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Green-synthesized iron nanoparticles (GAP-FeNP) were used as particle electrodes in a three-dimensional electro-Fenton (3DEF) process to accelerate the removal of hexavalent chromium [Cr (VI)]. Removal was evaluated by varying the pH (3.0, 6.0, and 9.0) and initial Cr (VI) concentrations (10, 30, and 50 mg/L) at 5 and 25 min. These results demonstrated that GAP-FeNP/3DEF treatment achieved more than 94% Cr (VI) removal under all tested conditions. Furthermore, it was observed that Cr (VI) removal exceeded 98% under pH 9.0 in all experimental parameters tested. The results of the response surface methodology (RSM) determined two optimal conditions: the first, characterized by a pH of 3.0, Cr (VI) concentration at 50 mg/L, and 25 min, yielded a Cr (VI) removal of 99.7%. The second optimal condition emerged at pH 9.0, with Cr (VI) concentrations of 10 mg/L and 5 min, achieving a Cr (VI) removal of 99.5%. This study highlights the potential of the GAP-FeNP to synergistically accelerate Cr (VI) removal by the 3DEF process, allowing faster elimination and expansion of the alkaline (pH 9.0) applicability. PRACTITIONER POINTS: The required time for >99% of Cr (VI) removal by the GAP-FeNP/3DEF process was shortened from 25 to 5 min. EF process with GAP-FeNP reduces the time necessary for Cr (VI) removal, which is 67% faster than conventional methods. EF process using GAP-FeNP removed >94% of Cr (VI) after 25 min for all initial Cr (VI) concentrations and pH treatments. Cr (VI) removal by the GAP-FeNP/3DEF process was >98% at a pH of 9.0, widening the solution pH applicability.

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Groundwater is one of the primary sources of water for both drinking and industrial use in northeastern Mexican territory, around 46% of the total, due to the lack of precipitation during the year and solar radiation index. The presence of arsenic in brackish soil and groundwater is a severe health issue, specifically in semi-arid and arid regions in the north of Mexico. Additionally, it represents the only source of drinking water in communities far from big cities, mainly due to the absence of hydric infrastructure. This work presents a new approach to treating polluted water with arsenic. The system based on activating jute fiber with nanoparticles of zero-valent iron immobilized over graphene oxide will allow nZVI particles to preserve their unique qualities for water sanitization. A dynamic flow test was designed to determine the effectivity of activated jute fibers as a water sanitation system. The results showed a reduction in the total arsenic content from 350 ppb to 34 ppb with a filtrate flow of 20 mL/min. The above represents 90% adsorption by the activated fiber. The analyzed sample corresponds to contaminated groundwater taken from Coahuila, Mexico. This sanitation system could be applied to low-income populations lacking robust infrastructure, such arsenic treatment plants.

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This work presents a long-term follow-up (300 days) of rats after a single intravenous injection of DMSA-coated magnetite nanoparticles (DMSA-MNP). The animals were systematically evaluated by hematological, biochemical, and ultrasound examinations, monitoring the same animal over time. In addition, oxidative stress evaluation, DMSA-MNP biodistribution, computerized tomography for ex vivo organs, and histopathology analysis were performed at the end of the experiment period. Overall, DMSA-MNP administration did not cause serious damage to the rats' health over the course of 300 days post-administration. All animals presented hematological parameters within the normal limits, and no alterations on serum creatinine, urea, ALT, and AST were related to DMSA-MNP administration. Liver and spleen showed no important alterations in any of the examinations. The kidneys of treated animals displayed intermittent pelvis dilation at ultrasound analysis, but without damage to the organ parenchyma after 300 days. The lungs of treated animals presented a light interalveolar septal thickening, but the animals did not present any clinical respiratory symptom. Nanoparticles were not detected in the vital organs of treated animals 300 days after administration. This work represents the first assessment of the long-term effects of DMSA-MNP and goes a step further on the safety of its use for biomedical applications.

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Anaerobic digestion (AD) is the most widely used technology for organic matter treatment. However, multiple types of research have reported on improving the process because different operation inhibition factors and limitations affect the performance of AD process. Owing to the increasing use of iron-nanoparticles (Fe-NP) on AD, this review addresses the knowledge gaps and summarizes the finding from academic articles based on (i) the AD upgrading operations: limitations and upgrade techniques, (ii) Fe-NPs mechanisms on AD, (iii) Fe-NP effect on microbial communities associated to AD systems, and (iv) perspectives. The selected topics give the Fe-NP positive effects on the AD methane-production process in terms of gas production, effluent quality, and process optimization. The main results of this work indicate that (i) Fe-NP addition can be adapted among different feedstocks and complement other pretreatments, (ii) Fe-NP physicochemical characteristics enhance biogas production via direct interspecies electron transfer (DIET) mechanisms, and Fe-ion release due to their structure and their conductivity capability, and (iii) syntrophic bacteria and acetoclastic methanogens have been reported as the communities that better uptake Fe-NPs on their metabolisms. Finally, our research perspectives and gaps will be discussed to contribute to our knowledge of using Fe-NPs on AD systems.

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The experiment was conducted with 644 Ross fertilized egg by 7 treatments 4 replicates and 23 eggs in each. Seven treatments included two control with and without injection, iron sulfate, iron sulfate nanoparticles, Alimet, Alimet + iron sulfate, Alimet + iron sulfate nanoparticles. After hatching 2 mg iron nanoparticles were applied as new treatment. The highest increased in the intestinal relative weight (p < 0.05) was observed by iron+Alimet in late feeding at day old of age. Also similar trend was found in cecum and duodenum length by iron control 2 and late feeding (18 hours’ after hatching). The highest cecum length was found among all treatments by in ovo injection of iron nanoparticles in early feeding at 21 days of age (p < 0.05). Significantly increased the duodenum length was found by iron sulfate in early feeding at 42 days of age (p < 0.05). In ovo injection of Alimet in late feeding was resulted in decrease jejunum crypt depth at 21 days of age (p < 0.05). The results of this study have shown that the highest jejunum villi width and surface area were recorded in dietary iron sulfate nanoparticles in late feeding at 21 and 42 days of age (p < 0.05).

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The experiment was conducted with 644 Ross fertilized egg by 7 treatments 4 replicates and 23 eggs in each. Seven treatments included two control with and without injection, iron sulfate, iron sulfate nanoparticles, Alimet, Alimet + iron sulfate, Alimet + iron sulfate nanoparticles. After hatching 2 mg iron nanoparticles were applied as new treatment. The highest increased in the intestinal relative weight (p < 0.05) was observed by iron+Alimet in late feeding at day old of age. Also similar trend was found in cecum and duodenum length by iron control 2 and late feeding (18 hours after hatching). The highest cecum length was found among all treatments by in ovo injection of iron nanoparticles in early feeding at 21 days of age (p < 0.05). Significantly increased the duodenum length was found by iron sulfate in early feeding at 42 days of age (p < 0.05). In ovo injection of Alimet in late feeding was resulted in decrease jejunum crypt depth at 21 days of age (p < 0.05). The results of this study have shown that the highest jejunum villi width and surface area were recorded in dietary iron sulfate nanoparticles in late feeding at 21 and 42 days of age (p < 0.05).(AU)

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Biofilm formation is one of the resistance mechanisms of Pseudomonas aeruginosa against antimicrobial compounds. Biofilm formation also characterizes for the infection and pathogenesis of P. aeruginosa, along with production of various virulence factors. With recent development of nanotechnology, the present study aims to employ the synthetic iron nanoparticle (FeOOH-NP) as an active agent to inhibit the formation of P. aeruginosa biofilm. The FeOOH-NP was synthesized and characterized with rod shape and average size of 40 nm. Inhibition of biofilm formation by the FeOOH-NP is in a concentration-dependent manner, with inhibition of biofilm formation increased as the FeOOH-NP concentration increased. Microscopic observations also confirmed the disruption of the biofilm architecture in the presence of the FeOOH-NP. In addition, the presence of the FeOOH-NP was also found to modulate bacterial motility as well as some other important virulence factors produced simultaneously with biofilm formation. These findings provide insights to anti-biofilm effect of a new iron NP, contributing to the search for an effective agent to combat P. aeruginosa infections resulted from biofilm formation.

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Iron-based nanoparticles were synthesized by a rapid method at room temperature using yerba mate (YM) extracts with FeCl3 in different proportions. Materials prepared from green tea (GT) extracts were also synthesized for comparison. These materials were thoroughly characterized by chemical analyses, XRD, magnetization, SEM-EDS, TEM-SAED, FTIR, UV-Vis, Raman, Mössbauer and XANES spectroscopies, and BET area analysis. It was concluded that the products are nonmagnetic iron complexes of the components of the extracts. The applicability of the materials for Cr(VI) (300 µM) removal from aqueous solutions at pH 3 using two Cr(VI):Fe molar ratios (MR), 1:3 and 1:0.5, has been tested. At Cr(VI):Fe MR = 1:3, the best YM materials gave complete Cr(VI) removal after two minutes of contact, similar to that obtained with commercial nanoscale zerovalent iron (N25), with dissolved Fe(II), and with a likewise prepared GT material. At a lower Cr(VI):Fe MR (1:0.5), although Cr(VI) removal was not complete after 20 min of reaction, the YM nanoparticles were more efficient than N25, GT nanoparticles and Fe(II) in solution. The results suggest that an optimal Cr(VI):Fe MR ratio could be reached when using the new YM nanoparticles, able to achieve a complete Cr(VI) reduction, and leaving very low Cr and Fe concentrations in the treated solutions. The rapid preparation of the nanoparticles would allow their use in removal of pollutants in soils and groundwater by direct injection of the mixture of precursors.

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This work studied the effects on the anaerobic digestion of sewage sludge by zero valent iron nanoparticles (NZVI) dosage. Biochemical methane potential tests were carried out with 5-9 mg/gVS (99.7%, 40-60 nm). The biogas yield increased from 132 (control) to 310 mL/gVS with 9 mg/gVS. The methane content increased from 63.2% (control) to 77.6% with NZVI, which corresponded to a maximum yield of 238 mLCH4/gVS with 9 mg/gVS. The maximum VS reduction was 19.6%. The highest INT-ETS activity (20.1-37.1 µgINTred/gVS·h) corresponding to the maximum values of sCOD was reached within the first days. NZVI decreased the ORP to -300 mV and increased the VFA's concentration (+2000 mg/L). The ORP-VFA-pH analysis showed that NZVI promoted the acidogenesis-acetogenesis without acidification. That is, NZVI was effective in intensifying the performance and stability of the process.

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In this work, the effect of coupling ultrasonic pretreatment with dosing of zero-valent iron nanoparticles (nanoferrosonication, "NFS") to improve the anaerobic digestion of sewage sludge was studied. Biochemical methane potential tests were conducted at 15,000 and 25,000 kJ/kgTS and their combinations with 2 and 7 mgFe0/gVS. The biogas yield increased from 106 (control) to 143 (25,000 kJ/kgTS) and 308 mL/gVS with NFS (7 mgFe0/gVS + 15,000 kJ/kgTS). The methane content increased from 55.6 to 66%, and the maximum VS removal was 11.5% at 7 mgFe0/gVS + 15,000 kJ/kgTS. The results demonstrated that NFS was effective in intensifying the process.

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Reactive Black 5, RB5, has been used as a model azo dye to evaluate the removal efficiency of sorption on Macrocystis pyrifera biomass (Mpyr) and commercial zerovalent iron nanoparticles (nZVI) in individual and combined treatments. The best conditions for the treatment with the isolated materials were first determined, and then, in series and combined treatments were performed under these conditions, achieving removal efficiencies higher than 80% of the initial dye concentration. Strengths and weaknesses of all removal strategies (individual, in series and combined) are analyzed regarding the application on real effluents. Mpyr efficiently adsorbed RB5, but also increased the total organic content by partial dissolution of components of the algal biomass. Removal experiments with commercial nZVI were also efficient but liberated Fe to the solution, and sulfanilic acid was observed after the treatment as a product of RB5 degradation. In contrast, after the Mpyr treatment, no sulfanilic acid was detected, suggesting that sulfanilic acid is efficiently adsorbed by the biomass. The best condition was the integrated use of Mpyr and nZVI, with a remarkable removal efficiency (69-80%) obtained after only 1 h of treatment. Finally, nZVI were successfully immobilized in Mpyr, and the hybrid material was used to remove RB5 in continuous flow experiments at pH 3, obtaining a removal capacity of 39.9 mg RB5 g-1 after a total processed volume of 630 mL of [RB5]0 = 100 mg L-1.

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The increasing use of nanotechnology in the last decade has raised concerns about the impact of nanoparticles in the environment. In particular, the potential harmful effects of iron oxide nanoparticles (IONPs) in aquatic organisms have been poorly addressed. We analyze here the toxic effects induced by IONPs in zebrafish using a combination of classical (genotoxicity, oxidative stress) and molecular (transcriptomic) methodologies. Adult animals were exposed for 96h to five sub-lethal IONP concentrations, ranging from 4.7 to 74.4mg/L. Comet and micronucleus assays revealed a significant number of DNA lesions induced by IONPs at all concentrations tested. Conversely, the thiobarbituric acid reactive substances (TBARS) test detected only a mild oxidative damage in liver cells (∼1.5-fold increase of malondialdehyde concentrations) and only at the two higher IONP concentrations tested. Microarray analysis of liver samples identified 953 transcripts (927 unique genes) differentially expressed between controls and IONP-exposed samples. Subsequent functional analysis identified genes related to cation/metal ion binding, membrane formation, and morphogenesis among the transcripts overrepresented upon IONP treatments, whereas mRNAs encompassing genes associated with RNA biogenesis, translation, ribosomes, and several metabolic processes became underrepresented in treated samples. Taken together, these results indicate considerable genotoxic effects of IONPs combined with general negative effect on cell growth and on the ability of the cell produce new proteins. On the contrary, IONPs showed only a limited capacity to induce oxidative stress. To our knowledge, this is the first study on IONPs toxicity using such an integrative approach in an aquatic organism.

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BACKGROUND: The use of microorganisms for the synthesis of nanoparticles (NPs) is relatively new in basic research and technology areas. PURPOSE: This work was conducted to optimized the biosynthesis of iron NPs intra- and extracellular by Escherichia coli or Pseudomonas aeruginosa and to evaluate their anticoagulant activity. STUDY DESIGN/METHODS: The structures and properties of the iron NPs were investigated by Ultraviolet-visible (UV-vis) spectroscopy, Zeta potential, Dynamic light scattering (DLS), Field emission scanning electron microscope (FESEM)/ Energy dispersive X-ray (EDX) and transmission electron microscopy (TEM). Anticoagulant activity was determined by conducting trials of Thrombin Time (TT), Activated Partial Prothrombin Time (APTT) and Prothrombin Time (PT). RESULTS: UV-vis spectrum of the aqueous medium containing iron NPs showed a peak at 275 nm. The forming of iron NPs was confirmed by FESEM/ EDX, and TEM. The morphology was spherical shapes mostly with low polydispersity and the average particle diameter was 23 ± 1 nm. Iron NPs showed anticoagulant activity by the activation of extrinsic pathway. CONCLUSION: The eco-friendly process of biosynthesis of iron NPs employing prokaryotic microorganisms presents a good anticoagulant activity. This could be explored as promising candidates for a variety of biomedical and pharmaceutical applications.

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This work describes the synthesis and characterization of supported green iron catalysts, prepared with Camellia sinensis tea extract, and their application in heterogeneous Fenton degradation of pollutant dyes. The influence of the catalyst synthesis conditions in the iron and organic content were investigated by X-ray fluorescence and thermogravimetric analyses. Irregular, chain-like nanoparticles, in the size range of 20-100 nm, capped by polyphenolic natural compounds, were visualized by TEM micrographs. TEM-EDS revealed a high iron content in the nanoparticles as well as a high carbon content all over the catalyst surface, indicating the coverage by the polyphenolic compounds of the tea. X-ray powder diffraction revealed the amorphous nature of the nanoparticles, tentatively ascribed to iron(II)/(III) oxides and oxohydroxides composites. The Fenton degradation of different dyes was successfully accomplished, leading to complete decolourization in less than 3 h of reaction. Influence of hydrogen peroxide concentration, catalyst dosage, pH, temperature and catalyst support, were investigated. The catalysts prepared with black tea over silica furnished the higher iron contents and were the most actives for dye degradation.

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Contamination of soils by persistent pollutants is considered an important matter of increasing concern. In this work, activated persulfate (PS) was applied for the remediation of a soil contaminated with polycyclic aromatic hydrocarbons (PAHs), such as anthracene (ANT), phenanthrene (PHE), pyrene (PYR) and benzo[a]pyrene (BaP). PS activation was performed by different ways; where ferric, ferrous sulfate salts (1-5mmol·L(-1)) and nanoparticles of zerovalent iron (nZVI) were used as activators. Moreover, in order to improve the oxidation rate of contaminants in the aqueous phase, the addition of sodium dodecyl sulfate (SDS), as anionic surfactant, was tested. On the other hand, it was also studied the role of humic acids (HA), as reducing agent or surfactant, on PAHs conversion. Removal efficiencies near 100% were achieved for ANT and BaP in all the runs carried out. Nevertheless, remarkable differences on removal efficiencies were observed for the different techniques applied in case of PHE and PYR. In this sense, the highest conversions of PHE (80%) and PYR (near 100%) were achieved when nZVI was used as activator. Similar results were obtained when activation was carried out either with Fe(2+) or Fe(3+). This can be explained by the presence of quinone type compounds, as 9,10-anthraquinone (ATQ), that can promote the reduction of Fe(3+) into Fe(2+), permitting PS radicals to be generated. On the other hand, the addition of HA did not produce an improvement of the process while surfactant addition slightly increases the PAHs removal. Furthermore, a kinetic model was developed, describing the behavior of persulfate consumption, and contaminants removal under first order kinetics.