Ciprofloxacin (CIP), a widely used fluoroquinolone antibiotic, poses a growing environmental concern due to its persistence in agricultural soils and potential adverse effects on crop production. While previous studies have documented CIP’s negative impacts on plant growth, effective strategies to protect crops from antibiotic stress remain limited. Biochar-based approaches show promise, but their application at the nanoscale for antibiotic stress management is largely unexplored. This study demonstrates how biochar nanoparticles (BNPs) effectively mitigate CIP-induced stress in rice seedlings through adsorption mechanisms. Rice seedlings were treated with 5 and 10 mg L⁻¹ CIP, with and without 0.2 g L⁻¹ BNPs. Results showed that CIP significantly disrupted plant growth, decreasing shoot length by 20.5% and root length by 45.2%, along with reduced biomass. Application of BNPs effectively reduced CIP bioavailability by over 80%, leading to a decreased CIP accumulation of 49.7% in shoots and 33.1% in roots. The addition of BNPs mitigated these growth impacts by restoring shoot length to 98.2% of control levels at 5 mg L⁻¹ CIP and improving root growth and biomass accumulation. BNPs also mitigated CIP-induced hormone imbalance, evidenced by a recovery in IAA levels by 8.9%, an increase in 6-BA by 152.6%, and an enhancement in SA levels by 12.7–13.6%. These findings demonstrate the significant potential of nanoscale biochar in reducing antibiotic stress in agricultural systems and provide insights into plant responses under these conditions. This research offers a promising strategy for enhancing crop resilience in areas affected by pharmaceutical pollutants.

Developing efficient and recyclable periodate (PI)-based advanced oxidation processes (AOPs) for the removal of emerging organic pollutants (EOPs) has attracted considerable attention. However, the structure–activity relationship of single-atom catalyst in PI-AOP systems remains poorly understood. In this study, a hollow carbon-supported single-Fe atom catalyst (HCFe800) was synthesized and applied for PI activation toward bisphenol A (BPA) degradation. Under neutral pH and ambient temperature, HCFe800 enabled complete removal of BPA within 1 min, achieving a degradation rate constant (k) of 5.094 min⁻¹—approximately 3 and 10 times higher than that of Fe-free and solid control catalysts, respectively. After normalization, the apparent degradation rate constant was 1–3 orders of magnitude greater than those of previously reported catalysts. The optimized Fe doping amount and pyrolysis temperature facilitated the formation of atomically dispersed FeN₄ sites, which outperformed Fe clusters and iron oxides in catalytic activity. The hollow porous structure further enhanced the exposure of active sites, contributing to the exceptional performance. The HCFe800/PI system remained highly effective across broad pH (3–7) and temperature (5–35 °C) ranges and in the presence of 100-fold concentrations of common inorganic ions. Mechanistic studies revealed that the main reactive species were ¹O₂, O₂^•−, and IO₃^•, with negligible involvement of high-valent Fe species. Eight less-toxic BPA degradation products were identified. Moreover, the system was extendable to various other EOPs and exhibited excellent recyclability via thermal regeneration. This work provided fundamental insights into designing and applying single-atom catalysts for PI-based advanced treatment of EOPs.

Non-graphitic nitrogen-doped nano-scale diamonds were tested in the laboratory for their ability to activate peroxydisulfate for treating Microcystis-laden water. Flocculation was observed and up to 99.8% of the cyanobacterial cells were removed. The flocs’ composition showed that nano-scale diamonds with activated persulfate promoted the release of protein-like and humic-like substances during the treatment, which could have promoted agglomeration. Comprehensive analyses suggest that both radical and radical-free mechanisms were involved. Extracellular substances associated with the Microcystis cells were modified to function as active bioflocculants, leading to self-flocculation and sedimentation.

This study presents the development and evaluation of an innovative modular ecological transition zone system for riparian restoration. Through systematic optimization, we developed a C25-grade ecological concrete module (100 mm × 100 mm × 100 mm) with a specialized cavity design (φ61 mm × H60 mm) that achieves optimal balance between structural integrity (20–30 MPa compressive strength) and environmental functionality (>15% porosity, >1 × 10⁻⁴ cm s⁻¹ permeability). The module incorporates precisely calibrated proportions of cement (378 kg m⁻³), reinforcing agent (12 kg m⁻³), aggregate (1650 kg m⁻³), and water (137 L m⁻³), creating a robust platform for environmental remediation. The system was evaluated at two scales: module-scale experiments in 25 L containers (833:1 mL g⁻¹ ratio) and kinetic studies (10:1 mL g⁻¹ ratio), revealing a sophisticated three-phase removal process. The initial rapid surface adsorption phase (0–4 h) achieved removal rates of 0.28–0.42 mg g⁻¹ h⁻¹, followed by pore diffusion (4–24 h) and chemical fixation phases, with removal patterns effectively modeled using a modified pseudo-second-order equation. The system demonstrated exceptional heavy metal removal capabilities across varying concentration ranges, achieving removal efficiencies of 95.6% for Pb²⁺ ions, 92.3% for Cd²⁺ ions, 84.2% for Cr³⁺ ions, 89.7% for Cu²⁺ ions, and 84.8% for Zn²⁺ ions under optimal conditions. Performance remained robust across two orders of magnitude in concentration ranges, with removal efficiencies maintaining above 80% at both experimental scales. The modular design’s cost-effectiveness is demonstrated through material costs of USD 45–60 m⁻³, with operational costs 40–60% lower than conventional systems. This research provides a practical, cost-effective solution for riparian zone restoration, combining structural durability with efficient pollutant removal capabilities while maintaining consistent performance across varying environmental conditions.