Magnetic Nanoparticles Modified With Moringa Seed Proteins For Water Treatment And Recovery Of Precious Metal Ions

ABSTRACT

Access to clean and safe water for everyday use is needed for a healthy society. Water treatment and recovery of precious metals is a serious challenge particularly for developing countries since the current technologies are not attractive because they are often expensive and not environmentally friendly. Precious metals such as gold, palladium, and platinum are valuable and hence crucial for any economy. Coagulants used in the treatment and recovery of precious metals have setbacks such as cost and health concerns associated with them. The study was aimed at addressing both the problem of water treatment and recovery of metal ions using magnetic magnetite nanoparticles modified with Moringa seed proteins. The proteins extracted from Moringa seeds are known to have water treatment properties. Magnetic iron oxide nanoparticles were synthesized by chemical co-precipitation of Fe3+ and Fe2+ in a 2:1 ratio and complete precipitation was achieved at approximately pH 12.0. The study further prepared aqueous protein solution (1%) extracted from M. oleifera seeds that were utilized to obtain the chemical co-precipitation of modified magnetic magnetite nanoparticles. Characterization techniques used were FTIR, SEM, TGA and Zeta potential. They were utilized to identify different functional groups responsible for adsorption, morphology, thermal stability, and surface charges of the nanoparticles. Synthetic turbid water was prepared using kaolin whereas chloride salts of gold, palladium, and platinum were spiked in distilled water to obtain the required concentrations of the respective metal ions. UV-Vis spectrometry was used to measure turbidity, and metal ions percentage recovery was measured using ICP-OES. The effect of pH and modified magnetic iron oxide nanoparticles dosage was studied for turbidity removal and yielded an optimal pH of 2.5 with maximal removal of 97.3% at approximately 0.005 g.The same optimal pH was obtained for the recovery of gold, palladium, and platinum precious metal ions. Gold yielded a maximal recovery of 99.8%, followed by platinum with 87.7% then palladium with 72.7% at 0.065 g optimal dosage of modified magnetic iron oxide nanoparticles. The equilibrium was reached within 120 minutes of agitation. The initial concentration was maximal at 10 mg/L.The data fitted Langmuir model better than the Freundlich one. The maximum adsorption capacities were 34.48 mg/g, 28.90 mg/g and 5.27 mg/g for Au, Pt and Pd respectively. These results demonstrated that modified iron oxide nanoparticles were effective in water treatment and recovery of the precious metal ions.