Preparation of an Ni5P4/Ni porous composite using a Ni foam as the skeleton and its application in the treatment of large-volume effluent with a high concentration of 4-nitrophenol at room temperature

Abstract

In the present work, an Ni₅P₄/Ni porous composite with a Ni foam as the skeleton was prepared through phosphorization calcination at 500 °C. Meanwhile, the catalytic activity of the as-prepared Ni₅P₄/Ni porous composite was explored for the treatment of a large-volume effluent with a high concentration of 4-nitrophenol at room temperature. At last, the catalytic mechanism was discussed preliminarily. The results indicated that the Ni₅P₄/Ni porous composite possessed remarkable catalytic activity for the borohydride-assisted reduction of 4-nitrophenol. When the concentration of 4-nitrophenol was 1.0 × 10⁻³ mol L⁻¹, the catalytic reduction efficiency of 4-nitrophenol was up to 99% within 13 min over the aforementioned sample. More interestingly, it was suitable for the treatment of a large-volume effluent with a high concentration of 4-nitrophenol. Almost 99% of 4-nitrophenol (1.0 × 10⁻² mol L⁻¹, 100 mL) could be removed within 30 min. Even when 4-nitrophenol was near saturation in water (5.0 × 10⁻² mol L⁻¹), 4-nitrophenol could still be removed absolutely from water after a 165 min reaction in the presence of the Ni₅P₄/Ni porous composite. In the catalytic process, Ni₅P₄ could serve as the active sites and accelerate the formation of hydrogen atoms from BH₄⁻. Meanwhile, the Ni skeleton could make the electron transfer faster in the catalytic system. Besides, the macroporous structure of the sample also played an important role in the catalysis process.