Oxide Powders Research Articles

Comparative evaluation of flexural strength of conventional heat polymerized denture base resin reinforced with non-silanized and silanized aluminum oxide powder- An in vitro study

Although denture base acrylic resins have been used since many decades, the problem of facture of denture base still remains. Many researchers have tried to reinforce the denture base by addition of metallic oxide nanoparticles. Silanization of such nanoparticles is recommended as it improves the bond between fillers and added nanoparticles. To evaluate and compare the flexural strength (FS) of heat polymerized acrylic resin denture base material reinforced with 2.5 wt % of non-silanized and silanized aluminum oxide powder (AlO). : Seventy-five specimens of heat polymerized acrylic resin were fabricated. The specimens were divided into three groups (n = 75) coded as Group N (non-silanized AlO), Group S (silanized AlO) and Group C (Control). The specimens of the remaining two groups were reinforced with 2.5 wt % of non-silanized and silanized AlO. The flexural strength of the specimens was measured using 3-point bending test in a Universal Testing Machine. Data analyses using analysis of variance and Tukey’s post-hoc test showed that adding 2.5 wt% of silanized AlO; GroupS significantly increased the flexural strength compared to Group C and GroupN (p<0.0001). Within the limitation of this study, AlO fillers are potential reinforcers in denture bases which increased flexural strength.

Charge transport mechanism in [GeOx](z)[SiO2](1-z) based MIS structures

The mechanisms of conductivity in metal–insulator–semiconductor (MIS) structures based on [GeOx](z)[SiO2](1-z) films (0.25 ≤ z ≤ 1) fabricated by co-evaporation of germanium oxide and silicon oxide powders in vacuum and deposition on a p+-type silicon substrate are studied. Indium tin oxide deposited by magnetron method is used as the top electrode. According to IR spectroscopy, Ge–O, Si–O, and Ge–O–Si bonds are detected in the films, while no features related to the presence of germanium clusters are found in the Raman spectra. The current–voltage characteristics (I–V curves) are measured at different temperatures and analyzed by applying the eight most common models of charge transport in MIS structures. It is found that the experimental I–V curves are most accurately approximated in the space charge limited current model, and the parameters of the charge traps are determined within this model.

Probing the Nanostructure and Reactivity of Epoxy-Amine Interphases.

Understanding and controlling the structure of interphase regions in epoxy resins have been a long-standing goal in high-performance composite and coating development, since these are widely considered to be weak points in the microstructure of these materials, determining key properties such as fracture strength and barrier performance. These buried nanoscale regions are, however, inaccessible to conventional analytical techniques, and little is understood about their underlying formation mechanism. Here, we combine molecular dynamics (MD) simulation with nanoscale infrared chemical mapping to develop new understanding of the interphase using model epoxy-amine binders composed of diglycidyl ether of bisphenol A (DGEBA) cross-linked using m-xylylenediamine (MXDA). Iron oxide powders are used as exemplary surfaces, where we demonstrate that the electrostatic binding energies between the amine cross-linker and particles range from repulsive (magnetite, Fe3O4) to weakly attractive (hematite, Fe2O3) to strong immobilization (goethite, FeOOH). We find that interfacial binding occurs upon mixing and determines the overall level of residual amine content in the bulk matrix but does not correlate with a detectable amine depletion in the vicinity of particles. In all cases, an excess of both epoxy and amine functionality is detected close to particles, and the extent of matrix undercuring is found to be dependent on the entropic segregation of the unreacted material during the ambient cure. Detailed MD simulations demonstrate that spatial segregation of the unreacted precursors is expected in the interphase, leading to the experimental observation that, even after extensive postcure heating, individual particles remain embedded in a nanoscale underdeveloped environment.

Mechanical effects on the preparation of copper oxide (CuO) and copper (Cu) nanoparticles and their properties

This study investigates the factors influencing the production of nanoparticles and the precise control over their size and shape, with a focus on optimizing milling time, pause duration, and rotation speed. These parameters must be carefully calibrated to enhance production efficiency and prevent particle aggregation. The research also explores the structural properties of nanostructured copper (Cu) and copper oxide (CuO) powders, which were synthesized using a planetary ball mill under an argon atmosphere. Milling was performed at various time intervals, and to prevent excessive temperature buildup, grinding was paused for 20 minutes after every 10 minutes of milling. The experimental procedure for producing copper- and copper oxide-based nanoparticles spans a time range of 48–72 hours, based on a series of experiments conducted over several years. Characterization techniques, including Scanning Electron Microscopy (SEM), X-ray Diffraction (XRD), and Fourier Transform Infrared Spectroscopy (FT-IR), were employed to analyze the crystallographic, chemical, and dimensional properties of the nanoparticles. SEM provided direct observation of the nanoparticle morphology, while XRD offered insights into their crystal structures and phases. FT-IR analysis was used for structural elucidation. The average nanoparticle sizes were determined to be approximately 20.8 nm for copper and 21.19 nm for copper oxide. Notably, at the nanoscale, the physical properties of these materials exhibited significant differences compared to their macroscopic counterparts.

A new metrology tool: using transmission Kikuchi diffraction (TKD) to identify and separate nanoparticles for regulatory purposes

Abstract The development of methods for characterising nanoparticles (NPs) at the nanometric scale is a major challenge facing metrology researchers today. The characterisation of the crystal structure of NPs for regulatory purposes is urgent as mixtures of NPs are frequently found in consumer products and this physicochemical parameter contributes to the understanding of potential health and environmental risks. Using the methods currently available, NPs cannot be individually identified and their size distribution cannot be correlated to crystallographic phases. Instead, a general identification of crystallographic phases is possible. New methods must be developed that identify individual particles on the nanoscale. This paper introduces transmission Kikuchi diffraction, an electron backscattered diffraction (EBSD) technique as a method for comprehensively characterizing a mixture of iron oxide NPs by crystal structure. After identifying the crystal structure of three different iron oxide powders using x-ray Diffraction, the samples were characterised by TKD. The results underline the relevance of TKD, which has sufficient spatial resolution to determine the crystal structure of individual NPs. This study also demonstrates the possibility of electron backscattered diffraction analysis on unpolished samples, something atypical for EBSD and TKD. The powders were then mixed and the individual NPs were correctly identified in a scanning electron microscope (SEM) using TKD. The results show that TKD can be used to correctly identify and classify NPs within a mixture and can be combined with SEM imaging to build size distribution histograms according to the NP crystal structure.

The effect of photoinitiator systems on resin-based composite containing ZnO-nanoparticles.

Zinc oxide (ZnO) powder possesses antibacterial activity and although white in color, it can severely reduce the depth of cure (DoC) of resin-based composite (RBC). This study investigated the effect of unary and binary photoinitiator systems on the DoC and degree of conversion (DC) of formulated RBC containing ZnO-nanoparticles. Fourteen RBCs (n = 3/group) were formulated consisting of 50 wt% mixture of monomers (Bis-GMA, TEGDMA, and UDMA) and 50 wt% fillers (inert barium glass powder and silica nanoparticles). ZnO-nanoparticles were added at 0 (control), 0.5, 1, 1.5 and 2 wt%. A unary initiator system consists of camphorquinone (CQ) 0.25, 0.5 and 1 wt% and ethyl 4-(dimethylamino)benzoate (EDMAB) 0.75 wt% or a binary initiator system consisting of diphenyliodonium hexafluorophosphate (DPI) 0.25, 0.5 and 1 wt%, CQ 0.25, 0.5 and 1 wt% and EDMAB 0.75 wt% were added to the monomer mixture. To measure the DoC, each specimen was prepared in a custom-made mold with a slot (16 x 8×2 mm) and a top cover plate, irradiated from one end (40 s), stored dry (37° C, 1 d) and measured at increasing depths using Vickers hardness (0.5 mm intervals). 1 mm thick specimens were prepared to measure DC continuously using FTIR, from zero up to 24 h post-irradiation. Increasing the concentrations of ZnO led to a significant reduction of DoC (p < 0.05). But most of the binary initiator groups showed significantly higher DoC (p < 0.05). Depth, at 80 % of max VHN, of unary initiator groups reduced from 6.8 mm (ZnO at 0 wt%) to 2.1 mm (ZnO at 2 wt%) and in binary initiator groups from 8.4 mm to 2.3 mm. Groups with lower photoinitiator concentrations (0.25 wt%) showed a significant increase in DoC compared with groups with higher concentrations (1 wt%) (p < 0.05). DC after 24 h was independent of either ZnO concentration or the photoinitiator system (p > 0.05). However, faster conversions were observed in binary initiator groups. The RPmax of binary groups ranged from 8.1 % to 10.1 %/s, and unary groups ranged from 5.2 % to 7.2 %/s. The addition of DPI resulted in an overall increased curing depth, which was enhanced when lower concentrations of photoinitiators were used. Also, DPI resulted in faster conversions. This is desirable in designing antibacterial RBC containing ZnO.

Crystallization behavior of smelting slag for recovery of platinum group metals from spent automotive catalysts and preparation of foamed glass-ceramics

Spent automotive catalysts (SAC), as a significant secondary resource for platinum group metals (PGMs), can be recovered on a large scale through high-temperature smelting. Besides, as a byproduct, the glass slag lacks high-value applications. This paper proposes a recyclable method to convert slag, graphite powder (GP), and ferric oxide (Fe2O3) into foamed glass-ceramics through low-temperature sintering, significantly reducing environmental impacts and production costs. Non-isothermal differential thermal analysis was used to explore the transition and crystallization temperature range, transition kinetic, crystallization kinetic, and crystallization behavior of the glass slag. Furthermore, the influence of the foaming agent composition and heat treatment temperature on the physical properties, chemical resistance, and mechanical properties of the foamed glass-ceramics was investigated. Foamed glass-ceramics composed of 60wt% slag-30wt% Fe2O3-10wt% GP exhibited the excellent properties of a geometric density of 1.43 g/cm3, a volumetric water absorption of 26.32%, a compressive strength of 8.08 MPa, and a mass loss of 3.56% in strong acid and 0.08% in strong alkali after low temperature heat treatment at 1160°C. This study provides an insight into transforming low-value waste into high-performance foamed glass-ceramics.

Preparation and performance study of three-dimensional interconnected structured electrodes with lamellar connections

In this study, we developed an innovative strategy to fabricate perovskite oxide powder with 12.356 m2/g of specific surface area. Polyacrylamide hydrogel was used as a template to prepare Sm0.5Sr0.5CoO3-δ (SSC) powders with lamellar structure. The three-dimensional interconnected structured SSC electrodes with lamellar connections were fabricate using screen printing method. As a result, the oxygen vacancy concentration of the SSC powder obtained by the polyacrylamide template method was 0.625 and 0.642 at 650 °C and 700 °C respectively. At 650°C, the polarization resistance value was 0.11 Ω cm2 for the novel SSC-PAM-V cathode. Compared with the SSC-SG cathode, the polarization resistance and activation energy of SSC-PAM-V were reduced by 50 % and 6.9 %, respectively. Furthermore, in a single cell with SSC-PAM-V electrodes, we achieved a maximum power density of 935 and 1243 mW cm−2 at 650 °C and 700 °C under wet H2 conditions, demonstrating good electrochemical output performance. The layered porous electrode was not only suitable for the diffusion of oxygen, but also for increasing the reactive active sites. The proposed powder prepared with polyacrylamide hydrogel as template, was not only suitable for the optimization of perovskite oxide, but also for the application in other types of catalysis, providing the potential for improving the electro-catalytic activity of perovskite electrodes.

Dilatometric measurements of sintering of samples from ultrafine powders of zirconium oxides, aluminum and their mixtures

Dilatometric measurements of sintering of samples from ultrafine powders of zirconium oxides, aluminum and their mixtures

Microstructure and pore structure of one-part geopolymer incorporating electrolytic copper powder and graphene oxide

This study investigates the effect of electrolytic copper powder (ECP) and graphene oxide (GO) on geopolymerisation and microstructural characterisation of one-part alkali-activated material (AAM), which strongly correlates to its thermal-mechanical performance. Various analytical techniques were employed to evaluate the chemical modifications, reaction kinetics, microstructure and pore structure induced by these additives, including X-ray diffraction (XRD), fourier transform infrared (FTIR), isothermal calorimetry, scanning electron microscopy coupling with energy dispersive spectroscopy (SEM/EDS), nitrogen adsorption-desorption (NAD) and nuclear magnetic resonance (NMR). The result findings show that the dissolved Cu2+ ions affect Al–O linkages at AlIV sites in the geopolymer framework. The presence of ECP and GO also reduce the physically-bound water within intralayer and promote the development of highly-crosslinked gel networks characterised by Q4(3Al) sites. ECP in forms of dissolved ions exhibits the adsorption mechanism onto C-(N)-A-S-H gels, while the remaining ECP particles with coral-like shape serve as micro-aggregate filling in the pores. The incorporation of ECP and GO accelerates the geopolymerisation with further gel formation and densification (reduced both total porosity and pore size). Both forms of ECP significantly enhance the thermal conductivity of the geopolymer, and this effect is further amplified by GO inclusion due to higher densification. Overall, the effect of ECP and GO significantly enhances the thermal and mechanical properties of one-part AAM, making them a promising approach for advanced materials such as thermal energy storage (TES) materials.

Oxidation of magnesium particles in a fluidized bed reactor

Magnesium is a promising fuel for the metal-enabled cycle of renewable energy and for space power systems. However, the existing methods for combustion of magnesium powders have difficulties with maintaining flame stability. Further, the kinetics and mechanisms of high-temperature oxidation of magnesium powders, needed for combustion modeling, are still not well understood. In the present work, a fluidized bed reactor was used to study the oxidation of spherical magnesium particles in an oxygen/helium environment at temperatures of 530, 550, and 570 °C. The extent of conversion was determined based on the measured oxygen concentration in the exhaust gas. The obtained curves of the extent of conversion and of the conversion rate were analyzed using the Avrami-Erofeev equation and the Mampel-Delmon model. The activation energy obtained with the Avrami-Erofeev equation was 191 or 198 kJ∙mol−1, depending on the dimension (3 or 2, respectively). The Mampel-Delmon approach has shown that the activation energies of nucleation and growth are equal to 189 and 120 kJ∙mol−1, respectively, i.e., the former is virtually the same as the apparent activation energy obtained with the Avrami-Erofeev model at a dimension of 3. With increasing temperature, the rate of nucleation rises faster than the rate of growth. The results obtained with the Mampel-Delmon approach help understand the oxidation mechanism, while the Avrami-Erofeev equation and the obtained apparent activation energy can be used in combustion modeling for simplicity.

Effects on microhardness, tensile strength, deflection, and drop weight impact resistance with the addition of hybrid filler materials for enhancing GFRP composites

The work evaluated the usage of various filler materials, namely aluminium oxide (Al2O3), magnesium (Mg), and glass powder, in the bidirectional glass fibre reinforced polymer (GFRP) composites. The required samples were fabricated using the hand lay-up technique by varying the filler material proportions from 0%wt. to 7.5%wt., including individual and hybrid mixture combinations. The prepared samples were evaluated for their microhardness, tensile strength, deflection characteristics, and drop-weight impact resistance. It was observed that the optimal addition of individual filler material improved the microhardness and tensile strength more than that of neat composites. In contrast, hybrid compositions at higher proportions exhibited brittleness and lower enactment due to their poor interfacial bonding and particle agglomerations. The deflection characteristics and drop-weight impact tests also showed enhanced stiffness and impact resistance with the addition of hybrid mixtures of filler materials to the composites. The study supports the potential use of adding filler materials to the composites for lightweight structural applications.

Effects of Cu(OH)F nanoparticles on the thermal oxidation and ignition characteristics of micron-sized Al powder

In this study, Cu(OH)F nanoparticles are prepared through a simple hydrothermal reaction and their effects on the thermal oxidation and ignition characteristics of micron-sized Al powder (μ-Al) are explored for the first time. Thermal analysis in air atmosphere (50∼1050 °C) shows that compared to raw μ-Al, the normalized weight gain of Al in Al-Cu(OH)F increases by about 36.9%, 64.8%, and 106.3% when the added Cu(OH)F is 1 wt%, 3 wt%, and 5 wt%, respectively. After mixed with NH4ClO4, electric ignition and open-air combustion tests show shortened ignition delay time (by 42.6%∼63.8%) and increased maximum light intensity (by 48.9%∼117.8%) for Al-Cu(OH)F. The effects of Cu(OH)F result from its decomposition products, namely, HF and CuO. HF reacts with alumina shell to form AlF3, which sublimes at high temperature and thus exposes Al core instantly, while CuO can react with Al core to release heat, further facilitating the thermal oxidation and ignition processes.

Exploring the mechanical and biological properties of a resin-ceramic composite with biomimetic nacre structure containing zinc used for prosthodontics

Enhancement of the mechanical and biological properties of dental restoration materials is of significant importance. Drawing inspiration from the architecture and mechanical properties of natural nacre, we employed a low-cost accumulative rolling process to develop resin-ceramic composites with suitable hardness and high toughness. Plate-like aluminum oxide powder with diameters of 5–10 μm and nano-zinc oxide (ZnO) with antibacterial properties were mixed as the ceramic phase of the composite. Aluminum oxide ceramic plates were stacked using an accumulative rolling process to achieve a consistent orientation, followed by sintering to obtain porous ceramic scaffolds. The ceramic scaffolds were subsequently immersed in methyl methacrylate resin to complete the fabrication of the biomimetic composites. The mechanical and biological properties of the composites were comprehensively tested. The composites had a suitable hardness (1.09–1.63 GPa), excellent flexural strength (156.7–167.8 MPa), and fracture toughness (KIC = 2.66–3.59 MPa m1/2). Biomimetic composites are expected to mitigate the wear of natural teeth without developing fractures or deformations, while also exhibiting excellent cytocompatibility and antibacterial activity. This study investigated the factors influencing crack propagation in fracture tests and provided insights into enhancing the toughness of dental restorative materials. The biomimetic resin-ceramic composites containing Zn developed in this study have the potential to be used as functional dental restoration materials.

A laboratory nondestructive instrument for joint X-ray diffraction and fluorescence measurements of material in a vial

This paper presents an innovative laboratory instrument equipped with high-energy tungsten target X-ray source and a cadmium telluride (CdTe) detector, designed to perform simultaneous X-ray diffraction (XRD) and X-ray fluorescence (XRF) analyses of materials in vials. By using the instrument we successfully captured fluorescence signals from cerium (Ce), erbium (Er), tungsten (W), and bismuth (Bi) in samples housed in vials made of 6061 aluminum (1 mm thick), 304 stainless steel (0.5 mm thick), and brass (0.5 mm thick). In addition, XRD signals from cerium oxide (CeO2) and bismuth oxide (Bi2O3) powders were captured in glass (0.5 mm thick) and 6061 aluminum (1 mm thick) vials. The experiment results reveal that the fluorescence signal also appears in the XRD patterns. The fluorescence analysis enriches the diffraction analysis by offering complementary insights that enhance the information of the overall material characterization. This instrument greatly improves inspection efficiency and enriches inspection information by performing diffraction and fluorescence measurements simultaneously.

Characterization and Synthesis of Graphite, Graphene Oxide, and Reduced Graphene Oxide Powder from Waste Dry Cell Battery Rod

In this paper, graphite, graphene oxide, and reduced graphene powders were successfully synthesized from waste dry cell batter through successive chemical solution methods. Graphite powder was extracted from the graphite electrode of waste batteries rod by acidic chemical treatment. The obtained powder was utilized as a precursor for synthesizing graphene oxide following the new modified Tour method. Eventually, reduced graphene oxide was prepared from the chemical reduction of graphene oxide (GO) by hydrazine hydrate treatment. The obtained recycled graphite, reduced graphene oxide (rGO), and GO materials have been characterized using scanning electron microscopy (SEM), energy dispersive X-ray (EDX), X-ray diffraction (XRD), photoluminescence (PL), and Raman spectroscopy effectively. All the above characterization results confirmed that graphite shows a strong peak at a diffraction angle of 26.5[Formula: see text], corresponding to the (002) plane, shifted to a lower angle of 25.2[Formula: see text] in the case of rGO. In addition, the unsmooth graphite sheet shifted to smooth and flake-like shape of the rGO’s surface morphology. The composite result revealed that different amounts of oxygen and carbon atoms are present in rG, GO and rGO. All the experimental findings ultimately launch the successful formation of exfoliated rGO and better synthesis approach was achieved.

Development of Technology for the Synthesis of Nanocrystalline Cerium Oxide Under Production Conditions with the Best Regenerative Activity and Biocompatibility for Further Creation of Wound-Healing Agents.

Background/Objectives: The issue of effective wound healing remains highly relevant. The objective of the study is to develop an optimal method for the synthesis of nanosized cerium oxide powder obtained via the thermal decomposition of cerium carbonate precipitated from aqueous nitrate solution for the technical creation of new drugs in production conditions; the select modification of synthesis under different conditions based on the evaluation of the physicochemical characteristics of the obtained material and its biological activity, and an evaluation of the broad-spectrum effect on cells involved in the regeneration of skin structure as well as antimicrobial properties. Methods: Several modes of the industrial synthesis of cerium dioxide nanoparticles (NPs) were carried out. The synthesis stages and the chemical and physical parameters of the obtained NPs were described using transmission electron microscopy (TEM), X-ray diffraction, Raman spectroscopy, and mass spectrometry. The cell cultures of human fibroblasts and keratinocytes were cultured with different concentrations of different nanoceria variations, and the cytotoxicity and the metabolic and proliferative activity were investigated. An MTT test and cell counting were performed. The antimicrobial activity of CeO2 variations at a concentration of 0.1-0.0001 M against Pseudomonas aeruginosa was studied. Results: The purity of the synthesized nanoceria powders in all the batches was >99.99%. According to TEM data, the size of the NPs varied from 1 nm to 70 nm under different conditions and methodologies. The most optimal technology for the synthesis of the nanoceria with the maximum biological effect was selected. A method for obtaining the most bioactive NPs of optimal size (up to 10 nm) was proposed. The repeatability of the results of the proposed method of nanoceria synthesis in terms of particle size was confirmed. It was proven that the more structural defects on the surface of the CeO2 crystal lattice, the higher the efficiency of the NPs due to oxygen vacancies. The strain provided the best redox activity and antioxidant properties of the nanoceria, which was demonstrated by better regenerative potential on various cell lines. The beneficial effect of synthesized nanoceria on the proliferative and metabolic activity of the cell lines involved in skin regeneration (human fibroblasts, human keratinocytes) was demonstrated. The antimicrobial effect of synthesized nanoceria on the culture of the most-resistant-to-modern-antibiotics microorganism Pseudomonas aeruginosa was confirmed. The optimal concentrations of the nanoceria to achieve the maximum biological effect were determined (10-3 M). Conclusions: It was possible to develop a method for the industrial synthesis of nanoceria, which can be used to produce drugs and medical devices containing CeO2 NPs.

Formation of Bio-based Derived Dicalcium Silicate Ceramics via Mechanochemical Treatment: Physical, XRD, SEM and FTIR Analyses

Beta-dicalcium silicate plays an important role in modern technology, but its tendency for polymorphic transformation results in the dusting phenomenon, is a major challenge. Therefore, mechanochemical treatment is used to reduce the particle size to retain the stability of the polymorph. In this study, pure dicalcium silicate ceramics of β-monoclinic structure with P 121/c1 space group were synthesized using calcium oxide and silicate powders derived from calcined eggshells and rice husks, respectively. The powders were mixed in a 2:1 molar ratio by mechanochemical treatment and heat-treated in the air at temperatures ranging from 900°C to 1100°C for 2 h. The results reveal that pure betadicalciumsilicate formed at 1100°C without adding stabilizers. The properties of the pristine and sintered bodies were characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, and scanning electron microscopy (SEM). SEM revealed that the grain and pore sizes increase with rising sintering temperatures. FTIR spectra indicate the existence of Si-O bonds in -4 4 SiO tetrahedrons on all the samples. The sample sintered at 1000°C attains the lowest bulk density (1.2463 g/cm3), whereas the apparent porosity is the highest (62.5%). The reason for this trend is due to the decomposition of carbonate into CO2 gas. The densification onset for the sample sintered at 1100°C as the bulk density rises and grain size achieves 6.06 μm. This study further explains the effect of sintering temperatures on the physical, structural, and morphological properties of Ca2SiO4 which would also be useful for further optimization of its use.

Ultrasonic-Assisted Synthesis of Lead Citrate as Precursor for Preparation of Lead Oxide from Lead Sulfate

ABSTRACT In this study, an efficient method of lead recovery from lead sulfate in spent lead-acid batteries assisted by ultrasonic is developed using the citric acid–sodium citrate solution. Ultrasonic-assisted technology is employed to enhance the kinetics of lead sulfate leaching. Initially, the predominance area of the lead citrate complexes was analyzed. The study was conducted to evaluate the effect of ultrasonic-assisted technology on the kinetic behavior of lead sulfate within the citric acid–sodium citrate solution, thereby unveiling the differences between ultrasonic-assisted leaching and the non-ultrasonic-assisted leaching. Kinetic study indicated that the employment of ultrasonic-assisted technology could effectively reduce the apparent activation energy during the desulfurization process, decreasing the energy initially required from 43.27 kJ/mol to 35.15 kJ/mol. Furthermore, the ultrasonic-assisted leaching led to successful preparation of lead citrate precursor, characterized by a smaller particle size and larger specific surface area. Systematic investigations were performed on the thermal decomposition process of these precursors and the effects of calcination temperature and holding time on the properties of calcination products. It was revealed that pure porous lead oxide powder with a purity of 99.9% could be produced successfully under the conditions of calcination temperature at 350°C and holding time of 1 h. The research provides an innovative process for the efficient recovery of lead from spent lead acid batteries.

Controllable mechanism of hazardous jarosite transformation into recyclable hematite in the leaching solution of secondary zinc oxide powder

The controlled synthesis of recyclable hematite in the leaching solution of secondary zinc oxide powder is an urgent problem in the chemical industry and metallurgy fields. In this paper, the effects of the temperature, agitation speed, and seed addition on the contents of iron, sulfur, potassium, sodium, and zinc in the iron removal residues, as well as the iron concentration in the supernatant after iron removal were systematically studied. In addition to the temperature control already reported, we found that the agitation speed can also control the transformation between jarosite and hematite phases. The content of jarosite in the residues can be effectively controlled by adjusting the agitation speed, thereby significantly improving the quality of hematite product, as indicated by SEM-EDS and XRD results. Under temperature of 185 °C, an agitation speed of 500 rpm, and a seed addition of 15 g/L, the iron, sulfur and zinc contents in the filter residues and the iron concentration in the supernatant were 59%, 3.22%, 0.92%, and 4.182 g/L, respectively. Kinetic studies show that the rapid oxidation kinetics is not conducive to the formation of high-quality hematite products. These results can directly guide the process of transformation of harmful jarosite into recyclable hematite from the leaching solution of secondary zinc oxide powder, which is of great practical significance for the controlled and waste-free removal of iron from aqueous solutions in the chemical industry and metallurgy fields.