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

• Mixed contaminants (Pb (II) and NO3−) were efficiently removed by K–Fe/Ni.
• 86.3% of Pb (II) and 73.6% of NO3− were removed simultaneously by K–Fe/Ni.
• The adsorption of Pb (II) onto kaolinite enhanced the reduction of Pb.
• K–Fe/Ni showed good stability and reusability within 4 days’ ageing.

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.

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