects. Eventually, the ecological assessment verified that eco-friendly SA/PEI aerogel had a powerful auxiliary effect on the anti-fouling growth of rice. Overall, such novel biomass aerogel adsorbent possessed great application potential and theoretical guiding significance for the purification of heavy metal wastewater. [ABSTRACT FROM AUTHOR]

[Display omitted] • A functionalized carboxymethyl chitosan aerogel is explored for Cu(Ⅱ) adsorption. • The maximum capacity of PCCSA-1.0 for absorbing Cu(Ⅱ) is 175.56 mg/g. • Continuous filtration of industrial wastewater with fixed bed columns is achieved. • PCCSA-1.0 is conducive to inhibit the enrichment of Cu(Ⅱ) ions in rice. • The generated waste after adsorption is converted into a material for secondary use. Copper ions (Cu(II)) in water pose a huge threat to human health and ecosystem security. Therefore, developing eco-friendly and sustainable strategies to eliminate the toxicity risk of Cu(II) in the aqueous environment remains a great challenge. In this work, an elastic polyethyleneimine-modified carboxymethyl chitosan aerogel was developed via a freeze-drying process for the adsorption of Cu(II). The adsorption kinetic and isotherm experiments demonstrated that the adsorption process was monolayer chemisorption and the maximum adsorption capacity calculated from Langmuir model was 175.56 mg g−1. The obtained aerogels exhibited preferential selectivity for Cu(II) even when the competing cations and organics existed. Besides, about 0.93 g of aerogel realized continuous fixed-bed column filtration of industrial wastewater with an effective purification volume of 4.14 L. Mechanistic analysis via FTIR and XPS revealed that the excellent adsorption performance for Cu(II) might be attributed to the strong electrostatic force, Vander Waals' force and coordination of N/O -containing functional groups. It is worth mentioning that the adsorbed Cu(II) ions in the aerogel were converted into a reusable photocatalyst, avoiding the secondary leakage of heavy metals. This work opened a door to synthesize carboxymethyl chitosan aerogel, promising for heavy metal wastewater treatment and realizing the concept of waste utilization. [ABSTRACT FROM AUTHOR]