Pd-Co bimetallic nanoparticles modified α-FeOOH nanorod for the catalytic reduction of organic pollutants

Abstract

The development of most effective reduction catalysts is an essential for promoting the sustainability by minimizing the waste and safeguard the environment. Herein, we prepared palladium-cobalt bimetallic nanoparticles modified on goethite nanorods (PdCo/alpha-FeOOH) as a catalyst for the catalytic degradation of various organic pollutants under mild reaction conditions. The structure and morphology of synthesized catalysts were tested by XRD, FT-IR, BET, SEM, TEM, HR-TEM and XPS techniques. The ultra-small PdCo bimetallic NPs (2.95 +/- 0.5 nm) synthesized onto the surface of alpha-FeOOH nanorod were confirmed by HR-TEM analysis. The prepared catalysts were played an important role in the reduction of toxic nitrocompounds such as (4-nitrophenol (4-NP), 4-nitroaniline (4-NA), 4-(4-nitrophenyl)morpholine (4-NM) and 4-(2-fluoro-4-nitrophenyl)morpholine (4-FNM)) and rhodamine B (RhB) dye. The PdCo/alpha-FeOOH nanocatalyst displayed a greater rate constant (similar to 1.5 min and k(app) = 2.631 min(-1)) compared to their respective mono-metallic counterparts (Pd/alpha-FeOOH and Co/alpha-FeOOH). The reusability results indicated that >97 % of conversion for 4-NP, and RhB dye over 10 consecutive reaction cycles in the batch method. Furthermore, the continuous flow reactor with PdCo/alpha-FeOOH catalyst was constructed, and it showed the ability to eliminate > 99 % of both 4-NP and RhB dye and maintained a degradation rate of >98 % for 20 consecutive recycles. The superior catalytic activity of the PdCo/alpha-FeOOH catalyst compared to other mono-metallic catalysts could be attributed to their particle size and synergistic effect. This study has the potential to facilitate the utilization of the synthesized bimetallic nanostructure in a wider range of other wastewater treatments.