Removal of 4-Nitrophenol from Wastewater Using ZIF-67-Derived Porous, Magnetic NiCo@C–N Using Catalytic Reduction: Optimization by Central Composite Design

In the present work, NiCo@C–N catalysts were synthesized by the pyrolysis of ZIF-67, a subclass of metal–organic frameworks (MOFs). Nickel addition and the pyrolysis process played an effective role for the catalytic reduction of 4-nitrophenol (4-NP). The structural properties of catalysts were examined by several techniques like XRD, SEM, Raman spectroscopy, N2 adsorption, VSM, and FTIR analysis. Nickel and cobalt metal particles in N-containing carbon frameworks enhanced the catalytic performance. The reduction reaction was completed within 80 s at 50 °C over Ni0.2Co@C–N catalyst. The reaction follows a pseudo-first-order mechanism, and the rate constant was calculated as 3.3 s–1g–1. The synthesized Ni0.2Co@C–N has been found to possess catalytic activity and stability, and its magnetic characteristic provides an advantage for catalyst separation. Future work may aim to increase the catalyst’s surface area and pore size to stabilize catalyst reusability, as suggested by the current findings. The role of tracing amounts of noble metals as promoters can also be examined.