Optimum Preparation Conditions Research Articles

Garlic Peel-Based Biochar Prepared under Weak Carbonation Conditions for Efficient Removal of Methylene Blue from Wastewater

Background: Due to it containing cellulose, hemicellulose, and lignin with abundant specific functional groups which could interact with organic dyes, garlic peel (GP) might be used as an efficient biosorbent. The aim of this study is to evaluate the adsorption performances of GP-based bio-adsorbents and obtain optimum preparation conditions. Methods: GP-based bio-adsorbents were prepared by thermal pyrolysis under different temperatures (150–400 °C). The morphologies, chemical states, and surface functional groups of the adsorbents were analyzed by X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), and thermogravimetric analysis (TGA). Batch experiments were conducted to investigate the adsorption of methylene blue (MB) under various conditions, including contact time, contact temperature, initial dye concentration, and initial pH value. The equilibrium adsorption data were fitted to different kinetic and isothermal models, and the adsorption thermodynamics were also calculated. Significant Findings: The physicochemical properties of the GP-based bio-adsorbents were primarily dominated by the pyrolysis temperature, because their morphologies and surface functional groups of GP-based bio-adsorbents significantly varied with the changes in pyrolysis temperature. The adsorption capacity of GP materials for MB decreased as the pyrolysis temperature increased. At an initial concentration of 50.00 mg L−1, GP150 possessed a higher adsorption capacity of 167.74 mg g−1 toward MB. The possible adsorbate–adsorbent interactions, including electrostatic attraction, hydrogen bonding, and π-π stacking, were recognized. After 10 consecutive adsorption–desorption cycles, GP150 maintained a high removal rate (88%) for MB, demonstrating its excellent adsorption performance, good reusability, and potential application in the treatment of MB-contaminated water.

Repurposing disposed surgical face masks into activated carbon for efficient sorption of bio recalcitrant malathion pesticide

Pesticides are essential for enhancing agricultural produce, but their excessive use poses risks to ecosystems due to persistence and toxicity. This study explores repurposing disposed surgical face masks (DSFMs), rich in polypropylene (PP), as a precursor for activated carbon (AC) synthesis, addressing plastic pollution. DSFM pieces were subjected to hydrothermal treatment with sulfuric acid and KOH activation, optimized via response surface methodology (RSM). Optimal AC preparation conditions were achieved at 800 °C, PP/KOH ratio 3 g/g, and 50 min resulting in AC (3AC800-50) with BET surface area 892.16 m2/g and pore volume 0.6353 cm3/g. The resulting carbon material demonstrated excellent adsorption affinity towards malathion pesticides (MP) with a capacity of 536.68 mg/g. The Freundlich adsorption model accurately fits the data with a high R2 of 0.9898. Kinetic analysis revealed the pseudo-second-order (PSO) model as the best fit, with negative ∆G° indicating the spontaneous nature of MP adsorption. These findings highlight the potential of utilizing ACs derived from DSFMs for sustainable plastic waste management and pesticide removal from water.

Optimization of the preparation process of Spirulina blended liquor and Spirulina fermented wine, analysis of volatile components and in vitro antioxidant study.

The optimal conditions were explored for the preparation of Spirulina blended liquor (SBL) and Spirulina fermented wine (SFW), respectively. The parameters obtaining highest alga polysaccharide were calculated by response surface methodology. The optimal conditions for SBL preparation were base liquor of 42%vol, ultrasonication time of 37-min and ultrasonic power of 80W with polysaccharide content (PC) and alcohol content (AC) of 0.2181g/L and 39.7%vol, respectively. In the case of SFW, optimum fermentation occurred at 22°C, with a 4% inoculum and 6-day period with PC and AC of 8.533g/L and 11.2%vol, respectively. Headspace solid-phase microextraction-gas chromatography-mass spectrometry was used to quantitatively analyze the volatile components of SBL and SFW. There were 32 and 40 main aroma compounds in SBL and SFW, respectively. Volatile organic compounds, including α-ionone and β-ionone, produced by Spirulina were detected in both SBL and SFW. Comparative evaluation of scavenging activity and total reducing power revealed the antioxidant capacity of SFW significantly outperformed that of SBL.

Preparation and Performance of Catalyst for Organic Peroxide Wastewater Treatment

To improve the oxidation pretreatment efficiency of wastewater from organic peroxides, a catalyst (CeO2-C catalyst) was developed using the calcination method with ceramic particles as the support. The crystalline structure and elemental composition of the CeO2-C catalyst were characterized by Scanning Electron Microscope (SEM), Energy Dispersive Spectrometer (EDS), and X-ray diffraction (XRD). This study explored the effects of CeO2 mass ratio, calcination temperature, and calcination time on the performance of the catalyst. The optimal preparation conditions were established through orthogonal experiments. Additionally, the synergistic effect of the catalyst on the ozone oxidation treatment of peroxide wastewater was investigated. The results indicated that the optimal preparation parameters were a CeO2 mass ratio of 4%, a calcination temperature of 500 °C, and a duration of 5 hours, respectively. After five cycles of reuse, the catalytic activity slightly decreased but remained relatively stable. With an ozone flow rate of 6L/min, the CeO2-C/ozone catalytic oxidation process achieved a Chemical Oxygen Demand (COD) removal rate of 28.11% in wastewater, and the B/C (the ratio of BOD concentration to COD concentration)of wastewater improved from 0.093 to 0.152. The calcination method proved effective for preparing the CeO2-C catalyst, which demonstrated significant catalytic performance and held promising application prospects in the oxidation pretreatment of organic peroxide wastewater.

Mechanism of enhancing the SO2-resistance and gaseous arsenic removal performance of Iron-modified pyrolusite

Arsenic pollution in the atmosphere caused by smelting flue gas is a huge environmental challenge, and the removal of gaseous arsenic (As2O3(g)) from smelting flue gas is a matter of urgency. Adsorption has been shown to be an effective method for the removal of As2O3(g) from high temperature smelting flue gas. However, due to the high concentration of SO2 in smelting flue gas, the capture of As2O3(g) by adsorbents is inhibited. In previous studies, the mechanism by which SO2 affects the adsorption of As2O3(g) by pyrolusite (PY) has been clearly elucidated. Therefore, this study proposes a method to improve PY’s resistance to SO2 and its As2O3(g) removal efficiency through Fe modification. Under optimal preparation conditions, the 10Fe/PY adsorbent exhibited an adsorption capacity for As2O3(g) that was nearly uninhibited by SO2. The 10Fe/PY achieving an adsorption capacity of 20.90 mg/g under 7.5 v/v% SO2, which is 1.4 times that of PY. The doped Fe increased the active sites on the 10Fe/PY surface for As2O3(g) adsorption, while preferentially reacting with SO2 to form Fe2(SO4)3, thereby reducing the competition between SO2 and As2O3(g) for the active sites on the adsorbent. The findings provide a theoretical basis for the adsorption and removal of As2O3(g) from high-SO2 smelting flue gas.

Promotion effect of nitrogen doping on the low-temperature NH3-SCR of NO over activated carbon: Characterization and mechanism analysis

Heteroatom nitrogen doping in carbon catalysts is recognized an effective strategy for tailoring the properties of carbon catalysts for various flue gas de-NOx applications. However, accurately discerning the active structures after nitrogen doping and elucidating the promotion effect on low-temperature selective catalytic reduction activity remains a formidable challenge under different nitrogen doping preparation conditions. In this study, a series of nitrogen-doped activated carbon catalysts was synthesized through the L16(45) orthogonal array design method, and the degree of influence of various preparation conditions on de-NOx catalytic activities was also assessed. The optimal preparation conditions determined by range analysis were employed to synthesize NOAC-17, achieving the NO conversion of 95% and N2 selectivity of 99% at 300 °C, respectively. Subsequently, various characterization results proved that nitrogen doping induced the formation of abundant basic groups. The imine, amide, amine, and N-6 groups altered the acid-base of the activated carbon surface and increased the adsorption of acidic NOx. The N-5 and N-Q groups enhanced electronic interaction in the carbon matrix and accelerated electron mobility in the catalytic reaction process. Moreover, the N-6 group played multiple roles beyond the aforementioned effect due to its special structure. It also enhanced the accumulation of oxygen vacancies, which were closely associated with further oxidation of adsorbed NO. The lone electron pair in the N-6 group within the activated carbon framework can alter the polarity of the catalyst, thereby exerting a positive influence on the adsorption and activation of NH3. The nitrogen-doped catalyst identified through range analysis of the orthogonal experiment primarily facilitated the NH3-SCR reaction via the E-R mechanism with supplementary contribution from L-H mechanism at low temperatures. The nitrogen doping conditions obtained for the activated carbon catalyst provide valuable insights for the strategic enhancement of its catalytic performance in low-temperature NH3-SCR reactions.

Structural and transport properties of newly synthesized ZSM-5 sourcing silica from coconut shell ash

ZSM-5 is a crucial catalyst in industrial chemistry and petrochemical processing, distinguished by its unique structural and chemical properties. The cost of its production is heavily influenced by the expense of silica-alumina sources, which are the primary precursors for the formation of the zeolitic network. This study introduces a pioneering approach to synthesizing the valuable zeolite ZSM-5 using waste coconut shell ash (CSA), a readily available and cost-effective alternative natural source of silica. High-purity amorphous silicon dioxide (SiO2) was successfully extracted from discarded coconut shells, as confirmed by X-ray diffraction (XRD) analysis, providing an eco-friendly approach to the production of this valuable material. The optimal preparation conditions for ZSM5 were found to be 150 °C and 60 h, yielding the ZSM-5 zeolite from extracted silica. The XRD pattern revealed the presence of a pure crystalline MFI phase in the ZSM-5, and the FT-IR findings corroborated its pentasil structure. Microscopic images (SEM and TEM) confirmed that the zeolite was polycrystalline, with agglomerated rod-shaped particles. The WDXRF data revealed a low SiO2/Al2O3 ratio of 17.84. Electrical characterization showed that the dielectric constant decreased with increasing frequency. Complex impedance spectroscopy enabled the distinction between grain and grain boundary contributions to total resistance, and the electric modulus indicated a hopping conduction mechanism. This study demonstrates the potential of a new ZSM-5 using CSA as the source of silica for various catalytic applications.

Enhancing resistant starch fraction in modified elephant foot yam starch: optimizing preparation conditions and exploring tribological properties

IntroductionElephant foot yam starch is highly susceptible to enzymatic digestion. To address this, heat-moisture treatment (HMT) has been used to modify its digestive properties and functionalities. However, when using modified starch in various food compositions, it is ultimately necessary to cook it in water-rich environments. The present work thus offers a systematic understanding of the heating and cooking procedures for modified starch, with a view to maintaining its structural and digestive properties.MethodsExperimental investigations employing X-ray diffraction, scanning electron microscopy, and enzymatic digestion have been utilized to gain insights into the characteristics of cooked starches. The interactions between amylose and amylopectin in native starch are more susceptible to disruption during cooking, which results in changes in texture and a reduction in resistant starch (RS) retention. Additionally, these preparations have been investigated by tribology to test structure and and friction.Results and discussionThe application of HMT has been observed to induce changes that stabilize the interactions between amylose and amylopectin, thereby ensuring better maintenance of granular integrity and higher RS retention under specific cooking conditions. The findings indicate that following a 2-min cooking period at 100°C, the modified elephant foot yam starch (EFYS) demonstrated enhanced granular stability, which was subsequently compromised after 10 min of cooking. Additionally, when modified elephant foot yam starch (EFYS) was heated at a temperature of 86°C for 2 and 6 min, it demonstrated superior preservation of resistant starch (RS) in comparison to a cooking time of 10 min. Moreover, the HMT starch exhibited the highest RS retention when cooked at 100°C for 2 and 6 min at approximately 39.12% and 20.23%, respectively. However, this retention decreased significantly to 1.08% after 10 min of cooking. Furthermore, the insights from tribology, when combined with the proposed naive models, enhance the understanding of how preparation conditions affect the functionalities of starches, which is crucial for designing food products with desired textural and nutritional qualities, especially in water-rich environments, where maintaining structural integrity and RS content is important.

Amine-modified SiO2 aerogel for efficient adsorption of low-pressure CO2: Response surface methodology optimization and adsorption mechanism

Amine-modified SiO2 aerogel (AMSA) has shown tremendous potential in CO2 capture due to its unique three-dimensional network structure and excellent stability. However, it still faces many challenges in the preparation optimization, adsorption enhancement at low CO2 partial pressure, and mechanism elucidation. Hence, in this paper, the response surface methodology is employed for the first time and the optimal preparation conditions for AMSA are determined. A regression model is successfully established to accurately predict the CO2 adsorption capacity of AMSA under different synthesis conditions (with a relative error of only 0.98 %). Additionally, the AMSA prepared at optimal conditions exhibits high CO2 adsorption capacity of 2.11 mmol/g and excellent stability (only decreased by 1.44 % after 8 cycles) at 10 % CO2 partial pressure, indicating enormous application potential. Notably, the CO2 adsorption mechanism by AMSA at different temperatures and partial pressures are revealed in detail through fitting with the Freundlich isotherm and the double-exponential model, as well as thermodynamic parameter calculations. Firstly, the CO2 adsorption behavior belongs to the multi-layer adsorption behavior with uneven energy of active sites. Secondly, the CO2 adsorption capacity and rate are jointly controlled by molecular motion and chemical reaction equilibrium, diffusion and chemical reaction steps, respectively. Finally, the adsorption process is exothermic and spontaneous, and the level of disorder decreases at the gas-solid interface. This study not only achieves efficient adsorption of low-pressure CO2, but also deepens the understanding of gas-solid interface adsorption mechanisms, providing scientific basis and technological support for the development of novel efficient AMSA adsorbent materials.

Determination of selenium in polyheteroatomic organic compounds by microwave plasma atomic emission spectrometry

Currently, the problem of selenium determination in various objects attracts a large number of scientists. Interest in this area is attributed to the biological importance of selenium, since it is both an important nutrient and has a toxic effect on the body, depending on its amount and the properties of the compounds in which it is contained. Checking the purity of selenium-containing organic compounds (both determination of impurities and analysis of the basic composition), which is carried out by methods of elemental analysis, is an important task, however, in modern literature there is lack of information regarding this problem. The purpose of the presented study is to develop a method for the determination of selenium in the basic composition of synthetic polyheteroatomic organic compounds by microwave plasma atomic emission spectrometry. Various selenodiazole derivatives were mainly used for analysis. Optimal conditions for sample preparation and atomic emission determination of the selenium content were specified. To mineralize the substances under study, oxygen flask combustion was used with the addition of potassium nitrate, which improves combustion and prevents the formation of soot. Hydrochloric acid at a concentration of 0.1 M was used as an absorption solution. It is noted that before measurements it is necessary to purge the monochromator and optimize the pressure in the atomic emission spectrometer nebulizer and optimize pressure in the atomizer. In addition, the number of replicates and sampling time were increased to optimize selenium measurement. Under specified conditions, the metrological characteristics of the technique were determined: the detection limit and quantitation limit, intra-laboratory precision and accuracy. Selenium was determined in 11 synthetic organic compounds with selenium content ranged from 12 to 51%. The error of the analysis did not exceed 0.3%, which meets the requirements of organic elemental analysis.

Preparation and application of a pseudo-templated multi-monomer aflatoxins imprinted polymer.

Afunctional material was developedwith specific recognition properties for aflatoxins for pre-processing enrichment and separation in the detection of aflatoxins in Chinese herbal medicines. In the experiment, ethyl coumarin-3-carboxylate, which has a highly similar structure to the oxonaphthalene o-ketone of aflatoxin, was selected as a pseudo-template, zinc acrylate, neutral red derivative, and methacrylic acid, which have complementary functions, were selected as co-monomers to prepare a pseudo-template multifunctional monomer molecularly imprinted polymer (MIP). The MIP obtained under the optimal preparation conditions has a maximum adsorption capacity of 0.036mg/mg and an imprinting factor of 3.67. The physical property evaluation of the polymers by Fourier infrared spectrometer, scanning electron microscopy, pore size analyzer, thermogravimetric analyzer, and diffuse reflectance spectroscopy showed that the MIP were successfully prepared and porous spherical-like particles were obtained. The synthesized polymer was used as a solid-phase extraction agent for the separation of aflatoxins from the extract of spina date seed. The linear range of the developed method was 10-1000ng/mL, the limit of detection was 0.36ng/mL, the limit of quantification was1.19ng/mL, and the recoveries of the extracts at the concentration level of 0.2μg/mL were in the range 88.0-93.4%, with relative standard deviations (RSDs) of 1.97% (n). The results showed that the preparation of MIPs using ethyl coumarin-3-carboxylate as a template was simple, economical, and convenient. It is expected to become a promising functional material for the enrichment and separation aflatoxins from complex matrices.

A red-emitting phosphor Na3AlF6:Mn4+: Green synthesis, optical characteristics, thermal stability and application in high-performance warm WLED

Mn4+-doped fluoride red phosphors have been widely used in warm WLEDs, but the preparation of such phosphor requires the use of a large amount of HF as a fluorine source and an acidic environment. How to reduce the excessive use of highly toxic HF in the preparation process and achieve green synthesis has become a hot research topic. Therefore, a simple green synthesis strategy is proposed in this work to synthesize a series of red-emitting phosphors Na3AlF6:Mn4+. The highly toxic HF solution is replaced by using a low toxicity reaction system (HCl/HNO3 + NH4F), which reduces the direct use of HF. X-ray powder diffraction, energy-dispersive X-ray spectrometer and scanning electron microscope are employed to determine the crystal structure, composition and morphology of all samples. Optical properties are characterized using excitation spectra, emission spectra and fluorescence lifetime curves. The calculation results indicate that the red-light has low correlated color temperature and the excellent color purity, and Na3AlF6 host can provide a strong crystal field environment for Mn4+. In addition, different aluminum sources and Mn4+ doping concentrations are used to explore the optimal preparation condition. The mechanisms of concentration quenching and thermal quenching have also been systematically explored. The stabilities of red-light emission intensity and color are investigated under the high temperature. The integral PL intensity at 423 K is 47 % of the initial value at 298 K. The activation energy, the chromaticity shift and the chromaticity coordinate variation are also systematically calculated. More importantly, a high-performance warm WLED with low correlated color temperature (CCT = 3296 K) and high color rendering index (Ra = 94.7) is achieved by using Na3AlF6:Mn4+ as a red-emitting material. Not only that, the warm WLED exhibits strong output stability under high driving current. The discovery of this work provides a comprehensive understanding for the rational design of high-performance Mn4+-activated fluoride red phosphors via a simple green synthesis strategy.

BioMOF@PAN Mixed Matrix Membranes as Fast and Efficient Adsorbing Materials for Multiple Heavy Metals' Removal.

Heavy metal ions are a common source of water pollution. In this study, two novel membranes with biobased metal-organic frameworks (BioMOFs) embedded in a polyacrylonitrile matrix with tailored porosity were prepared via nonsolvent induced phase separation methods and designed to efficiently adsorb heavy metal ions from oligomineral water. Under optimized preparation conditions, stable membranes with high MOF loading up to 50 wt % and a cocontinuous sponge-like morphology and a high water permeability of 50-60 L m-2 h-1 bar-1 were obtained. The tortuous flow path in combination with a low water flow rate guarantees maximum contact time between the fluid and the MOFs, and thus a high heavy metal capture efficiency in a single pass. The performances of these BioMOF@PAN membranes were investigated in the dynamic regime for the simultaneous removal of Pb2+, Cd2+, and Hg2+ heavy metals from aqueous environments in the presence of common interfering ions. The new composite adsorbing membranes are capable of reducing the concentration of heavy metal pollutants in a single pass and at much higher efficiency than previously reported membranes. The enhanced performance of the mixed matrix membranes is attributed to the presence of multiple recognition sites which densely decorate the BioMOF channels: (i) the thioether groups, deriving from the S-methyl-l-cysteine and (S)-methionine amino acid residues, able to recognize and capture Pb2+ and Hg2+ ions and (ii) the oxygen atoms of the oxamate moieties, which preferentially interact with Cd2+ ions, as revealed by single crystal X-ray diffraction. The flexibility of the pore environments allows these sites to work synergically for the simultaneous capture of different metal ions. The stability of the membranes for a potential regeneration process, a key-factor for the effective feasibility of the process in real life applications, was also evaluated and confirmed less than 1% capacity loss in each cycle.

Construction of S/g-C3N4@β-Bi2O3 heterojunction and its photocatalytic degradation of toluene in the gas phase.

In this paper, a modification of g-C3N4 was carried out by combining non-metal doping with the construction of heterojunctions, and a type II heterojunction composite, S/g-C3N4@β-Bi2O3, was prepared. The phase structure, morphology, elemental composition, valence band structure, and light absorption performance of the photocatalyst were analyzed using characterization techniques such as X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and UV-vis diffuse reflectance spectroscopy (UV-vis DRS). The performance of the composite photocatalyst in the photocatalytic degradation of gaseous toluene, one of the typical volatile organic compounds (VOCs), under simulated solar light was studied. The effects of preparation conditions, toluene concentration, and recycling on the photocatalytic performance of the composite photocatalyst were investigated. The results show that under the optimal preparation conditions, S/g-C3N4@β-Bi2O3 achieved a degradation efficiency of 74.0% for 5ppm toluene after 5h of light irradiation. Although the degradation efficiency decreased to 61.2% after five cycles, it maintained 83% of its initial activity, indicating good stability of the composite photocatalyst. Free radical quenching experiments demonstrated that h+ was the main active species in the photocatalytic degradation of toluene, followed by ·O2-. Based on all experimental results, the migration law of photo-generated charges was analyzed, and a possible photocatalytic mechanism was proposed. In this study, a new material was obtained for the photocatalytic removal of VOCs by improving the photocatalytic properties of g-C3N4.

Preparation of silver nanowires with controlled parameters for conductive transparent electrodes

Silver nanowires (AgNWs) have excellent flexibility, unique optical transmittance and high conductivity. The polyol process is appropriate for preparing AgNWs due to its simplicity, effectiveness, low cost, and high yield. This work aims to investigate the effect of preparation parameters of the polyol process on the silver nanowires properties. The parameters include the controlling agent, molecular weight of the polyvinylpyrrolidone (PVP), the temperature, and the reducing agent. The amount of silver nanoparticles formed during preparation was used to determine the optimum preparation conditions. The transmission electron microscope (TEM) images showed minimal amount of Ag nanoparticles when using mixed molecular weight of PVP-40K, and PVP-1.3M at 150 °C with the assistance of copper chloride as a controlling agent. The prepared AgNWs had an average length of 3.7 µm and aspect ratio of 15.3. The fabricated electrodes were characterized using a scanning electron microscope (SEM) and four probe resistivity measurements. The electrical measurement of the AgNWs electrodes indicated that the surfactant thickness is a critical parameter in having low sheet resistance electrodes. Also, the optical transmission was affected by the amount of nanoparticles. The prepared electrode with high concentration of AgNWs and a minimal amount of nanoparticles exhibited 80% optical transmission.

Alginate and chitosan-based polyamide 56 modified nanofiber membrane for highly effective capture of Escherichia coli: Antibacterial and cytotoxicity studies

In recent years, microbial fermentation has become a sustainable alternative to traditional petrochemical processes for producing biomass nylon 56 (i.e., PA56). This study is centered on creating a highly efficient antibacterial nanofiber membrane using bio-nylon 56 as the main material. The membrane was fabricated via a multi-step process involving sodium alginate, chitosan, and poly(hexamethylene biguanide) (PHMB). The PA56 nanofiber was chemically modified by sequential coupling with alginate (AG) and chitosan (CS), introducing a significant number of functional groups (-COOH and -NH2). This process resulted in the formation of PA56-AG and PA56-AG-CS nanofibers. Further modification with PHMB led to obtaining the PA56-AG-PHMB and PA56-AG-CS-PHMB antibacterial nanofiber membranes. The optimal preparation conditions for these membranes were determined, including the pH and concentration of AG, the molecular weight, pH, and concentration of CS, and the pH and concentration of PHMB. The PA56-based membranes demonstrated nearly 100 % antibacterial efficiency within a short time. However, the PA56-AG-PHMB membrane exhibited faster antibacterial rates and higher efficiency in repeated use compared to the PA56-AG-CS-PHMB membrane. The two-step coupling reaction in the preparation of PA56-AG-CS-PHMB may have reduced its surface accessibility to E. coli cells, resulting in slower bacterial attachment. Furthermore, the PA56-related membranes showed excellent biocompatibility, with a 100 % cell survival rate. Despite some limitations in reusability, biomass nylon PA56 stands out as an environmentally friendly material derived from renewable resources through microbial fermentation. It offers significant sustainability advantages over traditional petroleum-based nylons, as evidenced by the favorable cytotoxicity test results.

Anode glow discharge electrolysis synthesis of flower-like α-MnO2 nanospheres: structure, formation mechanism, and supercapacitor performance.

A novel green synthesis strategy-anode glow discharge electrolysis (AGDE) was employed for one-step preparation of a-MnO2 in 2 g L-1 KMnO4 solution, in which Pt needle and carbon rod were regarded as anode and cathode, respectively. The optimal preparation condition is 400 V for 60 min and the power consumption is below 45 W. The XRD, Raman spectra, XPS and EPR proved that a-MnO2 with structural defects (oxygen vacancies) is obtained. SEM and TEM revealed that a-MnO2 shows a flower-like nanospheres with a diameter of 165 nm, which is assembled by many nanosheets. A possible formation mechanism is that the MnO2 is generated via the reduction of MnO4- by H· and eaq- in plasma-liquid interface. Electrochemical test found that MnO2 nanospheres exhibit a specific capacitance of 365 F g-1 at 1 A g-1, and capacity retention of 79.8% after 10,000 cycles at 5 A g-1. The assembled asymmetric supercapacitor shows the maximum energy density of 23.1 Wh kg-1 at power density of 1.89 kW kg-1. In brief, AGDE is a simple, facile and green technique for the synthesis of a-MnO2 without adding extra chemicals, and prepared a-MnO2 can be considered as an excellent candidate of electrode materials for supercapacitor.

Preparation of hydroxy-terminated polydimethylsiloxane and nano-SiO2 hydrophobic polyurethane coated urea and investigation of controlled nitrogen release

In the present study, we successfully developed hydroxy-terminated polydimethylsiloxane (PDHT) and nano-SiO2 hydrophobic polyurethane-coated urea by applying the optimal conditions for hydrophobic polyurethane preparation. The hydrophobic polyurethane membrane material undergoes a comprehensive characterization. Infrared analysis confirmed the successful grafting of PDHT onto the polyurethane membrane material. X-ray Photoelectron Spectroscopy (XPS) and Energy Dispersive X-Ray Spectroscopy (EDX) analysis verify the even distribution of silicon on the surface of the membrane material. By Scanning Electron Microscopy (SEM) comparison, we elucidate the micro-structural disparity between the unmodified and modified castor oil-based polyurethane, accounting for the micro-level performance enhancement. The resulting modified membrane exhibited a water contact angle of 133.6°, indicative of its hydrophobic nature. The optimal ratios for PDHT and nano-SiO2 were determined to be 16 % and 2 %, respectively. Notably, hydrophobic polyurethane-coated urea demonstrated an extended-release period of 98 days (5 % coating amount), a 40 % improvement over its unmodified counterpart. In addition, the silicone-modified coated urea reduced the amount of ammonia volatilization by about 76.32 %, which plays a significant role in enhancing fertilizer utilization efficiency and is important for ecological environment protection. This research provides a straightforward and efficient way to fabricate slow-release fertilizers, with significant implications for the advancement of coated slow-release fertilizer technology.

Characterization, in vitro antioxidant activity and stability of cattle bone collagen peptides‑selenium chelate

In this study, cattle bone collagen peptides–selenium chelate (CCP-Se) was prepared and its structure, oxidation resistance and stability were characterized. The selenium binding capacity was 33.65 ± 0.13 mg/g by optimized preparation conditions. Structural analysis showed that selenium ions bound mainly to the amino nitrogen, carboxyl oxygen and hydroxyl oxygen atoms of the cattle bone collagen peptide (CCP). The microstructure and particle size analyses showed that the particle size of CCP-Se was increased and formed a regular and compact crystal structure compared with CCP. Additionally, CCP-Se exhibited excellent antioxidant activity. Stability analysis showed that CCP-Se was stable in thermal processing, simulated in vitro digestion and acid/alkali tolerance tests. The intestinal selenium permeability of CCP-Se was significantly better than sodium selenite (p < 0.05). This study provides reference for the high-value application of cattle bone and suggests the potential of CCP-Se as a new effective selenium supplement.

Fabrication of chitosan-encapsulated microcapsules containing wood wax oil for antibacterial self-healing wood coatings

Wood multifunctional smart coating is a new functional coating that combines smart material technology with traditional wood. In this study, wood wax oil based on thistle oil and flaxseed oil was used as the core material, and chitosan was used as the wall material to prepare self-repairing antibacterial microcapsules. The optimal preparation conditions were found to be an oil-water ratio (OWR) of 2:1, a core-to-wall ratio of 3:1, using OP-10 as the emulsifier at a concentration of 10.0 %, and a crosslinker concentration of 0.18 g/mL. The encapsulation efficiency of microcapsules was 73.7 % by spray drying, and the thermal stability was improved. The chitosan microcapsules exhibit the characteristics of water sensitivity and acid selective response, with rapid release at pH 7.0. Blending microcapsules at concentrations of 2.0 %, 5.0 %, and 8.0 % with UV topcoat and applying them to walnut plywood resulted in a multifunctional wood coating. Artificially simulated daily scratch damage was effectively repaired within 7 d. Furthermore, the 10.0 % microcapsules demonstrated antibacterial properties against Escherichia coli (E. coli) and Escherichia coli (E. coli), with an antibacterial E. coli and S. aureus rate of up to 75.82 % and 42.96 %. The IC50 of the wood coatings against E. coli was 5.667, while against S. aureus it was 15.45. The minimum inhibitory concentration (MIC) of the microcapsules against both E. coli and S. aureus was 10.0 %. The coating film containing 2.0 % microcapsules demonstrated superior overall performance. This research established a foundation for the development of self-healing antibacterial coatings for wood and addressed the gap in dual-functional self-healing antibacterial paint films for wood.