Efficient photocatalytic degradation of ammonia nitrogen by Z-scheme NH₂-MIL-101(Fe)/BiVO₄ heterostructures

A promising Z-scheme NH2-MIL-101(Fe)/BiVO4 heterostructure was fabricated by in-situ growth of monoclinic BiVO4 onto the surface of NH2-MIL-101(Fe) nanoparticles and employed for ammonia nitrogen removal in water for the first time. Experiments demonstrated that NH2-MIL-101(Fe)/BiVO4 composites displayed boosted performance for ammonia nitrogen removal. And 10%-MBVO exhibited optimal removal rate of ammonia nitrogen as 95.7% and N2 selectivity as 92.3% in 90 min at pH of 9.0 with initial concentration as 30 mgN/L. Moreover, effects of initial solution pH, stirring speed and impurity ions (k+, Ca2+, SO42- and CO32-) were investigated. The end products and net contributions of stripping, adsorption, photolysis, photocatalysis in ammonia nitrogen removal were revealed. The functions of center dot OH, center dot O2- and h+ in photocatalytic degradation of ammonia were explored by scavenging experiments. The proposed mechanism indicated that the enhancement may be primarily owing to the improved light harvesting capacity and stronger redox ability of photogenerated carriers provided by Z-scheme heterostructures. (c) 2022 Elsevier B.V. All rights reserved.