Background Red mud is the world’s most extensively generated waste in the non-ferrous metal industry, posing significant environmental risks due to its strong alkalinity and lack of effective disposal methods. It is urgent to find a reasonable and effective strategy to transform red mud into a Heterogeneous catalyst for environmental remediation. Methods α-MnO 2 nanorods were anchored on biochar-modified red mud composite (RMBC) via the hydrothermal method and utilized as a catalyst to activate PMS for the degradation of Rhodamine B (RhB). Reactive oxygen species generated during the catalytic process was identified through EPR, XPS, and Raman spectroscopy measurements. Degradation intermediates of RhB were identified using LC-MS. Furthermore, the ecotoxicity of RhB and its transformation products was evaluated using the ecological structure-activity relationship (ECOSAR) prediction model. Significant findings The as-prepared α-MnO 2 /RMBC achieves a remarkable RhB degradation efficiency of 98.6 % within 30 min, significantly outperforming control samples including α-MnO 2 /RM, α-MnO 2 /BC, and the mixture of α-MnO 2 /RM and α-MnO 2 /BC, suggesting a pronounced synergistic interaction between α-MnO 2 and RMBC. Mechanistic analysis reveals that RhB degradation is predominantly governed by an activated surface-PMS inner-sphere complex, signified as Mn III (s) -(O)OSO– 3. Furthermore, the Fe II species inherent to RM facilitates the redox-mediated reduction of Mn IV to Mn III , thereby sustaining the catalytic activity of active Mn III sites and enabling robust recyclability and reusability of the α-MnO 2 /RMBC catalyst.
Formaldehyde (HCHO), a ubiquitous gaseous pollutant in indoor environments, threatens human health under long-term exposure, necessitating its effective elimination. Due to its advantages in enhancing mass transfer and effectively exposing active sites, aerogels with a three-dimensional (3D) interconnected network structure are expected to achieve efficient and stable decomposition of HCHO at ambient temperature. However, how to realize the self-assembly of transition metal oxides to construct high-purity 3D network aerogels is still a huge challenge. Herein, the cation-induced self-assembly strategy was developed to construct high-purity self-standing 3D network manganese dioxide aerogels. The interaction between cations and the surface groups of nanowires is crucial for successful self-assembly, which leads to the cross-winding of nanowires with each other, forming a 3D-structured network. The K+-induced 3D-MnO2 exhibited excellent catalytic performance for HCHO, which could continuously and steadily decompose HCHO into CO2 and H2O at ambient temperature. Thanks to the 3D interconnected network structure, on the one hand, it provides a large specific surface area and porosity, reducing mass transfer resistance and promoting the adsorption of HCHO and O2 molecules. On the other hand, it is more important to fully expose the active sites, which can generate more surface active oxygen species and achieve effective recycling and regeneration. Importantly, 3D-MnO2 has a strong ability to capture and activate water molecules in the atmosphere, which could be further involved in the replenishment of the consumed hydroxyl groups. This study proposes a strategy for self-assembly of transition metal oxides through cation-induction, which provides a new catalyst design approach for the room temperature decomposition of VOCs.
Rechargeable Zn//MnO 2 batteries, the most widely studied aqueous zinc-ion batteries, suffer from poor electrochemical performance due to a series of issues on the zinc anode including corrosion, dendrites, and passivation. In this study, abundant and low-cost kraft lignin is used as a raw material to synthesize quaternized lignin (QL 80 ), which is upgraded to an electrolyte additive for the Zn//α-MnO 2 battery (ReZMB). According to corrosion and chronoamperometry tests, the electrolyte containing 1 wt% of the QL 80 (named as 1 % QL 80 ) has the lowest corrosion on the zinc electrode and is best able to promote the homogenous zinc deposition. Consequently, the ReZMB using the 1 % QL 80 records the highest open-circuit voltage after storage at full charge state and the optimal rate capability, and meanwhile, the Zn//Zn symmetric battery exhibits an extended lifespan of 200 h at 5 mA·cm −2 , 5 mAh·cm −2 . In addition, the passivation of the zinc anode is highly prevented because no byproducts appear on the zinc anode of the ReZMB with 3000 cycles at 1.5 A·g −1 , according to the results of XRD and SEM characterizations. Ultimately, the ReZMB using the 1 % QL 80 presents more outstanding cyclability (more stable operation and ∼74.5 % higher discharge capacity after 3000 cycles at 1.5 A·g −1 ) than that of the battery using the reference electrolyte (2 M ZnSO 4 + 0.2 M MnSO 4 ). This study paves the new way for designing green lignin-derived electrolyte additives for advanced rechargeable zinc-ion batteries.
危险品化学品经营许可证（带存储）