Pure Iron Oxide Research Articles

Facile Synthesis of Core-Shell Magnetic Iron Oxide@SiO2-NH2 Nanoparticles and Their Application in Rapid Boron Removal from Aqueous Solutions

In this study, amino-functionalized magnetic particles (iron oxide@SiO2-NH2) with core-shell structures were synthesized and evaluated for rapid boron removal from aqueous solutions. The results showed that the specific surface area of the iron oxide@SiO2-NH2 (131.24 m2⋅g−1) increased greatly compared to pure iron oxide (30.98 m2⋅g−1). The adsorption equilibrium was less than 2 h, with an adsorption capacity of 29.76 mg⋅g−1 at pH = 6 at 15 °C. The quasi-second-order kinetic model described the boron adsorption process well, and both the Langmuir and Freundlich models were suitable for characterizing the adsorption isotherms. The zeta potential and XPS analysis before and after adsorption revealed that the main adsorption mechanism was the hydrogen bonding formation between the terminal -NH2 groups of the adsorbent and the boric acid. In addition, the adsorbent still maintained a high adsorption performance after five adsorption–desorption cycles, which illustrated that the iron oxide@SiO2-NH2 may be a potential adsorbent for environmental boron removal treatment.

METHOD FOR OBTAINING NANOPARTICLES OF IRON-CONTAINING OXIDES AND STUDYING THEIR PROPERTIES

The synthesis of iron-containing oxide nanoparticles is of interest in medicine, electronics and ecology due to their unique physical and chemical properties, such as magnetic, catalytic and adsorption properties, which allow their use in various technological processes. In this regard, this article presents the results of obtaining nanoparticles of iron-containing oxides and studying their physical and chemical properties. It is known that stabilization with natural polymers is of great importance in the production of metal nanoparticles. Therefore, in this work, the synthesis is carried out at high temperature by stabilization with potassium humate. To study the properties of the resulting iron-containing nanoparticles, methods of X-ray phase analysis, transmission electron microscopy and infrared spectroscopy were used. As a result of physicochemical studies, the heterogeneity and monodispersity of the synthesized metal nanoparticles was established. The average particle size of the synthesized samples was 8.3 nm, the crystal lattice parameter was 0.8426 nm. The result of the study using IR spectroscopy confirms the assumption of oxidation of the samples. In addition, it was found that the prepared samples have a high degree of crystallization. Transmission electron microscopy revealed no differences in the sizes of nanoparticles. Pure iron oxide is not formed during the synthesis of iron nanoparticles using the method used in the research work. The unique properties of iron-containing oxide nanoparticles obtained as a result of research are promising for the creation of innovative technologies and solutions aimed at improving the quality of life and sustainable development of society.

Employing Atmospheric Pressure Plasma Jet Technology in Surface Treatment Iron Oxide Films for Industrial Applications

In this study, pure iron oxide nanostructures were prepared by a physical method (laser-induced plasma) inside a vacuum using a second harmonic laser Nd: YAG with a wavelength of 532 nm, a laser energy of 500 mJ and a number of pulses of 300 pulses per second. The effect of the plasma generated from argon gas under normal atmospheric pressure was studied using a "cold plasma jet" system with an output voltage of 13 kV and a frequency of 50 Hz. Iron oxide nanostructures were exposed to cold plasma for different periods. The optical and structural properties of the nanostructures were measured before and after exposure, and there was a clear change in them, thus improving the properties of the nanostructures for use in industrial applications such as gas sensors, photovoltaic cells, diodes, detectors, and solar cells.

Stable pharmaceutical composition of cryo-protected non-pyrogenic isotonic chains of magnetosomes for efficient tumor cell destruction at 45 ± 1 °C under alternating magnetic field or ultrasound application.

We report a method to prepare biocompatible, stable, and highly pure iron oxide nano-minerals by following the steps consisting of: (i) amplifying magnetotactic bacteria in non-toxic minimal growth media; (ii) extracting magnetosomes from magnetotactic bacteria under alkaline lysis; (iii) heating magnetosomes above 400 °C to yield sterile magnetosome minerals, M-uncoated, devoid of active non-denatured bacterial organic material; (iv) coating M-uncoated with biocompatible carboxymethyl-dextran (CMD) compounds to yield stable M-CMD; (v) adding 5% sorbitol to M-CMD; and (vi) lyophilizing these mixtures, resulting in formulated nano-minerals in powder forms, designated as (M-CMD)F. The long-term stability of the final products is demonstrated by re-suspending (M-CMD)F in water after 12 months of storage, and by showing that these formulated magnetosomes have preserved their stability in suspension, chain arrangement, carbon content, surface charge, and surface composition. Furthermore, the formulation is optimized to yield an isotonic magnetosome suspension with an osmolality of between 275 and 290 mOsm kg-1 H2O upon reconstitution. On one hand, these formulated magnetosomes are fully biocompatible, i.e. sterile, non-pyrogenic, and non-cytotoxic towards 3T3, L929, and V79 healthy cells up to 1 mg mL-1 NP concentration iron. On the other hand, when they are brought into the presence of PC3-Luc prostate tumor cells and heated moderately at ∼41-46 °C for 20-30 minutes under low-intensity ultrasound or alternating magnetic field conditions, they efficiently destroy these tumor cells.

The structure of molten calcium ferrite under various redox conditions.

Laser-heated melts based on the 43CaO-57Fe2O3-x eutectic, close to the calcium ferrite (CF) composition, were measured with high-energy X-ray diffraction using aerodynamic levitation over a range of redox states controlled by CO/CO2 gas atmospheres. The iron-oxygen coordination number was found to rise from 4.4 ± 0.3 at 15% Fe3+ to 5.3 ± 0.3 at 87% Fe3+. Empirical potential structure refinement modelling was used to obtain the ferric and ferrous partial pair distribution functions. It was found that the Fe2+ iron-oxygen coordination number is consistently approximately 10% higher in CF than in pure iron oxide, while Fe3+ is essentially identical in all but the most oxygen-rich environments (where it is higher in CF compared with FeOx). The model also shows calcium octahedra to be the dominant species across all redox environments, although the population of CaO7 increases with the availability of oxygen at the expense of CaO4 and CaO5. This article is part of the theme issue 'Exploring the length scales, timescales and chemistry of challenging materials (Part 1)'.

Analysis and characterization of opto-electronic properties of iron oxide (Fe2O3) with transition metals (Co, Ni) for the use in the photodetector application

There are several uses for ultraviolet photodetectors, including in the scientific, military, and industrial sectors. In this sense, UV photodetectors must have high responsiveness, be insensitive to visible light, and be inexpensive to produce. For this purpose, we report the development of Co and Ni based iron oxide nanoparticles via the cost effective low temperature sol–gel auto-combustion process. XRD study approves the cubic crystal structure of iron oxide (Fe2O3) with predominant orientation along (311) direction. A sharp and strong peak is obtained at 583 cm−1 and 594 cm−1 for both samples in FT-IR spectra assigned to metal oxide Fe–O network system which approves the formation of iron oxide. Raman spectroscopy analysis reveals the presence of two A1g and five Eg phonon modes in the case of both samples. Absorption study exhibits the strong absorption peaks for the iron oxide sample doped with cobalt and nickel, while poor absorption was noticed from the pure iron oxide nanoparticles. The large and low energy band gap values are found to be 2.77 eV and 1.68 eV for pure Fe2O3 and cobalt and nickel doped Fe2O3 nanoparticles, respectively. Stone and cloud-like shape morphology was observed from SEM analysis. The EDX spectra reveal the presence of essential elements, like Fe and O in the case of pure iron oxide while Fe, O, Co and Ni in the case of transition metals doped iron oxide nanoparticles. The photoluminescence (PL) spectroscopy technique was recorded the luminescent properties which reveals the decrease in PL intensity that confirms the decline in electron–hole recombination. Therefore, I–V characterization analysis reveals that electrical conductivity increases with the addition of metals due to decrease in electron–hole recombination with the co-doping of metals. These modified opto-electronic properties of the developed Fe2O3 by metals co-doping make it suitable candidate for the use in photodetector application.

Structural and surface functionalized L-tyrosine Iron Oxide (L-tyr-Fe) nanoparticles for antimicrobial impacts

Bacterial resistance results from changes in the ability of microorganisms to withstand antibacterial medicines, which can either render them inactive or reduce their therapeutic efficiency. This results in prolonged infection periods, elevated mortality rates and increased financial strain on healthcare systems. However, iron oxide nanoparticles (Fe NPs) have been explored as a potential candidate to improve the therapeutic and physicochemical activities among the studied metal-oxides due to their exceptional structural, optical, surface and magnetic impacts. The major goal of this research was to design the surface of Fe NPs by co-precipitating them with L-tyrosine (L-tyr-Fe NPs), improving their antimicrobial activity. UV–Vis spectrophotometry showed a characteristic optical absorption at 391 nm for the L-tyr-Fe NPs and 262 nm for pure iron oxide. The surface functionalized L-tyrosine (L-tyr-Fe NPs) was investigated by its vibrational frequencies using Fourier Transform Infrared (FTIR) spectrophotometry. The crystal phase and sizes of the L-tyr-Fe NPs were estimated using X-ray diffractometry (XRD), which revealed crystalline cubic diameters of 33.50 and 12.87 nm for the Fe NPs and L-tyr-Fe NPs, respectively. The particle size of the L-tyr-Fe NPs was 11.8 nm, confirmed by high-resolution transmission electron microscopy (HR-TEM). A DLS study revealed the monodispersed nature of the L-tyr-Fe NPs (polydispersity index, 0.314). The stable nature of the L-tyr-Fe Nps was checked by zeta potential measurements (zeta value −20.14 mV). The bioassay of L-tyr-Fe Nps showed comparable or better results against Escherichia coli and Bacillus subtilis as compared with common antibiotics. The L-tyr-Fe Nps at 150μg/mL showed an effective zone of inhibition of 15 ± 0.00 mm against Bacillus subtilis, which was comparable to streptomycin (16 ± 0.0 mm at 150μg/mL), amoxicillin (16 ± 0.0 mm at 150μg/mL) and chloramphenicol (16 ± 0.0 mm at 100μg/mL) and better than ampicillin (11 ± 0.0 mm at 150μg/mL) for Bacillus subtilis An inhibition zone of 22.66 ± 0.03 mm at 200 μg/mL was observed against Escherichia coli, which was better than streptomycin (17 ± 0.0 mm at 100μg/mL), ampicillin (18.5 ± 0.0 mm at 150μg/mL) and chloramphenicol (17 ± 0.0 mm at 150μg/mL). These discoveries could eventually be exploited to develop novel therapeutic approaches that may use nano-bio conjugates. Such amino acid-coated iron oxide materials are appreciated in the field of medical sciences and technologies. The surface modified iron oxides (Fe3O4) NPs formed using eco-friendly and cost-effective method were found to be potent biomaterials that can be used as antimicrobial agents for Gram-positive and Gram-negative bacteria with multiple antibiotic resistances.

Spouted fluidised bed reactor for kinetic measurements of the reduction of Fe2O3 in a CO/ CO2 atmosphere part II: An extended random pore model for solid-state diffusion

A generalised random pore model, including both gaseous diffusion and solid-state diffusion in the product layer was developed, and was successfully applied to the reduction of hematite to magnetite by CO. The initial surface rate constant, ks,0′ and effective diffusivity, DS in the original model were formulated to describe the surface reaction and solid-state diffusion in the product layer. This approach is also particularly useful to determine the solid-state diffusivity during the reduction of a metal oxide, which is difficult to obtain via direct measurement. As an extension of previous work, the generalised random pore model was satisfactorily applied to the kinetic data obtained from a spouted fluidised bed reactor for the reduction of pure iron oxide with CO. Kinetic and diffusion constants, ks,0′ and Ds, were derived by fitting the model to the kinetics data for temperatures up to 650 °C. The activation energy for ks,0′ and Ds were calculated to be 35 kJ mol-1 and 100 kJ mol-1. The overall reaction kinetics were likely to be control by both surface reaction and the product layer diffusion of iron ions, Fen+. The fitted random pore model was fed into a two-phase fluidised bed model to test against experimental measurements from the spouted fluidised bed reactor. The model outlet concentration was shown to agree closely with that observed in the experiment. This validated the key assumption required for intrinsic kinetic measurements using the fluidised bed reactor, and also give credence to the applicability of the random pore model to reactions limited by solid state diffusion.

Role of Fe/Co Ratio in Dual Phase Ce0.8Gd0.2O2-δ-Fe3-xCoxO4 Composites for Oxygen Separation.

Dual-phase membranes are increasingly attracting attention as a solution for developing stable oxygen permeation membranes. Ce0.8Gd0.2O2-δ-Fe3-xCoxO4 (CGO-F(3-x)CxO) composites are one group of promising candidates. This study aims to understand the effect of the Fe/Co-ratio, i.e., x = 0, 1, 2, and 3 in Fe3-xCoxO4, on microstructure evolution and performance of the composite. The samples were prepared using the solid-state reactive sintering method (SSRS) to induce phase interactions, which determines the final composite microstructure. The Fe/Co ratio in the spinel structure was found to be a crucial factor in determining phase evolution, microstructure, and permeation of the material. Microstructure analysis showed that all iron-free composites had a dual-phase structure after sintering. In contrast, iron-containing composites formed additional phases with a spinel or garnet structure which likely contributed to electronic conductivity. The presence of both cations resulted in better performance than that of pure iron or cobalt oxides. This demonstrated that both types of cations were necessary to form a composite structure, which then allowed sufficient percolation of robust electronic and ionic conducting pathways. The maximum oxygen flux is jO2 = 0.16 and 0.11 mL/cm2·s at 1000 °C and 850 °C, respectively, of the 85CGO-FC2O composite, which is comparable oxygen permeation flux reported previously.

Mn- and Fe-spinels' formation through sintering of pure and waste materials: Mechanical, electrical and magnetic properties

This study focuses on fabrication of some spinel composites from pure and waste materials for electronic and magnetic applications. Six batches were designed from pure MgO, ZnO, Fe2O3, MnO2 and iron oxide extracted from alum sludge. The designed batches were sintered at 1250 and 1350 °C then investigated for their phase composition, microstructure, physical, mechanical, electrical and magnetic properties. The results indicated that, after sintering at 1350 °C, all batches formed spinel structures as main phases. The formed spinel structures were MgFe2O4, MgMn2O4, ZnMn2O4 and ZnFe2O4, in addition to some minor pervoskite structures. The batch that prepared from pure manganese and zinc oxides (B4), formed ZnMn2O4 spinel and exhibited the best densification parameters (bulk density; 4.7 g/cm3 and apparent porosity; 10%) as well as highest hardness (4.53 GPa). On the other hand, the specimen that fabricated from pure MgO, MnO2 and Fe2O3 (B2) formed MgFe2O4 and MgMn2O4 spinel structures and exhibited the highest electrical resistivity (1.3E + 09 Ohm.cm) as well as highest saturation magnetization (Ms = 24.948 emu/g).

Morphological and structural differences of Fe-Zn-Al oxide nanocomposites obtained from citrate decomposition and microemulsion method

Ternary Fe-Zn-Al oxide nanostructured material was either co-precipitated in water-in-oil microemulsion or prepared by citrate method. After calcination, the structural features of both samples were studied by XRD, N2 physisorption, SEM, TEM, TPR-H2 and their catalytic behavior in CO2 hydrogenation was determined. The sample obtained from the citrate method consists of Fe2O3 and a Fe-containing spinel phase. The mixed oxide synthesized by the microemulsion method consists of pure iron oxide in Fe3O4 inverse spinel structure epitaxially grown on a Fe-Zn-Al oxide parent structure. Compared to the sample obtained by the citrate method, the structural features of the composite from the microemulsion method are of potential interest for catalytic applications or for transfer to other multinary systems due to the presence of epitaxy.

The impact of nanometric Fe2O3 on the magnetic, electronic, and photocatalytic behavior of TiO2@Fe2O3 heterostructures

The synthesis method we used enables the homogeneous deposition of both relatively large and small Fe2O3 nanoparticles on the surface of TiO2. SAED analysis shows that TiO2 NCs crystallize in anatase form and Fe2O3 as hematite in all cases. The formation of a TiO2@Fe2O3 heterostructure leads to an increase in photocatalytic activity (in the presence of H2O2) compared to pure titanium and iron oxides. Mössbauer spectra confirm the existence of the hematite structure of Fe2O3 and, together with XPS, the presence of Fe3+ only. Fe2O3 nanoparticles on the surface of TiO2 nanocrystals are in the paramagnetic/superparamagnetic state. Magnetization curves under ZFC and FC conditions also indicate the effect of the size of Fe2O3 particles on the magnetic properties of TiO2@Fe2O3 nanostructures. The magnetic properties of the TiO2@Fe2O3 heterostructure exhibit sensitivity to the size of nanometric Fe2O3 grains. The energies of optical transitions in nanometric Fe2O3 reveal the occurrence of a quantum-size effect. The heterostructures forms a complex structure; on the one hand, at the TiO2 acceptor level associated with the incorporation of Fe3+ into the structure of TiO2 anatase there is present on the other hand, the microstructure differentiation responsible for the occurrence of three optical transitions in Fe2O3.

Designing against phase and property heterogeneities in additively manufactured titanium alloys

Additive manufacturing (AM) creates digitally designed parts by successive addition of material. However, owing to intrinsic thermal cycling, metallic parts produced by AM almost inevitably suffer from spatially dependent heterogeneities in phases and mechanical properties, which may cause unpredictable service failures. Here, we demonstrate a synergistic alloy design approach to overcome this issue in titanium alloys manufactured by laser powder bed fusion. The key to our approach is in-situ alloying of Ti−6Al−4V (in weight per cent) with combined additions of pure titanium powders and iron oxide (Fe2O3) nanoparticles. This not only enables in-situ elimination of phase heterogeneity through diluting V concentration whilst introducing small amounts of Fe, but also compensates for the strength loss via oxygen solute strengthening. Our alloys achieve spatially uniform microstructures and mechanical properties which are superior to those of Ti−6Al−4V. This study may help to guide the design of other alloys, which not only overcomes the challenge inherent to the AM processes, but also takes advantage of the alloy design opportunities offered by AM.

Preparation of Hematite Nano Particles from Galvanizing Effluents for the Applications in Heavy Metal Removal

Due to climate change on earth, governments are pursuing the policy of gradually reducing Greenhouse Effects. For example, country like Germany has The demand for safe drinking water grows day by day together with the increasing world population. Meanwhile water resources become increasingly scarce, and quality of natural water decreases due to a combination of natural and anthropogenic factors. Industry and agriculture have become a premiere source of hazardous constituents, along with natural processes such as rock weathering and volcanic eruptions. The ability to remove hazardous components, particularly heavy metals from water depends on the selected technology and nature of pollutant. Water purification technologies, mostly involved with sorption and ion-exchange processes, often uses natural iron oxides as ion-exchangers for removal of harmful contaminants from water. These technologies are based on the unique cation-exchange behavior of iron oxides, thus making this sorbent limited to cation removal. Arsenic, copper and nickel are commonly found in water supplies and, therefore, are selected for this study to represent heavy metals in water systems. In this work, hematite nanomaterials were synthesized from the galvanizing effluent collected from the LTL Galvanizers at Makola, Sri Lanka. The industry generates approximately 50 m3 of galvanizing effluent per month and it composes both iron and zinc chlorides. To synthesize pure iron oxide materials, we used the effluents from none re-galvanized chemical baths, which does not contain any zinc chlorides. The synthesized materials were characterized using X-ray diffraction (XRD) and scanning electron microscopy (SEM). Sorption behaviors of As(III), Cu(II) and Ni(II) were examined batch-wise as a function of pH, temperature, contact time, adsorbent dosage and initial metal ion concentration. Residual concentrations of As(III), Cu(II) and Ni(II) in the solution were determined by the inductively coupled plasma mass spectroscopy (ICP-MS). The adsorption studies were performed by changing one of the conditions while keeping all others fixed. According to the results, maximum percent removals (%) for all metal ions tested were reached within a short period of 30 minutes. For a given parameter the maximum percent removal (%) of both Cu(II) and As(III) reached more than 95%, while the Ni(II) had percent removal between 35% and 65%.

Dimethyl Ether Oxidation over Copper Ferrite Catalysts

The depletion of fossil energy sources and the legislation regarding emission control demand the use of alternative fuels and rapid progression of aftertreatment technologies. The study of dimethyl ether (DME) catalytic oxidation is important in this respect, as DME is a promising clean fuel and at the same time a VOC pollutant present in the tail gases of industrial processes. In the present work, copper ferrite catalysts synthesized via the citrate complexation method have been evaluated in DME oxidation. N2-physisorption, XRD, H2-TPR, and XPS were employed for the characterization of the mixed oxide catalysts. The copper ferrite spinel phase was detected in all samples accompanied by a gradual decrease in the bulk CuO phase upon increase in iron content, with the latter never vanishing completely. The Fe0.67Cu0.33 catalyst exhibited the highest catalytic activity in DME oxidation, attaining approximately a 4-fold higher oxidation rate compared to the respective pure copper and iron oxides. The enhanced catalytic performance was attributed to the higher specific surface area of the catalyst and its enhanced redox properties. Highly dispersed copper species were developed owing to the formation of the spinel phase. DME-TPD/TPSR experiments showed that the surface lattice oxygen of the Fe0.67Cu0.33 catalyst can oxidize preadsorbed DME at a lower temperature than all other catalysts which is in agreement with the H2-TPR findings.

Anticancer and Antimicrobial Activity of PVA/Fe2O3/TiO2 Hybrid Nanocomposite

A new nano-hybrid material prepared by physical mixing of the components was used in biomedical applications where three samples of the prepared materials were used to determine the best composition as an antibacterial and anticancer agent in addition to its use as an antifungal agent. In the case of antimicrobials, two types of bacteria were used: Staphylococcus aureus and Escherichia coli and one type of fungus was used: Candida albicans. The area of inhibition was calculated after using the hybrid material of 2.5% titanium oxide with iron oxide, which gave better results than pure iron oxide and that mixed with 5% titanium dioxide.

Immobilization and recycling of contaminated marine sediments in cement-based materials incorporating iron-biochar composites

Sustainable stabilization/solidification (S/S) incorporating biochar for hazardous wastes has attracted increasing attention. In this study, contaminated marine sediments were remediated and recycled as useful materials via cement-based S/S process incorporating iron-biochar composites derived from incinerated sewage sludge ash (ISSA) and peanut shell. Results showed that incorporation of 20% iron-biochar composites notably increased the Cr immobilization (52.8% vs 92.1–99.7%), while attained similar As (70%) and Cu (95%) immobilization efficiencies compared to the control group (CK) prepared with plain cement as the binder based on the Toxicity Characteristic Leaching Procedure. S/S products with the addition of ISSA derived iron-biochar composite had a mechanical strength of 5.0 MPa, which was significantly higher than its counterparts derived from pure iron oxide or pristine biochar (< 4.5 MPa). Microstructural and spectroscopic characterizations and chemical leaching experiments demonstrated that reduction of Cr(VI) to Cr(III) followed by formation of Cr-Fe precipitates by zero valent iron in iron-biochar composites contributed to the enhanced immobilization efficacy of Cr(VI) compared to CK. Overall, these results demonstrated the potential of applying ISSA and peanut shell derived iron-biochar composites as additives in the cement-based S/S treatment for contaminated sediments.

Green synthesis of manganese-doped superparamagnetic iron oxide nanoparticles for the effective removal of Pb(ii) from aqueous solutions

Abstract In the current study, pure and manganese-doped superparamagnetic iron oxide nanoparticles (Mn-doped SPIONPs) were successfully prepared by a green approach using a fresh aqueous extract of Asparagus officinalis as a reducing and stabilizing agent. Magnetic behaviors of pure and Mn-doped SPIONPs were measured at room temperature against various field strengths by a vibrating sample magnetometer (VSM). The saturation magnetization was in the range of 5.39–2.07 emu. Absorption at 340 nm in the UV-visible spectrum confirmed the presence of iron oxide nanoparticles (IONPs). The presence of plant extract as a capping agent was confirmed by Fourier transform infrared (FTIR) spectroscopy. The crystalline nature of IONPs was confirmed by X-ray diffraction. A gradual increase in size was observed with increasing concentration of Mn. The synthesized materials were applied successfully as sorbent for the effective removal of lead ions (Pb(ii)). Experimental results of adsorption were also analyzed by Langmuir and Freundlich isotherm equations at different temperatures. The results suggested that sorption processes were spontaneous, and the synthesized SPIONPs displayed PbII removal capacity at higher loadings with q m of 21.3 and 29.56 mg·g−1 for undoped and 7% Mn-doped IOPNs, respectively, as compared to the commercial activated carbon.

The Structural and Optical Properties of Nanocrystalline Fe3O4 Thin Films Prepared by PLD

In this study, thin films of pure iron oxide (Fe3O4) were prepared using pulsedlaser deposition technique under vacuum (2×10-3 mbar) using Nd: YAG laser atdifferent laser energies (700, 800, 900, and 1000 mJ) on quartz slides at thesubstrate temperature of 200 °C with different thickness (170,190, 220, and 250nm). The prepared thin films were examined using different techniques. The Xray diffraction showed a polycrystalline structure of cubic Fe3O4 phase, enhancedits crystallinity, and increased the crystalline size when increasing the laser energyto 1000 mJ. The results revealed that high transparency samples decreased pulselaser energy. As the laser pulse power increases, the transparency decreases from91% to 61%, where optical properties deteriorate significantly. The bandgapvalues were detected to be 3.9 eV, 3.75 eV, 3.21 eV, and 3 eV when the laserenergies were increased with thickness (170– 250) nm. In addition, the extinctioncoefficient, dielectric constants, optical constants, and refractive constants werestudied

Elucidating the mechanisms determining the availability of phosphate by application of biochars from different parent materials.

The consortium of minerals and organic matter notably alters and affects minerals' surface characteristics and nutrients providence. Organic matter such as biochar can modify the availability status of macronutrients like phosphorus (P). Despite some investigation, the adsorption/desorption of P with pure iron (hydr)oxides and the probable mechanisms involved are still unknown. In the present study, the goethite/hematite or goethite-biochar/hematite-biochar complexes were prepared, and a batch experiment with different P concentrations, time spell, pH, and ionic strength is performed to evaluate the sorption characteristics of P. The results of our study suggest that the P adsorption on mineral surface decreased with the increasing pH. Furthermore, the coexistence of biochar and minerals significantly inhibits P adsorption on the minerals surface. The results of Languimner and Freundlich's equations signify that the biochar-minerals complexes have heterogeneous adsorption sites and the presence of biochar reduces P adsorption on minerals surface. Among four biochars including peanut straw biochar (PC (B1)), rice straw biochar (RC (B2)), canola straw biochar (CC (B3)), and soybean straw biochar (SC (B4)), PC was more effective than other biochars to inhibit P adsorption on minerals surfaces.