Green fabrication and photoactivity of novel heteroatom modified metal heaxcyanocobaltate nanocomposites for efficient removal of organic pollutants from wastewater

Abstract

Herein, structural design of nitrogen-doped metal hexacyanocobalate nanocomposite (N-MHCC; M = Zn, Ni, Fe) have been synthesized via facile precipitation and green synthesis methodology—aqueous leaves extract of A. marmelos used as a natural surfactant. The unique cubical morphology (particle size less than 100 nm) of nanocomposite and the binding energy peak of N at 399 eV confirmed the successful doping of nitrogen in MHCC. The green synthesized N-MHCC treated with toxic Endosulfan (ES) pesticide and phenazinium Safranin (SF) dye under various reaction conditions (pollutant conc: 10–30 mgL-1; catalytic dosage: 20–40 mg; pH: 3–10, irradiation source: artificial bulb, dark, sunlight). N–ZnHCC showed maximum degradation (ES-90%: SF-95%) followed by Ni–NiHCC (ES-82%; SF-87%) and N–FeHCC (ES- 75%; SF-79%) under sunlight irradiation due to negative zeta potential (−20.0 mV), higher surface area (29.1 m2g-1) and lower band gap (1.7 eV). First-order kinetics followed by initial Langmuir adsorption constituted the degradation process. The presence of different radical quenchers (t-BuOH, p-BZQ, Na2EDTA) concluded that hydroxyl radical plays a significant role in the degradation of toxic ES and SF. Green fabricated N-MHCC also showed excellent efficiency for the degradation of ES and SF pollutant in actual wastewater sample. Nanocomposite demonstrated remarkable sustainability and cost-effectiveness by remaining effective for up to eight cycles without experiencing any appreciable activity reduction. Overall, due to its favourable surface features, N-MHCC nanocomposite made in green is a unique and potential photocatalyst for industrial applications.