Removal of pollutants from landfill leachate by adsorption with nano zero-valent iron particles: adsorption isotherms and kinetic studies

Nano zero-valent iron (nZVI) is an effective adsorbent for removing various organic and inorganic contaminants. In this study, nZVI particles, synthesized in our previous work, were used for landfill leachate pretreatment. The adsorption performance was tested at various adsorbent concentrations (50–500 mg Fe0/L), pH (3–8), and contact times (15–330 min). Chemical oxygen demand, dissolved organic carbon (DOC), nitrate (NO3-), and ammonium (NH4+) removal efficiency were approximately 75%, 60, 57, and 33%, respectively. The obtained data were fitted well by the Langmuir isotherm and adsorption kinetics of pseudo-second-order equations (R2 > 0.9). The adsorption capacities were found to be 29.62, 21.01, and 3.12 mg/g for DOC, NH4+, and NO3−, respectively, at Fe0 concentration of 50 mg Fe0/L, pH of 8, and contact time of 120 min, which was determined as the effective operational conditions in this work. The obtained removal levels were higher compared to the conventional activated carbon adsorption (72.3%). Results suggest that nZVI has the potential to create effective adsorption relevant to landfill leachate pretreatment, thereby providing more efficient biological treatment by decreasing important pollutants before biological treatment.