Investigate the multipath erasure of nitrobenzene over nanoscale zero-valent-iron/N-doped biochar hybrid with extraordinary reduction performance

Sodium salt promoted the generation of nano zero valent iron by carbothermal reduction: For activating peroxydisulfate to degrade antibiotic

Carbothermal reduction is a promising method for the industrial preparation of nano-zero-valent iron. Preparing it also involves very high pyrolysis temperatures, which leads to a significant amount of energy consumption. The temperature required for the preparation of nano-zero-valent iron by carbothermal reduction was reduced by 200 °C by the addition of sodium salt. Carbon-loaded nano zero-valent iron (Fe0/CB-Na) was prepared by carbothermal reduction through the addition of sodium salt. The results showed that Fe0/CB-Na@700 had the same activation performance as Fe0/CB@900 and the newly prepared nano-zero-valent iron. The addition of sodium salt promoted the transfer of oxygen from the iron oxide to the carbon structure during the roasting process so that the iron oxide was reduced to as much Fe0 as possible. Thus, sodium salts were optimized for the preparation of nano-zero-valent iron by carbothermal reduction through interfacial amorphization and oxygen transfer, thus reducing the preparation cost.

Magnetized algae catalyst by endogenous N to effectively trigger peroxodisulfate activation for ultrafast degraded sulfathiazole: Radical evolution and electron transfer

An innovative Fe-N co-coupled catalyst MN-2 was prepared from waste spirulina by co-pyrolysis as a highly active carbon-based catalyst for the activation of peroxydisulfate (PDS) for the degradation of sulfathiazole (ST). The protein-rich raw material Spirulina provided sufficient N during the pyrolysis process, thus achieving N doping without an additional nitrogen source, optimizing the interlayer structure of the biochar material and effectively inhibiting the leaching of the ligand metal Fe. MN-2 showed highly efficient catalytic activity for peroxydisulfate (PDS), with a degradation efficiency of 100% for ST within 30 min and a kinetic constant (kobs) reached 0.306 min-1, benefiting from the excellent adsorption ability of MN-2 forming MN-2-PDS* complexes and the electron transfer process generated by Fe3+ and Fe2+ cycling, oxygen-containing functional groups. The effects of PDS dosage, initial pH and coexisting anions on the oxidation process were also investigated. Free radical quenching, electron paramagnetic resonance and electrochemical measurements were employed to explain the hydroxyl (·OH) and sulfate (SO4·-) as the dominant active species and the electron transfer effect on the removal of ST. MN-2 maintained a ST removal rate of 84% after four recycling experiments, showing a high reusability performance. This work provides a simple way to prepare magnetized N-doped biochar, a novel catalyst (MN-2) for efficient activation of PDS for ST degradation, and a feasible method for removing sulfanilamide antibiotics in water environment.

Synergistic effect and mechanism of Cd(II) and As(III) adsorption by biochar supported sulfide nanoscale zero-valent iron

Biochar derived from bamboo was used to support sulfide nanoscale zero-valent iron (S-nZVI@BC) for simultaneous removal of Cd(II) and As (III) from aqueous media. Scanning electron microscopy (SEM) and X-ray diffraction spectroscopy (XRD) characterization confirmed the successful synthesis of the S-nZVI@BC. Adsorption kinetics and isotherms indicated that co-adsorption of Cd(II) and As(III) onto S-nZVI@BC was well represented by pseudo-second-order model (R²_Cd(II) = 0.990, R²_As(III) = 0.995) and Langmuir model (R²_Cd(II) = 0.954, R²_As(III) = 0.936). The maximum adsorption was 162.365 and 276.133 mg/g for Cd(II) and As(III), respectively, in a co-adsorption system, which was significantly higher than that in a single adsorption system (103.195 and 223.736 mg/g, respectively). Batch experiments showed that the Cd(II)-to-As(III) concentration ratio significantly affected the co-adsorption with the optimal ratio of 1:2. Ca²⁺ and Mg²⁺ significantly inhibited Cd(II) removal. In contrast, phosphate and humic acid significantly inhibited As(III) removal. Electrochemical analysis indicated S-nZVI@BC had a lower corrosion potential and resistance than nZVI@BC, making it more conducive to electron transfer and chemical reaction. Electrostatic adsorption, complexation, co-precipitation, and redox were the primary mechanisms for Cd(II) and As(III) removal. Overall, the present study provides new insights into the synergistic removal of Cd(II) and As(III) by S-nZVI@BC, which is a very promising adsorbent for the effective removal of Cd(II) and As(III) from contaminated wastewater.