Biodegradable soy protein-based matrices for the controlled release of zinc in horticulture

Nowadays, biodegradable protein-based matrices capable of storing micronutrients and releasing them in a controlled manner are being studied in order to avoid an excessive use of fertilizers. One of the methods to add micronutrients into matrices is through an immersion stage in a saturated solution, which provides matrices with high superficial content of zinc but no incorporation of this element inside the matrix. This is due to the growth of an external layer that keeps the ions from entering the structure. In this study, the plasticizer was modified with the aim of creating more free space to help the ions penetrate the matrices. Thus, the water incorporation generated more rigid matrices with less micronutrient incorporation but with a more homogeneous distribution of the micronutrient (Zn) within it, being more suitable for its controlled release.     

Processing of biodegradable and multifunctional protein-based polymer materials for the potential controlled release of zinc and water in horticulture

Recent high levels of horticulture production cause an impoverishment of soil nutrients that may seriously impair crop yields. This forces farmers to rely on the use of fertilizers. However, it also involves an increase in the contamination risks associated with their supply. A possible alternative to supply these fertilizers could be the use of biodegradable protein-based matrices, which can contain the essential elements required by the soil. Therefore, the main objective of this work is the evaluation of different alternative methods for the incorporation of a selected micronutrient (MN) zinc (Zn) to soy protein-based matrices. As a result, it has been possible to incorporate high levels of Zn into the matrices. However, depending on the method used for MN incorporation, there are variations in the microstructure, MN distribution, and mechanical properties. This work brings forward an innovative application of these matrices as a source of controlled release of MN for horticulture applications.     

Hydrometallurgical Recovery of Zinc from Fine Blend of Galvanization Processes

Abstract

In many factories, which are working in the field of steel industry, there are galvanization units in which steel products are galvanized for corrosion protection. About 15% of the total amount of the used zinc are accumulated as zinc ash and dust at the surface of molten zinc bath and in the chimney respectively. In a previous work, zinc was successfully recovered from the coarse ash by applying pyrometallurgical processing. In this work, zinc fine blend (of fine ash and flue dust) was hydrometallurgically treated using sulfuric acid. Two alternative techniques were applied for producing zinc sulfate salt or pure zinc metal. In the first technique, the salt was separated from the leach solution as zinc sulfate hydrate (ZnSO₄ · H₂O). It was crystallized by concentrating the leach liquor to a density of 1.52 g/cm³. The purity of the produced zinc sulfate was 99.5%. In the second technique, the leach solution has been purified with respect to the soluble impurities using precipitation. The electrowinning technique was applied for producing a pure zinc metal from the purified solution. Electrolysis was performed at ambient temperature (25–28°C) with current density (c.d.) of 40 mA · cm^?2. The recovery of zinc proceeds down to a concentration of 50 g · l^?1 with acceptable cathodic current efficiency of 96.5%, and energy consumption for the electrolysis step of 2.75 KWh/Kg. The zinc purity in the deposit obtained from the electrolysis was 99.9%.     

Preparation, characterization, and antibacterial activity evaluation of collagen–Zn complex

The different kinds of collagen–Zn complexes were prepared by zinc acetate, zinc chloride, zinc nitrate, and zinc sulfate reacted with collagen protein. Their antibacterial activities have been investigated by MIC method. It was found that the antibacterial activity of collagen–ZnSO₄ complex is better than that of others. To obtain a better antibacterial activity, collagen–ZnSO₄ complexes with different zinc amount were prepared using zinc sulfate as starting material. These complexes were characterized by FT-IR, XRD, and atomic absorption spectrometry. The results showed that zinc ion could chelate with N–H, C–O, and C=O group in collagen to form the stable complex. Antibacterial activities of collagen–ZnSO₄ complexes containing different Zn amount were evaluated against Escherichia coli and Staphylococcus aureus. The results suggested that antibacterial activity increases with the increase of zinc amount.     

Sulfate binding in zinc(II) complexes of a monopyridylurea ligand N-(1-naphthyl)-N′-(3-pyridyl)urea

Two zinc(II) complexes of a urea-functionalized pyridyl ligand, [Zn(SO₄)L₃]·CH₃OH (1) and {[Zn(μ₂-SO₄)L₂]·0.5CH₃OH}_n (2) (L = N-(1-naphthyl)-N′-(3-pyridyl)urea), have been synthesized by the reaction of L with ZnSO₄·7H₂O under different conditions. Complex 1 is a hydrogen-bonded 2D grid structure in which the sulfate anion not only coordinates to the Zn^II ion as a monodentate ligand but also forms multiple hydrogen bonds with the urea groups of adjacent molecules. In complex 2 the sulfate ion serves as a μ₂-bridging ligand, connecting the Zn^II ions to form an infinite 1D organic–inorganic hybrid framework. Meanwhile, the sulfate anion is also bound by neighboring ligands through hydrogen bonds between urea groups and the non-coordinated oxygen atoms. The solid-state emission spectra of 1 and 2 show a red shift of the fluorescence emission of ligand L.     

Metastable equilibrium for the quaternary system containing with lithium+potassium+magnesium+chloride in aqueous solution at 323K

The metastable equilibrium of the system contained with lithium, potassium, magnesium, and chloride in aqueous system was investigated at 323 K using an isothermal evaporation method. The isothermal experimental data and physicochemical properties, such as density and refractive index of the equilibrated solution, were determined. With the experimental results, the stereo phase diagram, the projected phase diagram, the water content diagram and the physicochemical properties versus composition diagrams were constructed. The projected phase diagram consists of three invariant points, seven univariant curves and five crystallization fields corresponding to single salts potassium chloride (KCl), lithium chloride monohydrate (LiCl·H₂O), bischofite (MgCl₂·6H₂O) and two double salts lithium carnallite (LiCl·MgCl₂·7H₂O) and potassium carnallite (KCl·MgCl₂·6H₂O). Salt KCl has the largest crystallization region; it contains almost 95% of the general crystallization field.     

Simulation studies on metastable phase equilibria in the aqueous ternary systems (NaCl-MgCl2-H2O) and (KCl-MgCl2-H2O) at 308.15 K

The solubilities and densities of the aqueous metastable ternary systems (NaCl-MgCl₂-H₂O) and (KCl-MgCl₂-H₂O) at 308.15 K were determined by the isothermal evaporation method. On the basis of the experimental results, the phase diagrams for those systems were plotted. It was found that the former system belongs to the hydrate-I type with one invariant point of (NaCl + MgCl₂·6H₂O), two univariant curves, and two crystallization regions corresponding to halite (NaCl) and bischo.te (MgCl₂6H₂O); and the latter system belongs to the type of incongruent-double salts with two invariant points of (KCl + KCl·MgCl₂6H₂O) and (MgCl₂·6H₂O + KCl·MgCl₂·6H₂O), three univariant curves, and three crystallization regions corresponding to potassium chloride (KCl), carnallite (KCl·MgCl₂·6H₂O) and bischofite (MgCl₂·6H₂O). No solid solutions were found in both systems.     

Production of nano zinc borate (4ZnO·B2O3·H2O) and its effect on PVC

In this study, nano sized zinc borate powder with a formula of 4ZnO·B₂O₃·H₂O was synthesized using 2ZnO·3B₂O₃·3.0–3.5H₂O as a starting chemical which was produced using a wet chemical method. After dissolving 2ZnO·3B₂O₃·3.0–3.5H₂O in an ammonia solution, the clear solution was boiled until a white powder formed. The resultant powder was characterized with XRD, FTIR, TGA and TEM. XRD, FTIR and TGA results proved that the powder was belonged to the 4ZnO·B₂O₃·H₂O. Nano composites of 4ZnO·B₂O₃·H₂O–polyvinylchloride (PVC) were produced by injection moulding by adding 1 and 5 wt% zinc borate powders into PVC to enhance its flame retardancy. Limiting oxygen index (LOI) of virgin PVC increased from 41% to 47% and 54% for the 1 and 5 wt% zinc borate added PVC, respectively. Nano zinc borate addition into the PVC does not have considerable negative effect on the mechanical properties of zinc borate–PVC composites even at high amounts of 5 wt%.     

Four coordination polymers derived from 4-amino-3,5-bis(3-pyridyl)-1,2,4-triazole and copper sulfate

The reaction of 4-amino-3,5-bis(3-pyridyl)-1,2,4-triazole (3-bpt) with copper sulfate in EtOH/H₂O solvent yields four coordination polymers [Cu(3-bpt)(H₂O)₄](SO₄)·H₂O (1), [Cu(3-bpt)(H₂O)₄][Cu(3-bpt)(H₂O)₃(SO₄)](SO₄)·7H₂O (2), [Cu(3-bpt)(H₂O)₃(SO₄)]·2H₂O (3) and [Cu(3-bpt)(H₂O)(SO₄)] (4), showing one-dimensional undulated chain, zigzag chain and two-dimensional network. The formations of compounds 1, 2 and 3 are controlled by the EtOH/H₂O ratio. The synthesis of compound 4 may be controlled by the EtOH/H₂O ratio and the temperature because it is prepared under solvothermal condition. The thermal properties have been investigated.     

Solution and solid-state photoluminescence of dinuclear Pb(II) dicarboxylate compound with 2,6-bis(benzimidazolyl)pyridine: The lone-pair stereochemistry and its effect on supramolecular interaction

[Pb₂(boa)(Hbbp)₂] has been synthesized by treating 4-carboxylphenoxyacetic (H₂boa) and 2,6-bis(benzimidazolyl)pyridine (H₂bbp) with metal salts under hydrothermal conditions. Adjacent metal centers forms dinuclear metal complex through carboxylato groups as building blocks. The arrangement of the half deprotonated H₂bbp ligand and carboxylate groups exhibits a coordination gap around the Pb(II) ion, occupied possibly by a stereoactive lone pair of electrons on Pb(II), with the coordination environment around the lead atoms is hemidirected. This system is a particularly clear example that coordination sphere of a unique dinuclear Pb(II) compound was controlled by lone pair activity, weak Pb···O interactions, π–π stacking and the hydrogen bonds. The above weak interactions influence differently strong red-shifted effect about the solution and solid-state photoluminescence of the compound, compared to the free ligand.     

A metal-organic framework with unusual nanocages: Drug delivery

An unusual nanocage-based framework of [Zn₂(L)(H₂O)_1.5]·5H₂O (1) was used as a drug carrier of 5-fluorouracil (5-FU) for drug delivery. The incorporation of drug 5-FU into the 1 was around 48.6 wt% per gram of dehydrated 1. 5-FU is released in a highly controlled and progressive manner with 98% of the drug release after 101 h at acidic condition and with 62% after 72 h at PBS. 1 did not exhibit any significant cytotoxicity using the vitro cytotoxicity assays. The result from this study suggested a new approach for MOFs to be used as potential drug delivery.     

A green process for recovery of H2SO4 and Fe2O3 from FeSO4·7H2O by modeling phase equilibrium of the Fe(П)– –H+–Cl– system

Ferrous sulfate heptahydrate FeSO₄·7H₂O is a major waste produced in titanium dioxide industry by the sulfate process and has caused heavy environmental problem. A new green process for the treatment of FeSO₄·7H₂O was proposed to make use of iron source and recycle sulfate source as H₂SO₄. It was found that by adding concentrated HCl to the FeSO₄ solution, FeCl₂·4H₂O was crystallized out, which was subsequently calcined to produce Fe₂O₃ and HCl. Concentrated H₂SO₄ solution (about 65 wt %) was obtained by evaporating the FeCl₂·4H₂O‐saturated filtrate. To facilitate the process development and design, the solubilities of FeCl₂·4H₂O in HCl, H₂SO₄, and HCl + H₂SO₄ solutions were measured and the experimental data were regressed with both the mixed‐solvent electrolyte model and the electrolyte NRTL model. On the basis of the prediction of the optimum conditions for the crystallization of FeCl₂·4H₂O, material balance of the new process was calculated. FeCl₂·4H₂O and Fe₂O₃ were obtained from a laboratory‐scale test with about 70% recovery of ferrous source for a single cycle, indicating the feasibility of the process. © 2017 American Institute of Chemical Engineers AIChE J, 63: 4549–4563, 2017     

Controlled Growth of WO3 Nanostructures with Three Different Morphologies and Their Structural, Optical, and Photodecomposition Studies

Tungsten trioxide (WO₃) nanostructures were synthesized by hydrothermal method using sodium tungstate (Na₂WO₄·2H₂O) alone as starting material, and sodium tungstate in presence of ferrous ammonium sulfate [(NH₄)₂Fe(SO₄)₂·6H₂O] or cobalt chloride (CoCl₂·6H₂O) as structure-directing agents. Orthorhombic WO₃ having a rectangular slab-like morphology was obtained when Na₂WO₄·2H₂O was used alone. When ferrous ammonium sulfate and cobalt chloride were added to sodium tungstate, hexagonal WO₃ nanowire clusters and hexagonal WO₃ nanorods were obtained, respectively. The crystal structure and orientation of the synthesized products were studied by X-ray diffraction (XRD), micro-Raman spectroscopy, and high-resolution transmission electron microscopy (HRTEM), and their chemical composition was analyzed by X-ray photoelectron spectroscopy (XPS). The optical properties of the synthesized products were verified by UV–Vis and photoluminescence studies. A photodegradation study on Procion Red MX 5B was also carried out, showing that the hexagonal WO₃ nanowire clusters had the highest photodegradation efficiency.     

Kinetics of the Decolorization by Fenton's Reagent

Fenton's reagent was employed in the decolorization of aqueous solutions of one of three dyestuffs (Acid Red 27, Reactive Blue 81, Acid Blue 62). The decolorization with Fenton's reagent was found to be simple and fast. In order to determine the reaction kinetics of the decolorization the stopped-flow technique under pseudo-first order conditions was used. Experiments were carried out at pH=2, at the excess of ferrous salts (FeCl₂·4H₂O or FeSO₄·7H₂O). The rate constants of the decolorization determined by us are in the same order of magnitude: 90 to 100 dm³/(mol-s) for FeSO₄·7H₂O/H₂O₂, and 40 to 50 dm³/(mol-s) for FeCl₂·4H₂O/H₂O₂ systems. The difference between the rate constants for both ferrous salts indicates that the Fenton's reaction may proceed via different mechanisms.     

Electrocrystallisation of zinc from acidic sulphate baths; A nucleation and crystal growth process

The electrochemical nucleation and growth of zinc on low-carbon steel from acidic (pH 2.0-4.5) baths containing ZnSO₄, NaCl, and H₃BO₃, was studied by means of chronoamperometry at various cathodic potentials under a charge-transfer controlled regime. It is shown that at overpotentials in the range 0.30-0.55 V (negative to the Zn²⁺/Zn redox value) the electrodeposition proceeds by instantaneous three-dimensional nucleation, which turns to progressive at higher overpotentials and/or very acidic baths. At low cathodic overpotentials (<0.30 V), a two-dimensional contribution limited by the incorporation of Zn ad-atoms in the developing lattice becomes significant at the early stages of deposition, and is more progressive in type the more acidic is the bath pH. Nucleation rate constants were calculated and correlated analytically with the respective potentials, using the classical theory of heterogeneous nucleation, which though fails to lead to reasonable values for the critical nucleus size.     

Synthesis and characterization of wurtzite ZnS nanoplates through simple solvothermal method with a novel approach

A thio Schiff-base-assisted solvothermal process has been developed to synthesize zinc sulfide (ZnS) nanoplates via the reaction between a metal salt, Zn(NO₃)₂·6H₂O and thio Schiff-base of 2-(benzylidene amino) benzenethiol (C₁₃H₁₁NS) as a new precursor. XRD, TEM, SEAD, UV–vis spectroscopy, TG-DTA and FT-IR spectra were employed to characterize the obtained product. The results of this paper indicate that the shape and size of zinc sulfide nanoplates can be controlled systematically by setting certain reaction parameters, such as the reaction temperature and duration and type of solvent. Zinc sulfide nanoplates with different morphology and size have been successfully prepared.     

Preparation and antibacterial properties of titanium-doped ZnO from different zinc salts

To research the relationship of micro-structures and antibacterial properties of the titanium-doped ZnO powders and probe their antibacterial mechanism, titanium-doped ZnO powders with different shapes and sizes were prepared from different zinc salts by alcohothermal method. The ZnO powders were characterized by X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), ultraviolet-visible spectroscopy (UV-vis), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and selected area electron diffraction (SAED), and the antibacterial activities of titanium-doped ZnO powders on Escherichia coli and Staphylococcus aureus were evaluated. Furthermore, the tested strains were characterized by SEM, and the electrical conductance variation trend of the bacterial suspension was characterized. The results indicate that the morphologies of the powders are different due to preparation from different zinc salts. The XRD results manifest that the samples synthesized from zinc acetate, zinc nitrate, and zinc chloride are zincite ZnO, and the sample synthesized from zinc sulfate is the mixture of ZnO, ZnTiO₃, and ZnSO₄ · 3Zn (OH)₂ crystal. UV-vis spectra show that the absorption edges of the titanium-doped ZnO powders are red shifted to more than 400 nm which are prepared from zinc acetate, zinc nitrate, and zinc chloride. The antibacterial activity of titanium-doped ZnO powders synthesized from zinc chloride is optimal, and its minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) are lower than 0.25 g L⁻¹. Likewise, when the bacteria are treated by ZnO powders synthesized from zinc chloride, the bacterial cells are damaged most seriously, and the electrical conductance increment of bacterial suspension is slightly high. It can be inferred that the antibacterial properties of the titanium-doped ZnO powders are relevant to the microstructure, particle size, and the crystal. The powders can damage the cell walls; thus, the electrolyte is leaked from cells.     

Kinetics of the catalytic esterification of castor oil with lauric acid using <Emphasis Type="Italic">n</Emphasis>-butyl benzene as a water entrainer

The esterification of castor oil with lauric acid was investigated using tetra n-butyl titanate (TBT), SnCl₂·2H₂O (stannous chloride), CoCl₂·6H₂O (cobalt chloride), and (CH₃COO)₂Zn·2H₂O (zinc acetate dihydrate) as catalysts. Effects of catalyst concentration and reaction temperature on the progress of the reaction were investigated. TBT was the best catalyst for the esterification of castor oil with lauric acid at temperatures lower than 200°C. The reaction was first order with respect to each reactant. The activation energy for the esterification reaction of castor oil with lauric acid using TBT was 26.69 kcal/mol. The rate constants obtained for the esterification of castor oil with decanoic, lauric, palmitic, and stearic acids were nearly the same (15.80, 15.44, 15.06, and 14.67 mL mol⁻¹ min⁻¹), as were the rate constants obtained for the reaction of castor oil and hydrogenated castor oil.     

Metal Chelates with Some Cellulose Derivatives: V. Synthesis and Characterization of Some Iron(III) Complexes with Cellulose Ethers

Two types of monoligand complexes of FeCl₃, Fe(NO₃)₃ and Fe₂(SO₄)₃ with hydroxyethyl cellulose (HEC) and carboxymethyl cellulose (CMC) were prepared and characterized. Elemental analysis, UV and IR spectro-scopies, conductance and magnetic measurements were used to assign the mode of coordination in the isolated species. The investigation revealed that Fe(III ) exhibits tetrahedral coordination with HEC and CMC. These ligands act as a bidentate chelating agent via the two oxygen atoms of the vicinal hydroxyl and ether groups (ethoxyl or carboxymethyl groups). The prepared complexes have the formula [(HEC) FeCl]Cl, [(HEC) FeNO₃]NO₃, [(HEC)FeSO₄·H₂O]H₂O, [(CMC)FeCl·H₂O]Cl·2H₂O, [(CMC)Fe·2NO₃]3H₂O and [(CMC)-FeSO₄·H₂O]H₂O. The results also showed that the type of cellulose ether (functional group) and the anion of the metal salts used have an effect on the conductivity, structure and absorptivity of Fe(III ) complexes. © of SCI.     

Novel oligonuclear ZnII4, ZnII8 and ZnII2NiII2 complexes with bis(benzoylacetone)-1,3-diiminopropan-2-ol

Reactions of bis(benzoylacetone)-1,3-diiminopropan-2-ol (abbreviated as H₃L) with zinc salts in the presence of triethylamine afforded the compounds [Zn₄(HL)₄]·4CH₃CN (1·4CH₃CN) and [Zn₈L₄(OH)₄]·2CH₃CN (2·2CH₃CN). Further reaction of 1 with Ni(CH₃COO)₂·4H₂O gave the heteronuclear species [Zn₂Ni₂(L)₂(CH₃O)₂(CH₃OH)₂] (3). The crystal structures of 1·4CH₃CN, 2·2CH₃CN and 3 were determined by the X-ray diffraction method.