Nano zero-valent iron activated persulfate (nZVI/PS) advanced oxidation technology is a novel approach with advantages in treating high-concentration and refractory organic pollutants. This paper aims to provide a comprehensive review of the research progress on nZVI/PS technology for the degradation of organic pollutants in recent years. This paper comprehensively introduces the activation methods of persulfate, the basic principles, and reaction mechanisms of nZVI/PS technology, as well as the degradation of pollutants using supported nano zero-valent iron activated persulfate. The paper discusses the mechanisms and degradation effects of different types of supported nano zero-valent iron (nZVI) activated persulfate (PS) technology for the degradation of organic pollutants under various conditions. The composite material formed by loading nZVI onto a solid support material is beneficial for improving nZVI dispersibility, stability, and reactivity. The synergistic effect of the carrier and nZVI in the composite material significantly improves the removal efficiency of organic pollutants. Furthermore, the paper discusses in detail the degradation efficiency of this technology under different conditions for various types of organic pollutants, including trichloroethylene (TCE), phenol, pyrene, and Ciprofloxacin. The PS/nZVI process can remove the majority of organic pollutants within 60 minutes. Organic pollutant molecules in the solution are degraded into small intermediate products such as organic acids and simple compounds, ultimately transforming into CO₂ and H₂O. The paper identifies the challenges of nZVI/PS technology in engineering applications and proposes future research directions to further promote the application of this technology in organic pollutant treatment. This review is a valuable reference for further research and application of nZVI/PS technology in the field of organic pollutant control.

Nanoscale zero-valent iron (nZVI) has a high chemical reactivity for heavy metals, but it forms aggregates easily. In this study, a synthesis of sludge biochar supported nanoscale zero-valent iron (nZVI@SBC) by the liquid-phase reduction method can effectively overcome this problem and shows good potential to remove Cd(II) in an aqueous solution. Scanning electron microscopy (SEM) images showed that sludge biochar (SBC) as a stable carrier could effectively prevent the aggregation of nZVI, and only some particles were chain-shaped. EDS analysis showed that the iron content on the SBC surface increased from 9.76% to 66.91% after loading of nZVI. The maximum adsorption of Cd(II) by nZVI@SBC (149.67 mg g⁻¹) could be achieved at 298 K and pH = 5.0 ± 0.2, which indicated that nZVI@SBC had a good effect on the removal of Cd(II). The pseudo-second-order kinetic model could more accurately explain the removal kinetics. The Freundlich adsorption isotherm model could well fit the adsorption process. Adsorption thermodynamics showed that the adsorption process was a spontaneous endothermic reaction. The presence of Ca(II) and Mg(II) in the solution strongly inhibited the removal of Cd(II), while HA had no significant effect. The removal mechanism of Cd(II) by nZVI@SBC obtained from SEM-EDS, BET, XRD, FTIR and XPS included electrostatic adsorption, precipitation/co-precipitation and the formation of complexes.

The mobility and phytotoxicity of heavy metals in the sludge produced by municipal wastewater treatment plants are key environmental factors limiting the agricultural application of sludge. To reduce the mobility and phytoavailability of Cr, Ni, Zn and Cu, the effect of attapulgite as a stabilizer on metal stabilization in sludge was investigated. Loess soil amended with attapulgite-stabilized sludge was used to grow corn under greenhouse conditions. Attapulgite was most suitable for the stabilization of these metals because it reduced the mobile fraction while increasing the contents of the residual fractions. Meanwhile, attapulgite amendment significantly reduced the DTPA-extractable Cr, Ni and Zn concentrations in the sludge and the accumulation of heavy metals in corn, which increased the dry biomass of corn. The amounts of acid-soluble, reducible and oxidizable fractions in rhizosphere soils were significantly positively correlated with the heavy metal contents in corn, in contrast to the residual metals.