Prussian-blue (PB)-modified γ-Fe 2 O 3 magnetic nanoparticles (PBMNPs) were successfully synthesized based on electric interactions between negatively charged [Fe(CN) 6 ] 4− and positively charged γ-Fe 2 O 3 nanoparticles. The in situ PB coating was generated by the coordinating reaction between the adsorbed [Fe(CN) 6 ] 4− and the ferric ions on the surface of γ-Fe 2 O 3 NPs. The as-prepared PBMNPs were characterized by FT-IR, XRD, TEM, and used to remove organic pollutants from aqueous solution, namely, using methylene blue (MB) as model compound. The experimental results showed that the target compound could be removed efficiently from solution over a wide pH range from 3 to 10 in the presence of PBMNPs as peroxidase-like catalyst and H 2 O 2 as oxidant. Under optimal conditions, MB could be removed completely after 120 min of reaction at 298 K; the chemical oxygen demand (COD) removal efficiency and the total organic carbon (TOC) abatement efficiency were 53.6% and 35%, respectively. Furthermore, the PBMNPs catalysts showed high magnetization, temperature tolerance, long-term storage and operational stability, and they could be readily separated from solution by applying an external magnetic field. Finally, a possible reaction mechanism for MB degradation was also discussed.
Yan Fu,Ye Li,Jun Zhang,Dongxue Liu,Chang Liu,Yi Ke
Antimony is a new type of pollutant with potential toxicity and carcinogenicity. Therefore, the restoration of antimony-contaminated water has attracted wide attention from all over the world. In this research, we synthesized chloride intercalated Ni-Al layered double hydroxide (Ni-Al LDH) with a good laminated structure by co-precipitation and ion exchange. We investigated the adsorption performance of Ni-Al LDH for Sb(V) in a one-component system for the first time through a series of batch experiments. The effect of key process variables, such as pH, reaction temperature, adsorbent dosage, contact time and initial concentration on the adsorption was studied in single-factor experiments separately. The reaction rapidly reached adsorption equilibrium within 30 min and it maintained the antimony removal rate at about 91% at the optimum reaction conditions. Multiple models were applied to fit the adsorption isotherm, kinetic and thermodynamic data to describe the adsorption behaviors of Sb(V) on Ni-Al LDH. A perfect fit between the Langmuir model and isothermal adsorption experimental data confirmed a maximum adsorption capacity of material could be up to 142.86 mg/g. SEM-EDS, XPS, and other characterization analyses demonstrated that ion exchange and ligand exchange are the primary mechanisms for triggering the adsorption process. It proved the excellent regeneration performance of the material by data from five stable adsorption/desorption cycles. It could be demonstrated that Ni-Al LDH could be an applicable adsorbent for the removal of Sb(V) .
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