Experimental overview of nanoferrites: synthesis, characterization and performance evaluation in wastewater treatment

Abstract

Abstract This study investigates the potential of ferrite nanoparticles (BaFe12O19, MnFe2O4, NiFe2O4, and Co1–0.5Ni0.5Fe2O4) as eco-friendly adsorbents for the removal of heavy metals (Zn2+, Ni2+, Co2+, and Mn2+) from wastewater. Moreover, the adsorption experiments were conducted under varying contact times (30 min, 1 h, 2 h, and 4 h) and pH levels (2, 7, and 12) for five cycles to evaluate their significant dynamic effects on the removal efficiency. All ferrite nanoparticles were synthesized by the co-precipitation method and characterized (XRD, FT-IR, and SEM) to ascertain their crystal structure, morphology, size distribution, and crystallographic structures before wastewater treatments. The results demonstrated that BaFe12O19 had a particle size of 8.65 nm and achieved maximum adsorption ability of 93%, 91%, 94%, and 91% for Zn2+, Ni2+, Co2+, and Mn2+, respectively, at a pH of 7 after 4 h of treatment. Since the neutral pH value affects the binding of heavy metal ions, therefore governing the adsorption efficiency and selectivity. In contrast, NiFe2O4 (1.41 nm) revealed maximum removal of Zn2+, Ni2+, Co2+, and Mn2+ were 78%, 71%, 88%, and 83%, respectively, at a pH of 12 after 4 h. This was attributed to the negatively charged surface leading to stronger electrostatic attractions between the positively charged metal ions and the adsorbent surface, resulting in higher adsorption uptake. Notably, the higher removal rate of ions was observed during initially 1 h, suggesting a decline in efficiency rate with extended treatment time. Additionally, the experimental study over five cycles concluded that the adsorbent could be effectively regenerated and reused.