Reuse of Bimetallic Nanoparticles for Nitrate Reduction

The aim of this research is investigation of FeNi bimetallic nanoparticles effectiveness after their using in the reduction of the high nitrate concentration. The advantage of the reusability is opportunity to create cost effective and environmentally friendly technologies. In this paper the efficiency of the same bimetallic nanoparticles was described. The same nanoparticles were used for nitrate reduction in the first, second and third times. After each use they were collected and used again for reduction of 300 mg L
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nitrates. Fe/Ni based bimetallic nanoparticles were synthesized freshly and used for nitrate removal. Synthesis of bimetallic nanoparticles was carried out in the presence of sodium oleate as dispersing agent by widely known borohydride reduction method. Batch experiments were performed on nitrate contaminated water samples. The parameters investigated were the reaction pH (acidic, alkaline conditions) and nitrates concentration after their reusing. The results showed that the total nitrate reduction (99.75%) was occurred after 5 min of reaction in the presence of freshly synthesized nanoparticles. Then the same nanoparticles were repeatedly used for nitrate reduction. This test has been performed thrice to study nanoparticles effectiveness after each use. It was investigated that the efficiency of nitrate degradation decreased after reusing. The second remediation by the same nanoparticles consisted 64.67% of nitrates removal and the third one – 47%. To evaluate the nitrate reduction rate and the kinetic of reaction, additional tests were performed at different temperatures. The structural characterization of freshly synthesized and reused bimetallic nanoparticles was investigated by TEM. Results showed that bimetallic nanoparticles were covered with an oxide layer after nitrates reduction. Decreased efficiency of reused bimetallic nanoparticles can be due to the appearance of an oxide layer.