Fe Solution Research Articles

Efficient removal of fluoroquinolones antibiotics by using kaolin-tannic acid-Fe(III) composite adsorbents from water

In this work, a series of novel composite adsorbents (k-TAFe) was designed and fabricated through a one-step method, that is, the chelation crosslinking of tannic acid, kaolin particles and different contents of Fe(III). k-TAFe had a high efficiency in adsorption of various fluoroquinolones antibiotics (FQs) from water. The detailed performance of k-TAFe in FQs adsorption, including the influences of Fe(III) content, solution pH, inorganic and organic additives, adsorption time and FQs' concentration, has been investigated systematically using ofloxacin (OFL), one of popular FQs, as an example. The maximal OFL uptake of k-TAFe was 0.405mmol/g at an initial pH of 6.0. On the basis of the analysis of the x-ray photoelectron and fourier transform-infrared spectra before and after adsorption, the comparison in the apparent performance of k-TAFe in adsorption of seven FQs with similar structures and their two sub-structural analogs, and theoretical calculation, multiple adsorption mechanisms, including chelating effect, hydrogen bonding, electrostatic attraction, and π-π electron–donor–acceptor interactions, were involved and discussed in detail. Among them, chelating effect due to Fe(III) played a key role in OFL adsorption, and the addition of kaolin particles synergistically enhanced Fe(III) fixed on the composite adsorbents, increased the Fe(III) contents, and caused an improved OFL uptake of k-TAFe. Because of the evident advantages of environmental-friendliness, high adsorption performance and low cost, k-TAFe as an efficient adsorbent has notable application potentials in removal of FQs from water.

Superparamagnetic Poly(aniline-co-m-phenylenediamine)@Fe3O4 Nanocomposite as an Efficient Heterogeneous Catalyst for the Synthesis of 1H-pyrazolo[1,2-a]pyridazine-5,8-diones & 1H-pyrazolo[1,2-b]phthalazine-5, 10-diones Derivatives.

The use of polymer-based catalysts has increased because of their high potential application as an effective catalyst in organic reactions. They have benefits such as high efficiency and reactivity, simple separation, and safety compared to other heterogeneous catalysts. The objective of the current research is to prepare solid polymer-based catalysts, poly(aniline-co-m-phenylenediamine) (PAmPDA), and its superparamagnetic nanocomposite. Then, the catalytic activity of the resulting superparamagnetic nanocomposite was investigated in the synthesis of 1H-pyrazolo[1,2-b]phetalazine-5,10-diones and 1H-pyrazolo[1,2-a]pyridazine-5,8-dione derivatives. A series of some 1H-pyrazolo[1,2-b]phetalazine-5,10-diones and 1H-pyrazolo[1,2-a]pyridazine-5,8-dione derivatives was tested for its antibacterial properties against the Staphylococcus aureus and E. coli bacteria. PAmPDA copolymer was synthesized in a 1:2 molar ratio of Ani to mPDA via radical oxidative polymerization at room temperature. Superparamagnetic PAmPDA@Fe3O4nanocompo-site was synthesized from a mixture of Fe(II), Fe(III) solution, and PAmPDA copolymer via the in-situ co-precipitation technique. 1H-pyrazolo[1,2-b]phetalazine-5,10-diones were synthesized via one-pot three-component condensation reaction of Phthalhydrazide, aromatic aldehyde derivatives, and malono-nitrile in the presence of PAmPDA under solvent-free conditions at 80 °C. The synthesis of 1H-pyrazolo[1,2-a]pyridazine-5,8-dione derivatives was carried out via a one-pot three-component condensa-tion reaction of maleic hydrazide, aromatic aldehyde derivatives, and malononitrile in the presence of PAmPDA under reflux conditions at EtOH/H2O 1:1. The antibacterial activity of some derivatives was tested against Gram-positive and Gram-negative bacteria. First, superparamagnetic PAmPDA@Fe3O4 nanocomposite was synthesized and characterized successfully, and then the resulting nanocatalyst was used for the synthesis of pyrazolo[1,2-b]phthalazine and pyrazolo[1,2-a]pyridazine. We obtained the maximum yield of the desired 1H-pyrazolo[1,2-b]phthalazine-5,10 dione derivatives with 0.05 g of catalyst at 80°C, under solvent free conditions, whereby the reaction was complete within 30 min. A wide range of 1H-pyrazolo[1,2-b]phthalazine-5,10 dione derivatives were synthesized in good to excellent yield. On the other hand, pyrazolo[1,2-a]pyridazine derivative was synthesized successfully in high yield using PAmPDA as a nanocatalyst. The antibacterial activity of some derivatives, according to the data (inhibition zone%), showed good ac-tivity against Staphylococcus aureus and E. coli. In this research, PAmPDA was used for mild preparation of 1H-pyrazolo [1,2-a]pyridazine-5,8-diones & 1H-pyrazolo[1,2-b]phetalazine-5,10-diones derivatives with excellent yields and short reac-tion times. The attractive features of this protocol are simple procedure, cleaner reaction, and the use of recyclable nanocatalyst. Satisfactory yields of products and easy workup make this a useful protocol for the green synthesis of this class of compounds. The antibacterial activity of some derivatives, according to the data (inhibition zone%), showed good activity against Staphylococcus aureus and E. coli.

A cohesion-friction combined hardening plastic model of concrete with the nonorthogonal flow rule: Theory and numerical implementation

A cohesion-friction combined hardening model of concrete was developed. Combined with the Mohr-Coulomb strength criterion, the yield curve is determined directly by the test data of concrete. Then, a method to determine the hardening law from the evolutionary process of the yield curve is elaborated. To consider the influence of the multiaxial stress state on the ductility of concrete, a stress dependent plastic internal variable is proposed. Based on the nonorthogonal flow rule implemented by fractional order derivative, the direction of plastic strain increment is directly determined by the nonorthogonal gradient of the yield function without the need for plastic potential function. The comparison with the test data shows that the proposed model can capture the strength and deformation characteristics of concrete reasonably. Finally, the model is implemented into ABAQUS via an open-source user defined material subroutine UMAT (https://github.com/zhouxin615/CFCH_model.git) based on the implicit return mapping algorithm. In particular, the integral-type nonlocal approach was adopted to regularise FE solution. Moreover, through the structural analysis of reinforced concrete columns, the operation process of the friction and cohesion mechanism of concrete materials is well reproduced.

Stress-dependent nonlinear magnetoelectric effect in press-fit composites: A numerical and experimental study

Magnetoelectric (ME) composites have posed an immense research interest over the past few decades. Their multifunctional capabilities enable a wide array of applications like field and pressure sensors, energy harvesters, gyrators, etc. The voltage developed under applied magnetic fields in these composites is governed strongly by the stress and magnetization state of the magnetostrictive phase, which needs to be characterized effectively. Towards this end, magnetostriction measurements are carried out under applied stresses in Nickel to understand its magnetomechanical response. A three-dimensional magnetostrictive constitutive model is used to predict the magnetostrictive behavior, which is later implemented in COMSOL Multiphysics® using the external material module. The FE solutions obtained are validated against analytical solutions. The model is subsequently used to obtain FE solutions for the magnetoelectric response of press-fit composites subjected to general magneto-thermo-mechanical loading. Experiments are performed on the press-fit composite to validate the voltage response predicted by the developed model, which shows a good agreement. The developed FE model is used to conduct a parametric study to quantify the effect of external loading conditions, the shape of inclusion, and the field orientation with an effort to optimize the ME response in press-fit ME composites.

Analytical prediction of yield stress and strain hardening in a strain gradient plasticity material reinforced by small elastic particles

The influence on macroscopic work hardening of small, spherical, elastic particles dispersed within a matrix is studied using an isotropic strain gradient plasticity framework. An analytical solution for strain hardening, i.e. the flow stress as a function of plastic strain, based on a recently developed model for initial yield strength is proposed. The model accounts for random variations in particle size and elastic properties, and is numerically validated against FE solutions in 2D/3D unit cell models. Excellent agreement is found as long as the typical particle radius is much smaller than the material length scale, given that the particle volume fraction is not too large (<10%) and that the particle/matrix elastic mismatch is within a realistic range. Finally, the model is augmented to account for strengthening contribution from shearable particles using classic line tension models and successfully calibrated against experimental tensile data on an Al−2.8wt%Mg−0.16wt%Sc alloy.

Parametric study and speciation analysis of rare earth precipitation using oxalic acid in a chloride solution system

Oxalic acid precipitation is a common step in the purification of rare earth elements (REE) from a concentrated pregnant leach solution (PLS). However, the presence of contaminants such as Al, Fe, and Ca in given amounts decreases the REE precipitation efficiency and product purity while also increasing the amount of oxalic acid needed to maximize recovery. As such, a statistically designed test program was performed to identify the optimal conditions necessary for a relatively low REE content PLS containing elevated concentrations of contaminant ions. The performance objective was maximization of REE precipitation efficiency while minimizing the oxalic acid dosage. A central composite design was utilized to quantify performance impacts and identify the ultimate set of parameter values for oxalic acid dosage, Fe(III) contamination concentration, solution pH, and reaction temperature. The resultant model suggested that oxalic acid dosage and reaction pH are the most significant factors for the REE precipitation efficiency, followed by the interaction of oxalic dosage and Fe concentration. Test results indicate that increasing the oxalic acid concentration from 0 g/L to 80 g/L improved the REE precipitation efficiency from approximately 4.2% to 95.0%. Furthermore, raising the solution pH from 0.5 to 2.5 considerably enhanced the precipitation efficiency from 0.0% to 98.9%. A solution temperature elevation decreased REE recovery, which indicated an exothermic reaction between REEs and oxalate anions. Finally, a high level of Fe contamination adversely impacted REE precipitation efficiency. To further the understanding of the REE-oxalate system, a fundamental solution chemistry study was performed using the equilibrium constants of the reactions. The study resulted in the development of oxalate speciation diagrams and provided an analysis of the REE precipitation characteristics at various oxalate anion concentrations and Fe(III) contamination levels using MINTEQ software. The dominant Fe(III) species in the solution system were found to be Fe-(C2O4)33-, Fe-(C2O4)2-, and Fe-(C2O4)+, which consume the majority of the oxalate anions. The simulated model was found to be in agreement with the experimental findings and helped to explain the adverse impact of increased iron concentrations on REE precipitation efficiency.

Development of Membrane Filter for Water Treatment Using Anionic and Cationic Cellulose Nanofibers

This study examined the effect of cellulose nanofiber (CNF) type on the performance of ion absorbing membrane filters made of anionic and cationic CNFs. Four types of anionic and cationic CNFs were made by beating, micro-grinding, carboxymethylation and quaternization using hardwood bleached kraft pulp (Hw-BKP): refining-CNF (RE-CNF), carboxymethylated CNF (CM-CNF), surface-modified CNF with cationic poly-DADMAC (pD-CNF), and quaternized CNF (Q-CNF). The membrane filters were composed of two-layers: One layer was made of anionic CNF and poly-aminiamide-epi-chlorohydrin (PAE) and the other layer was made of cationic CNF. The membrane filter was produced by vacuum filtration and the use of two CNF slurries. In addition, the capacity to remove Fe and Cl ions from the water was analyzed by carrying out high-pressure filtration experiments with a 500 ppm concentration of the Fe and Cl standard solutions respectively, using the same methods as the previous study.BRFour types of CNFs were sufficiently fibrillated at the nano-level and had electrostatically intended zeta-potential. The CM-CNF, which had a strong negative zeta-potential, was effective in the adsorption of Fe ions, and the Q-CNF, which was strong in cationic property, was effective in the adsorption of Cl ions. Therefore, it was concluded that cationic Q-CNF and anionic CM-CNF could be effectively utilized for the manufacture of a membrane filter to remove metal and anionic ions from water simultaneously.

Spatial stability of pre-stressed mono-symmetric steel beams with un-bonded/bonded deviators under compression and end moments

This paper intends to propose a lateral-torsional buckling (LTB) theory of pre-stressed simple/cantilever steel beams with deviators subjected to compression and end moments in which their cross sections are mono-symmetric, initially tensions are introduced by rectilinear single/double tendons, and discrete un-bonded/bonded deviators are taken into account. Firstly, in-plane linear solutions of the PS system are presented under combined compression and moments. After that, analytically exact buckling solutions and approximate Ritz solutions are obtained based on the total potential energies derived. As a result, it is demonstrated that both exact and Ritz solutions by this study are very well matched with FE solutions by Abaqus. In addition, pre-tension effects on LTB behaviors of the PS beams are investigated with increase of the number of deviators.

Removal of Fe (II) ions from Aqueous solution using Rice-husk Adsorbents in fixed-bed column

Rice husk has been converted into activated carbon for the adsorbent to remove the heavy metal from the aqueous solution. This study aimed to convert rice husk to activated carbon (AC) for use in the adsorption of Fe ions in a fixed-bed column. Rice husk was first pyrolyzed in an atmosphere of nitrogen gas at 400 oC, then a chemical activation method using sodium hydroxide. The rice husk activated carbon (RH-AC) was characterized using Fourier transform infrared (FTIR) and Scanning electron microscope (SEM) to identify the functional group and microstructure of carbon. The performance of the carbon was tested on the Fe removal from an aqueous solution in a continuous column. The adsorption process was carried out using Fe solution with an initial concentration of 3 mg/L as an artificial sample. The amount of carbon is 25, and 50 g were filled in an adsorber column with a diameter of 5.4 cm and height of 40 cm. SEM images revealed that the activated carbons shown with well-developed pore sizes and pore structure were produced after the chemical activation. The FTIR absorption bands observed in the RH-AC sample confirmed the presence of hydroxyl (-OH), carbonyl, and carboxylic (-COOH) groups of RH-AC adsorbent. The highest Fe removal efficiencies were 91.9% on chemically activated carbon and column mass 50 g at 400 minutes. The overall study revealed the potential value of chemically activated RH-AC as a possible commercial adsorbent in a continuous column wastewater treatment strategy.

Reinvestigation of Ferrate(VI) Oxidation of Bisphenol A over a Wide pH Range

Ferrate (Fe(VI), K2FeO4) has attracted much attention in water treatment for its high redox potential, especially under acidic conditions. Although interests have been arising in the performance of Fe(VI) at pH below 7.0, a contradicting trend of second order reaction rates (kapp) was observed at acidic conditions, and the reactive species (i.e., high-valent iron species or hydroxyl radicals (HO•)) of Fe(VI) oxidation at acidic pH remains unclear. Thus, the kinetics of Fe(VI) oxidizing bisphenol A (BPA) under a wide pH range was reinvestigated. The kapp value of Fe(VI) with BPA strongly depends on pH, which increased from 7.31 × 101 to 2.44 × 103 M–1 s–1 with pH decreasing from 10.0 to 3.0. Moreover, high-valent iron species were identified as the reactive species, i.e., Fe(VI), Fe(V), and Fe(IV), in both alkaline and acidic solutions, while HO• was identified as the secondary reactive species at acidic conditions with negligible contribution. Theoretical calculation was used to predict the reactive sites, and similar degradation products of BPA were identified under both acidic and alkaline conditions, ascribed to the similar reactive species. Toxicity assessment based on the Toxicity Estimation Software Tool suggested that Fe(VI) can alleviate the bioaccumulation toxicity efficiently. Humic acid (0.2–2.0 mgC L–1) and ubiquitous anions (1.0 mM) showed no obvious adverse effect on Fe(VI) oxidation while 1.0 mM Fe3+ or Cu2+ could accelerate it, and Fe(VI) showed a promising performance for the abatement of BPA in real waters.

Enhanced degradation of 2,6-dimethylphenol by photocatalytic systems using TiO2 assisted with H2O2 and Fe(III)

ABSTRACT In this study, several photocatalytic degradation systems were investigated using 2,6-dimethylphenol (2,6-DMP) as a model compound. Highly reactive species are formed in four systems, Fe(III), TiO2, TiO2/H2O2 and TiO2/Fe(III) where complete degradation of 2,6-DMP was achieved under UV radiation. Photodegradation of the 2,6-DMP has been described by pseudo-first order kinetic model in the presence of TiO2. In UV/TiO2–H2O2 system, the addition of H2O2 in the TiO2 suspension improves the degradation rate of 2,6-DMP from 70% to 100% for a H2O2 concentration of 10− 2 M in 3 h. In homogeneous system, HO• and Fe2+ can be generated by the irradiation of Fe(III) solution. The speciation of Fe(III) obtained from Visual MINTEQ soft showed the formation of several species and Fe(OH)2+ were the most predominant and active species in a pH range of 2.5–3.5. At a low concentration of TiO2 (30 mg L−1), an important positive effect due to the iron addition has been shown in TiO2/Fe(III) system, the entrance of metallic ions at different concentrations enhanced the photocatalytic activity of TiO2. A degradation percentage of 90% was achieved in the UV/TiO2–Fe(III) system under optimal conditions against 57% in UV/TiO2 system. Strong synergistic effect was observed in the UV/TiO2–H2O2 binary system. On the basis of literature, a pathway for 2,6-DMP degradation was proposed. The mechanism of degradation of the 2,6-DMP did not involve only HO• radicals, an interaction of Fe(III) in the excited state with 2,6-DMP occurred giving rise to the formation of 2,6-dimethylphenoxyl radical.

Graphene oxide-mediated the reduction of U(VI), Re(VII), Se(VI) and Se(IV) by Fe(II) in aqueous solutions investigated via combined batch, DFT calculation and spectroscopic approaches

Although thermodynamically feasible, reduction of U(VI), Re(VII), Se(VI) and Se(IV) in homogeneous Fe(II) solution could be hardly observed. Whereas, surface-mediated reduction by Fe(II) has been generally regarded as a major pathway for the immobilization of these radionuclides. In this paper, graphene oxide (GO) was firstly revealed to mediate the reduction of U(VI), Re(VII), Se(VI) and Se(IV) by aqueous Fe(II) via a combined batch, DFT calculation and spectroscopic investigation. The kinetics for all adsorption systems could be fitted by the pseudo-second-order model, which was indicative of a chemical interaction. The isotherms for all reaction systems could be described by the Freundlich model better than that by the Langmuir model. Spectroscopic studies indicated that the enhancement effects of GO were attributable to the facilitated electron transfer by the graphitic surfaces and particularly to the decreased Fe(III)-Fe(II) redox potential by surface adsorption of Fe(II) with O-bearing functional groups on GO. Additionally, the presence of coexisting dissolved fulvic acid (FA) could significantly promoted GO-mediated reduction, by enhancing the electron shuttle ability of GO. Therefore, owning to the combined strong mediation efficiency and excellent adsorption affinity, GO exhibited an important role in mediating the reductive immobilization of radionuclides in a wide range of redox-stratified environments.

Iron-Nickel Alloy with Starfish-like Shape and Its Unique Magnetic Properties: Effect of Reaction Volume and Metal Concentration on the Synthesized Alloy.

Iron-nickel alloy is an example of bimetallic nanostructures magnetic alloy, which receives intensive and significant attention in recent years due to its desirable superior ferromagnetic and mechanical characteristics. In this work, a unique starfish-like shape of an iron-nickel alloy with unique magnetic properties was presented using a simple, effective, high purity, and low-cost chemical reduction. There is no report on the synthesis of such novel shape without complex precursors and/or surfactants that increase production costs and introduce impurities, so far. The synthesis of five magnetic iron-nickel alloys with varying iron to nickel molar ratios (10–50% Fe) was undertaken by simultaneously reducing Fe(II) and Ni(II) solution using hydrazine hydrate as a reducing agent in strong alkaline media for 15 min at 95–98 °C. The effect of reaction volume and total metal concentration on the properties of the synthesized alloys was studied. Alloy morphology, chemical composition, crystal structure, thermal stability, and magnetic properties of synthesized iron-nickel alloys were characterized by means of SEM, TEM, EDX, XRD, DSC and VSM. ImageJ software was used to calculate the size of the synthesized alloys. A deviation from Vegard’s law was recorded for iron molar ration higher than 30%., in which superstructure phase of FeNi3 was formed and the presence of defects in it, as well as the dimensional effects of nanocrystals. The saturation magnetization (Ms), coercivity (Hc), retentivity (Mr), and squareness are strongly affected by the molar ratio of iron and nickel and reaction volume as well as the total metal concentration.

Modelling of ducted noise sources in the proximity of acoustic liners

This paper focuses on modelling and predicting the acoustic field generated by ducted point sources in close proximity to an acoustic liner. Two analytical models are presented. The first model comprises a point monopole or dipole source in an infinite lined duct based on an existing Green’s function. The predictions are compared with classic solutions for a source over an infinite lined plane and with a high frequency asymptotic duct approximation. The second model extends the Green’s function to include a liner section of finite length connected to hard-wall extensions by using mode-matching techniques. The new model features the inclusion of point sources in the vicinity of an impedance discontinuity. The accuracy of this model is demonstrated by comparison with reference FE solutions. Both models indicate a significant impact of the source proximity to the liner surface in the source power output. These models offer insight on the source modification effects beyond the conventional approach in the design of liners solely based on acoustic absorption.

Titanium-pillared montmorillonite composite as an efficient catalyst for 2-nitrophenol reductive transformation by Fe(II): The effects of aqueous chemistry and mechanistic insights

The abiotic reduction of 2-nitrophenol (2-NP) to 2-aminophenol is the major remediation strategy used to remove 2-NP from contaminated aquifers and groundwaters. In the present study, both the aqueous chemistry and surface nature of a titanium-pillared montmorillonite (TPMnt) catalyst were investigated in-depth, to obtain comprehensive insight into the reductive transformation mechanisms of 2-NP in a Fe(II)/TPMnt reaction system. The results show that almost all the 2-NP disappeared within 0.5 h in the Fe(II)/TPMnt3 reduction system in stark contrast to just 26% of 2-NP removal within 4.0 h in a Fe(II) solution, and 85% of 2-NP removal within 4.0 h in a Mnt system. These results demonstrate that the specially adsorbed Fe(II) species bound to the mineral surface is one key species crucial for achieving the 2-NP transformation. Among the aqueous chemistry, i.e., the ratio of [Ti]/Mnt, the solution pH, the initial Fe(II) concentration, the dose of TPMnt, the solution pH, and the initial Fe(II) concentration significantly influenced the 2-NP transformation. High effectiveness was achieved under these conditions: TPMnt3 with a content of 20.0 mmol/g TiO2, pH of 7, an initial Fe(II) concentration of 10.0 mmol/L, and a dose of TPMnt at 2 g/L. There was a positive correlation between the constant k values of the reduction rate and the amounts of adsorbed Fe(II) species on the TPMnt surface. Further, the TPMnt was shown to possess good recyclability, and the catalytic activity of TPMnt3 for the 2-NP reduction remained mostly unchanged when reused four times. Our results for cyclic voltammograms and electrochemical impedances confirmed that the enhanced performance of the 2-NP reduction can be attributed to a negative shift of the oxidation potentials of Fe(II) along with decreased impedance values (RCT) of the Fe(II)/Fe(III) coupling on the GC electrodes. The intercalated TiO2 in TPMnt functionalized as an ideal promoter for the efficient transformation of 2-NP by Fe(II). Taken together, these results suggest the TPMnt surface-mediated 2-NP reduction by Fe(II) is a promising application for the remediation of 2-NP-contaminated aquifers and groundwaters.

An Approximate Thermo-Mechanical Solution of a Functionally Graded Cylinder Using Hybrid Integral Transform and Finite Element Method

This article introduces a novel mixed method that combines the Fast Fourier Transform technique and a conventional Finite Element Method for investigating thermo-mechanical behavior of a thick functionally graded cylinder under asymmetric loadings. Material properties are assumed to vary along the radial direction according to a power function. Thermo-elastic governing equations of the cylinder are derived using principle of virtual work in cylindrical coordinates. Plane strain assumption is considered for a long cylinder during the analysis. Fast Fourier Transform technique is utilized in circumferential direction to discretize equations and related boundary conditions. Finite element method is then applied to remaining equations. For convergence study, the results obtained from this method are compared with those extracted from exact and complete FE solutions. It is observed from the results that the method has a super algebraic convergence behavior in circumferential direction. Influence of the mesh refinement is also investigated in the radial direction. According to ability of the mixed FFT-FE method for asymmetric analyzing, two kinds of loadings are considered here and results are presented. In thermo-elastic analyzing of the long cylinder, it’s obvious that the present method benefits from some features such as fast convergence and low computational cost in comparison with FE solution.

Finite element analysis of smart composite plate structures coupled with piezoelectric materials: Investigation of static and vibration responses

This research presents a generalized-energy-based finite element modeling of smart composite plates with distributed piezoelectric materials for the static and vibration responses under electrical and mechanical loading. The zigzag kinematics in conjunction with a non-polynomial higher-order shear deformation theory is used to derive the model. The plate theory accounts for the non-linear variations of the transverse shear strains across the thickness of the plates and also accommodates the inter-laminar continuity effects of transverse shear stresses at the interfaces. Eight noded isoparametric serendipity elements are used to discretize the physical domain. The solutions in the time domain are obtained from the discretized system of ordinary differential equations with Newmark’s time integration scheme. Several numerical examples are solved for different types of smart composite plates with various piezoelectric materials, boundary conditions, static and dynamic loadings. The classical negative feedback controller is used for deriving the suppressed and controlled vibration responses of the smart composite plates with distributed actuators and sensors. A comparison of the present FE solutions with the elasticity and other analytical and numerical solutions shows good agreement, thereby ensures the applicability of the present finite element model for studying the coupled electromechanical problems of piezoelectricity.

Enhancing the accumulation and bioavailability of iron in rice grains via agronomic interventions

Suboptimal or inadequate diet of iron (Fe) represents a latent health problem affecting over two billion people worldwide. To tackle micronutrient deficiency in crops, a short-term approach is agronomic biofortification in which nutrients can be enhanced by their accumulation in food plant tissue either by fertilisation or by other eliciting aspects. The present study evaluated the comparative influence of various Fe application methods, including (i) Fe seed coating (300 mg Fe kg–1 seed), (ii) Fe osmopriming (0.5% Fe solution), (iii) surface broadcasting (8 kg ha–1), (iv) Fe foliar application (0.3% Fe solution), on paddy yield, net benefits, grain Fe accumulation, bioavailability, and Fe-use efficiencies in conventional (puddled transplanted rice, PTR) and conservational (direct-seeded aerobic rice, DSAR) production systems. Hydro-priming and foliar water spray were also included in treatments as a positive control for osmopriming and foliar spray of Fe respectively. Iron application by either method enhanced productivity, profitability, and biofortification in both rice systems. Grain yield improved in both years by the application of Fe in the following order: osmopriming &gt; foliar application &gt; surface broadcasting &gt; seed coating, with the respective increase of 18%, 14%, 10%, 8% relative to no Fe application. Grain Fe concentration was the highest by Fe applied as foliar (37% over control) in both production systems. Similarly, minimum phytate concentration and phytate:Fe molar ratio were recorded with foliar-applied Fe. In crux, Fe application by osmopriming increased the productivity and profitability under PTR and DSAR systems, whereas foliar-applied Fe improved the grain Fe accumulation.

Durable, scalable and affordable iron (III) based coconut husk photothermal material for highly efficient solar steam generation

Biomass-based photothermal materials, being fabricated based on agricultural waste, are widely applied in solar steam generation (SSG) recently. The evaporation rate of the SSG systems while utilizing these materials can reach 1.4–1.6 kg m-2 h-1 under 1 sun condition. In this study, a coconut husk (CH), a common agricultural waste, was utilized to fabricate the photothermal material that can be applied in the SSG system. CH consists of coconut fibers containing many vascular bundles with 10-20 μm diameter and cocopeat that has honeycomb-like structure. After treating CH with tannic acid and Fe (III) solution, the coordination of phenolic compounds with Fe3+ in the CH is formed. The resulting CH-TA-Fe3+ (CHP) material demonstrated significant advantages such as high light absorption, low thermal conductivity, ultra-fast water transportation, low moisture enthalpy, and self-cleaning properties. The CHP-based SSG system possessed high seawater evaporation rate (1.83 kg m-2 h-1) and evaporation efficiency (73.2%), which are comparable to those in the previous studies on biomass material based SSG systems. Especially, the CHP-based SSG system exhibited excellent structural stability that ensures their long-term performance in the seawater desalination. With simple fabrication process, affordable price, and eco-friendly materials, the CHP proves great potential in seawater desalination application.

Photo-Fenton Process Using Fe(III) Ions from Modified Sugarcane Bagasse for Reactive Black 5 Dye (RB5) Removal

Brazil is one of the largest generators the sugarcane bagasse, this kind of biomass has already shown efficiency related to its in natura adsorption potential (when physically or chemically activated), it can also be used to remove contaminants from water in methods such as advanced oxidative processes. In this study, chemical modifications were carried out in sugarcane bagasse to enable its application in photo-Fenton processes for the degradation of reactive black 5 dye. The materials were chemically activated through immersion in Fe(III) solution for different periods of time: 3, 6, 9, 12, 24, 48 and 96 h; and were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), zeta potential analysis, internal surface area and leached metal quantification. The results showed the cellulose structure, which is predominant in the sugarcane bagasse it was not considerably modified after activation with FeCl3 and evidence of the presence of Fe(III) ions on the surface of the studied material. The degradation efficiency (after 5 min and using 11.5 mg L-1 hydrogen peroxide) for the activated materials was respectively: 55.85%, 49.44%, 71.22%, 92.87%, 88.16% and 98.02%, considering the decrease of the band related to the chromophore group (598 nm). DOI: http://dx.doi.org/10.17807/orbital.v13i2.1482