Two types of surface modified magnetite (Fe3O4) nanoparticles, coated with either tannic acid (TA) or dissolved natural organic matter (NOM), were evaluated as magnetic heterogeneous catalysts. Simple and efficient procedures for the synthesis of the magnetic catalysts were employed, their properties being fully assessed by various characterization techniques. The catalytic activity in heterogeneous oxidation of aqueous solutions containing Bisphenol A (BPA) over the catalysts was comparatively studied. The optimum experimental parameters were: 1g/L of catalysts, 10 mM H2O2, under UV irradiation. The highest mineralization rates were observed for Fe3O4-TA catalyst. More than 80% of BPA were removed after 30 minutes of reaction time under the specified experimental conditions. The results showed that the obtained catalysts are suitable candidates for the removal of pollutants in wastewaters by means of heterogeneous reaction
The efficiency, relatively low cost and eco-friendly nature of hydrogen peroxide-assisted photocatalysis treatment procedures are significant advantages over conventional techniques for wastewater remediation. Herein, we evaluate the behaviour of g-cyclodextrin (g-CD) immobilised on either bare or chitosan (CS)–functionalised Fe3O4 nanoparticles, for photodegrading Bisphenol A (BPA) in ultrapure water and in real wastewater samples. The BPA removal efficiencies with Fe3O4/g-CD and Fe3O4/CS/g-CD were compared with those of Fe3O4/b-CD, and were monitored under UVA irradiation at near-neutral pH. The addition of H2O2 at low concentrations (15 mmol L-1) significantly increased BPA photodegradation in the presence of each nanocomposite. The highest catalytic activity was shown by both Fe3O4/g-CD and Fe3O4/CS/g-CD nanocomposites (,60 and 27%BPA removal in ultrapure water and real wastewater effluent, respectively). Our findings reveal the superior performance of g-CD-functionalised Fe3O4 relative to that of Fe3O4/b-CD. The use of CD-based nanocomposites as photocatalytic materials could be an attractive option in the pre- or post-treatment stage of wastewaters by advanced oxidation processes before or after biological treatment.
Green Fenton-like magnetic nanocatalysts: Synthesis, characterization and catalytic application
(2015)
Five iron oxalate core–shell magnetite nanoparticles catalysts are evaluated as magnetic heterogeneous materials. Simple and efficient procedures for the preparation of magnetic iron oxalate coated nanoparticles are presented. The catalysts are fully characterized using various investigation techniques. Additionally, the formation of photo-sensitized oxygen by spin-trapping using electron spin resonance is investigated. The catalytic activity of two model substrates (carbamazepine and bisphenol A) is also evaluated. The effect of operational parameters (catalyst and H2O2 concentration, UVA light) on the degradation performance of the oxidation process is investigated. The obtained reaction rates depend on the nature of the compound and increase with iron oxide shell thickness of the catalyst. Moreover, these materials show a significant activity during two consecutive tests. The optimum experimental parameters are found to be 1.0 g L−1 of catalysts, 10 mM H2O2, under UVA irradiation. More than 99% of both substrates are removed after 30 min of reaction time under the experimental conditions given above. The results obtained show that the catalysts are suitable candidates for the removal of pollutants in wastewaters by means of the Fenton heterogeneous reaction.