Fe Molar Ratio Research Articles

Sulfidation of Nanoscale Zero-Valent Iron by Sulfide: The Dynamic Process, Mechanism, and Role of Ferrous Iron.

Sulfidation of nanoscale zerovalent iron (nZVI) can enhance particle performance. However, the underlying mechanisms of nZVI sulfidation are poorly known. We studied the effects of Fe2+ on 24-h dynamics of nZVI sulfidation by HS- using a dosed S to Fe molar ratio of 0.2. This shows that in the absence of Fe2+, HS- rapidly adsorbed onto nZVI particles and reacted with surface iron oxide to form mackinawite and greigite (<0.5 h). As nZVI corrosion progressed, amorphous FeSx in solution deposited on nZVI, forming S-nZVI (0.5-24 h). However, in the initial presence of Fe2+, the rapid reaction between HS- and Fe2+ produced amorphous FeSx, which deposited on the nZVI and corroded the surface iron oxide layer (<0.25 h). This was followed by redeposition of colloidal iron (hydr)oxide on the particle surface (0.25-8 h) and deposition of residual FeSx (8-24 h) on S-nZVI. S loading on S-nZVI was 1 order of magnitude higher when Fe2+ was present. Surface characterization of the sulfidated particles by TEM-SAED, XPS, and XAFS verified the solution dynamics and demonstrated that S2- and S22-/Sn2- were the principal reduced S species on S-nZVI. This study provides a methodology to tune sulfur loading and S speciation on S-nZVI to suit remediation needs.

Effects of Temperature and Precursor Concentration on the Morphological and Optical Properties of Iron Oxide Nanoparticles

Iron oxide nanoparticles are inexpensive materials that are environmentally friendly and have properties that render them suitable for wide range of applications. A facile and time-effective coprecipitation method was used to prepare iron oxide nanoparticles in a 1:1 molar ratio of Fe2+ and Fe3+ ions in solution. Iron oxide nanoparticles obtained at 18 and 60 °C yielded spherical magnetite nanoparticles with particle sizes of 7.63 and 8.5 nm respectively while comprising a mixture of magnetite and hematite nanorods, with a mean width of 9.5 nm and a mean length of 75 nm were obtained at 90 °C. Iron oxide nanoparticles synthesized at 18 °C have energy band gap of 4.16 eV while those synthesized at 60 and 90 °C have the same band gap of 4.66 eV. Precursor concentrations of 0.042, 0.08 and 0.0126 M yielded spherical magnetite nanoparticles with particle sizes of 7.94, 8.5 and 8.5 nm respectively and the particle size range increased with increasing concentration. Magnetite nanoparticles synthesized with concentrations of 0.042, 0.08 and 0.126 M have optical band gaps of 4.65, 4.88 and 5.19 eV respectively. The magnetite crystalline phase was produced regardless of concentration at temperatures of 18 and 60 °C while a temperature of 90 °C yielded a mixture of magnetite and hematite phases. The band optical band gap showed direct proportionality with temperature and concentration in an inert environment.

Hard Magnetic FePt Nanoparticles within Nanostructured Silicon to Improve the Maximum Energy Product

In this work nanostructured silicon, silicon nanotubes (SiNTs) and porous silicon (PSi), with embedded hard magnetic FePt nanoparticles (NPs) is used as platform to create nanomagnet-arrays. The magnetic response of FePt-loaded composite materials is investigated, which have potential in high-performance magnets and as rare earth magnet alternatives. PSi/FePt demonstrates superior hard magnetic behavior with a higher coercivity and remanence compared to SiNTs/FePt. Varying the Fe molar ratio in deposits results in a small coercivity range. FePt-loaded samples consistently show increased coercivity and remanence compared to Co-loaded samples, with PSi exhibiting a stronger effect compared to SiNTs.The fabrication of the PSi samples was performed by anodization of p+ silicon in a 5 wt% HF solution. A current density of 50 mAcm-2 was applied during the etching. The samples offer an average diameter of 50 nm. The SiNTs were produced by using arrays of ZnO nanowires (NWs) as template, followed by Si deposition and finally etching off the ZnO NWs which is described in (1). FePt nanocrystals were formed within the SiNTs by a multistep process, consisting of soaking previously APTES functionalized SiNTs in a solution containing 0.1 mM Citric acid, 0.5 mM of H2PtCl6 6H2O, and depending on the given ratio 0.5-1.5 mM of Fe(NO3)3 9H2O. The samples were dried in a vacuum oven, followed by a heat treatment at 500° C for 1 hr in Ar atmosphere, then the samples were washed several times with water and ethanol. In a similar way FePt NPs were formed in PSi samples, however PSi did not receive the APTES functionalization before the solution soaking.For these samples, the average FePt particle size is 5 (± 2) nm in SiNTs samples and 9 (± 4) nm for the particles inside PSi, however it should be pointed out that the FePt ratios calculated from reactants was different than the ratios determined from EDX experimental data. The calculated stoichiometry of Pt:Fe (based on reactant concentrations) of 1:1, 1:3 and 1:6 was experimentally determined values via EDX to be 10:1, 1.6:1 and 0.5:1 for SiNTs; for the corresponding PSi samples of calculated 1:3 and 1:6 ratios was experimentally 40:1 and 10:1.Magnetization measurements were carried out by VSM in recording the magnetic response dependent on the magnetic field. Samples with different Fe content (Pt:Fe = 1:1, 1:3, 1:6) offer a variation of the coercivity in the range of 5% for both types of matrices (SiNTs, PSi). Furthermore the investigations show that the coercivities of PSi loaded with FePt NPs is about twice the coecivities of SiNTs loaded with FePt NPs. SiNTs/FePt samples with a ratio Pt:Fe 1:6 offer a coercivity of about 240 Oe and PSi/FePt offers a coercivity more than twice as high of about 560 Oe.Comparing the FePt loaded samples with samples loaded with Co NPs, in both sample types an increase of the coercivity is observed for FePt. Also in the case of Co-loading the utilization of PSi as template offers higher coercivities compared to SiNTs as template. From the investigated composite systems the ones consisting of PSi and FePt offer the highest energy product.(1) Huang, X., Gonzalez-Rodriguez, R., Rich, R., Gryczynski, Z., Coffer, J.L., Chem. Comm. 2013, 49, 5760.

Bioinspired Self-Growing Layered Hydrogel Enabled by Catechol Chemistry-Mediated Interfacial Catalytic System.

Tissue-inspired layered structural hydrogel has attracted increasing attention in artificial muscle, wound healing, wearable electronics, and soft robots. Despite numerous efforts being devoted to developing various layered hydrogels, the rapid and efficient preparation of layered hydrogels remains challenging. Herein, inspired by the self-growth concept of living organisms, an interfacial catalytic self-growth strategy based on catechol chemistry-mediated self-catalytic system of preparing layered hydrogels is demonstrated. Typically, the tannic acid-metal ion (e.g., TA-Fe3+) complex embedded in the hydrogel substrate would catalytically trigger rapid solid-liquid interfacial polymerization to grow the hydrogel layer without bulk solution polymerization. The self-growth process can be finely controlled by changing the growth time, the molar ratio of Fe3+/TA, and so on. The strategy is applicable to prepare various layered hydrogels as well as complex layered hydrogel patterns, allowing the customization of the physicochemical properties of the hydrogel. In addition, the self-adhesive layered hydrogel was prepared and can be utilized as a wearable strain sensor to monitor physiological activities and human motions. The demonstrated interfacial catalytic self-growth strategy will provide a route to design and fabricate layered hydrogel materials.

Recovery of phosphorus from chemical-enhanced phosphorus removal sludge: Influence of sodium sulfide dosage on phosphorus fractionation, sludge dewaterability, and struvite product

Despite the potential of sodium sulfide (Na2S) for phosphorus (P) recovery from iron-phosphate waste, the underlying mechanism regarding its impact on P conversion and product quality has not been well addressed. In this study, the effects of Na2S addition on P release and recovery from a chemical-enhanced phosphorus removal (CEPR) sludge during anaerobic fermentation were systematically investigated. The results revealed that the effective mobilization of P bound to Fe (Fe–P) by Na2S dominated the massive P release from the CEPR sludge, while the organic P (OP) release was not significantly enhanced during anaerobic fermentation. Due to the rapid reaction of Na2S with Fe–P and the prevention of Fe(II)–P precipitation by excess S2−, the Fe–P was decreased by 9.7%, 15.2% and 24.9% at S:Fe molar ratios of 0.3, 0.5 and 1, respectively. After anaerobic fermentation, the released P mainly existed as soluble phosphate (SP), P bound to Ca (Ca–P) and P bound to Al (Al–P). The nitrogen and P contents in the fermentation supernatant significantly increased with higher S:Fe ratios, facilitating the efficient recovery of P as high-purity struvite. However, the increased Na2S dosage deteriorated the sludge dewaterability because of the dissolution of hydrophilic extracellular polymeric substances and the looser secondary structure of proteins. Comprehensively considering the P recovery, sludge dewaterability and economic cost, the optimal Na2S dosage was determined at the S:Fe ratio of 0.3. These findings provide novel insights into the role of Na2S in P recovery as struvite from CEPR sludge.

Integrated Struvite Precipitation and Fenton Oxidation for Nutrient Recovery and Refractory Organic Removal in Palm Oil Mill Effluent

Anaerobically treated palm oil mill effluent (AnT-POME), containing a high concentration of ammoniacal-nitrogen (NH4+-N) and soluble chemical oxygen demand (sCOD) was subjected to sequential processes of struvite precipitation to recover NH4+-N and Fenton oxidation for sCOD removal. The optimization of treatment was conducted through response surface methodology (RSM). Under optimized struvite precipitation conditions (Mg2+/NH4+, PO43−/NH4+ molar ratios: 1; pH 8.2 ± 0.1), NH4+-N concentration decreased to 41 ± 7.1 mg L−1 from an initial 298 ± 41 mg L−1 (78.8 ± 1.6 % removal). Field emission scanning electron microscopy (FESEM) coupled with energy-dispersive X-ray spectroscopy (EDX) confirmed NH4+-N was recovered as struvite. Subsequent Fenton oxidation under the optimized conditions (H2O2 dosage: 2680 mg L−1; molar ratio of Fe2+/H2O2: 0.8; reaction time: 56 min) reduced sCOD concentration to 308 ± 46 mg L−1 from an initial 1350 ± 336 mg L−1 (76.0 ± 1.0 % removal). The transparent appearance of treated AnT-POME validated the removal of sCOD responsible for the initial brownish appearance. Models derived from RSM demonstrated significance, with high coefficients of determination (R2 = 0.99). Overall, integrated struvite precipitation and Fenton oxidation effectively removed NH4+-N and sCOD from AnT-POME, contributing to nutrient recovery and environmental sustainability.

Structural Evolution of Mn-Substituted FeOOH and Its Adsorption Mechanism for U(VI): Effect of the Mole Ratio of Mn/(Fe + Mn)

Mn-substituted FeOOH with different Mn/(Mn + Fe) molar ratios are synthesized, and characterized using FESEM, XRD, FTIR, ICP-OES, BET, Zeta potential, TG-DSC, XPS, and VSM. The results show that the actual doping amounts of Mn are 0%, 3.05%, 6.13%, 9.04%, 12.70%, and 15.14%, respectively. The substitution of Mn promotes the transformation of goethite from FeOOH to MnFe2O4, resulting in a saturation magnetization intensity of up to 14.90 emu/g for G-Mn15%, laying a theoretical foundation for magnetic recovery. The specific surface area of Mn-substituted FeOOH increases from 57.15 m2/g to 315.26 m2/g with an increasing Mn substitution amount. Combined with the abundant oxygen-containing functional groups such as -OH, Fe-O, and Mn-O on the surface, sufficient active sites are provided for the efficient adsorption of U(VI). The TG-DSC analysis results indicate that the substitution of Mn improves the thermal stability of goethite. In addition, XPS analysis results indicate that the substitution of Mn leads to the conversion of Fe3+ to Fe2+ in goethite, and the conversion of Mn2+ to Mn3+ replaces Fe3+ in the structure of goethite. Fe-O and Mn-O coordinate participate in the adsorption and reduction process of U(VI). The batch experiment results show that the substitution of Mn promotes the adsorption performance of goethite for U(VI). When T = 303 K, pH = 4.0, m/V = 0.5 g/L, and I = 0.01 mol/L NaCl, the maximum adsorption capacity of G-Mn15% for U(VI) is 79.24 mg/g, indicating the potential value of Mn substitution for goethite in the treatment of uranium-containing wastewater.

Effects of blending ratios variation on micronutrient compositions and phytate/minerals molar ratios of dabi teff-field pea based novel composite complementary flours

Mixtures of multiple grains at varied ratios can provide multiple and higher micronutrients than a single grain. Thus, this research was aimed at examining the effect of blending ratios variation on micro-compositions and phytate/minerals molar ratios of pre-processed local dabi teff-field pea based novel composite complementary flours. Inductively Coupled Plasma-Optical Emission Spectrometry was used to determine dietary minerals. Nutrisurvey software was employed to define ranges of the mixture components and they were constrained at 20–35% for dabi teff, 0–30% field pea and 5–20% maize, while the remaining were set constant at 25% barley, 15% oats and 5% linseed. Design-Expert ® software version 11, D-optimal was used to generate eleven experimental blends and to examine the effects of blending ratio variation on the responses. Mean mineral contents were significantly different (P < 0.05) among the blends (as affected by component ratios variation) and ranged from 24.01–31.58 mg/100 g for iron, 73.46 -78.81 mg/100 g for calcium, and 2.33–2.61 mg/100 g for zinc contents. The phytate/minerals molar ratios were significantly different among the blends except phytate/calcium molar ratio (Ph:Ca), ranged from 0.232–0.344 for phytate/iron molar ratio (Ph:Fe), 0.067–0.085 for (Ph:Ca), 3.356–4.18 for phytate/zinc molar ratio (Ph:Zn) and 6.457–7.943 for phytate by calcium to zinc molar ratio (Ph*Ca:Zn). A linear model was significant (P < 0.05) and adequate to describe variations in iron, zinc, Ph:Fe, Ph:Zn and Ph*Ca:Zn. There was a remarkably linear increase in iron and calcium contents with an increased dabi teff ratio in the blends accompanied by a significant decrease (P < 0.05) in phytate/minerals molar ratios. The findings showed that increasing dabi teff ratio in the blends notably increased iron content with reduced Ph:Fe molar ratio, providing the bases for developing iron-dense novel composite complementary flour with improved iron bioavailability to combat iron deficiency anemia among children.Graphical

Outstanding performance of magnetic La2O2CO3/Fe3O4 nanosheets for simultaneous removal of phosphate and arsenate from wastewater

The chemical similarities and co-occurrence of phosphate and arsenate contamination have heightened the focus on their efficient simultaneous removal. In this study, magnetically recoverable La2O2CO3/Fe3O4 nanosheets were synthesized through the calcination of La-Fe binary metal glycolate. Based on magnetic and adsorption properties, La2O2CO3/Fe3O4 nanosheets with a La to Fe molar ratio of 1:1 (La2O2CO3/Fe3O4-1) were selected for further exploration. Electron microscopy characterization revealed that the nanocomposites consist of stacked La2O2CO3 and Fe3O4 nanosheets. The La2O2CO3/Fe3O4-1 nanocomposites exhibited exceptional adsorption capacities of 114.6 mg P/g and 230.2 mg As/g. Additionally, the material exhibited rapid adsorption kinetics and maintained excellent adsorption performance within a pH range of 3.0 to 9.0, showing significant selectivity for phosphate and arsenate even in the presence of various coexisting ions. Adsorption-desorption cycling tests indicated good potential for recycling. When applied to the spring water of Yangzonghai Lake, the material efficiently reduced the concentrations of phosphate and arsenate from 0.725 mg P/L and 1.380 mg As/L to below 0.020 mg P/L and 0.010 mg As/L, respectively. Mechanistic studies suggest that La2O2CO3 facilitates the removal of phosphate and arsenate primarily through electrostatic attraction and ligand exchange. These findings indicate that La2O2CO3/Fe3O4 holds significant promise for the co-removal of phosphate and arsenate, even at low concentrations.

Atmosphere matters: The protection of wet ball milling instead of dry ball milling accelerates the electron transfer effect of sulfurized micron iron/biochar to Cr (VI)

Obstacles such as aggregation and low activity of micron zero-valent iron in pollutant treatment could be overcome by sulfidation and biochar support. Ball milling is a promising method for the preparation of iron-based composites but the milling atmosphere is critical. To maximize the reactivity and identify the effects of ball mill atmosphere, ball milling technology under wet and dry atmosphere was applied to prepare composites from mZVI, Na2S2O4, and pine wood biochar (BC) for Cr(VI) removal. The results showed that S-mZVI/BC-wet was highly dispersible with more FeS2 coverage and thus more efficient on Cr (VI) removal than S-mZVI/BC-dry (99.9 % removal in 80 min vs. 87.9 % removal in 24 h) at the optimum Fe: C mass ratio (1:1), S: Fe molar ratio (1:10), and reaction conditions. Cr(VI) was adsorbed by a spontaneous, endothermic mechanism that combined physisorption and chemisorption. The reduction process was vulcanization efficiency and iron cycle dependent. Reduction outperformed adsorption on the Cr(VI) removal and high reduction rateswere electron-selectively related (59.15 % for S-mZVI/BC-wet and 46.72 % for S-mZVI/BC-dry), implying S-mZVI/BC-wet was more capable. S-mZVI/BC-wet presented excellent anti-ageing property and slightly inferior regeneration performance. In conclusion, the composite prepared by wet ball milling have excellent performance in rapid and complete removal of Cr(VI), and S-mZVI/BC-wet has superior potential in acidic wastewater treatment.

Effect of preparation of iron-based oxygen carriers on its agglomeration behavior with application to biomass chemical looping gasification

Iron-based oxygen carrier (OC) plays a crucial role in biomass chemical looping gasification (BCLG) to produce high quality syngas. However, a significant challenge during BCLG is the OC deactivation due to agglomeration, which is an urgent problem to be solved. In this study, the agglomeration behavior of iron-based OC preparation during the application for BCLG was obtained under the investigation of different preparation methods, carriers and ratios of active metal to carrier. The results revealed that preparation method affected the dispersion, crystal structure and stability of OC, thereby affecting the agglomeration. Among four preparation methods, the OC prepared by co-precipitation method achieved a 58.57 % lower agglomeration degree and 38.38 % smaller particle size than that of mechanical mixing method. Moreover, the carrier played a role in structural support and lattice oxygen transport, affecting crystalline structure and the agglomeration. Among four carriers, the OC prepared with Al2O3 carrier exhibited 36.18 % lower agglomeration degree and 25.15 % smaller particle size than that of CeO2 carrier. In addition, higher Fe content would weaken the metal-carrier interaction and reduce the structural stability of OC, causing serious agglomeration. With the decrease of Al:Fe molar ratio, the average particle size and agglomeration degree of spent OC increased by 43.56 % and 78.26 %, respectively. With the increase of cycles, the average particle size and agglomeration degree of spent OC increased gradually, while the reaction performance decreased obviously.

Influence of different Ni:Fe molar ratios on the properties of NiFe-LDH as electrode materials for supercapacitor applications

Layered double hydroxides (LDH) are being explored as a promising electrode material for supercapacitors due to their cost-effectiveness, high reactivity, and environmental friendliness. Nowadays, considerable efforts about LDH as electrode material have focus on the composition of different bimetals or trimetals, and few studies on the impact of the different bimetal ratio. In this study, NiFe-LDH materials with different proportions were synthesized by one-step hydrothermal method. The results show that the content of Ni and Fe in NiFe-LDH has a certain effect on the electrochemical performance of the electrode. In particular, the Ni5Fe1-LDH electrode exhibits outstanding performance in terms of both specific capacity and energy density, even than some composite materials based on NiFe-LDH. Specifically, the Ni5Fe1-LDH electrode demonstrates a specific capacity of 139.83 mAh g−1at 0.5 A g−1, maintaining a cycle efficiency of 66.36 % after 3000 cycles. Furthermore, the Ni5Fe1-LDH//AC demonstrates a high energy density of 35.85 Wh kg−1 at a power density of 800 W kg−1.

Hydrolysis Products of Fe(III)‐Si Systems With Different Si/(Si + Fe) Molar Ratios: Implications to Detection of Ferrihydrite on Mars

AbstractFerrihydrite, a nanocrystalline iron (oxyhydr)oxide mineral, is widely distributed in soils and sediments on Earth and is probably an important component and/or precursor of widespread nanophase iron minerals on Mars. Terrestrial ferrihydrite often co‐occurs with amorphous silica and/or contains a certain amount of Si in its structure. However, it remains ambiguous how environmental Si concentration affects the formation‐evolution and structure‐spectral features of ferrihydrite in the Fe(III)‐Si systems. To this end, hydrolysis experiments were carried out for Fe‐Si systems at an unprecedentedly wide range of initial Si/(Fe + Si) molar ratios (0–0.80), followed by characterizing the products detailly. X‐ray diffraction, Fourier transform infrared (FTIR) spectroscopy, Raman spectroscopy, Mössbauer spectroscopy, and transmission electron microscopy results showed that at Si/(Fe + Si) molar ratios ≤0.30, the main phase of the products was ferrihydrite, of which the unit cells enlarged, the crystallinity decreased, and the existing state of Fe changed with increased Si contents; at Si/(Fe + Si) molar ratios ≥0.40, ferrihydrite was no longer formed and a novel amorphous Fe‐O‐Si phase was instead obtained, with the excess Si forming amorphous silica. The visible and near‐infrared spectroscopy, the most powerful tool to detect hydrous minerals on the surface of Mars at global or regional scales, showed weakness in identifying ferrihydrite‐like materials obtained in the Fe‐Si systems. Raman spectroscopy can identify ferrihydrite and Si‐containing ferrihydrite but cannot differentiate between them. Mössbauer spectroscopy showed great potential in both identifying and differentiating between ferrihydrite and Si‐containing ferrihydrite, and thus can be used to characterize the poorly ordered iron (oxyhydr)oxides on Mars.

Nickel-Iron-Modified 2D Metal-Organic Framework as a Tunable Precatalyst for Electrochemical Water Oxidation.

Mixed-metal metal-organic framework (MOF)-based water oxidation precatalysts have aroused a great deal of attention due to their remarkable catalytic performance. Yet, despite significant advancement in this field, there is still a need to design new MOF platforms that allow simple and systematic control over the final catalyst's metal composition. Here, we show that a Zr-BTB 2D-MOF could be used to construct a series of Ni-Fe-based oxide hydroxide water oxidation precatalysts with diverse Ni-Fe compositions. In situ Raman spectroscopy characterization revealed that the MOF precatalysts could be electrochemically converted to the active catalysts (NiFeOOH). In turn, it was found that the highest water oxidation activity was obtained with a catalyst containing a 47:53 Ni:Fe molar ratio. Additionally, the obtained catalyst is also active toward electrochemical methanol oxidation, exhibiting high selectivity toward the formation of formic acid. Hence, these results could pave the way for the development of efficient electrocatalytic materials for a variety of oxidative reactions.

Preparation of Nickel-Based Bimetallic Catalyst and Its Activation of Persulfate for Degradation of Methyl Orange

In this research, a new catalyst for activating persulfate was developed by loading iron and nickel ions onto powdered activated carbon (PAC) for treating methyl orange, and the preparation process was optimized and characterized. The efficacy of the treatment was evaluated using the Chemical Oxygen Demand (COD) removal rate, which reflects the impact of various process parameters, including catalyst dosage, sodium persulfate dosage, and reaction pH. Finally, the recovery and reuse performance of the catalyst were studied. The optimal conditions for preparing the activated sodium persulfate catalyst were determined to be as follows: a molar ratio of Fe3+ and Fe2+ to Ni of 4:1, a mass ratio of Fe3O4 to PAC of 1:4, a calcination temperature of 700 °C, and a calcination time of 4 h. This preparation led to an increase in surface porosity and the formation of a hollow structure within the catalyst. The active material on the surface was identified as nickel ferrite, comprising the elements C, O, Fe, and Ni. The magnetic property is beneficial to recycling. With the increase in catalyst and sodium persulfate dosage, the COD removal efficiency of the oxidation system increased first, and then, decreased. The catalyst showed good catalytic performance when the pH value was in the range of 3~11. Furthermore, Gas Chromatography–Mass Spectrometry (GC-MS) analysis indicated the complete oxidation of methyl orange dye molecules in the system. This result highlights the important role of the newly developed catalyst in activating persulfate.

Preparation of Y–TiO2@MIL-53(Fe) and performance study of photocatalytic degradation of tetracycline

Y–TiO2@MIL-53(Fe) photocatalyst composites were synthesized by a facile solvothermal method and their photocatalytic activity were assessed by photodegradation of tetracycline (TC) under visible light irradiation. Comprehensive material characterization, including XRD, XPS, BET, UV–Vis, SEM, and PL techniques, were employed to analyze the properties of the composites. Experimental results revealed that the removal rates of TC from a 20 mg/L TC solution using Y–TiO2, MIL-53(Fe), and Y–TiO2@MIL-53(Fe) were 61.0%, 75.1%, and 93.2% respectively, under specific conditions of 500 W UV-Hg lamp irradiation, a 30 min dark reaction, a 60 min light reaction, a Ti:Fe molar ratio of 1:1, and a catalyst concentration of 0.6 g/L. The Y–TiO2 component in Y–TiO2@MIL-53(Fe) primarily existed in the form of anatase, while Fe3+ ions entered the lattice gap or replaced Ti4+ ions at certain lattice positions, effectively inhibiting the recombination of photoelectrons and holes and broadening the light absorption band. This modification positively influenced the photocatalytic ability of the composites. Quenching experiments and ESR characterization confirmed that •O2−, •OH, and h+ were the active species involved in the photocatalytic process, with •O2− being the main active species. This investigation of the photocatalytic properties of the composites provides valuable insights into the photocatalytic reaction mechanism, supporting the application and further development of photocatalytic technology.

Bimetal-oxide (Fe/Co) modified bagasse-waste carbon coated on lead oxide-battery electrode for metronidazole removal

Current study covers the preparation and application of a commercial modified lead oxide battery electrode (LBE) in electrochemical oxidation (ECO) of metronidazole (MNZ) in an aqueous phase. Modified electrode is prepared by doping of bimetal-oxide (Fe and Zn) nanoparticles (NPs) & single metal-oxide (Fe/Zn) on bagasse-waste carbon (bwc) which is further coated on LBE. The modified LBE electrode surface was examined for metal-oxide NPs through X-ray diffraction analysis (XRD). Different electrodes are prepared by varying combinations of two metal-oxide based on molar ratio and tested for electrochemical characterization and MNZ removal test. Based on large oxygen evolution potential in a linear sweep volumetry (LSV) analysis and high MNZ removal rate, the best electrode has been represented as Fe1:Co2-bwc/LBE which contains Fe & Co molar ratio of 1:2. Moreover, equilibrium attained at faster rate in degradation process of MNZ, where pseudo first order kinetics of 2.29 × 10−2 min−1 was obtained under optimized condition of (MNZ:100 mg/L, pH:7, CD: 30 mA/cm2 and electrolyte: 0.05 M Na2SO4). Maximum MNZ removal, total organic carbon removal (TOC), mineralization current efficiency (MCE) & energy consumption (EC) of 98.7%, 85.3%, 62.2% & 96.143 kW h/kg-TOC removed are found in 180 min of treatment time for Fe1:Co2-bwc/LBE electrode. Accelerated service life test confirms that the stability of modified electrode is enhanced by 1.5 times compared to pristine LBE. Repeatability test confirms that modified LBE (Fe1:Co2-bwc/LBE) can be utilized up to 3 times.

Synthesis of ZnFe2O4 spinel nanoparticles at varying pH values and application in anode material for lithium-ion battery

Spinel materials have attracted increasing attention as anode materials for lithium-ion batteries (LIBs) owing to their unique structures. ZnFe2O4 spinel was synthesized by a co-precipitation method at different pH values — pH 11, pH 12, and pH 13 — followed by annealing in air at 750 °C for 3 h. The pH of the medium significantly influences the properties of ZnFe2O4. At pH 11, ZnFe2O4 particles of sizes 25–70 nm were covered by amorphous layers with thicknesses of approximately 2 nm, whereas higher degrees of crystallinity and larger particle sizes were obtained at higher pH values (12 and 13). Additionally, at pH 12, the Zn:Fe molar ratio in the prepared sample was 1:1.3, which deviated significantly from the nominal formula (1:2). Possibly, owing to the presence of amorphous layers that allow an isotropic volume change during the lithiation/delithiation steps, ZnFe2O4 prepared at pH 11 exhibited the best performance when employed as an anode material in LIBs. Namely, its reversible specific capacity at the 1st and the 160th cycles at 0.1 A g−1 were 0.69 Ah g−1 and 0.72 Ah g−1, respectively. Although ZnFe2O4 prepared at pH 12 gave an initial reversible specific capacity up to 0.89 Ah g−1, its capacity retention after 160 cycles was only 20%. Therefore, adjusting the pH of the coprecipitation step can improve the final lithium storage performance by controlling the degree of crystallinity, particle size, and chemical composition of the anode material ZnFe2O4.

Synthesis of Fe Atom-Doped Monodisperse Co2P Nanorods with a Dual-Ligand Strategy for Excellent Electrocatalytic Hydrogen Evolution Performance.

Cobalt phosphide has been widely used in various catalytic reactions due to its excellent catalytic activity and stability. In contrast to the conventional synthesis of Co2P nanorods using expensive and toxic trioctylphosphine (TOP), this study employs a dual-ligand strategy to prepare iron-atom-doped monodisperse Co2P nanorods. The strategy involves the use of triphenylphosphite (TPOP) as a cost-effective and relatively less toxic strong ligand, alongside hexadecylamine (HDA) as a weaker ligand. The resultant atom-doped Co2P nanorods exhibited a large aspect ratio, providing a plentiful supply of active sites for electrocatalytic hydrogen evolution. In both alkaline and acidic electrolytes, achieving a current density of 10 mA cm-2 required overpotentials of 91 and 141 mV, respectively, with the optimal Co:Fe molar ratio of 1:0.2. The introduction of Fe atoms through doping increased the electron density at the Co atom sites, thereby enhancing H adsorption. This research offers a cost-effective and relatively low-toxicity method for the controlled fabrication of monodisperse transition-metal phosphide nanorods, enabling efficient catalytic reactions.

Direct immobilization of Se(IV) from acidic Se(IV)-rich wastewater via ferric selenite Co-precipitation

The attenuation of acidic Se(IV)-rich wastewater, including those associated with acid mine drainage (AMD) and nonferrous metallurgical wastewater (NMW), presents a serious environmental challenge. This study investigates the effects of diverse factors from pH values to Se(IV)/Fe(III) molar ratios, initial Se(IV) concentrations, and alkali neutralization agents on the direct co-precipitation of ferric selenites in AMD and NMW systems involving different orders of Fe(III) and alkali addition. Our results show that amorphous sulfate-substituted ferric (hydrogen) selenite and Se(IV)-bearing ferrihydrite-schwertmannite are the major Se(IV)-attenuation solids except that gypsum is an additional phase in the NMW system with Ca(OH)2 neutralization. Produced ferric selenites achieve 98–99.8% of Se(IV) immobilization under optimal conditions of pH 4.5, Se(IV)/Fe(III) molar ratios of 0.0625–0.5, and initial Se(IV) concentrations of 0.15–1.3 mmol·L-1. Moreover, completing FeSO4+ and FeHSeO32+/FeSeO3+ complexes as well as different ferric selenite co-precipitates are shown to collectively control aqueous Se(IV) remaining. Specifically, three distinct trends of aqueous Se(IV) concentrations separately correspond to changes in the four factors. The co-precipitation in the NMW system via pH adjustment followed by Fe(III) addition is more efficient for Se(IV) fixation than that in the AMD system because of minimal complexation, concurrent Fe(III) hydrolysis, and enhanced ferric selenite co-precipitation in the former.