One-step Co-precipitation Method Research Articles

Defect-Healing Induced Monoclinic Iron-Based Prussian Blue Analogs as High-Performance Cathode Materials for Sodium-Ion Batteries.

Prussian blue analogs (PBAs) have attracted wide interest as a class of ideal cathodes for rechargeable sodium-ion batteries due to their low cost, high theoretical capacity, and facile synthesis. Herein, a series of highly crystalline Fe-based PBAs (FeHCF) cubes, where HCF stands for the hexacyanoferrate, is synthesized via a one-step pyrophosphate-assisted co-precipitation method. By applying this proposed facile crystallization-controlled method to slow down the crystallization process and suppress the defect content of the crystal framework of the PBAs, the as-prepared materials demonstrate high crystallization and a sodium-rich induced rhombohedral phase. As a result, the as prepared FeHCF can deliver a high specific capacity of up to 152.0mAhg-1 (achieving ≈90% of its theoretical value) and an excellent rate capability with a high-capacity retention ratio of 88% at 10C, which makes it one of the most competitive candidates among the cathodes reported regarding both capacity and rate performance. A highly reversible three-phase-transition sodium-ion storage mechanism has been revealed via multiple in situ techniques. Furthermore, the full cells fabricated with as-prepared cathode and commercial hard carbon anode exhibit excellent compatibility which shows great prospects for application in the large-scale energy storage systems.

Boosting the H2O resistance and NH3-SCR activity over sulfated FeCe0.5 SmaTi4Ox-S catalysts by Sm modification

In this work, a series of Sm modified sulfated FeCe0.5Ti4Ox-S catalysts were successfully prepared by a concise one-step co-precipitation method for application in flue gases denitrifications (de-NOx) generated from high sulfur content coal-fired power plants. The catalysts were carried out by XRD, Raman, N2 adsorption and desorption, TEM, EDS spectroscopy, NH3-TPD, H2-TPR, XPS, and in-situ DRIFTS characterization. Among these catalysts, FeCe0.5Sm0.3Ti4Ox-S showed the best catalytic activity, maintaining 100% NO conversion in 260–450 °C, high N2 selectivity and good resistance to water and SO2 poisoning. The results demonstrated that the addition of appropriate amount of Sm promoted the interaction between Sm, Ce, Fe and Ti, which increased the oxidation capacity and L-acid sites on the catalyst surface, improving the catalytic activity. Additionally, the increase of L acid sites also contributed to the improvement of water resistance of the catalyst. In-situ DRIFTS studies also indicated that the Sm addition promoted NH3 adsorption in the presence of water due to the reaction of special surface sulfates with H2O to form additional B acid sites, which may be the reason for the negligible effect of water on the catalytic activity. Based on various characterizations, the NH3-SCR de-NOx processes are proposed over FeCe0.5Sm0.3Ti4Ox-S in presence of H2O.

Single-atom Pt-CeO2/Co3O4 catalyst with ultra-low Pt loading and high performance for toluene removal

The design and manufacture of high activity and thermal stability catalysts with minimal precious metal loading is essential for deep degradation of volatile organic compounds (VOCs). In this paper, a novel single-atom Pt-CeO2/Co3O4 catalyst with ultra-low Pt loading capacity (0.06 wt%, denoted as 0.06Pt-SA) was fabricated via one-step co-precipitation method. The 0.06Pt-SA exhibited excellent toluene degradation activity of T90 = 169 °C, matched with the nanoparticle Pt-supported CeO2/Co3O4 catalyst with more than six times higher Pt loading (0.41 wt%, denoted as 0.41Pt-NP). Moreover, the ultra-long durability (toluene conversion remains 99% after 120 h stability test) and excellent toluene degradation ability in a wide space speed range of 0.06Pt-SA were superior to that of 0.41Pt-NP catalyst. The excellent performance was derived from the strong metal-support interaction (SMSI) between the single atomic Pt and the carrier, which induced more Pt0 and Ce3+ for oxygen activation and more Co3+ for toluene removal. The in situdiffuse reflectance infrared spectroscopy (DRIFTS) experiments confirmed that the conversion of intermediates was accelerated in the reaction process, thereby promoting the toluene degradation. Our results should inspire the exploitation of noble single-atomic modification strategy for developing the low cost and high performance VOCs catalyst.

Surface synergistic effect of sub-2 nm NiFeCr hydroxide nanodots yielding high oxygen evolution mass activities

Designing cost-effective electrocatalysts with high efficiency and stability for oxygen evolution reaction (OER) is crucial for hydrogen generation by water splitting and meta-air batteries. NiFe catalysts doped with transition-metal cations have offered an efficient approach to tuning the atomic and electronic structure, thus enhancing OER activity. However, most research focused on regulating the composition of atoms in large-sized catalysts, which remains a major challenge to achieving high atom utilization efficiency and optimal surface synergistic effect. Herein, a one-step co-precipitation method is presented to directly synthesize ultrafine NiFeCr trimetallic amorphous hydroxide nanodots (AND-NiFeCr, < 2 nm) to fully expose the atoms at the surface and near-surface region. Electronic-structure investigation revealed a strong synergistic electronic interaction between Ni, Fe, and Cr cations, which subtly tailors ternary catalysts' local atomic and electronic configuration. Due to the refined ultrafine nano- and electronic-structure modulation, the optimized AND-NiFeCr (Ni:Fe:Cr = 5:3:2) catalysts demonstrated superior OER activity with a low overpotential of 271 mV at 10 mA cm−2. Moreover, an extraordinarily high mass activity of 4926 A gMetal-1 at the overpotential of 300 mV was achieved. This work provides a novel surface synergistic effect strategy to design highly efficient NiFe-based ultrafine hydroxide OER catalysts with high atomic utilization efficiency.

Electron transfer degradation of ciprofloxacin by peroxydisulfate intercalated MgAlFe-layered double hydroxides: Roles of laminate structure and interlayer peroxydisulfate

Peroxydisulfate intercalated MgAlFe-layered double hydroxides (S2O8·LDHs) are synthesized by the one-step co-precipitation method. The Fe content in LDH laminates affects the insertion of S2O82−, and further affects the catalytic activity of S2O8·LDHs. Fe-S2O8·LDH-0.2 with Fe/(Al + Fe) = 0.2 shows superior performance that 1 g/L of dosage leads to 99.55 % degradation of ciprofloxacin (CIP, 10 mg/L) within 60 min. It is fully clarified that electron transfer rather than SO4•−, •OH, O2•− and 1O2 is responsible for CIP degradation. Interlayer S2O82− with longer OO bond length than free S2O82− exists in metastable form, which deprives electrons from the piperazine ring of CIP mainly through the transport of LDH laminates, leading to the degradation of CIP through the cleavage and oxidation of piperazine ring. The efficient degradation of other fluoroquinolones and the modest even negligible influence of Cl−, NO3–, HCO3–/CO32– and natural organic matter on the performance prove the practical application potential of S2O8·LDHs. This work not only provides an in-depth study on the degradation of emerging pollutants by PDS intercalated LDHs, but also provides some new insights into the non-radical mechanism.

Sustainable synthesis of vanadate/fluorapatite nano-crystallites from solid waste for enhanced photocatalysis and pollution removal

In this work, vanadate-fluorapatite, V2O5/Ca10(PO4)6F2, nanocrystals were successfully synthesized through a straightforward one-step co-precipitation method. This method was based on two toxic solid wastes, which are mainly generated as by-products during sulfuric acid manufacturing and in the phosphate industry. The two solid wastes were mainly based on phosphogypsum as a source of calcium and vanadium pentoxide as a source of vanadate. In comparison to numerous conventional methods for FAP synthesis, this innovative method is not laborious, not complex, cost-effective, and environmentally friendly, thanks to the recovery of toxic solid wastes. Furthermore, it consists of mixing various contents of anhydrous gypsum with phosphoric acid, vanadium pentoxide, and ammonium fluoride at one time and at room temperature with no further adjustment of the pH. Several physicochemical characterization techniques were used, including X-ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FT-IR), and Ultraviolet-Visible Spectroscopy (UV-vis). Whereas SEM analysis of the crystals obtained showed a nanometer-scale fluorapatite crystallites was obtained. The obtained results offer exciting potential for applying the prepared nanomaterial in both photocatalysis and pollution removal. They hold great promise and are expected to generate significant interest in these fields.

Ultra-small manganese dioxide nanoparticles with high T1 relaxivity for magnetic resonance angiography.

Gadolinium (Gd)-based contrast agents (CAs) for clinical magnetic resonance imaging are facing the problems of low longitudinal relaxivity (r1) and toxicity caused by gadolinium deposition. Manganese-based small molecule complexes and manganese oxide nanoparticles (MONs) are considered as potential alternatives to Gd-based CAs due to their better biocompatibility, but their relatively low r1 values and complicated synthesis routes slow down their clinical translation. Herein, we presented a facile one-step co-precipitation method to prepare MONs using poly(acrylic acid) (PAA) as a coating agent (MnO2/PAA NPs), which exhibited good biocompatibility and high r1 values. A series of MnO2/PAA NPs with different particle sizes were prepared and the relationship between the particle size and r1 was studied, revealing that the MnO2/PAA NPs with a particle size of 4.9 nm exhibited higher r1. The finally obtained MnO2/PAA NPs had a high r1 value (29.0 Mn mM-1 s-1) and a low r2/r1 ratio (1.8) at 1.5 T, resulting in a strong T1 contrast enhancement. In vivo magnetic resonance angiography with Sprague-Dawley (SD) rats further proved that the MnO2/PAA NPs showed better angiographic performance at low-dosage administration than commercial Gadovist® (Gd-DO3A-Butrol). Moreover, the MnO2/PAA NPs could be rapidly cleared out after imaging, which effectively minimized the toxic side effects. The MnO2/PAA NPs are promising candidates for MR imaging of vascular diseases.

Metal-organic frameworks-derived In2O3/ZnO porous hollow nanocages for highly sensitive H2S gas sensor

The detection of hydrogen sulfide (H2S) is critical because of its potential harm and widespread presence in the oil and gas sectors. The zeolitic imidazolate framework-8 (ZIF-8) derived ZnO nanostructures manufactured as gas sensors have exceptional sensitivity and selectivity for H2S gas. In/Zn-ZIF-8 template material was synthesized by a simple one-step co-precipitation method followed by thermal annealing in air. The heat treatment resulted in In2O3/ZnO nanostructures with mixed heterostructures. The crystal structure (XRD), morphology (SEM/TEM), chemical state (XPS), surface area (BET), etc were investigated to ascertain the nature of the as-prepared material. SEM imagery revealed that the as-prepared In2O3/ZnO sensitive material had a microstructure of porous hollow nanocages with an average particle size of about 200 nm, which is beneficial to the diffusion and adsorption of gas molecules. The gas sensing performance test results of the In2O3/ZnO hollow nanocages show that their response to H2S gas is significantly improved 67.5 @50 ppm H2S (about 11 times that of pure ZnO nanocages) at an optimal temperature of 200 °C, better selectivity, lower theoretical detection limit and good linearity between gas concentration and response values. The enhanced gas sensing feat to H2S gas is mainly attributed to the formation of n-n heterojunction and the wide surface area of the newly formed In2O3/ZnO porous hollow nanocages.

Unravelling the active sites and structure-activity relationship on Cu–ZnO–Al2O3 based catalysts for water-gas shift reaction

Herein, we investigated the main active sites and structure-sensitivity of the water-gas shift (WGS) reaction over ternary Cu–ZnO–Al2O3 (CZA) catalysts. CZA catalysts with various Cu contents were synthesized by the homogeneous one-step coprecipitation method. The Cu content mainly affected the number of active Cu sites and was closely related to the WGS activity. Turnover frequency (TOF) values were independent of Cu dispersion, indicating that the CZA catalyst is structure-insensitive in WGS. The ratio of surface Cu+ species also strongly influenced the activity of the CZA catalyst. TOF based on the total active Cu species showed a constant value, but the CO conversion was linearly increased with the number of surface Cu+ species.

Covalently-Bonded Coating of L-Arginine Modified Magnetic Nanoparticles with Dextran Using Co-Precipitation Method.

In this study, L-arginine (Arg) modified magnetite (Fe3O4) nanoparticles (RMNPs) were firstly synthesized through a one-step co-precipitation method, and then these aminated nanoparticles (NPs) were, again, coated by pre-oxidized dextran (Dext), in which aldehyde groups (DextCHO) have been introduced on the polymer chain successfully via a strong chemical linkage. Arg, an amino acid, acts as a mediator to link the Dext to a magnetic core. The as-synthesized Arg-modified and Dext-coated arginine modified Fe3O4 NPs were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transformation infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), and vibrating sample magnetometer (VSM). Both synthesized samples, XRD pattern and FT-IR spectra proved that the core is magnetite. FT-IR confirmed that the chemical bonds of Arg and Dext both exist in the samples. SEM images showed that the NPs are spherical and have an acceptable distribution size, and the VSM analysis indicated the superparamagnetic behavior of samples. The saturation magnetization was decreased after Dext coating, which confirms successive coating RMNPs with Text. In addition, the TGA analysis demonstrated that the prepared magnetic nanocomposites underwent various weight loss levels, which admitted the modification of magnetic cores with Arg and further coating with Dext.

Facile synthesis of FeCoW oxides: Effects of amorphous structure, electronic configuration and catalytic sites on water oxidation

Catalysts with amorphous structures have shown excellent performance in electrocatalytic water oxidation, but it remains a challenge to prepare efficient catalysts using simple methods while maintaining high yields. Herein, amorphous FexCoyWz oxides nanoparticles were prepared by a one-step co-precipitation method, and the Fe content was optimized to ensure efficient water oxidation. The prepared Fe0.05Co0.09W0.61O0.25 had the best OER performance with a yield of 95.6% when the Co and Fe feeding ratio was 2:1. The Fe0.05Co0.09W0.61O0.25 possessed an overpotential of 267 mV at 10 mA cm−2 with a small Tafel slope of 39.4 mV dec−1. The activation energy at 1.5 V is only 49.4 kJ mol−1, and Faraday efficiency is close to 100%. The water oxidation performance of the two-electrode test shows that the voltages at 10 mA cm−2 are only 1.50 V. In addition, it still maintained high activity after 72 h of chronoamperometry test, which exhibits excellent water oxidation performance among similar non-precious transition metal catalysts. Therefore, the present work provides a simple and easy way to prepare high-activity and high-yield transition metal amorphous electrocatalysts.

V2O5-WO3 catalysts treated with titanium isopropoxide using a one-step co-precipitation method for selective catalytic reduction with NH3

Selective Catalytic Reduction (SCR) of nitrogen oxides (NOx) is the most effective way to reduce NOx emissions. However, the most used catalysts for this purpose, V2O5-WO3/TiO2 (VWTi) hybrid system, have limited applicability owing to its narrow operating temperature range (300–400 °C). Therefore, catalysts with abundant active sites are needed to extend the temperature range to more acceptable values (200–400 °C). The number of active sites depends on the catalyst synthesis method. The aim of this study is to increase the dispersion of V-OH and W-OH through a one-step process, this is achieved by treating the TiO2 support with titanium isopropoxide (TTIP) and simultaneously incorporating the V-OH and W-OH. This synthesis method used here is expected to enhance the interaction between the support and V-OH and W-OH by increasing the number of catalytically active sites. This process is simple and could be applied for the catalyst manufacturing process in the industrial scale. The optimal performance observed for the catalysts prepared at a TTIP loading of 5 wt% using a one-step method is due to its higher catalytic activity at lower temperatures, the observed results could be explained based on the formation of abundant V-OH and W-OH functional groups and the V4+/V5+ ratio (≈1). The scope of this study is to develop a new catalyst for selective catalytic reduction of nitrogen oxides.

Facile design of wolframite type CoWO4 nanoparticles: A selective and simultaneous electrochemical detection of quercetin and rutin

Facile construction of CWO/SPCE for electrochemical detection of QCT and RU. • Wolframite type CoWO 4 was synthesized by the facile one-step coprecipitation method. • CoWO 4 /SPCE showed improved performance for simultaneous detection of QCT and RU. • The proposed sensor demonstrated low LOD, high selectivity, and good stability. • Real-time analyses of QCT and RU was investigated in fruit juice sample. Flavonoids (FLs) have impressive attention in food-related items and medicinal areas because of their significant impact on the quality, function, and safety of the products. Thus, it is crucial to develop a simple and fast detection method for FLs in food and pharmaceutical samples. Consequently, we chose the rapid and cost-effective electrochemical detection method for FLs in a food sample. Herein, we report the facile design of wolframite type CoWO 4 (CWO) as an efficient electrocatalyst for simultaneous detection of quercetin (QCT) and rutin (RU). Crystallinity, structural morphology, and electrochemical investigations of CWO were characterized by using various spectrometric techniques and electroanalytical methods. The CWO modified screen-printed carbon electrode (SPCE), compared with a bare electrode demonstrated high electrochemically active surface area, better conductivity, and improved electrochemical sensing performance toward QCT and RU. Considering these advantages of CWO/SPCE, the optimized differential pulse voltammetric results showed the lowest detection limit of QCT as 0.022 µM and RU as 0.018 µM with the linear concentration of 0.2–521 µM (QCT) and 0.2–681 µM (RU). Significantly, CWO/SPCE displayed excellent selectivity for QCT and RU with effective interfering molecules, good stability (cyclic and storage), and reproducibility with five successive measurements. The practical analysis test was applied to QCT and RU in real fruit juice with the observed recoveries being acceptable.

Computational and experimental elucidation of the boosted stability and antibacterial activity of ZIF-67 upon optimized encapsulation with polyoxometalates.

Water microbial purification is one of the hottest topics that threats human morbidity and mortality. It is indispensable to purify water using antimicrobial agents combined with several technologies and systems. Herein, we introduce a class of nanosized metal organic framework; Zeolitic imidazolate framework (ZIF-67) cages encapsulated with polyoxometalates synthesized via facile one-step co-precipitation method. We employed two types of polyoxometalates bioactive agents; phosphotungstic acid (PTA) and phosphomolybdic acid (PMA) that act as novel antibacterial purification agents. Several characterization techniques were utilized to investigate the morphological, structural, chemical, and physical properties such as FESEM, EDS, FTIR, XRD, and N2 adsorption/desorption isotherms techniques. The antibacterial assessment was evaluated using colony forming unit (CFU) against both Escherichia coli and Staphylococcus aureus as models of Gram-negative and Gram-positive bacteria, respectively. The PTA@ZIF-67 showed higher microbial inhibition against both Gram-positive and Gram-negative bacteria by 98.8% and 84.6%, respectively. Furthermore, computational modeling using density functional theory was conducted to evaluate the antibacterial efficacy of PTA when compared to PMA. The computational and experimental findings demonstrate that the fabricated POM@ZIF-67 materials exhibited outstanding bactericidal effect against both Gram-negative and Gram-positive bacteria and effectively purify contaminated water.

Ternary metal oxide nanocomposite for room temperature H2S and SO2 gas removal in wet conditions

A ternary Mn–Zn–Fe oxide nanocomposite was fabricated by a one-step coprecipitation method for the remotion of H2S and SO2 gases at room temperature. The nanocomposite has ZnO, MnO2, and ferrites with a surface area of 21.03 m2 g−1. The adsorbent was effective in mineralizing acidic sulfurous gases better in wet conditions. The material exhibited a maximum H2S and SO2 removal capacity of 1.31 and 0.49 mmol g−1, respectively, in the optimized experimental conditions. The spectroscopic analyses confirmed the formation of sulfide, sulfur, and sulfite as the mineralized products of H2S. Additionally, the nanocomposite could convert SO2 to sulfate as the sole oxidation by-product. The oxidation of these toxic gases was driven by the dissolution and dissociation of gas molecules in surface adsorbed water, followed by the redox behaviour of transition metal ions in the presence of molecular oxygen and water. Thus, the study presented a potential nanocomposite adsorbent for deep desulfurization applications.

Effect of Magnetic Graphene Oxide on Heavy Oil Demulsification

Chemical demulsification is the most efficient demulsification approach that can attain the desired separation efficiency and meet the environmental regulation standards whilst impose minimal economic burden on the petroleum industry. However, current demulsification methods using chemical demulsifiers suffer from significant secondary pollution, particularly after the demulsification process. Therefore, in this work, magnetic graphene oxide (MGO) was synthesized by a one-step co-precipitation method from graphene oxide (GO). The properties of MGO were then characterized by X-ray diffraction and Fourier transform infrared. MGO was successfully synthesized and used as the demulsifier for diluted heavy oil emulsions. Different MGO concentrations (40, 80, 120, 160, and 200 ppm) were used at different water cuts (20:80, 30:70, 40:60, 50:50, and 60:40 v/v%). Demulsification tests using the bottle test method indicated that MGO could separate the emulsions up to 99.98% efficiency due to the high surface area-to-volume ratio of nanoparticles and magnetic features, which enhanced the adsorptive capacity for separating water from the oil. The residual oil content in the separated water was then analyzed by an ultraviolet-visible spectrophotometer. The oil concentration in the separated water reduced to 398.8 mg/ml, corresponding to a demulsification efficiency of 99.98% observed at 40 ppm MGO concentration. The interfacial tension of the emulsions during demulsification was also analyzed, where the interfacial tension decreased with increasing MGO concentration.

Enhanced carbon tolerance of hydrotalcite-derived Ni-Ir/Mg(Al)O catalysts in dry reforming of methane under elevated pressures

Pressurized dry reforming of methane (DRM) is highly desirable in terms of economy and efficiency, but imposes increased risk of catalyst carbon deposition. Here, hydrotalcite-derived Ni-Ir/MgAl(O) catalysts with various Ir/Ni molar fractions (0, 5, 10, 15, 20, 25 and 30%) have been successfully prepared by one-step co-precipitation method. The promoting effect of Ir on the catalytic performance of catalysts in pressurized DRM was focused. After adding Ir, the catalyst stabilities (reflected by the deactivation degree) were significantly improved and were comparable when the amount of Ir was high (≥15%). Long-term stability for 180 h at 1.0 MPa and 850 °C under 60,000 mL·gcat−1·h−1 was achieved on catalyst 100Ni20Ir, and the final CH4 conversion was still above 68.5%. Detailed characterizations disclosed that the addition of Ir favored the formation of smaller Ni particles and enhanced the carbon tolerance properties of catalysts. The effective inhibition of the formation of encapsulated graphitic carbon and better carbon nanotubes removal characteristics were responsible for the enhanced carbon tolerance behaviors. The carbon deposition, especially the encapsulated graphitic carbon, was proved to be the major cause of catalyst deactivation. Our findings bring us one step closer to developing durable and coke-resistant catalysts suitable for high pressure DRM.

Effect of Fe doping on the surface properties of δ-MnO2 nanomaterials and its decomposition of formaldehyde at room temperature

In this paper, δ-MnO2 and Fe/δ-MnO2-X (X = 0, 1, 2 and 5) nanomaterials were prepared by a one-step water bath co-precipitation method, and then their performance in catalytic oxidation of HCHO at room temperature was investigated. The catalytic oxidation performance of Fe/δ-MnO2-5 nanomaterials for formaldehyde was significantly improved by the modification with iron doping and sulfuric acid, and the conversion of 3.35 ppm HCHO reached 99.4% within 8 h at room temperature. Next, the nanomaterials were characterized by X-ray diffraction (XRD), spectroscopy scanning electron microscope (SEM), High-resolution transmission electron microscopy (HR-TEM)，Brunauer-Emmett-Teller (BET), temperature-programmed reduction by H2 (H2-TPR), X-ray photoelectron spectroscopy (XPS) methods to investigate the structural properties of the nanomaterials. It was found that the specific surface area of the composite nanomaterials increased, the particle distribution was more uniform, and the distribution of Mn on the catalyst surface changed significantly. Among them, the content of Mn3+ increased significantly, which was beneficial to the catalytic oxidation of formaldehyde.

Gentle one-step co-precipitation to synthesize bimetallic CoCu-MOF immobilized laccase for boosting enzyme stability and Congo red removal

Laccase has received extensive attention in pollutant degradation due to its high efficiency and environmental friendliness, but free laccase has poor stability, easy inactivation, and difficulty in recycling, which limited its application. It was a smart strategy to construct a synergistic system for the efficient adsorption and degradation of pollutants by enzyme immobilization to improve the stability and recyclability of the enzyme. In this study, the materials were synthesized by a one-step co-precipitation method. With Cu-MOF as the main body, Co2+ was introduced to construct bimetallic CoCu-MOF as the protective carrier of the enzyme. The enzyme-carrying capacity and enzyme activity of Lac@CoCu-MOF were 2-fold and 3.5-fold higher than those of Lac@Cu-MOF, respectively. Lac@MOF composites had a good protective effect on enzyme in various interfering environments. At pH = 7, free laccase was completely inactivated and Lac@CoCu-MOF maintained 51.76% enzyme activity. In addition, the removal rate of Congo red by Lac@CoCu-MOF reached 90 % in 1 h at pH = 4 % and 95 % in 5 h at pH = 7, and the final TOC mineralization rate reached 86.05 %. After six cycles, the degradation rate of Lac@CoCu-MOF remained above 75 %. Therefore, Lac@CoCu-MOF was constructed with the advantages of enzyme immobilization (enhanced stability and easy operation), material adsorption, and biocatalysis (fast diffusion and high activity), which has great guiding significance for the industrial application of enzyme.

Anti-microbial Nanohybrids Based on Naturally Derived Citric Acid Intercalated Layered Double Hydroxides

Currently, there is an increased demand for advanced food packages, which can significantly increase the shelf life of food items. In the current context, it is envisaged that nanotechnology has the potential to address stability, toxicity, shelf-life, and low-cost issues of antimicrobials associated with the packaging industry. Antimicrobial nanocomposite systems are believed to be more efficient than their microscale counterparts due to the high surface area to volume ratio and quantum mechanical involvement in deciding their properties. As a result of high surface area, they are able to attach more copies of microbial molecules and cells, thus reducing the quantity of material required while significantly improving their activity. This study focuses on the development of slow-release antimicrobial material based on natural citrate (α-hydroxycitrate) intercalated layered double hydroxide (LDH) nanohybrid. Natural citrate ions available in Citrus aurantifolia (lime) were extracted by a simple chemical method and intercalated into Mg-Al-Layered Double Hydroxide following a one-step co-precipitation method. Successful intercalation of the citrate ion was confirmed by powder X-ray diffraction (PXRD) and Fourier transform infrared (FTIR) spectroscopic analysis. Release kinetics of resulted nanohybrid was studied and compared using different release kinetic models. Antimicrobial properties of this novel nanohybrid were confirmed against two common food pathogens, Colletotrichum gloeosporioides and Saccharomyces cerevisiae, and the results were compared against sodium benzoate, which is the commonly used commercial antimicrobial agent in the food industry. Successful intercalation of natural citrate ions into LDH and its activity against the tested microbes show the potential of using it as a slow-release nanohybrid material in many food-related applications.&#x0D; &#x0D; Keywords: Layered Double Hydroxide, α-Hydroxycitrate, Natural, Safe, Lime Extract, Slow Release, Antimicrobial