The loading of nano-bimetallic catalysts onto coal tar pitch-based activated carbon fibers for the efficient reduction of p-nitrophenol

The reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) in wastewater faces challenges in terms of conversion rate and stability. We used coal tar pitch-based activated carbon fibers (ACFs) as an support material for loading transition metal catalysts to catalyze the reaction. Fe–Ni nanoparticles were loaded onto the coal tar pitch-based ACF through a simple hydrothermal–calcination method. The results showed that the coal tar pitch-based ACFs had a high specific surface area (1847 m2/g) and a unique microporous structure, and the metals were loaded onto them. The average diameter of the nanoparticles formed was approximately 100 nm. By changing the metal loading it was shown that the performance was best when the reaction temperature was 45 °C, the 4-NP concentration was 2.5 mmol L−1, and the molar concentration ratio of Fe3+ to Ni2+ was 1∶2 (total 7.5 mmol L−1). Under these conditions the conversion efficiency reached 99.88%. Fe2.5/Ni5–ACF exhibited excellent catalytic activity and recyclability for 4-NP after five cycles. The inherent advantages of nanomaterials increase the catalytic efficiency of 4-NP, which expands the use of coal tar pitch-based ACFs as supporting materials in the field of catalysis.