High-performance Ni@CM catalytic membranes for continuous 4-NP hydrogenation: A sustainable approach for wastewater treatment

The efficient removal of pollutants, such as 4-nitrophenol (4-NP), from wastewater is a critical environmental challenge. Catalytic hydrogenation of 4-NP to 4-aminophenol (4-AP) is an improving approach for the efficient removal of 4-NP from wastewater. While traditional powder catalysts are widely used for hydrogenation reactions, they suffer from issues like separation difficulties and low stability. This study introduces a novel non-precious metal-based catalytic membrane (Ni@CM) that integrates the advantages of continuous flow reaction and stable catalytic performance. The Ni@CM was synthesized by growing Ni-BTC on the multi-channel ceramic membrane and converting it into Ni@C catalytic materials via pyrolysis. The metal-to-ligand molar ratio, hydrothermal temperature, and pyrolysis temperature are key factors in controlling the microstructures and catalytic performance of Ni@CM for the 4-NP hydrogenation. Ni@CM-2-150-435 exhibits superior catalytic efficiency, achieving a 91.5 % 4-NP conversion in 20 min, which outperforms Ni@CM-*-150-435 (3.3 % conversion) by 27.7 times, Ni@CM-0.5-150-435 (29.7 % conversion) by 3.1 times, and Ni@CM-4-150-435 (58.3 % conversion) by 1.6 times. This superior catalytic activity is attributed to its well-developed pore structure, small Ni particle size, and accessible carbon layer. Furthermore, Ni@CM-2-150-435 shows excellent reusability. The findings demonstrate that the developed Ni@CM-2-150-43 catalytic membrane provides a promising approach for continuous, efficient 4-NP removal from wastewater.