Iron(II,III)–Polyphenol Complex Nanoparticles Derived from Green Tea with Remarkable Ecotoxicological Impact

Abstract

There are several green methods available to synthesize iron-based nanoparticles using different bio-based reducing agents. Although their useful properties in degradation of organic dyes, chlorinated organics, or arsenic have been described earlier, their characterization has been ambiguous, and further research is needed in this area. Synthesis and characterization details on iron-based nanoparticles produced by green tea extract are described in detail; characterization was carried out by transmission electron microscopy (TEM), X-ray powder diffraction (XRD), and UV−vis spectrometry followed by ecotoxicological assay. XRD and TEM analyses revealed that iron forms amorphous nanosized particles with size depending on reaction time. Moreover, low-temperature Mossbauer spectroscopy confirmed progressive reduction of Fe 3+ to Fe 2+ during the reaction. Finally, the iron(II,III) nanoparticles prepared by green tea extract (GT−Fe nanoparticles) were found to have negative ecotoxicological impacts on important aquatic organisms such as cyanobacterium (Synechococcus nidulans), alga (Pseudokirchneriella subcapitata), and even invertebrate organisms (Daphnia magna). The EC 50 values are 6.1 ± 0.5 (72 h), 7.4 ± 1.6 (72 h), and 21.9 ± 4.3 (24 h) mg of Fe per L, respectively.

Reduction of Hexavalent Chromium Using Sorbaria sorbifolia Aqueous Leaf Extract

“…Hydroxyl groups from sugars and phenolics can affect the reduction of metal salts including also vitamins [35][36][37][38][39][40][41][42]. Aerial parts of Sorbaria sorbifolia are known to contain a variety of polyphenols, flavonoids and glycosides [23][24][25]; glycosides are non-reducing sugars, but polyphenols and flavonoids are known …”

“…Hydroxyl groups from sugars and phenolics can affect the reduction of metal salts including also vitamins [35][36][37][38][39][40][41][42]. Aerial parts of Sorbaria sorbifolia are known to contain a variety of polyphenols, flavonoids and glycosides [23][24][25]; glycosides are non-reducing sugars, but polyphenols and flavonoids are known antioxidants that serve as reducing agents [36][37][38][39] and are thus most likely responsible for the reduction of Cr(VI) to Cr(III) using 'greener' PLE as a reductant. A schematic presentation delineates the reduction mechanism (Figure 8a-c); captured image for the gradual conversion of carcinogenic Cr(VI) into nontoxic Cr(III) is shown in Figure 8e. antioxidants that serve as reducing agents [36][37][38][39] and are thus most likely responsible for the reduction of Cr(VI) to Cr(III) using 'greener' PLE as a reductant.…”

Biosynthesis of Multicomponent Nanoparticles with Extract of Mortiño (Vaccinium floribundum Kunth) Berry: Application on Heavy Metals Removal from Water and Immobilization in Soils

“…Additionally, peaks from 210 to 260 nm are seen in the two analyzed samples, and it is suggested that they resemble the presence of polyphenols. Markova et al [25] biosynthesized nanoparticles with green tea leaves and compared with nanoparticles synthesized with sodium borohydride. Nanoparticles prepared with green tea leaves showed peaks at 210, 220, and 270 n, whereas in the inorganic samples (nanoparticles with sodium borohydride), these peaks do not show up.…”

Liquid nitrogen cryostat for the low-temperature Mössbauer spectra measurements

“…Low-temperature measurements, especially in materials research, bring on many positives, i.e., characterizing the superparamagnetic materials in magnetically ordered state (below the blocking temperature), resolving spectral components or analyzing the liquid samples in a frozen state, etc. [1][2][3].…”

“…A cryostat operating at the stable temperature of liquid nitrogen, i.e., 77 K, offers a possible way how to easily perform low temperature analyses, moreover without extra vibrations. This system can be used in cases when it is necessary to stop the chemical reaction at a given time [3]. Additionally, the cryostat can be equipped with the temperature control system with the heater, which allows achieving a higher temperature than the temperatures of the cryogen liquids.…”