Reaction Period Research Articles

Biodiesel production from cagaite seeds (Eugenia dysentericaDC) oil: An alternative for biofuel production

AbstractIn the present work, cagaite (Eugenia dysenterica DC.) seed oil was studied as a potential inedible raw material for biodiesel production. The oil was extracted using a Soxhlet extractor and the fatty acids acyl esters that make up biodiesel were obtained by alkaline transesterification using sodium hydroxide. The influence of reaction parameters was also evaluated: molar ratio, time, and amount of catalyst. The conversion of fatty acids into fatty acid methyl esters (FAME), which make up biodiesel, was calculated using Nuclear Magnetic Resonance Spectroscopy (1HNMR) spectra. In a 30 min reaction period, the molar ratio of oil to methanol was 1:4, resulting in a conversion of 63.57%. However, when the molar ratio was increased to 1:8, the conversion reached 81.74% during the same 30 min reaction period. After 60 min of reaction, additional increases in conversion were observed when molar ratios of 1:4, 1:6, and 1:8 were used. Under these conditions, the conversions achieved were 92.08%, 98.24%, and 98.78%, respectively. The physico‐chemical properties were evaluated and the results showed that cagaite seed oil biodiesel was similar to soybean biodiesel, which is the most commonly produced biodiesel in Brazil. It was thus an important substitute for soybean biodiesel.

Glycerol Conversion into Allyl Alcohol Using a Coke‐tolerant ZnAl2O4‐β Zeolite Catalyst: Effect of Structural, Textural, and Acidic Properties on Catalytic Stability

AbstractCatalysts with different ZnAl2O4 contents impregnated in beta zeolite were synthesized and their catalytic activity in glycerol dehydration to allyl alcohol was investigated. The materials were characterized by XRD, XRF, FTIR, DRIFTS‐ pyridine, NH3‐TPD, and N2 physisorption. In addition, the surface electrostatic potential maps were generated by a molecular mechanics approach. The XRD patterns indicated a high dispersion of the ZnAl2O4, evidenced by the absence of reflections in the diffractograms, except for the sample containing the highest spinel content. The FTIR spectra indicated the presence of zinc aluminate spinel in the zeolite matrix. The DRIFTS‐pyridine and NH3‐TPD analyses indicated that the incorporation of ZnAl2O4 modifies the acidic properties of the zeolite concerning the number, type, and distribution of acid sites. The N2 physisorption tests showed the maintenance of the micro and mesoporous properties of H‐BEA after modification, despite the reduction of the specific area and pore volume values. The samples impregnated with the ZnAl2O4 phase showed larger mesopores sizes, which may favor its catalytic performance. The catalytic tests indicated the allyl alcohol production for the impregnated materials, which the best results were obtained by the sample containing 2 % of ZnAl2O4, with 90.65 % glycerol conversion and 37 % allyl alcohol selectivity due to appropriate tuning of the acidic and textural properties, as well as the presence of basic sites evidenced by CO2‐TPD analysis and electrostatic potential maps. The presence of acid‐base sites is essential to conduct hydrogen transfer, according to the proposed mechanism, generating allyl alcohol. Finally, the results with a longer reaction period showed greater stability for the sample impregnated with low spinel content, whose coke deposition was smaller, which may be related to the larger size of secondary mesopores.

Phytotoxic Effects of Tetracycline and its Removal Using Canna indica in a Hydroponic System.

Wetland plants are gaining interest as potential agents for removing emerging contaminants. However, there have been limited studies examining the ability of these plant species to remove antibiotics and their tolerance to stress. This study aimed to investigate the potential of Canna indica, an indigenous wetland plant species in India, for tetracycline-induced oxidative stress, antioxidant activity, and removal of antibiotics from nutrient media and domestic wastewater. Canna indica exhibited a removal rate of approximately 91.05 ± 0.18% for tetracycline in antibiotic containing nutrient media and 87.97 ± 0.39% in domestic wastewater. Notably, the exposure to the drug during the 30 d reaction period led to the accumulation of reactive oxygen species in the plant tissues. Consequently, there was a decline in chlorophyll content, alongside an increase in antioxidant activity, membrane permeability, and K + ion leakage. These findings emphasize the importance of monitoring tolerance levels induced by antibiotics in plant species. Thus, monitoring the antibiotic-induced-tolerance levels in plant species is crucial for maintaining plant health and effectively managing abiotic stress, ensuring efficient recovery and facilitating an effective wetland treatment system.

Advances in Starch Nanoparticle for Emulsion Stabilization.

Starch nanoparticles (SNPs) are generally defined as starch grains smaller than 600-1000 nm produced from a series of physical, chemical, or biologically modified starches. Many studies have reported the preparation and modification of SNPs, which are mostly based on the traditional "top-down" strategy. The preparation process generally has problems with process complexity, long reaction periods, low yield, high energy consumption, poor repeatability, etc. A "bottom-up" strategy, such as an anti-solvent method, is proven to be suitable for the preparation of SNPs, and they are synthesized with small particle size, good repeatability, a low requirement on equipment, simple operation, and great development potential. The surface of raw starch contains a large amount of hydroxyl and has a high degree of hydrophilicity, while SNP is a potential emulsifier for food and non-food applications.

In situ growth of SiC wires on CVI densification of SiC foam

AbstractSilicon carbide (SiC) foam prepared by polymer infiltration and pyrolysis (PIP) process was further densified with β‐SiC by chemical vapor infiltration (CVI) technique. Scanning electron microscopy and high‐resolution transmission electron microscopy images confirmed the presence of highly entangled and branched in situ grown SiC wires of uniform diameter (∼500 nm) over the struts of open‐cell SiC foam. A uniform rate increase in diameter from nanometer to micron range (∼11 μm) was observed with an increase in the CVI reaction period. X‐ray diffraction results showed the formation of highly crystalline β‐SiC structure along the <111> direction with stacking faults. The formation of SiC wires was explained by the vapor–liquid–solid mechanism and evenness of the surface and uniform growth rate of SiC confirmed the homogeneous concentration of gaseous species during CVI reaction. The compressive strength increased with relative density, with maximum values of 5.5 ± 1.26 MPa for ultimate SiC foam (ρ = 400 kg/m3) prepared by hybrid PIP/CVI technique. The thermo‐oxidative stability of the resultant foam was evaluated up to 1650°C under air and shows excellent thermal stability compared to SiC foam prepared by PIP route. The densified SiC foam can find potential applications in the field of hot gas filters, catalyst supports, microwave absorption properties, and heat insulation for high‐temperature applications.

Investigating the dissolution of soil phosphate

AimsThe effectiveness of phosphate fertilisers decreases with increasing period of reaction. One explanation for this is that the phosphate (P) has changed its chemical form. Evidence for this is provided by fractionation schemes which include extraction with alkali, followed by extraction with acid. Our aim was to test whether alkali and acid extracted different moieties and to test their ability to reflect changes in phosphate form over time.MethodsWe measured the effect of period of reaction between P and an iron (hydroxy)oxide (goethite), an aluminium oxide, and a soil, using two methods. These are: extraction with acid and extraction with alkali.ResultsExtraction of P by acid was similar to extraction by alkali. This is not consistent with the idea that they extract different kinds of phosphate. With increasing period of reaction, more iron and more aluminium needed to be dissolved in order to dissolve the same amount of P. The rate of dissolution of iron and of aluminium decreased with increasing period of reaction with phosphate.ConclusionsOur results are consistent with diffusion of P into the reacting materials rather than formation of different chemical forms. We think the increased resistance to disolution occurred because phosphate diffused into defects and repaired them. Fractionation methods reflect increasing vigour of extraction rather than the presence of separate forms.

Hydrogenation of Nitrobenzene in Trickle Bed Reactor over Ni/Sio2 Catalyst

Trickle bed reactor was used to study the hydrogenation of nitrobenzene over Ni/SiO2 catalyst. The catalyst was prepared using the Highly Dispersed Catalyst (HDC) technique. Porous silica particles (capped cylinders, 6x5.5 mm) were used as catalyst support. The catalyst was characterized by TPR, BET surface area and pore volume, X-ray diffraction, and Raman Spectra. The trickle bed reactor was packed with catalyst and diluted with fine glass beads in order to decrease the external effects such as mass transfer, heat transfer and wall effect. The catalyst bed dilution was found to double the liquid holdup, which increased the catalyst wetting and hence, the gas-liquid mass transfer rate. The main product of the hydrogenation reaction of nitrobenzene was aniline. Reaction operating conditions, i.e., temperature, liquid flow rate, and initial feed concentration were investigated to find their influences on the conversion and rate of nitrobenzene hydrogenation. Under normal conditions without bed dilution, the system was mass transfer controlled. In the diluted reactor, on the other hand, the resistance of mass transfer was nearly absent and the system became under surface kinetic control. The catalyst showed significant deactivation during the reaction period due to the adsorption of intermediate amine products on the surface of the catalyst. The kinetic study revealed that the reaction is zero order with respect to nitrobenzene concentration for the range of concentration between 0.58 to 1.17 mol/L while it was of positive order for the initial concentration less than 0.58 mol/L

Computed X‐ray Tomography Investigation of Porosity and Permeability of the Liujiagou Formation Sandstone Exposed to CO2‐Saturated Brine

AbstractIn order to improve CO2 capture, utilization and storage (CCUS) to solve carbon emission, sandstone from the Triassic Liujiagou Formation (LF) from the Ordos Basin in China was investigated using permeability tests and computed X‐ray tomography (CT) scanning. The presence of reactive minerals within the geological CO2 sequestration target storage formation can allow reaction with injected CO2, which changes the porosity and permeability of the LF beds, affecting storage effectiveness. To investigate the effect of chemical reactions on the pore structure and permeability of sandstone cores representing the LF CO2 storage, tests were conducted to analyze the changes in porosity and permeability of sandstone cores induced by CO2‐saturated brine at different reaction times (28‐day maximum reaction period). Porosity and permeability of the sandstone increased after reaction with CO2‐saturated brine due to mineral dissolution. The sandstone exhibited an increase in porosity and permeability after 15 days of reaction with CO2‐saturated brine. Moreover, there was an increase in the volume of large pores in the sandstone after the 28‐day period. The pore network of the sandstone was established through CT results, and the porosity calculated based on the obtained pore network was close to that measured in the test, demonstrating the feasibility to use CT to study the evolution of the microstructure of sandstone after long‐time exposure to CO2‐saturated brine.

FEATURES OF NEURODYNAMIC AND SENSORIMOTOR REACTIONS IN CHILDREN AGED 5-7 YEARS

Abstract. The study presents the results of research on sensorimotor reactions and neurodynamic indicators in children aged 5-7 years, which serve as a necessary and essential criterion for assessing the psychophysiological development of preschool participants. The aim is to prevent maladaptive disorders and preserve the health of the future generation.
 Objective. To investigate and analyse the dynamics of neurodynamic and sensorimotor response features in children aged 5-7 years. Research Methods and Discussion. The study was conducted with children aged 5-7 years at the educational institution “Primary School — Preschool Educational Establishment” No. 42 in the city of Sumy. To study the age dynamics of neurodynamic and sensorimotor indicators, an instrumental diagnostic method was chosen using the “Diagnos-1M” device. Functional mobility of nervous processes (FMNP), strength of nervous processes (SNP), and balance of nervous processes (BNP) were evaluated. To identify individual characteristics of sensorimotor reactions of different complexity levels, latent periods of simple visual-motor reaction (PZMR), latent periods of choice reaction to one of three (CR 1–3) and two of three (CR 2-3) signals were determined.
 Conclusions: The study revealed that children at the age of 7, in comparison to children aged 5 and 6, have significantly higher indicators in all neurodynamic parameters (SNP, FMNP, BNP) and sensorimotor reactions (PZMR, CR (1–3), CR (2–3)). This may indicate not only the completion of the anatomical structure of the brain but also the morphological and functional development of subcortical structures and the cerebral cortex.

Comparative characteristics of professionally important psychophysiological parameters of operators of unmanned aircraft complexes, practically healthy and patients with stress-associated diseases

Annotation. The article is devoted to the study and comparison of the professionally important psychophysiological parameters of the operators of unmanned aerial systems (UAVs), practically healthy (40 people) and those suffering from stress-related diseases (80 people), who are serving in the Armed Forces of Ukraine. In patients with stress-associated diseases of UAVs operators, we found the significance of the changes in the indicators of the latent period of simple and complex visual-motor reaction, balance during the study of the reaction to a moving object, and the number of false marks when performing a concentration test with a reliability of p<0.05. The structure of the correlations of practically healthy and patients with stress-related diseases of UAVs operators in the parameters of concentration of attention, orientation in space and short-term visual memory are definitely different, which indicates a major restructuring of the functional system of the operators' professional activity in these aspects. Therefore, in order to prevent the occurrence of such changes, it is necessary to develop a set of organizational and medical measures to compensate for the negative impact of stress-associated diseases on the functional state of UAVs operators.

Live Biomass of Rigidoporus vinctus: A Sustainable Method for Decoloration and Detoxification of Dyes in Water.

In this study, white-rot fungus, Rigidoporus vinctus, collected from an unidentified fallen twig from Pathankot, Punjab, India, was used for biosorption of anionic Congo red and cationic Methylene blue dyes from an aqueous medium. The biosorption efficiency of the live biomass of Rigidoporus vinctus was investigated to optimize biosorbent dosage, process time, concentrations of dyes, and pH of solutions. The results indicated that Rigidoporus vinctus is more efficient than other reported bio-adsorbents for Congo red and Methylene blue dyes. The maximum biosorption activity of Rigidoporus vinctus for Congo red was found at pH 2, and that for Methylene blue was at pH 10, after 24 h of the reaction period. The process followed pseudo-second-order kinetics, which indicated that the interaction of both dyes to the adsorption sites on the surface of Rigidoporus vinctus was responsive to biosorption. The biosorption process could be well explained by the Langmuir isotherm for both dyes. The maximum monolayer biosorption capacity of Rigidoporus vinctus for Congo red and Methylene blue was observed to be 54.0 mg/g and 80.6 mg/g, respectively. The seed germination test was carried out, and it was assessed that the toxicity of dyes was reduced up to significant levels. Based on the present experimental findings, it can be concluded that biosorption using the live biomass of Rigidoporus vinctus can effectively decolorize dye-containing wastewater, thus reducing the hazardous effects of dyes on human beings.

Synergistic effect of novel biosynthesis SnO2@Fe3O4 nanocomposite: A comprehensive study of its photocatalytic of Dyes & antibiotics, antibacterial, and antimutagenic activities

Herein, we report that the biogenic Cassiterite SnO2@Fe3O4 nanocomposite (NC) was successfully synthesized using aqueous leaf extract of Laurus nobilis L. The indigenous population of Algeria frequently used this aromatic plant for both medicinal applications and as a spice source. The biosynthesis of SnO2@Fe3O4 NC was confirmed by the shift color from black to light peanut color and further confirmed by the UV–Visible spectrophotometry (UV–Vis). Scanning Electron Microscopy (SEM) confirmed the nanoscale of the NC 25–35 nm. X-Ray Diffraction (XRD) determined a tetragonal nature for SnO2 and orthorhombic for Fe3O4. The successful synthesis of green SnO2@Fe3O4 NC was verified through Fourier transformed infrared (FT-IR) spectroscopy, which detected the functional groups present in the composite.Interestingly, the SnO2@Fe3O4 NC showed excellent degradation of Rose Bengal/RB (96.7%), Methylene Blue/MB (88.3%), and Toluidine Blue/TB (96.5%) within a reaction period of 120 min at 10 ppm. The reaction kinetics followed the pseudo-first order and indicated rate constant (k) values 0.0244 min−1, 0.0263 min−1, and 0.0164 min−1 for RB, MB, and TB, respectively. The high dyes degradation rate assigned to the low band gap of NC that found to be 4.6 eV for indirect bandgap and direct bandgap 1.5 eV. Furthermore, SnO2@Fe3O4 NC exhibits an excellent degradation rate for Cephalexin /CEX (95%) and Amoxicillin /AMOX (88%) with rate constant 0.134 min−1 and 0.124 min−1 respectively. Also, the NC exerted a strong antibacterial activity at (1, 3, and 5 mM), particularly the 1 mM of NC showed the most effect against Escherichia coli (16 ± 1 mm), and in a lesser extent against Staphylococcus aureus (14 ± 0.5 mm) and Pseudomonas aeruginosa(13 ± 0.8 mm). Antimutagenic activity of the SnO2@Fe3O4 NC aqueous solution at (0–250 μg/tube) was assessed by the Salmonella micro-suspension experiment (YG1024 strain) and 1-nitropyrene (1-NP) (100 ng/tube) as the mutagen. The NC exhibit strong anti-mutagenicity against S. typhimurium TA98 and the percent inhibition was 78% at 250 µg/tube of SnO2@Fe3O4 NC.

Adsorption mechanism and synthesis of adjustable hollow hydroxyapatite spheres for efficient wastewater cationic dyes adsorption

The efficient adsorption of toxic dyes has been an important issue in water pollution control. Nowadays, researchers are experimenting with various methodologies to determine the optimal conditions for synthesizing hydroxyapatite (HAP) particles with a fine, hollow morphology, which has been a major difficulty in the field of study. In this research work, controlled hollow mesoporous HAP particles were successfully prepared using a CaCO3 core as a template at various hydrothermal reaction times. It was noted that by adjusting the hydrothermal process, the hollow morphology of the HAP particles could be regulated, with the best hollow mesoporous hydroxyapatite (HM-HAP) particles formed at the 6 h reaction period. Adsorption characteristics were determined via the adsorption of cationic dyes (methylene blue and methyl violet) onto synthesized HM-HAP particles. Langmuir’s adsorption isotherm was the best fit for describing the adsorption of methylene blue (MB) and methyl violet (MV) (R2 = 0.99 and 0.98), indicating monolayer adsorption. For kinetic studies, the adsorption of MB and MV fits well with the pseudo-second-order model (R2 = 0.99), demonstrating the chemisorption process. The maximal uptake capacities determined using the Langmuir model were 143 mg/g and 453 mg/g for MB and MV, respectively. According to the results of the sorption-desorption experiment, it was possible to renew and reuse synthesized HM-HAP for a maximum of four cycles. Therefore, the HM-HAP particles synthesized in this study were demonstrated to be effective adsorbents for the elimination of MB and MV in aqueous solutions.

Growth and passivation of individual carbon nanoparticles by C2H2 addition at high temperatures: Dependence of growth rate and evolution on material and size.

Absolute kinetics for reactions of C2H2 with a series of ∼60 individual carbon nanoparticles (NPs) from graphite, graphene, graphene oxide, carbon black, diamond, and nano-onion feedstocks were measured for temperatures (TNP) ranging from 1200 to 1700K. All the NPs were observed to gain mass by carbon addition under conditions that varied with feedstock but with large variations in initial growth rate. Long reaction periods were studied to allow the evolution of growth rates over time to be observed. Diamond NPs were found to passivate against C2H2 addition if heated above ∼1400K, and the highly variable initial reactivity for carbon nano-onions was found to depend on the presence of non-onion-structure surface carbon. For graphitic and carbon black NPs, three distinct growth modes were observed, correlated with the initial NP mass (Minitial). Smallest graphitic and carbon black NPs, with masses <∼25 MDa, initially grew rapidly but also passivated quickly after adding <4% of Minitial. NPs in the 20-50 MDa range also passivated but only after multiple waves of fast growth separated by periods of low reactivity, with up to ∼11% total mass gain before passivation. The largest carbon black and graphitic NPs, with Minitial >50 MDa, grew rapidly and continuously, adding up to ∼300% of Minitial with no signof rate slowing as long as C2H2 was present. The efficiencies for C2H2 addition and etching by O2 are strongly correlated, but the correlation changes as the NPs passivate. Growth and passivation mechanisms are discussed.

Tailoring defects in In2S3/Zn0.3Cd0.7S heterojunctions for efficient photocatalytic CO2 conversion

Defect engineering is a highly effective approach to regulate the electronic structure of the catalyst surface, widely employed in the field of photocatalytic energy conversion. In this study, we have successfully synthesized a novel dual-defective In2S3/Zn0.3Cd0.7S (IS/ZCS) heterojunction structure via a self-assembly method, composed of Zn-vacancy-rich Zn0.3Cd0.7S (ZCS) and S-vacancy-rich In2S3 (IS). Under visible light illumination, 3% IS/ZCS sample exhibits remarkable photocatalytic performance in the synergistic reaction of CO2 reduction and 4-chlorobenzyl alcohol (Cl-PhCH2OH) oxidation with the CO yield significantly improved by a factor of 3.5 and 51 compared to that of ZCS and IS, respectively. The combined experimental data and theoretical calculations demonstrate that the dual-defective structure and Z-scheme transfer mode are the key factors behind the enhanced photocatalytic activity, providing more active sites and effectively improving the utilization of photogenerated charge carriers (PCCs). Moreover, the reaction pathway and catalytic mechanism of photocatalytic CO2 reduction were elucidated by the in-situ FTIR technique combined with DFT calculations, monitoring the intermediate and final products during the reaction period. Our results provide a powerful example of designing novel heterojunction photocatalysts with high activity and accelerating the separation of PCCs, with broad implications for the development of efficient photocatalytic systems.

Low-temperature liquid-phase formation of environmentally stable copper halide nanocrystal superlattices and their application to anticounterfeiting patterns

Nanocrystal superlattices have the potential to create a new class of semiconductor materials by combining the photophysical properties of individual nanocrystals with bulk-like structure performance. However, the principles underlying the direct formation of superlattices in liquid phase have not been thoroughly investigated, particularly, those consisting of exciton self-trapping metal halides. Here, we explore the formation of Cs3Cu2Br5 nanocrystal superlattices via liquid-phase crystallization of growing nanocrystals over a reaction period of only a few seconds. Importantly, the reaction temperature and the precursor concentration were found to be key parameters governing the concomitant nanocrystal growth and superlattice formation. The resulting Cs3Cu2Br5 superlattices had a well-defined face-centered cubic structure and emitted a single-band bright blue emission when exposed to 280 nm light. Owing to their advantages, such as low toxicity, reabsorption-free, narrow absorption, strong emission, and high environmental stability, the Cs3Cu2Br5 superlattices were applicable to anti-counterfeiting applications. Our findings shed light on the liquid-phase assembly of nanocrystals into superlattices and highlight the potential applications of the superlattices.

Change In Middle Cerebral Artery Pulsatility Index Over Time Due To Fetal Response To Defined Sound Stimulation: Human fetal responses to airborne sound stimulation

The estimation of fetal reactions to different stimuli indicates the cortical structure’s development and maturity. Recent studies pointed out that Pulsatility index (PI) changes could be associated with auditory stimulation. Each reaction to a particular stimulus has time dynamics which include: the period before the stimulus, the period during and immediately after the stimulus, the period of response and reaction to the stimulus, and the period of returning to the state of rest. Bearing in mind this principle, the preliminary results of the analysis of PI changes measured in the middle cerebral artery (MCA) as a fetal reaction to a defined sound stimulus are given in the paper. The study was conducted at the Clinic for Gynecology and Obstetrics "Narodni front" in Belgrade, Serbia. The research sample included 5 women with no-risk pregnancies. The PI measuring in fetal MCA was conducted in the period between the 31th and the 32nd week of gestation. The results indicate the time dynamics of PI change exist and point to the necessity of a different approach to PI measurement in the conditions of defined sound stimulation, concerning the procedures described so far in the literature.

Vacuum-assisted adsorption of Candida rugosa lipase with nanotubes for monooleoglycerol synthesis

A surplus of crude glycerol has been produced as a by-product due to the escalating production of biofuels. Utilization of crude glycerol for monoolein production which offers a different approach using the abandoned crude glycerol from the biodiesel sector is the main aim of this study. Immobilized lipase was used in this investigation to catalyse the direct esterification of oleic acid and glycerol, which resulted in monoolein. The immobilized Candida rugosa lipase onto the halloysite nanotubes (HNTs) has shown remarkably promising attainment of lipase activity and loading capacity. The immobilised lipase was optimised for crucial parameters (HNT to lipase ratio, pH, temperature, and pressure) via response surface methodology (RSM). The recommended optimum conditions obtained are pH 6, 38.6 °C, and 0.33 atm (81.92% lipase activity). To analyse influences of reaction period, temperature, mixing rate, and crude glycerol to oleic acid molar ratio on the esterification reaction was carried out using the optimized conditions of immobilization process. The optimum conditions for physically immobilised lipase were to yield 88.97% monoolein produced at 42 °C in a substrate ratio of 1:4 (oleic acid: glycerol) stirred at 200 rotations per minute (rpm) with 16 h’ incubation time. Based on the research's findings, it was confirmed that HNT has good application potential for enzyme immobilization carriers.

Ecofriendly green synthesis and characterization of silver zinc oxide nanocomposite using the aqueous leaf extract of Rumex Crispus: Evaluation of its antimicrobial and antioxidant activity

The hydrothermal approach is used in the current study to create an environmentally friendly silver zinc oxide nanocomposite utilizing an aqueous leaf extract of Rumex Crispus. The photochemical components of Rumex Crispus, a synthetic nanocomposite with antioxidant and antibacterial activity, were also assessed. The Response Surface Methodology of Definitive Screen Design (DSD) was used to examine and optimize the effects of four independent variables on the amount of green synthesized silver zinc oxide nanocomposite in Rumex Crispus extract. According to the experimental findings, the green synthesized silver zinc oxide nanocomposite's maximum 1.89 absorbance intensity was achieved at a reaction temperature of 60 °C, a concentration of silver nitrate salt of 100 mM, a pH value of 11, and a reaction period of 3 h. The synthesized nanocomposite was characterized using Fourier-transform infrared, UV, X-ray, UV–vis, Dynamic Light Scattering, thermogravimetric analysis, and differential thermal analysis to determine its functional group, structure, bandgap energy, size distribution, a mass of loss, and energy gain or loss, respectively. The minimum lethal doses for the gram-positive, gram-negative, and fungal strains were 1.25, 0.625, and 2.5 g ml−1 respectively. The 1-1-diphenyl-2-picryl hydrazyl (DPPH) which was used to measure antioxidant activity is scavenged by Ag–ZnO nanocomposites, and the IC50 value of a Rumex Crispus extract is 29.31 g ml-1 IC50 value is.29.31 μg ml–1. Their findings show that Rumex Crispus extract-derived synthetic silver zinc oxide nanocomposite is a promising alternative against both Gram-positive and Gram-negative bacterial strains and fungal strains, as well as a prospective choice for antioxidants under the given conditions.

Biochars from Olive Stones as Carbonaceous Support in Pt/TiO2-Carbon Photocatalysts and Application in Hydrogen Production from Aqueous Glycerol Photoreforming.

Several biochars were synthesized from olive stones and used as supports for TiO2, as an active semiconductor, and Pt as a co-catalyst (Pt/TiO2-PyCF and Pt/TiO2-AC). A third carbon-supported photocatalyst was prepared from commercial mesoporous carbon (Pt/TiO2-MCF). Moreover, a Pt/TiO2 solid based on Evonik P25 was used as a reference. The biochars used as supports transferred, to a large extent, their physical and chemical properties to the final photocatalysts. The synthesized catalysts were tested for hydrogen production from aqueous glycerol photoreforming. The results indicated that a mesoporous nature and small particle size of the photocatalyst lead to better H2 production. The analysis of the operational reaction conditions revealed that the H2 evolution rate was not proportional to the mass of the photocatalyst used, since, at high photocatalyst loading, the hydrogen production decreased because of the light scattering and reflection phenomena that caused a reduction in the light penetration depth. When expressed per gram of TiO2, the activity of Pt/TiO2-PyCF is almost 4-times higher than that of Pt/TiO2 (1079 and 273 mmol H2/gTiO2, respectively), which points to the positive effect of an adequate dispersion of a TiO2 phase on a carbonaceous support, forming a highly dispersed and homogeneously distributed titanium dioxide phase. Throughout a 12 h reaction period, the H2 production rate progressively decreases, while the CO2 production rate increases continuously. This behavior is compatible with an initial period when glycerol dehydrogenation to glyceraldehyde and/or dihydroxyacetone and hydrogen predominates, followed by a period in which comparatively slower C-C cleavage reactions begin to occur, thus generating both H2 and CO2.