Removal of sodium azide from aqueous solution by Fenton-like process using natural laterite as a heterogeneous catalyst: Kinetic modeling based on nonlinear regression analysis

Treatment of sodium azide aqueous solution by heterogeneous Fenton process in the presence of natural laterite as catalyst was studied. Influence of initial pH, dosages of laterite and H2O2, sodium azide concentration and reaction time on removal efficiency was investigated. Optimized experimental conditions were as pH = 3, 1 g/L laterite, 3 mmol/L H2O2. Under optimal conditions, removal efficiency of sodium azide was 97% after 60 min. Laterite sample was characterized by XRD, SEM and BET analysis. XRD pattern presents that laterite is source of iron. Also, experimental results demonstrated that laterite was a suitable alternative for typical ferrous salts. A kinetic model based on nonlinear regression analysis was developed to calculate the pseudo-first order rate constant (kapp) as a function of initial pH and concentrations of NaN3 and laterite. The calculated results were in consistent with the experimental data (R2 = 0.975).