Spinel ferrite-enhanced Cr(VI) removal performance of micro-scale zero-valent aluminum: Synergistic effects of oxide film destruction and lattice spacing expansion

Ammonium persulfate-triggered modified chitosan biochar for co-adsorption of Cr(VI) and tetracycline antibiotics: Behavior and mechanisms

Antibiotic and heavy metal contamination of soil and groundwater together constitute a serious environmental issue. This study developed APS@CHI-1:3, a high-performance biochar derived from chitosan modified with ammonium persulfate (APS) and acetic acid, through a two-step carbonization process: hydrothermal pre‑carbonization at 180 °C for 6 h, followed by K₂CO₃ activation (1,3 mass ratio) at 800 °C for 2 h under N₂. The resulting material exhibited a high specific surface area (1656 m2/g) and abundant surface functional groups. The optimized adsorbent exhibited exceptional adsorption capacities of 851.5 mg/g for tetracycline (TET) and 777.4 mg/g for chlortetracycline (CTC) at 308 K, surpassing most reported biochars. In binary systems containing Cr(VI), APS@CHI-1:3 achieved 60.54 % Cr(VI) removal (48.45 mg/g) alongside simultaneous TET/CTC adsorption, demonstrating robust performance under competitive conditions. Mechanistic studies revealed that the adsorption was governed by electrostatic attraction, Lewis acid-base interactions, hydrogen bonding, and π-π interactions. The material maintained >92 % adsorption efficiency after 5 regeneration cycles, highlighting its reusability. These findings highlight its potential application in remediating complex wastewater systems co-contaminated by heavy metals and antibiotics.

Study of Barium Adsorption from Aqueous Solutions Using Copper Ferrite and Copper Ferrite/rGO Magnetic Adsorbents

The development of advanced materials for the removal of heavy metal ions is a never-ending quest of environmental remediation. In this study, a facile and cost-effective approach was employed to synthesize copper ferrite (CF) and copper ferrite/reduced graphene oxide (CG) by microwave assisted combustion method for potential removal of barium ions from aqueous medium. The physiochemical characterizations indicated the formation of magnetic nanocomposite with an average crystallite size of CF and CG is 32.4 and 30.3 nm and with specific surface area of 0.66 and 5.74 m2/g. The magnetic results possess multidomain microstructures with saturation magnetization of 37.11 and 33.84 emu/g for CF and CG. The adsorption studies prove that upon addition of rGO on the spherical spinel ferrite, the adsorption performance was greatly improved for CG nanocomposite when compared with the bare CF nanoparticles. The proposed magnetic adsorbent demonstrated a relatively high Ba2+ adsorption capacity of 161.6 mg·g-1 for CG nanocomposite when compared to 86.6 mg·g-1 for CF nanoparticles under optimum conditions ( $\text{pH}=7;T={25}^{°}\text{C}$ ). The pseudo-first-order (PFO), pseudo-second-order (PSO), and Elovich models were fitted to the kinetic data, the yielded $R^2$ value of 0.9993 (PSO) for CF and 0.9994 (PSO) for CG which is greater than the other two models, which signify that the adsorption process is chemisorption. Thermodynamic studies show that barium adsorption using CF and CG adsorbents is endothermic. The as-fabricated CuFe2O4/rGO nanocomposite represents a propitious candidate for the removal of heavy metal ions from aqueous solutions.