Heavy metal ions (HMIs) are serious threats to the environment. Sub-critical water treatment was used to mimic contamination of squid oil in aqueous, metal-soap and oil phases. Isothermal adsorption of HMIs (Cu, Pb, Cd and Zn) was studied from aqueous phase to oil phase (493, 523, 548, and 573K) for solutions with different initial concentration of HMIs was studied. Decomposition of glycerides into fatty acids was favored at high subcritical temperatures, with metal-soap phase showing the highest chelation ability toward Cu (96%, isotherm 573K). The removal-ability of HMIs from contaminated oil was performed by CR11 chelate ion exchanger, showing facilitated removal from metal-soap and oil phases at low temperatures compared to general-purpose PEI-chitosan bead and PEI-chitosan fiber sorbents. The chelation behavior of Pb and Cd was the same in the OIL, with maximum values of 5.7×10 (mol/l) and 5.0×10 (mol/l) at 573K, respectively. By contrast, concentration of Zn ion showed a slight increase with increasing temperature due to electrostatic forces between Zn and active sites of glycerides in oil phase. For oil solution, the selectivity of adsorption for CR11, especially for Zn, was at least five-fold larger compared to PEI-chitosan bead and PEI-chitosan fiber adsorbents.
AbstractMetal nanoparticles are being extensively used in a variety of sectors, including drug delivery, cancer treatment, wastewater treatment, DNA analysis, antibacterial agents, biosensors and catalysts. Unlike chemically produced nanoparticles, biosynthesized metal nanoparticles based on green chemistry perspectives impose limited hazards to the environment and are relatively biocompatible. This review is therefore focused on green methods for nanoparticle synthesis by emphasizing on microbial synthesis using bacteria, fungi, algae, and yeasts, as well as phytosynthesis using plant extracts. Furthermore, a detailed description of bioreducing and capping/stabilizing agents involved in the biosynthesis mechanism using these green sources is presented.
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