Metal hexacyanoferrates nanoparticles mediated degradation of carcinogenic aromatic amines

Abstract

Aromatic amines (AAs), the major group of industrial and environmental chemicals have raised concern due to their thermodynamic stability coupled with carcinogenicity. Thus, their effective elimination was carried out by nanomaterials especially metal hexacyanoferrates (MHCFs). Iron hexacyanoferrate (FeHCF), Nickel hexacyanoferrate (NiHCF) and Cobalt hexacyanoferrate (CoHCF) were synthesized using green methodology. TEM analysis showed the formation of hexagonal nanorods (<60 nm) of FeHCF and nanospheres ofCoHCF and NiHCF (<10 nm). DRS investigation revealed the lower band energy (NiHCF:1.35 eV, CoHCF:1.7 eV and FeHCF:1.145 eV). Under optimized conditions—targeted amine(1.0 × 10−4 M), catalyst (25 mg) and neutral pH, NiHCF (adsorption capacity: 5.114 mg/g) was found to be best with maximum degradation efficiency (84% of p-anisidine,69% of p-toluidine,67% of aniline and 62% of p-chloroaniline) followed by CoHCF (80%, 69%, 66% and 59%) and FeHCF (75%, 65%, 66% and 54%). This phenomenon was seemed to depend on surface acidity and surface-area supported by highest and least zeta potential and BET value of NiHCF and FeHCF, respectively. The highest adsorption (%) of p-anisidine is probably due to its highest basicity. Degradation followed first-order kinetics involving initial Langmuir adsorption. Comparative to dark, catalysts were found more active under sunlight and photocatalytic behavior is further supported by addition of OH scavenger that lowers the efficacy of the catalyst. AAs ultimately undergo mineralization via the path of small and non-toxic by-products analysed with GC–MS. Overall, MHCFs synthesized by green methods are cheap, recyclable with virtue of potential photocatalysts and multiple usages for remediating wastewater problems.