One-step solution auto-combustion process for the rapid synthesis of crystalline phase iron oxide nanoparticles with improved magnetic and photocatalytic properties

Oxygen-containing functional groups coupled Fe sites of FeOx/OAC overcome the trade-off between desulfurization activity and regeneration performance

The introduction of metal oxides is a general strategy to enhance the SO2 removal activity of carbon materials. However, the formation of stable metal sulfates poses challenges to low-temperature thermal regeneration of metal active sites. To overcome the trade-off between activity and regenerability, we developed oxygen-containing functional groups (OCFGs) coupled Fe sites on oxygen-functionalized activated carbon supported iron oxides (FeOx/OAC). Specifically, -COOH and C=O/C-OH groups coupled Fe sites were constructed to enhance SO2 oxidation and Fe2(SO4)3 decomposition, respectively. Comprehensive characterization and DFT calculations revealed that -COOH groups mediated Fe3+ anchoring via Fe-O-C coordination, enhancing electron transfer efficiency to generate oxygen vacancies for SO2 oxidation. C=O/C-OH groups coupled with Fe sites reduced the Fe2(SO4)3 decomposition energy from 153.67 to 128.26 kJ mol-1via Fe-S bond elongation, enabling efficient regeneration. The optimized FeOx/OAC exhibited a 75 % increase in SO2 capacity (from 40.88 to 71.62 mg/g) and a reduced regeneration temperature (from 500 to 400 °C). Over five desulfurization-regeneration (S-R) cycles, FeOx/OAC maintained high SO2 capacity and recovered over 90 % of sulfur resources. This study presents a synergistic experimental-theoretical framework, which delves into the intricate mechanisms underpinning the enhanced desulfurization and regeneration performances via the interaction effect between OCFGs and Fe sites.

Ligand modulated charge transfers in Z-scheme configured Ni-MOF/g-C3N4 nanocomposites for photocatalytic remediation of dye-polluted water

The development of photocatalysts must be meticulous, especially when they are designed to degrade hazardous dyes that cause mutagenesis and carcinogenesis. In this meticulous approach, Ni-based metal-organic frameworks with different ligands, including terephthalic acid (NTP), 2-aminoterephthalic acid (NATP), and their composite with g-C3N4 (NTP/GCN, and NATP/GCN) have been synthesized using hydrothermal method. Structural analysis by XRD and ATR-IR revealed synergistic properties due to robust chemical interactions between the NATP-MOFs and GCN systems. A flower-like morphology was observed for both NTP and NATP, while their composites showed mixed-particulate structures mimicking the morphology of GCN. Optical analyses indicated visible-light driven properties with modulated recombination resistance in the system. Among the synthesized bare and composite systems, NATP/GCN exhibited the highest photocatalytic degradation efficiency for the cationic rhodamine B dye (~ 93% in 120 min), while it was relatively less efficient for the anionic Congo red dye, (~ 64% in 120 min). The insights gained from the fundamental characterizations including Mott-Schottky, scavenger, and electrochemical impedance analysis revealed that the amino-groups in NATP/GCN composite offered the band edge potentials suitable for the effective generation of energetic radical species with the improved carrier delocalization, recombination resistance, and charge transfer properties in the composite system through Z-scheme formation. Parametric investigations by varying the concentration of catalyst, dye, and pH along with recycle studies, demonstrated the excellent stability of the developed composites for sustainable photocatalytic applications.

Immobilization and property of penicillin G acylase on amino functionalized magnetic Ni0.3Mg0.4Zn0.3Fe2O4 nanoparticles prepared via the rapid combustion process

Penicillin G acylase plays an important role in the biocatalytic process of semi-synthetic penicillin. In order to overcome the disadvantages of free enzymes and improve the catalytic performance of enzymes, it is a new method to immobilize enzymes on carrier materials. And magnetic materials have the characteristics of easy separation. In the present study, the Magnetic Ni0.3Mg0.4Zn0.3Fe2O4 nanoparticles were successfully prepared by a rapid-combustion method and calcined at 400°C for 2 h. The surface of the nanoparticles was modified with sodium silicate hydrate, and the PGA was covalently bound to the carrier particles through the cross-linking of glutaraldehyde. The results showed that the activity of immobilized PGA reached 7121.00 U/g. The optimum pH for immobilized PGA was 8 and the optimum temperature was 45°C, the immobilized PGA exhibited higher stability against changes in pH and temperature. The Michaelis–Menten constant (Km) values of the free and immobilized PGA were 0.00387 and 0.0101 mol/L and the maximum rate (Vmax) values were 0.387 and 0.129 μmol/min. Besides, the immobilized PGA revealed excellent cycling performance. The immobilization strategy presented PGA had the advantages of reuse, good stability, cost saving and had considerable practical significance for the commercial application of PGA.