A Reactive Nano-Fe/Cu Composite Supported on Expanded Graphite for Nitrate Reduction in Water

摘要

A novel bimetallic nano-Fe/Cu composite supported on expanded graphite (EG) was prepared through a synthesis procedure that includes consecutive steps of an incipient wetness impregnation method, heat treatment and borohydride reduction. SEM, XRD and ICP-OES were employed to characterize the morphology, crystallinity and metal contents respectively. The SEM images show that the metal particles are spherical and arrange closely but orderly, the particle size is uniform and no larger than 100 nm. The XRD data indicate the composite consists of elementary Fe and Cu deposited on the inert EG. Batch experiments with nitrate show that the composite works efficiently for nitrate reduction in wastewater without pH control. Although nitrite as much as 40% of the degraded nitrate persisted in the reaction system, nitrite as target pollutant has been found to be easily reduced to nitrogen with a selectivity of 99.9% at pH 6 by catalytic hydrogenation. Therefore, the composite EG-Fe/Cu will play an indirect role in nitrogen selectivity. Based on the environmental friendliness and the efficiency on nitrate, both EG and the composite may be considered into the experimental teaching of environmental chemistry course.