Facile Precipitation Route Research Articles

Influence of the iron-oxide mass fractions of magnetic powdered activated carbon on its hexavalent chromium adsorption performance in water

Magnetic powdered activated carbon (Mag-PAC) is an effective adsorbent to remove hexavalent chromium (Cr(VI)) from water and can be recovered for reuse. However, the tradeoff between the adsorption performance of Cr(VI) and magnetic properties of Mag-PAC remains unclear. Herein, we prepared a series of Mag-PAC adsorbents containing various iron-oxide mass fractions with FeSO4·7H2O as the precursor, using a facile wet-chemical precipitation route and conducted batch experiments to evaluate the Cr(VI) adsorption performance. Results revealed that Mag-PAC was functionalized by magnetic iron oxide comprising crystalline goethite and magnetite structures. Furthermore, its adsorption performance was highly dependent on pH and was most effective at an initial solution pH of 2. Both the sorption rate constant and Cr(VI) adsorption capacity were greatly influenced by magnetization, and they gradually decreased as the iron-oxide mass fraction increased. Among the prepared adsorbents, Mag-PAC-75 (∼32% wt iron) exhibited not only an excellent Cr(VI) adsorption performance (Langmuir adsorption capacity: 75.76 mg/g) but also effective magnetic properties (saturation magnetization: 9.66 emu/g). Coexisting anions had a negligible competitive effect on Cr(VI) removal by Mag-PAC-75 at an initial pH of 2, whereas the presence of tannic acid markedly improved the Cr(VI) elimination. The presence of trivalent chromium on the surface of Mag-PAC-75 confirmed via X-ray photoelectron spectroscopy indicated that some synergistic redox reactions may occur during the sorption process. After five regeneration cycles using NaOH, Mag-PAC-75 continued to exhibit a high Cr(VI) removal efficiency and magnetic stability. These findings indicate that optimizing the adsorption performance and magnetic properties is a key factor for realizing the practical application of Mag-PAC for Cr(VI) removal. Overall, Mag-PAC may have been a promising application prospect for Cr(VI) removal from water due to its high adsorption capacity and magnetic properties, coupled with its good reusability and magnetic stability after regeneration cycles.

Energy Transfer Processes in NaBiF4 Nanocrystals Co‐Doped with Tb3+ and Eu3+ Dispersed in Aqueous Solution

AbstractThe synthesis of hexagonal NaBiF4 co‐doped with Tb3+ and Eu3+(NaBi0.75−xTb0.25EuxF4; with x=0, 5, 10, 20 and 30) was achieved via a facile and fast precipitation route at 35 °C. Powder X‐ray diffraction (PXRD) and luminescence spectroscopy have been employed to characterize and investigate the materials. The study of luminescence spectroscopy and decay kinetics of the 5D4 excited state of Tb3+ provides the evidence of a Tb3+→Eu3+ energy transfer process. Sodium citrate has been adopted as capping agent to promote a homogeneous dispersion of the materials into water and to protect the inorganic host, which is water sensitive, from direct contact with this molecule. The comparison of luminescence properties between bare and citrate‐capped samples of NaBiF4 co‐doped with Tb3+ and Eu3+ reveals a marked difference in the Tb3+→Eu3+ energy transfer efficiency, which has been tentatively explained on the basis of a different environment surrounding the lanthanide ions in the two families of compounds.

Genesis of copper oxide nanoparticles from waste printed circuit boards and evaluation of their photocatalytic activity

Discarded Printed Circuit Boards (PCBs) are one of the secondary resources of high-purity copper, and precious materials, which if disposed off inappropriately may present several environmental risks. This study focuses on the production of copper oxide nanoparticles (CuO NPs) from reclaimed copper via a facile precipitation route to obtain a value-added nanoproduct. The synthesis involved the dissolution of downsized PCBs, leaching of Cu into the solution phase and the precipitation of nanoparticles (NPs) in an alkaline medium. XRD analysis confirmed the as-synthesized NPs were monoclinic CuO of size 19.23 nm without any impurity. HRTEM analysis confirmed that the NPs were nearly round spheres with average particle size of 19.973 ± 6.036 nm. The NPs have a specific surface area of 200 m2/g and mesoporous structure with mean pore diameter of 18.051 nm. The CuO NPs photocatalyzed the degradation of Congo Red under visible light irradiation. Hence, the PCB e-waste was utilized to produce nanomaterials with added-values, decreasing environmental problems.

A facile homogeneous precipitation route synthesis of LiNi1/3Co1/3Mn1/3O2 cathode material for lithium-ion batteries

LiNi1/3Co1/3Mn1/3O2 (NCM111) cathode material has widen prospects due to its high thermal stability, long battery life and high safety. However, the electrochemical performance of NCM111 is affected by particle distribution microstructure. In this paper, NCM111 cathode material is prepared by urea-based homogeneous precipitation method. The obtained NCM111 has small particle and well distributed, which has good electrochemical performance. The as-synthesized NCM111 cathode material exhibits a good initial discharge specific capacity of 205 mAh/g at 0.2 C. The study manifested that homogeneous precipitation method is a simple way to prepare high property NCM111 cathode material.

Extraction and characterization of highly pure alumina (α, γ, and θ) polymorphs from waste beverage cans: A viable waste management approach

The recycling and recovery of important materials from inexpensive feedstock has now become an intriguing area and vital from commercial and environmental viewpoints. In the present work, extraction of different single phases of alumina (α, γ, θ-Al2O3) having high purity (>99.5 %) from locally available waste beverage cans (∼95 % Al) through facile precipitation route calcined at distinct temperatures has been reported. The optimization of process technology was done by a variety of different synthesis parameters, and the production cost was estimated between 84.47-87.45 USD per kg of alumina powder. The as prepared alumina fine particles have been characterized using different sophisticated techniques viz. TG-DTA, WD-XRF, XRD, FT-IR, SEM, DLS-based particle size analysis (PSA) with zeta (ζ) potential measurement and UV–Visible Spectroscopy. X-ray diffractogram confirms the formation of γ-, θ-, and α-alumina at 500–700 °C, 900–1000 °C, and 1200 °C respectively and crystallite size, crystallinity, strain, dislocation density, and specific surface area were measured using major X-ray diffraction peaks which varies with temperature. The SEM studies showed that the as prepared alumina particles were agglomerated, irregular-shaped with particle size (0.23–0.38 µm), pore size, and porosity were calculated from SEM image. ζ-potentials at different pH values as well as isoelectric point (IEP) of α, γ, and θ alumina were calculated in an aqueous medium which changes with temperature. The direct band gap (Eg) energies were found between 4.09 and 5.19 eV of alumina obtained from different calcination temperatures. The synthesized materials can be used in sensors, ceramics, catalysis, and insulation applications.

A facile surfactant-assisted precipitation route to self-assembled 3D flower-shaped NiO nanostructures with enhanced surface area

A facile surfactant-assisted precipitation route to self-assembled 3D flower-shaped NiO nanostructures with enhanced surface area

Preparation of Novel Triangular Prism e -Zn(OH)2 by the Facile Precipitation Route for the Photocatalysis Under Visible Light

Objective: This study aims to decompose antibiotic of tetracycline hydrochloride (TCH) in aqueous medium by photocatalysis under the visible light irradiation. Method: Photocatalyst e -Zn(OH)2 was synthesized by facile precipitation method from an aqueous containing zinc nitrate, using trisodium citrate dihydrate. The characterization of as-prepared material was confirmed by XRD, SEM, FI-IR, and UV-Vis-DR. The catalytic performance of catalyst was evaluated by batch reaction. Finding: e -Zn(OH)2 has an orthorhombic structure with a length prism of 5-7 mm and triangle angles of 56.92, 69.46, and 66.71o e -Zn(OH)2 has been shown to efficiently degrade tetracycline hydrochloride. The degradation efficiency (DE) and reaction rate at the TCH concentration of 5 mg/L were the highest, exhibiting 89.51% and 0.120 min-1, respectively. The alkaline medium was an appropriate condition for degradation of TCH on catalyst. Application/Improvement: e -Zn(OH)2 was synthesized by the facile precipitation method, it has relatively strong photocatalytic ability for applying in treatment of medical wastewater. Novelty: Novel triangular prism e -Zn(OH)2 was prepared for photocatalysis. The relationship between structure and catalytic efficiency was investigated in detail. In addition, the photocatalytic mechanism of TCH on e -Zn(OH)2 has been proposed. Keywords: Photocatalyst; Zn(OH) 2; Tetracycline hydrochloride; Degradation; Kinetic

Development of Ag-dendrites @Cu nanostructure for removal of selenium (IV) from aqueous solution.

Removal of selenite (Se (IV)) from wastewater is vital due to its more toxic and mobile properties. In this study, a novel dendritic silver-dendrites@ copper with hierarchical side-branches were synthesized through a two-pot rapid, facile, and green precipitation route. Characterization of the dendrites by transmission electron microscope (TEM), scanning electron microscope (SEM), dynamic light scattering (DLS), and X-ray diffraction spectroscopy (XRD) confirmed the proper preparation of dendritic AgCu nanostructure. Significantly, the Ag@Cu nanostructure has high specific surface area (150 m2/g) and excellent adsorption activity toward selenite. The adsorption rate of Se (IV) on the dendritic AgCu reaches 94% within 60 min under normal adsorption procedures. Both adsorption kinetics and isotherms have been described well by the pesudo-second order model and Langmuir model, respectively. The noticeable high adsorption capabilities can mainly accredit to the effect of the hierarchical side-branched structure. Therefore, the dendritic AgCu nanostructure has a room of treating heavy metals-contaminated industrial wastewater streams. PRACTITIONER POINTS: Silver-dendrites@ copper with hierarchical side-branches were synthesized through a rapid and green precipitation route using copper nanoparticles. The prepared nanostructure was applied for Se (IV) adsorption at varying operational conditions (contact time, pH, and dose). High adsorption capacity for Se (IV) up to 173.1 mg/g was achieved using the prepared nanoparticles applying Langmuir isotherm model.

Insights of precursor phase transition of (Cu-Zn-Al)/γ-Al2O3 hybrid catalyst for one step dimethyl ether synthesis from syngas

The concerns on environmental pollution and climate change, along with ever-growing energy demands, have driven interest in dimethyl ether (DME) as a clean fuel alternative and a versatile chemical intermediate. Due to the advantages of single-step synthesis of DME, we investigated the influence of precursor phase transition of methanol synthesis catalyst from hydrotalcite to zincian malachite on the hybrid catalyst’s activity for direct syngas to DME process by varying its Cu/Al content. A series of Cu-Zn hybrid catalysts were prepared via a kneading extrusion process by physical mixing of methanol synthesis catalyst (CuO:ZnO:Al2O3) prepared via facile forward precipitation route with CuO/Al2O3 ratios 1.5–6 and the dehydration component boehmite (γ-AlO(OH)). The physicochemical aspects of prepared hybrid catalysts were studied in detail by BET, XRD, N2O chemisorption, H2-TPR, NH3-TPD, SEM, and TEM. The activity studies revealed that the catalyst with a lower CuO/Al2O3 (1.5) ratio derived from the phase pure hydrotalcite precursor showed enhanced catalytic activity with a high CO conversion 60.5% and DME selectivity 71.5%. Whereas the catalyst with a high CuO/Al2O3 (6) ratio showed relatively lower DME selectivity, although it was derived from the phase-rich zincian malachite, which is a preferred active phase for methanol synthesis. The higher yield of DME with hydrotalcite-derived hybrid catalyst was most likely attributed to the well dispersed nanostructured active Cu sites and the higher number of weak and medium strength acidic sites. Moreover, the phase transition of dehydration component boehmite to γ-Al2O3 helps in methanol dehydration with its characteristic Lewis acidity.

Well-defined Gd(OH)CO3, Gd2O(CO3)2·H2O, and Gd2O3 compounds with multiform morphologies and adjustable particle sizes: Synthesis, formation process, and luminescence properties

A variety of monodisperse size-tunable Gd(OH)CO3 nanospheres and Gd2O(CO3)2·H2O microplates have been synthesized via a facile homogeneous precipitation route with a mixing solvent of isopropanol (IPA) and H2O. The morphology and particle size of the gadolinium compounds can be tuned in a controlled manner by simply adjusting the volume ratio of IPA/H2O in solvent or reaction temperature and time. Both the amorphous Gd(OH)CO3 nanospheres and crystalline Gd2O(CO3)2·H2O microplates have been transformed into cubic phase of Gd2O3 after a calcination process in air. Interestingly, the Gd2O3 products perfectly inherit the well-defined morphology, good unifomity and dispersity of the precursor samples except for a shrinkage in particle size due to crystallization and coalescence at high temperature. The Gd2O3:Eu3+ and Gd2O(CO3)2·H2O:Tb3+ samples show red and green emission colors under ultraviolet excitation, and Gd2O3:Yb,Ln3+ (Ln = Er and Ho) samples exhibit characteristic orange-red and green emissions when excited at near-infrared (NIR) excitation. The morphology- and particle size-dependent luminescence performances of phosphors are studied in detail. Moreover, the light emitting diode (LED) devices fabricated with the corresponding down-conversion or up-conversion phosphors can display dazzling characteristic multicolor emissions, revealing that the as-synthesized luminescent materials have potential application prospect in the fields of LEDs, light display systems, and optoelectronic devices.

ZnS quantum dots and Bi metals embedded with two dimensional β-Bi2O4 nanosheets for efficient UV-visible light driven photocatalysis

In this work, the ZnS QDs, Bi/β-Bi2O4 and ZnS/Bi/β-Bi2O4 nanocomposite were synthesized through a facile precipitation, solvothermal and wet impregnation route respectively. The combination of bare ZnS QDs with Bi/β-Bi2O4 nanocomposite exhibits superior photocatalytic activity against toxic pollutants (MB & Rh B) and it’s attributed to the increased light-absorption capacity, efficient charge transfer process, extraordinary exciton separation, less photogenerated electron-hole recombination. The ZnS/Bi/β-Bi2O4 nanocomposite was found to be 3 times more efficient as a photocatalyst than pristine ZnS QDs. Besides, this composite demonstrates good stability for photocatalytic activities, no substantial decomposition of activity is being observed after 5 cycle’s run devoid of a main defeat in their performance. Scavenger test were also implemented in order to appreciate the possible mechanism of photodegradation. This superior photocatalytic activity and stability may offer a new sight in the improvement of a photocatalyst with large efficiency for practical application of wastewater treatment.

Synthesis of Core/Shell Structured Zinc Borate/Silica and Its Surface Charring for Enhanced Flame Retardant Properties

An efficient zinc borate/silica composite flame retardant (CFR), with accumulating nano-silica (SiO2) on the surface of grown zinc borate (ZnB) flakes to form a core/shell structure, was synthesized via a facile precipitation route. When mixed with methyl vinyl silicone rubber (VMQ), this combined structure of CFR brought advantages in both flame retardancy and mechanical properties. During a process of combustion, these CFR particles migrated and assembled on the surface of combustion zone, increasing the local concentration and generating a tight and intumescent surface char layer even at a lower loading amount. In comparison with the VMQ/physical mixture (PM, with the same proportion of SiO2 and ZnB), the EVA/CFR formulation passed a UL94 V–0 rating and got a LOI value of 29.5, when used as an alternative of SiO2 filler. Meanwhile, CFR played an effective role in inhibiting the spread of fire; VMQ/CFR showed a fire growth index (FGI) of 0.56 much lower than 0.92 of VMQ/PM. In this case, the heat release rate (HRR), total heat released (THR) and smoke production rate (SPR) were considerably reduced. Moreover, the mechanical properties of VMQ/CFR blends, including both tensile strength (TS) and elongation at break (EAB), were significantly enhanced.

Room-temperature one-step synthesis of tube-like S-scheme BiOBr/BiO(HCOO)Br-x heterojunction with excellent visible-light photocatalytic performance

Ultrathin-nanosheet-based bismuth oxide formate (BiOHCOO, denoted as BiOR) tubular hierarchitecture was prepared by a facile room-temperature precipitation route. In order to enlarge its visible-light absorption, tubular solid solutions BiO(HCOO)Br-x (BiORBr-x, x referring to the feeding molar ratio of Br/Bi) were obtained by using similar method through simultaneously adding KBr and HCOONa into Bi(NO3)3 aqueous solution. By controlling the x value at 0.6, the heterojunction BiOBr/BiORBr-0.6 was obtained, which exhibited greatly enhanced visible-light photocatalytic activity and malachite green (MG) could be completely decomposed within 60 min of visible light irradiation, whereas the degradation efficiency of MG on BiOR, BiOBr, the solid solution BiORBr-0.4 and BiOBr/BiOR was only 7%, 50%, 49%, 60%, respectively. In addition, BiOBr/BiORBr-0.6 exhibited excellent removal rate to rhodamine B (RhB, 98%) and antibiotic tetracycline (TC, 80%) within 120 min of the irradiation. The detailed characterization indicates that good photocatalytic performance of BiOBr/BiORBr-0.6 could be attributed to the construction of interfacial-close-contacted step-scheme (S-scheme) heterojunction between BiOBr and the solid solution BiORBr-0.4, which could preserve electrons and holes with higher redox ability. And also, tube-like microstructure of BiOBr/BiORBr-0.6 facilitated highly efficient and directional transfer of charge carriers and transportation of chemical substances.

A novel ternary mica-titania@rGO composite pearlescent pigment for the photocatalytic degradation of gaseous acetaldehyde

The photocatalytic application of TiO2 is limited due to low light harvesting abilities in the whole solar spectrum and fast recombination of the photoinduced electron-hole pairs. Herein, we report a TiO2-based ternary composite photocatalyst (MT@rGO-x; x = 0.05–0.2) with a pearlescent color effect, which incorporates a mica reflection core and a rGO multifunctional shell as cocatalysts. The micro flake composites were synthesized by a facile precipitation route and applied first to photodegrade gaseous acetaldehyde. MT@rGO-0.1 composite has optimal performance, which is 2.5 times photodegradation efficiency and 3 times CO2 mineralization efficiency higher than those of pure TiO2. The enhanced photocatalytic performance of MT@rGO composite is associated with effectively improved light harvesting of TiO2 by mica reflection. The presence of rGO facilitates the separation of electron-hole pairs and pollutant absorption. In addition, the superoxide radical was proved as the decisive active species for the photodegradation of acetaldehyde by electron spin resonance analyses and radical quenching tests. Our MT@rGO photocatalyst is expected to be applied as a functional and decorative additive of car paint, which is subject to photodegradation due to air pollutants.

Study on photocatalytic and impedance spectroscopy investigations of composite CuO/ZnO nanoparticles

This paper reports the preparation of composite CuO/ZnO nanoparticles by facile precipitation route and their photocatalytic activity against organic dyes. The red shift caused in the UV–Vis absorption spectrum suggests the enhancement of visible light photocatalytic activity of the material. The collective vibrations of Cu–O and Zn–O in FTIR spectrum clearly illustrate the formation of composite CuO/ZnO nanoparticles. Powder XRD profile suggests the formation of highly crystalline material and the chemical states of the elements is investigated by XPS analysis. A slightly agglomerated cluster-like structure of the particles is visualized by SEM analysis and EDS mapping illustrates the homogeneous distribution of the sample, which is most favorable for the photocatalysis analysis. The photocatalytic activity of material is studied against degradation of Rhodamine B and Methylene blue dyes using simulated solar light irradiation. The dielectric analysis of the composite CuO/ZnO nanoparticles demonstrates the enhanced dielectric permittivity and low loss factor in comparison with pure CuO and ZnO nanoparticles.

Facile fabrication of a novel BiPO4 phase junction with enhanced photocatalytic performance towards aniline blue degradation.

A novel BiPO4 photocatalyst has been fabricated via a facile precipitation route using dimethyl sulfoxide (DMSO) as a solvent. The physical and chemical properties of the BiPO4 photocatalyst material were analyzed using XRD, Rietveld refinements XRD, FE-SEM, TEM, HR-TEM, EDS, XPS, FT-IR, Raman spectra, UV-Vis (DRS), and PL. The results confirm that hexagonal phase BiPO4 (HBIP) nanorods were successfully synthesized. FE-SEM images reveal that the addition of surfactant “CTAB” during preparation can control the surface morphology of BiPO4. The Rietveld refinement technique revealed the formation of a monazite monoclinic (nMBIP) and monoclinic (mMBIP) phase junction resulting from the calcination of HBIP at 500 °C. The photocatalytic behavior of the as-synthesized hexagonal and monoclinic BiPO4 nanostructures towards aniline blue (AB) degradation under UV light was systematically investigated. Among all catalysts, the phase junction (nMBIP–mMBIP) structure demonstrated the highest photocatalytic activity. The degradation rate of AB over the (nMBIP–mMBIP) phase junction structure was 3.4 times higher than that by HBIP. These results suggested that the surface-phase junction provides a synergistic effect for the electron–hole transfer process.

A facile coordination precipitation route to prepare porous CuO microspheres with excellent photo-Fenton catalytic activity and electrochemical performance

Porous CuO microspheres were prepared via a coordination precipitation route and exhibited superior photocatalytic activity and electrochemical performance.

Na-Rich Prussian White Cathodes for Long-Life Sodium-Ion Batteries

Prussian blue analogues (PBA) recently have received great interest for promising applications in low-cost sodium-ion batteries (SIBs). However, controlled synthesis of high-performance PBA is still challenging. In this work, a facile precipitation route was used to synthesize Na-rich PBAs with superior electrochemical performance. It was found that two shapes of the products, namely, small irregular particles and large cuboid particles, coexist by adding sodium citrate in the sodium hexacyanoferrate side during the synthesis. The product shows large capacity (144 mAh g–1 under a 0.1 C rate), good rate performance (115.6 mAh g–1 under a 1 C rate, 86.6 mAh g–1 under a 10 C rate), and long-term cycling stability (73.4% retention after 780 cycles under a 0.5 C rate, 72.7% retention after 2100 cycles under a 1 C rate). This work offers a promising route to prepare PBA-based cathode materials for high-performance SIBs.

Facile synthesis of porous LiMn2O4 micro-/nano-hollow spheres with extremely excellent cycle stability as cathode of lithium-ion batteries

In present work, the porous LiMn2O4 micro-/nano-hollow spheres are directly prepared from the globe precursor MnCO3 obtained via a facile precipitation route without any intermediate and ethanol. X-ray diffraction and scanning electron microscopy results indicate that the as-synthesized porous LiMn2O4 micro-/nano-hollow spheres are composed of nanometer-sized primary particles. Charge–discharge tests, cyclic voltammetry, and electrochemical impedance spectra show that the obtained LiMn2O4 delivered higher reversible capacity, extremely excellent cycle stability, superior kinetic properties, and rate capacities. Specially, there are nearly no any capacity loss after 200 cycles, and the coulombic efficient is nearly close to 100%, which are attributed the unique porous micro-/nano-hollow structure and a better crystallinity.

A Green Route to Synthesize Pr3+/Dy3+-Doped Nd2O3 Nanoreplicas from Nd–Fe–B Magnets

This paper details a green and sustainable process for synthesizing highly concentrated Pr3+/Dy3+-doped Nd2O3 nanoparticles from Nd–Fe–B magnets sourced from e-waste via a facile homogeneous precipitation route under mild conditions. Rare earth elements (REEs) are under a serious crisis owing to their uncertain supply and increasing global demand. REEs’ future demand growth is mainly linked to the use of Nd–Fe–B magnets, which are currently one of the most widely used types of rare-earth magnets with extensive implementation in a variety of applications. Using REEs (i.e., Nd, Pr, and Dy) derived from Nd–Fe–B magnets, we applied a low temperature urea-based homogeneous precipitation method and synthesized crystallized RE (i.e., Nd, Pr, and Dy) OHCO3 nanoparticles with diameters of 40–50 nm and high specific surface area of 60 m2 g–1. The synthesized REOHCO3 was used as a precursor for the synthesis of REO nanoparticles through a thermal degradation process at 700 °C. FE-SEM images revealed that the synthes...