Palladium Impregnation on Electrospun Carbon Fibers for Catalytic Reduction of Bromate in Water

José R M Barbosa,Olívia S G P Soares,Manuel F R Pereira,Juliana P S Sousa,João Restivo

doi:10.3390/pr10030458

José R M Barbosa, Olívia S G P Soares + Show 3 more

Open Access

https://doi.org/10.3390/pr10030458

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Abstract

The remediation of bromate in water is a concern due to the reported health issues caused by its ingestion. Catalytic processes, wherein bromate is reduced to non-hazardous bromide, have been studied. In the present work, catalysts of 1% palladium supported in electrospun carbon fibers (Pd-CFs) using different methods for palladium incorporation were prepared. The textural properties, morphology, crystalline structure, and hydrogenation capacity by H2 chemisorption analysis of the Pd-CFs catalysts were characterized. The catalytic tests were performed in a semi-batch reactor, and the obtained results showed different catalytic activity by each prepared Pd-CFs catalyst. The catalysts prepared by incipient wetness impregnation—1% Pd/CF1 and 1% Pd/CF2, using CFs obtained with electrospinning flow rates of 0.5 mL h−1 and 2 mL h−1, respectively—achieved total bromate reduction after 120 min of operation; however, 1% Pd/CF1 obtained total reduction as early as 30 min. Taking into account the catalyst properties, 1% Pd/CF1 showed a good catalytic activity due to CFs morphology obtained using a low electrospinning flow rate, while the Pd incorporation method allowed a high availability of active sites with hydrogenation properties for bromate reduction.

Highlights

Bromate (BrO3 − ) is classified as a contaminant according to the pollution concept byGeert Potters: “any form of contamination in an ecosystem with a harmful impact upon the organisms in this ecosystem, by changing the growth rate and reproduction of plant or animal species, or by interfering with human amenities, comfort, health, or property values” [1]
The carbon fibers prepared with a flow rate of 0.5 mL h−1 present a very low surface area of 20 m2 g−1, but the incorporation of the palladium precursor in the polymer solution (CF3, CF4 and CF5) increased the surface area of materials
Catalysts of Pd supported on electrospun CFs were prepared by varying the method of Pd incorporation, the Pd precursor and the flow rate of the electrospinning process

Summary

Introduction

Bromate (BrO3 − ) is classified as a contaminant according to the pollution concept byGeert Potters: “any form of contamination in an ecosystem with a harmful impact upon the organisms in this ecosystem, by changing the growth rate and reproduction of plant or animal species, or by interfering with human amenities, comfort, health, or property values” [1]. Its ecotoxicity has been studied and the reported results demonstrated that fish exposed to bromate developed chronic pathological disorders [4,5]. This compound is not reported as occurring naturally in surface waters [6] but exists as salts (KBrO3 and NaBrO3 ) with high solubility in water [4]. Recently, it has been detected after industrial or urban oxidation/disinfection processes for water treatment, such as ozonation [7] and disinfection with concentrated hypochlorite solutions [8], wherein BrO3 − is formed in water when bromide ions in the reduced form, Br− , are present [9]. The recent introduction of parts-per-billion drinking water standards may raise concerns about further contaminated sites within potable water supplies, leading to increased requirements for remediation of BrO3 − [4] and the development of efficient water treatment technologies

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