Investigation of Heterogeneous Catalytic Activity of Ni (II) Complexes with H2L1 and H2L2-Stabilized Ligand of TiO2-Stabilized Ligands on Reduction of 4-nitrofenol

Several studies have been carried out to remove and reduce p-nitrophenol from contaminated water and industrial effluents, and various methods have been used such as catalytic oxidation electro-Fenton, electrochemical, microbial degradation, and so on. But these methods have problems such as low sensitivity, high cost the need for specific temperature conditions, and a long time. One of how scientists have considered the catalytic hydrogenation of these materials in recent years is to convert para nitrophenol into aminophenol derivative by making heterogeneous nanocatalyst, toxic substances, and carcinogens of p-nitrophenol. For this purpose [NiLx(DMF)], [NiLx(PPh3)] (L1= salicylidene-2-aminothiophenol and L2= salicylidene-2-aminophenol) complexes were placed on a titanium dioxide and the catalyst was identified with techniques such as IR،FE-SEM, EDX/mapping،XRD and ICP. Then, after selecting the best nanocatalysts, evaluate  for the reduction of p-nitrophenol to p-aminophenol in the presence of NaBH4 as a reducing agent and at ambient temperature and pressure. The reaction was followed by UV-Vis spectroscopy. In presence of [NiL1(PPh3)]/TiO2 catalyst, the reaction was completed at about 8 min with k = 5/3× 10-3 s-1. The reported results so far in various sources have often been used a lot of the amount of reducing agent or catalyst, or the reaction has been completed over a longer period of time. In this work, in addition to using the minimum amount of catalyst and NaBH4, the completion time of the reaction is also appropriate.