Iron-based electrode material composites for electrochemical sensor application in the environment: A review.

This review explores the expanding role of electrochemical sensors across diverse domains such as environmental monitoring, medical diagnostics, and food quality assurance. In recent years, iron-based electrocatalysts have emerged as promising candidates for enhancing sensor performance. Notable for their non-toxicity, abundance, catalytic activity, and cost-effectiveness, these materials offer significant advantages. However, further investigation is needed to fully understand how iron-based materials' physical, chemical, and electrical properties influence their catalytic performance in sensor applications. It explores the overview of electrochemical sensor technology, examines the impact of iron-based materials and their characteristics on catalytic activity, and investigates various iron-based materials, their advantages, functionalization, and modification techniques. Additionally, the review investigates the application of iron-based electrode material composites in electrochemical sensors for real sample detections. Ultimately, continued research and development in this area promise to unlock new avenues for using iron-based electrode materials in sensor applications.

A comparative study on adsorption and catalytic degradation of tetracycline by five magnetic mineral functional materials prepared from steel pickling waste liquor.

Palygorskite (Pal), bentonite (Bent), sepiolite (Sep), zeolite (Zeol), and kaolin (Kaol) were used with steel pickling waste liquor to synthesize magnetic palygorskite (Pal@Fe3O4), magnetic bentonite (Bent@Fe3O4), magnetic sepiolite (Sep@Fe3O4), magnetic zeolite (Zeol@Fe3O4), and magnetic kaolin (Kaol@Fe3O4), for adsorption and catalytic degradation of tetracycline (TC), respectively. Through the study of adsorption kinetics and adsorption isotherms, the maximum adsorption capacity of Pal@Fe3O4 to TC was 149.439 mg/g, which was 1.239 times, 2.260 times, 3.161 times, and 3.448 times of Bent@Fe3O4, Zeol@Fe3O4, Kaol@Fe3O4, and Sep@Fe3O4, respectively. The kinetic study of tetracycline degradation demonstrated that the maximum reaction rate constant of Bent@Fe3O4/H2O2 system was K(obs) = 2.12 × 10-2 min-1, which was close to that of Pal@Fe3O4/H2O2, Kaol@Fe3O4/H2O2 system, and was 2.000 times, 2.356 times, 2.650 times, and 4.711 times of Fe3O4/H2O2, Zeol@Fe3O4/H2O2, Sep@Fe3O4/H2O2, and H2O2 system, respectively. The results showed that Pal@Fe3O4 and Bent@Fe3O4 were more advantageous in the treatment of wastewater containing tetracycline, and efficient reuse of exhausted magnetic minerals and deep mineralization of organic pollutants were achieved by constructing an advanced oxidation system. The BET, VSM, SEM, XPS, XRD, and FTIR were used to characterize the five clay minerals before and after magnetic modification. It was speculated that the surface structure - OH groups of clay minerals might be significant factors influencing the adsorption performance of magnetic minerals on TC, and reduction ability of clay minerals to Fe3+ importantly affected the catalytic performance of magnetic minerals. The specific surface area and morphological structure of clay minerals both affected the adsorption and catalytic degradation of TC by the five magnetic minerals.

Column study of enhanced Cr(VI) removal by bio-permeable reactive barrier constructed from novel iron-based material and Sporosarcina saromensis W5.

In this study, the feasibility of Cr(VI) removal from synthetic groundwater by bio-permeable reactive barrier constructed from novel iron-based material (SiO2/nano-FeC2O4 composite, SNFC) and Sporosarcina saromensis W5 was investigated. According to breakthrough study, an enhanced Cr(VI) removal was found in Bio-SNFC column. The Cr(VI) removal performances of biotic column with 0.2 g biomass and 0.4 g biomass were 16.2 mg/g and 17.9 mg/g, respectively, which were 19.6% and 32.1% higher than that of abiotic column (13.5 mg/g). However, excessive biomass (0.9 g) would cause pore clogging and have a negative impact on the Cr(VI) removal performance of the biotic column, whose removal capability (29.1%) was lower than that of abiotic column. The introduction of proper microorganisms enhanced the utilization of iron and enabled a higher proportion of Fe(II) in biotic column, which provided more reactive sites for Cr(VI) removal. The solid phase characterization indicated the generation of Fe(III) oxide/hydroxide on SNFC surface. The removal of Cr(VI) in Bio-SNFC column was depended on reduction-precipitation, and the final products related to chromium were mainly Cr(OH)3 and Cr2O3. The present work provides a new and sustainable remediation technology for in situ bioremediation of Cr(VI)-contaminated groundwater.

Are Fe-Based Stenting Materials Biocompatible? A Critical Review of In Vitro and In Vivo Studies.

Fe-based materials have increasingly been considered for the development of biodegradable cardiovascular stents. A wide range of in vitro and in vivo studies should be done to fully evaluate their biocompatibility. In this review, we summarized and analyzed the findings and the methodologies used to assess the biocompatibility of Fe materials. The majority of investigators drew conclusions about in vitro Fe toxicity based on indirect contact results. The setup applied in these tests seems to overlook the possible effects of Fe corrosion and does not allow for understanding of the complexity of released chemical forms and their possible impact on tissue. It is in particular important to ensure that test setups or interpretations of in vitro results do not hide some important mechanisms, leading to inappropriate subsequent in vivo experiments. On the other hand, the sample size of existing in vivo implantations is often limited, and effects such as local toxicity or endothelial function are not deeply scrutinized. The main advantages and limitations of in vitro design strategies applied in the development of Fe-based alloys and the correlation with in vivo studies are discussed. It is evident from this literature review that we are not yet ready to define an Fe-based material as safe or biocompatible.

Pyrolysis of different biomass pre-impregnated with steel pickling waste liquor to prepare magnetic biochars and their use for the degradation of metronidazole.

In this study, Fenton-like catalysts (magnetic biochar) were synthesised by pyrolysis the different biomass pre-impregnated with steel pickling waste liquor. The results of degradation of metronidazole illustrated that the catalytic performance of magnetic biochar was significantly affected by biomass feedstocks. Electron spin resonance (ESR) and radical quenching experiments showed that the hydroxide radicals (OH) were the key reactive oxygen species responsible for the metronidazole removal. Levels of OH varied among different systems consistent with the removal of metronidazole. The activation of H2O2 by carbon-containing components and Fe species (Fe2O3 and Fe3O4) in magnetic biochar were confirmed to be less crucial to the degradation of metronidazole. Moreover, the Fe(II) (FeO) in magnetic biochar played the dominating role in degradation of metronidazole, and the Fe(II) content difference caused by biomass feedstocks was responsible for differences in the catalytic performance of different types of magnetic biochar.

Addition of iron materials for improving the removal efficiencies of multiple contaminants from wastewater with a low C/N ratio in constructed wetlands at low temperatures.

Constructed wetlands (CWs) are widely used in wastewater treatment. Wastewater generally contains multiple contaminants. In this study, CWs were applied to treat wastewater with a low COD/TN ratio and containing heavy metals. Iron-based material was added in CWs to enhance the treatment efficiency. The contaminant removal efficiency was positively correlated with the dosage of iron-based material. Considering the operation cost, we added 1 g of iron-based material in CW and realized the multi-contaminant removal efficiency after 4-day treatment at low temperature: 99.51% of Cu(II), 87.22% of Cr(VI), 65.62% of TN, and 60.23% of COD. Microbial community analysis and kinetic analysis predicted that the removal mechanism involved ion exchange and microbial denitrification. Specific bacteria were found in CWs with iron-based material, such as Thiobacillus spp. and Thauera spp., indicating that the nitrate removal in the denitrification process was triggered by carbon sources and that Fe2+ worked as both the electron donor and the adjuster of the abundances of specific bacteria. The addition of iron-based material into CWs was a green option to improve the pollutant removal performance.

Enhanced hexavalent chromium removal by activated carbon modified with micro-sized goethite using a facile impregnation method.

In this study, activated carbon (AC) was modified with micro-sized geothite (mFeOOH) using a facile and cost-effective impregnation method for enhanced Cr(VI) removal from aqueous solutions. X-ray diffraction (XRD) and scanning electron microscope (SEM) analysis showed that FeOOH particles with a diameter of 0.1-1 µm were dispersed homogeneously on the surfaces and pores of the AC. Fourier transform infrared spectrum (FTIR) and X-ray photoelectron spectra (XPS) analysis indicated that Cr(VI) was easily adsorbed onto the mFeOOH and reduced to Cr(III) by the AC, eventually deposited as Cr(III)-Fe(III) hydroxides (e.g., (CrxFe1-x)(OH)3). Hence, the mFeOOH@AC achieved a significantly higher Cr(VI) removal efficiency of 90.4%, 4.5 times of that the AC. The adsorption of Cr(VI) onto the mFeOOH@AC agreed well with the Langmuir adsorption model, demonstrating that the adsorption process was controlled by monolayer adsorption. This adsorption process also followed the pseudo second-order kinetics and the adsorption rate constant K2 was determined to be 0.013 g/mg·min. The Cr(VI) removal efficiency decreased with pH values as the adsorption process was highly pH-dependent. After the desorption-adsorption process by 0.1 M HCl solution for 4 cycles, the removal efficiency of Cr(VI) was still kept up to 75.1%, indicating that the mFeOOH@AC has a good stability and can be easily regenerated. In addition, the mFeOOH@AC also exhibited a promising potential for reutilization since a Cr(VI) removal efficiency of 85.4% was achieved after stripping all the mFeOOH and Cr(III)-Fe(III) hydroxides by 1 M HCl solution and regeneration with mFeOOH. We demonstrate that the modified AC with micro-sized goethite can remarkably enhance its ability for Cr(VI) removal in water treatment.

"Cuju"-Structured Iron Diselenide-Derived Oxide: A Highly Efficient Electrocatalyst for Water Oxidation.

Electrocatalysts with outstanding performance have been highly desired toward exploration of new energy storage and conversion devices/systems as well as making an efficient and eco-friendly utilization of green energy. In this study, we composed an iron-based binary diselenide-derived oxide (Fe-SDO) with a facile one-step hydrothermal method to utilize the earth-abundant iron and the probably prosperous catalytic performance of metal-selenides compounds. The catalyst exhibits an overpotential of 226 mV at a current density of 10 mA/cm2, a Tafel slope of 41 mV dec-1, and robust durability after catalyzing vigorous OER for 36 h constantly. Through several analytical methods conducted before and after the oxygen evolution reaction activation on FeSe2 it was discovered that such catalyst possessed a morphology as "Cuju"-like balls with porosity inside in which we explored the vacancy defects and lattice distortion that play significant roles in generating the high electrocatalytic performance of our proposed catalyst by inducing remarkable electron conductivity in the porous Cuju balls (a Chinese traditional football). Throughout our work the superb electrocatalyst performance of the iron-based compounds was demonstrated, and subsequently the underlying reason for such electrocatalyst performance was addressed, which may push boundaries for the exploration of iron-based compounds as OER catalyst and large-scale commercial application of such compounds in the future.

The application of iron-based technologies in uranium remediation: A review.

Remediating uranium contamination is of worldwide interest because of the increasing release of uranium from mining and processing, nuclear power leaks, depleted uranium components in weapons production and disposal, and phosphate fertilizer in agriculture activities. Iron-based technologies are attractive because they are highly efficient, inexpensive, and readily available. This paper provides an overview of the current literature that addresses the application of iron-based technologies in the remediation of sites with elevated uranium levels. The application of iron-based materials, the current remediation technologies and mechanisms, and the effectiveness and environmental safety considerations of these approaches were discussed. Because uranium can be reduced and reoxidized in the environment, the review also proposes strategies for long-term in situ remediation of uranium. Unfortunately, iron-based materials (nanoscale zerovalent iron and iron oxides) can be toxic to microorganisms. As such, further studies exploring the links among the fates, ecological impacts, and other environmentally relevant factors are needed to better understand the constraints on using iron-based technologies for remediation.