Al–Fe pillared bentonite−Fe3O4–CaO2 nanocomposite for efficient adsorption and degradation of trichloroethylene

Abstract

The agglomeration of magnetic nanoparticles significantly affects their catalytic efficiency, and the reduction of oxidant dosage is crucial for the practical application of heterogeneous catalysis from the perspective of cost and environmental friendliness. Al–Fe pillared bentonite−Fe3O4–CaO2 nanocomposite (PB@Fe3O4–CaO2) was synthesized in this study to form a heterogeneous catalytic system, and trichloroethylene (TCE) was used as the target contaminant because of its universality and volatility. The adsorption of TCE in the PB@Fe3O4–CaO2 system reached 63.9% under the condition of release inhibition of H2O2 from CaO2, and the value decreased to 28.2% and 29.8% under conditions favoring H2O2 release owing to the efficient catalytic degradation of TCE (68.0% and 65.4%, respectively). A higher systematic pH would result in a significant decrease in the TCE removal efficiency in the PB@Fe3O4–CaO2 system owing to the decrease in the yield of H2O2 and the tendency toward O2 generation. The co-existing inorganic anions and cations also resulted in a decrease in the efficiency of TCE removal, which was attributed to the generation of weak free radicals and promote the aggregation of the catalyst, respectively. Although the adsorption effect was 50.9% for TCE removal in actual groundwater, the degradation efficiency of TCE in the PB@Fe3O4–CaO2 system (41.9%) was approximately the same as that of the PB@Fe3O4/H2O2 system (40.9%) considering TCE volatilization. This research provides a material for the efficient adsorption and degradation of trichloroethylene without the need for the exogenous addition of oxidants.