Degradable, anti-swelling, high-strength cellulosic hydrogels via salting-out and ionic coordination.

Cellulosic hydrogels are widely used in various applications, as they are natural raw materials and have excellent degradability. However, their poor mechanical properties restrict their practical application. This study presents a facile approach for fabricating cellulosic hydrogels with high strength by synergistically utilizing salting-out and ionic coordination, thereby inducing the collapse and aggregation of cellulose chains to form a cross-linked network structure. Cellulosic hydrogels are prepared by soaking cellulose in an Al2(SO4)3 solution, which is both strong (compressive strength of up to 16.99 MPa) and tough (compressive toughness of up to 2.86 MJ/m3). The prepared cellulosic hydrogels exhibit resistance to swelling in different solutions and good biodegradability in soil. The cellulosic hydrogels are incorporated into strain sensors for human-motion monitoring by introducing AgNWs. Thus, the study offers a promising, simple, and scalable approach for preparing strong, degradable, and anti-swelling hydrogels using common biomass resources with considerable potential for various applications.

Facile synthesis of lignin-based Fe-MOF for fast adsorption of methyl orange.

To rapidly remove dyes from wastewater, iron-based metal-organic frameworks modified with phenolated lignin (NH2-MIL@L) were prepared by a one-step hydrothermal method. Analyses of the chemical structure and adsorption mechanism of the NH2-MIL@L proved the successful introduction of lignin and the enhancement of its adsorption sites. Compared with NH2-MIL-101-Fe without phenolated lignin, the modification with lignin increased the methyl orange (MO) adsorption rate of NH2-MIL@L. For the best adsorbent, NH2-MIL@L4, the MO adsorption efficiency in MO solution reached 95.09% within 5 min. NH2-MIL@L4 reached adsorption equilibrium within 90 min, exhibiting an MO adsorption capacity of 195.31 mg/g. The process followed pseudo-second-order kinetics and the Dubinin-Radushkevich model. MO adsorption efficiency of NH2-MIL@L4 was maintained at 89.87% after six adsorption-desorption cycles. In mixed solutions of MO and methylene blue (MB), NH2-MIL@L4 achieved an MO adsorption of 94.02% at 5 min and reached MO adsorption equilibrium within 15 min with an MO adsorption capacity of 438.6 mg/g, while the MB adsorption equilibrium was established at 90 min with an MB adsorption rate and capacity of 95.60% and 481.34 mg/g, respectively. NH2-MIL@L4 sustained its excellent adsorption efficiency after six adsorption-desorption cycles (91.2% for MO and 93.4% for MB). The process of MO adsorption by NH2-MIL@L4 followed the Temkin model and pseudo-second-order kinetics, while MB adsorption followed the Dubinin-Radushkevich model and pseudo-second-order kinetics. Electrostatic interactions, π-π interactions, hydrogen bonding, and synergistic interactions affected the MO adsorption process of NH2-MIL@L4.

Fully Biobased Degradable Vitrimer Foams: Mechanical Robust, Catalyst-Free Self-Healing, and Shape Memory Properties.

Thermosetting foams have limited capabilities for recycling, reprocessing, or reshaping. Moreover, most of the foaming agents currently employed in these foams are derived from organic compounds sourced from petrochemicals, thereby posing a significant environmental threat due to heightened pollution. To solve these problems, a fully biobased degradable vitrimer foam (EPC-X) was fabricated using an environmentally friendly all-in-one foaming strategy by cross-linking epoxidized malepimaric anhydride (EMPA), 1,5-diaminopentane (PDA), and 1,5-diaminopentane carbamate (PDAC) as a latent curing-blowing agent. To our delight, the vitrimer foams exhibit excellent mechanical properties (2.86 ± 0.11 MPa compressive strength) owing to their unique rigid rosin backbone and cross-linking networks. The presence of dynamic ß-hydroxy ester bonds and the self-catalytic behavior of tertiary amine groups facilitate network rearrangement without requiring additional catalysts, thereby resulting in the development of EPC-X with rapid self-healing and shape memory properties. The self-healing foam could support a weight of 500 g (approximately 562 times its own mass). Moreover, these high-performance vitrimer foams can also be easily degraded in an ethanolamine (EA) or NaOH solution under mild conditions. Such a design strategy offers an alternative approach for developing superior degradable and thermal stimuli-responsive thermosetting foams.

Active Center Size-Dependent Fenton-Like Chemistry for Sustainable Water Decontamination.

Accurately controlling catalytic activity and mechanism as well as identifying structure-activity-selectivity correlations in Fenton-like chemistry is essential for designing high-performance catalysts for sustainable water decontamination. Herein, active center size-dependent catalysts with single cobalt atoms (CoSA), atomic clusters (CoAC), and nanoparticles (CoNP) were fabricated to realize the changeover of catalytic activity and mechanism in peroxymonosulfate (PMS)-based Fenton-like chemistry. Catalytic activity and durability vary with the change in metal active center sizes. Besides, reducing the metal size from nanoparticles to single atoms significantly modulates contributions of radical and nonradical mechanisms, thus achieving selective/nonselective degradation. Density functional theory calculations reveal evolutions in catalytic mechanisms of size-dependent catalytic systems over different Gibbs free energies for reactive oxygen species generation. Single-atom site contact with PMS is preferred to induce nonradical mechanisms, while PMS dissociates and generates radicals on clusters and nanoparticles. Differences originating from reaction mechanisms endow developed systems with size-dependent selectivity and mineralization for treating actual hospital wastewater in column reactors. This work brings an in-depth understanding of metal size effects in Fenton-like chemistry and guides the design of intelligent catalysts to fulfill the demand of specific scenes for water purification.

Adsorption of methyl orange from aqueous solution with lignin-modified metal-organic frameworks: Selective adsorption and high adsorption capacity.

The lignin-based metal-organic framework (UIO-g-NL) was prepared by a Schiff base reaction of aminated lignin and the zirconium cluster-based MOF (UIO-66-NH2) as an adsorbent of methyl orange (MO). The results showed that UIO-g-NL maintained the original crystal structure and aminated lignin was successfully introduced after functionalization. UIO-g-NL selectively adsorbed MO from a mixed solution 50 mg/L MO and 50 mg/L methylene blue (MB), with an adsorption efficiency of nearly 100%. In a mixed solution 250 mg/L MB and 250 mg/L MO, UIO-g-NL adsorbed both dyes with 1120.70 mg/g for MB and 961.54 mg/g for MO. Hydrogen bonding, π-π and NH-π interactions, and electrostatic attraction contribute to the MO adsorption by UIO-g-NL. In the MO/MB mixture, MO adsorption by UIO-g-NL follows the pseudo-second-order kinetic and Freundlich isotherm models, which is an endothermic, spontaneous, and feasible adsorption process. Furthermore, the MO adsorption efficiency of UIO-g-NL remained high (>90%) after six re-use cycles.

Dual Lewis Acid-Base Sites Regulate Silver-Copper Bimetallic Oxide Nanowires for Highly Selective Photoreduction of Carbon Dioxide to Methane.

Highly selective photoreduction of CO2 to valuable hydrocarbons is of great importance to achieving a carbon-neutral society. Precisely manipulating the formation of the Metal1 ⋅⋅⋅C=O⋅⋅⋅Metal2 (M1 ⋅⋅⋅C=O⋅⋅⋅M2 ) intermediate on the photocatalyst interface is the most critical step for regulating selectivity, while still a significant challenge. Herein, inspired by the polar electronic structure feature of CO2 molecule, we propose a strategy whereby the Lewis acid-base dual sites confined in a bimetallic catalyst surface are conducive to forming a M1 ⋅⋅⋅C=O⋅⋅⋅M2 intermediate precisely, which can promote selectivity to hydrocarbon formation. Employing the Ag2 Cu2 O3 nanowires with abundant Cu⋅⋅⋅Ag Lewis acid-base dual sites on the preferred exposed {110} surface as a model catalyst, 100 % selectivity toward photoreduction of CO2 into CH4 has been achieved. Subsequent surface-quenching experiments and density functional theory (DFT) calculations verify that the Cu⋅⋅⋅Ag Lewis acid-base dual sites do play a vital role in regulating the M1 ⋅⋅⋅C=O⋅⋅⋅M2 intermediate formation that is considered to be prone to convert CO2 into hydrocarbons. This study reports a highly selective CO2 photocatalyst, which was designed on the basis of a newly proposed theory for precise regulation of reaction intermediates. Our findings will stimulate further research on dual-site catalyst design for CO2 reduction to hydrocarbons.

Lignin-modified metal-organic framework as an effective adsorbent for the removal of methyl orange.

Herein, lignin-modified metal-organic frameworks (NH2-UIO@L) are prepared using a one-step synthesis as sorbents for the removal of organic dyes from water. The introduction of lignin improved the adsorption sites. NH2-UIO@L2 adsorption of MO conforms to Langmuir model, and the adsorption capacity of NH2-UIO@L2 on MO was 214.13 mg·L-1 with an adsorption efficiency up to 99.28 %, which was significantly higher than values for other adsorbents. Due to hydrogen bonds, π-π interactions and electrostatic interactions, MO was effectively removed by NH2-UIO@L2 and its adsorption efficiency is maintained at 90.55 % after six cycles. The adsorption kinetics showed that the NH2-UIO@L2 adsorption of MO was chemical adsorption and controlled by intraparticle diffusion and external mass transfer. Further, the adsorption performance of NH2-UIO@L2 on MO and MB in mixed MO/MB solution was investigated. The adsorption capacity of NH2-UIO@L2 in mixed MO/MB solution was 207.04 mg·L-1 for MO and 243.31 mg·L-1 for MB; the adsorption of NH2-UIO@L2 on MO followed the Dubinin-Radushkevich and pseudo-second-order models, and the adsorption on MB followed the Temkin and pseudo-second-order models. Hydrogen bonds, π-π interactions, and pore filling are all implicated in the removal of MO and MB. In particular, the electrostatic attraction between MB and MO improves the adsorption efficiency of NH2-UIO@L2 on MB. NH2-UIO@L2 has good reusability, maintaining an adsorption efficiency of 97.66 % for MO and up to 99.15 % for MB after six cycles. Its simple preparation and superior adsorption suggest that NH2-UIO@L2 has considerable potential to remove organic dyes from wastewater.

Bacterial mineralization of chromium-copper spinel with highly performance in electroplating effluent.

Cr (VI) contamination has posed severe challenges to water quality, food safety, and land resources. Microbial reduction of Cr(VI) to Cr(III) has drawn considerable attention due to its low cost and environmental friendliness. However, recent reports have shown that Cr(VI) generates highly migratable organo-Cr(III) rather than stable inorganic chromium minerals during the biological reduction process. In this work, it was reported for the first time that spinel structure CuCr2O4 was formed by Bacillus cereus in Cr biomineralization process. Different from known biomineralization models (biologically controlled mineralization and biologically induced mineralization), the chromium-copper minerals here appeared as specialized minerals with extracellular distribution. In view of this, a possible mechanism of biologically secretory mineralization was proposed. In addition, Bacillus cereus demonstrated a high conversion ability in the treatment of electroplating wastewater. The Cr(VI) removal percentage reached 99.7%, which satisfied the Chinese emission standard of pollutants for electroplating (GB 21,900-2008), indicating its application potential. Altogether, our work elucidated a bacterial chromium spinel mineralization pathway and evaluated the potential of this system for application in actual wastewater, opening a new avenue in the field of chromium pollution treatment and control.

Self-healing, EMI shielding, and antibacterial properties of recyclable cellulose liquid metal hydrogel sensor.

Flexible hydrogels are promising materials for the preparation of artificial intelligence electronics and wearable devices. Introducing a rigid conductive material into the hydrogels can improve their electrical conductivities. However, it may have poor interfacial compatibility with the flexible hydrogel matrix. Therefore, we prepared a hydrogel containing flexible and highly ductile liquid metal (LM). The hydrogel can be used as a strain sensor to monitor human motion. The hydrogel showed many properties (i.e., recyclability, EMI shielding properties (33.14 dB), antibacterial (100 %), strain sensitivity (gauge factor = 2.92), and self-healing) that cannot be achieved simultaneously by a single hydrogel. Furthermore, the recycling of LM and their application to hydrogel-based EMI shielding materials have not been investigated previously. Due to its excellent properties, the prepared flexible hydrogel has great potential for applications in artificial intelligence, personal healthcare, and wearable devices.

Lignin/sodium alginate hydrogel for efficient removal of methylene blue.

In this work, a class of bio-based hydrogels (LN-NH-SA hydrogel) were prepared from aminated lignin and sodium alginate. The physical and chemical properties of the LN-NH-SA hydrogel were fully characterized using field emission scanning electron microscopy, thermogravimetric analysis, fourier transform infrared spectroscopy, N2 adsorption-desorption isotherms, and other techniques. LN-NH-SA hydrogels were tested for the adsorption of dyes (methyl orange and methylene blue). The LN-NH-SA@3 hydrogel showed better adsorption efficiency for MB with a maximum adsorption capacity of 388.81 mg·g-1, a bio-based adsorbent with a high adsorption capacity. The adsorption process followed the pseudo-second-order model and fitted to the Freundlich isotherm equation. More importantly, LN-NH-SA@3 hydrogel maintained 87.64 % adsorption efficiency after 5 cycles. Overall, the proposed hydrogel with environmentally friendly and low cost is promising for the absorption of dye contamination.

Interfacial Coordinational Bond Triggered Photoreduction Membrane for Continuous Light-Driven Precious Metals Recovery.

Chemical/electric energy-driven processes dominate the traditional precious metal (PM) recovery market. The renewable energy-driven selective PM recycling approach crucial for carbon neutrality is under exploration. Herein, via an interfacial structure engineering approach, coordinational-active pyridine groups are covalently integrated onto the photoactive semiconductor SnS2 surface to construct Py-SnS2. Triggered by the preferred coordinational binding force between PMs and pyridine groups, together with the photoreduction capability of SnS2, Py-SnS2 shows significantly enhanced selective PM-capturing performance toward Au3+, Pd4+, and Pt4+ with recycling capacity up to 1769.84, 1103.72, and 617.61 mg/g for Au3+, Pd4+, and Pt4+, respectively. Further integrating the Py-SnS2 membrane into a homemade light-driven flow cell, 96.3% recovery efficiency was achieved for continuous Au recycling from a computer processing unit (CPU) leachate. This study reported a novel strategy to fabricate coordinational bonds triggered photoreductive membranes for continuous PM recovery, which could be expanded to other photocatalysts for broad environmental applications.

Interfacial Coordination Bonding-Assisted Redox Mechanism-Driven Highly Selective Precious Metal Recovery on Covalent-Functionalized Ultrathin 1T-MoS2.

Rational design of functional material interfaces with well-defined physico-chemical-driven forces is crucial for achieving highly efficient interfacial chemical reaction dynamics for resource recovery. Herein, via an interfacial structure engineering strategy, precious metal (PM) coordination-active pyridine groups have been successfully covalently integrated into ultrathin 1T-MoS2 (Py-MoS2). The constructed Py-MoS2 shows highly selective interfacial coordination bonding-assisted redox (ICBAR) functionality toward PM recycling. Py-MoS2 shows state-of-the-art high recovery selectivity toward Au3+ and Pd4+ within 13 metal cation mixture solutions. The related recycling capacity reaches up to 3343.00 and 2330.74 mg/g for Au3+ and Pd4+, respectively. More importantly, above 90% recovery efficiencies have been achieved in representative PMs containing electronic solid waste leachate, such as computer processing units (CPU) and spent catalysts. The ICBAR mechanism developed here paves the way for interface engineering of the well-documented functional materials toward highly efficient PM recovery.

Changes in the m6A RNA methylome accompany the promotion of soybean root growth by rhizobia under cadmium stress.

Cadmium (Cd) is the most widely distributed heavy metal pollutant in soil and has significant negative effects on crop yields and human health. Rhizobia can enhance soybean growth in the presence of heavy metals, and the legume-rhizobia symbiosis has been used to promote heavy-metal phytoremediation, but much remains to be learned about the molecular networks that underlie these effects. Here, we demonstrated that soybean root growth was strongly suppressed after seven days of Cd exposure but that the presence of rhizobia largely eliminated this effect, even prior to nodule development. Moreover, rhizobia did not appear to promote root growth by limiting plant Cd uptake: seedlings with and without rhizobia had similar root Cd concentrations. Previous studies have demonstrated a role for m6A RNA methylation in the response of rice and barley to Cd stress. We therefore performed transcriptome-wide m6A methylation profiling to investigate changes in the soybean RNA methylome in response to Cd with and without rhizobia. Here, we provide some of the first data on transcriptome-wide m6a RNA methylation patterns in soybean; m6A modifications were concentrated at the 3' UTR of transcripts and showed a positive relationship with transcript abundance. Transcriptome-wide m6A RNA methylation peaks increased in the presence of Cd, and the integration of m6A methylome and transcriptome results enabled us to identify 154 genes whose transcripts were both differentially methylated and differentially expressed in response to Cd stress. Annotation results suggested that these genes were associated with Ca2+ homeostasis, ROS pathways, polyamine metabolism, MAPK signaling, hormones, and biotic stress responses. There were 176 differentially methylated and expressed transcripts under Cd stress in the presence of rhizobia. In contrast to the Cd-only gene set, they were also enriched in genes related to auxin, jasmonic acid, and brassinosteroids, as well as abiotic stress tolerance. They contained fewer genes related to Ca2+ homeostasis and also included candidates with known functions in the legume-rhizobia symbiosis. These findings offer new insights into how rhizobia promote soybean root growth under Cd stress; they provide candidate genes for research on plant heavy metal responses and for the use of legumes in phytoremediation.

Photo-assisted reductive cleavage and catalytic hydrolysis-mediated persulfate activation by mixed redox-couple-involved CuFeS2 for efficient trichloroethylene oxidation in groundwater.

Persulfate (PS, S2O82-) activation through transition metal sulfides (TMS) has gained increasing attention since it can decompose a wide variety of refractory halogenated organic compounds in groundwater and wastewater. However, the processes of PS activation by TMS and particularly the formation of •OH radical under anoxic and acidic conditions (pH ∼2.8) remain elusive. Herein, by employing mixed redox-couple-involved chalcopyrite (CuFeS2) (150 mg/L) nanoparticles for PS (3.0 mM) activation, 96% of trichloroethylene was degraded within 120 min at pH 6.8 under visible light irradiation. The combination of experimental studies and theoretical calculations suggested that the Cu(I)/Fe(III) mixed redox-couple in CuFeS2 plays a crucial role to activate PS. Cu(I) acted as an electron donor to transfer electron to Fe(III), then Fe(III) served as an electron transfer bridge as well as a catalytic center to further donate this received electron to the O-O bond of PS, thus yielding SO4•- for trichloroethylene oxidation. Moreover, for the first time, •OH radicals were found to form from the catalytic hydrolysis of PS onto CuFeS2 surface, where S2O82- anion was hydrolyzed to yield H2O2 and these ensuing H2O2 were further transformed into •OH radicals via photoelectron-assisted O-O bond cleavage step. Our findings offer valuable insights for understanding the mechanisms of PS activation by redox-couple- involved TMS, which could promote the design of effective activators toward PS decomposition for environmental remediation.

Molecular Dynamics Beyond the Monolayer Adsorption as Derived from Langmuir Curve Fitting.

Langmuir adsorption model is a classic physical-chemical adsorption model and is widely used to describe the monolayer adsorption behavior at the material interface in environmental chemistry. Traditional adsorption dynamic modeling solely considered the surface physiochemical interaction between the adsorbent and adsorbate. The surface reaction dynamics resulting from the heterogeneous surface and intrinsic electronic structure of absorbents were rarely considered within the reported adsorption experiments. Herein, by employing the chlorine hybrid graphene oxide (GO-Cl) to adsorb Ag+ in an aqueous solution, complicated molecular dynamics significantly deviated from the monolayer adsorption mechanism, as suggested by Langmuir adsorption curve fitting, has been elucidated down to atomic scale. In the time-dependent Ag adsorption experiments, both Ag single atoms and Ag/AgCl nanoparticle heterostructures are observed to be formed sequentially on GO-Cl. These observations indicate that for the surface adsorption dynamics, not only the surface chemical adsorption process involved but also photoreduction and the C-Cl bond cleavage reaction has been heavily engaged within the GO-Cl interface, suggesting a much more complicated vision rather than the monolayered adsorption algorithm as derived from curve fitting. This study uses GO-Cl as a simple example to disclose the complicated adsorption dynamic process underneath Langmuir adsorption curve fitting. It advocates the necessity of imaging the interfacial atomic-scale dynamic structure with high-resolution microscopy techniques in modern adsorption studies, rather than simply explaining the adsorption dynamics relying on the curve fitting results due to the complicated physiochemical reactivity of the adsorbents.

Unlocking bimetallic active sites via a desalination strategy for photocatalytic reduction of atmospheric carbon dioxide.

Ultrathin two-dimensional (2D) metal oxyhalides exhibit outstanding photocatalytic properties with unique electronic and interfacial structures. Compared with monometallic oxyhalides, bimetallic oxyhalides are less explored. In this work, we have developed a novel top-down wet-chemistry desalination approach to remove the alkali-halide salt layer within the complicated precursor bulk structural matrix Pb0.6Bi1.4Cs0.6O2Cl2, and successfully fabricate a new 2D ultrathin bimetallic oxyhalide Pb0.6Bi1.4O2Cl1.4. The unlocked larger surface area, rich bimetallic active sites, and faster carrier dynamics within Pb0.6Bi1.4O2Cl1.4 layers significantly enhance the photocatalytic efficiency for atmospheric CO2 reduction. It outperforms the corresponding parental matrix phase and other state-of-the-art bismuth-based monometallic oxyhalides photocatalysts. This work reports a top-down desalination strategy to engineering ultrathin bimetallic 2D material for photocatalytic atmospheric CO2 reduction, which sheds light on further constructing other ultrathin 2D catalysts for environmental and energy applications from similar complicate structure matrixes.

Bi2O3/BiO2 Nanoheterojunction for Highly Efficient Electrocatalytic CO2 Reduction to Formate.

Heterostructure engineering plays a vital role in regulating the material interface, thus boosting the electron transportation pathway in advanced catalysis. Herein, a novel Bi2O3/BiO2 heterojunction catalyst was synthesized via a molten alkali-assisted dealumination strategy and exhibited rich structural dynamics for an electrocatalytic CO2 reduction reaction (ECO2RR). By coupling in situ X-ray diffraction and Raman spectroscopy measurements, we found that the as-synthesized Bi2O3/BiO2 heterostructure can be transformed into a novel Bi/BiO2 Mott-Schottky heterostructure, leading to enhanced adsorption performance for CO2 and *OCHO intermediates. Consequently, high selectivity toward formate larger than 95% was rendered in a wide potential window along with an optimum partial current density of -111.42 mA cm-2 that benchmarked with the state-of-the-art Bi-based ECO2RR catalysts. This work reports the construction and fruitful structural dynamic insights of a novel heterojunction electrocatalyst for ECO2RR, which paves the way for the rational design of efficient heterojunction electrocatalysts for ECO2RR and beyond.

Exploration of interaction between angiotensin I-converting enzyme (ACE) and the inhibitory peptide from Wakame (Undaria pinnatifida).

The interaction between angiotensin I-converting enzyme (ACE) and the inhibitory peptide KNFL from Wakame was explored using isothermal titration calorimetry, multiple spectroscopic techniques and molecular dynamics simulations, and an inhibition model was established based on free energy binding theory. The experiments revealed that the binding of KNFL to ACE was a spontaneous exothermic process driven by enthalpy and entropy and occurred via multiple binding sites to form stable complexes. The complexes may be formed through multiple steps of inducing fit and conformational selection. The peptide KNFL had a fluorescence quenching effect on ACE and its addition not only affected the microenvironment around the ACE Trp and Tyr residues, but also increased the diameter and altered the conformation of ACE. This study should prove useful for improving our understanding of the mechanism of ACE inhibitory peptides.

Regulation of the luminescence mechanism of two-dimensional tin halide perovskites.

Two-dimensional (2D) Sn-based perovskites are a kind of non-toxic environment-friendly luminescent material. However, the research on the luminescence mechanism of this type of perovskite is still very controversial, which greatly limits the further improvement and application of the luminescence performance. At present, the focus of controversy is defects and phonon scattering rates. In this work, we combine the organic cation control engineering with temperature-dependent transient absorption spectroscopy to systematically study the interband exciton relaxation pathways in layered A2SnI4 (A = PEA+, BA+, HA+, and OA+) structures. It is revealed that exciton-phonon scattering and exciton-defect scattering have different effects on exciton relaxation. Our study further confirms that the deformation potential scattering by charged defects, not by the non-polar optical phonons, dominates the excitons interband relaxation, which is largely different from the Pb-based perovskites. These results enhance the understanding of the origin of the non-radiative pathway in Sn-based perovskite materials.

Transferring waste red mud into ferric oxide decorated ANA-type zeolite for multiple heavy metals polluted soil remediation.

Herein, a novel "waste reclamation for soil remediation" strategy has been developed for both alkaline waste red mud (RM) recycling and heavy metal (HM) polluted soil remediation. Through a direct one-pot hydrothermal reaction process, the Al, Si, alkali, and Fe2O3 components in waste RM have been transferred into ferric oxide decorated ANA-type zeolite (Fe2O3-ANA). As tested by the HMs polluted soil remediation and oilseed rape planting experiment, when 25 g/kg Fe2O3-ANA is added into the Pb2+, Cu2+, Cr3+ and anionic AsO2- polluted soil (HM concentration: 100-200 mg/kg), it can effectively suppress the HMs mobility in soil and reduce the bio-accumulation concentrations of HMs in the harvested oilseed rape (reduce ratio: 37.9-69.5%). The detailed mechanism study using energy dispersive X-ray energy spectroscopy, in-depth X-ray photoelectron spectroscopy and density function theory calculation concludes that the Cu2+, Pb2+ and Cr3+ in soil have been adsorbed and trapped in the framework structure of ANA in Fe2O3-ANA mainly via the cation exchange process. While the anionic AsO2- species are mainly caught by the Fe2O3 component in Fe2O3-ANA via surface adsorption. Overall, this work firstly transforms waste RM into Fe2O3-ANA for soil remediation, which is valuable to waste resource recycling and environmental conservation.