Functional kaolinite supported Fe/Ni nanoparticles for simultaneous catalytic remediation of mixed contaminants (lead and nitrate) from wastewater.

Kaolinite supported bimetallic Fe/Ni nanoparticles (K-Fe/Ni) demonstrated capacity for simultaneous removal of both cationic and anionic contaminants such as Pb (II) and NO3(-). The dispersion of Fe/Ni nanoparticles was improved when kaolinite was used as a stabilizer, and also enhanced the reactivity of K-Fe/Ni. The adsorption of Pb (II) onto the kaolinite and the consequent simultaneous catalytic reduction of Pb (II) and NO3(-) kaolinite were confirmed by SEM, BET, EDS, XRD and batch adsorption-reduction test. Orthogonal method showed that initial concentrations of Pb (II) and NO3(-), as well the dosage of K-Fe/Ni showed the most significant impact on the removal rates, where 86.3% of Pb (II) and 73.6% of NO3(-) was removed at optimized conditions. In addition, K-Fe/Ni could be stored for 15 days in dry air without losing reactivity. Reusability test of K-Fe/Ni indicated that the removal efficiency decreased by 12.5% for Pb (II) and 27.2% for NO3(-) after using 3 times successively. Two electroplating wastewater samples were tested and showed K-Fe/Ni could remove more than 96% of Pb (II) and NO3(-) under the optimized conditions.