Reaction Period Research Articles

Improving the early-age properties of eco-binder with high volume waste gypsum: Hydration process and ettringite formation

The long setting times and low early-age mechanical properties resulting from the insufficient hydration products (especially ettringite at early age), limited the application of an eco-binder with minor clinker and without calcination, in which phosphogypsum was intensively reused (45 wt%) as raw material. The external addition of aluminate phase was proposed to promoting the ettringite formation in this study by using sodium aluminate (0∼2.5 wt% of binder). The hydration kinetics and products, microstructure, slag reaction degree, etc. Were thoroughly investigated. The results showed that, with sodium aluminate addition, the setting times were significantly improved and complied with standard requirements, the compressive strengths were increased, especially the 3 d-hydration samples. The hydration heat released in the initial reaction period was highly increased and the induction period was accelerated. And the ettringite and C-A-S-H gels formation at early ages was enhanced, and ettringite morphology was modified. The slag reaction degree was increased from 48% to 70% when 1.5% sodium aluminate was used. The early-age property improvement of this phosphogypsum slag binder could enlarge its application potential.

Syngas production from dry reforming of glycerol by the NiO/M-Al2O3 catalysts: Effect of various support promoters and various ZrO2 content

Glycerol dry reforming presents an intriguing approach for converting CO2, a greenhouse gas, and glycerol, a renewable resource, into syngas. This study delves into the impact of introducing 5 wt% of ZrO2, CeO2, La2O3, and Y2O3 to the Al2O3 support. Additionally, the study examines the influence of the optimal metal oxide ratio within the support formula on both structural properties and catalytic performance in the glycerol dry reforming process. To investigate these aspects, various catalyst supports were synthesized using a mechanochemical method. Subsequently, nickel-based catalysts were prepared through a wet impregnation technique. The catalysts underwent comprehensive characterization employing techniques such as XRD, BET, H2-TPR, CO2-TPD, TPO, and FESEM analyses to determine their physicochemical properties. The results demonstrated that the sample enhanced with 5 wt% ZrO2 exhibited remarkable performance metrics. Notably, it achieved a catalytic activity of 85.4% glycerol conversion at 650 ℃, while also displaying better stability and resistance to carbon deposition compared to the unpromoted catalyst throughout a 600 minutes reaction period. These enhanced attributes were attributed to the heightened specific surface area of the support (241.95 m2/gr), the effective dispersion of Ni on the support and the increase in basic sites.

Thermochemical energy storage analysis of solar driven carbon dioxide reforming of methane in SiC-foam cavity reactor

Solar energy is an abundant renewable energy source, and the use of solar energy for carbon dioxide reforming of methane (CRM) is a promising thermochemical energy storage scheme, but the reactor using the traditional powder catalyst has the disadvantages of complex encapsulation and low energy storage efficiency. In this paper, porous SiC-foam with high thermal conductivity is used to prepare Ni/CeO2–Al2O3/SiC catalyst, and then is loaded into a cavity reactor to achieve highly efficient and stable CRM under solar simulator. After a period of reaction, methane conversion rate remains high. As inlet flow rate decreases and incident energy flux rises, methane conversion rate is improved, and thermochemical energy storage efficiency first rises and then drops with maximum 31.4%. The numerical model of the cavity reactor under concentrated heat flux is established, and the simulation results are in good agreement with the experimental data. The structure of catalyst bed directly influences the heat storage performance, and the optimal bed thickness, radius and porosity are obtained. For thick bed, the reverse reaction appears in the end region of the bed, and then this region expands with bed thickness rising, so the reaction rate first increases and then decreases.

Hydrothermal-assisted synthesis of Sr-doped SnS nanoflower catalysts for photodegradation of metronidazole antibiotic pollutant in wastewater promoted by natural sunlight irradiation.

In this study, we report a facile hydrothermal synthesis of strontium-doped SnS nanoflowers that were used as a catalyst for the degradation of antibiotic molecules in water. The prepared sample was characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), and ultraviolet-visible absorption spectroscopy (UV-Vis). The photocatalytic ability of the strontium-doped SnS nanoflowers was evaluated by studying the degradation of metronidazole in an aqueous solution under photocatalytic conditions. The degradation study was conducted for a reaction period of 300 min at neutral pH, and it was found that the degradation of metronidazole reached 91%, indicating the excellent photocatalytic performance of the catalyst. The influence of experimental parameters such as catalyst dosage, initial metronidazole concentration, initial reaction pH, and light source nature was optimized with respect to metronidazole degradation over time. The reusability of the strontium-doped SnS nanoflowers catalyst was investigated, and its photocatalytic efficiency remained unchanged even after four cycles of use.

Ability of Selected Monoterpenes to Reduce Fe(III) Ions Being Pro-Neurodegenerative Factors: Tests Based on a FRAP Reaction Extended to 48 Hours.

Monoterpenes are secondary plant metabolites, and such volatile compounds have antioxidant, antibacterial, antiviral, and enzyme inhibitory properties. These compounds are also able to reduce the potentially pro-neurodegenerative trace metal ions that can be sources of free radicals. One basic method used to evaluate the ability of chemical compounds to reduce Fe(III) is FRAP. To date, most studies based on a FRAP assay were performed within several dozen minutes. However, taking into account the diversity of compounds, it is justified to observe their activity over a much longer period of time. The present study aimed to observe the activity of isopulegol, γ-terpinene, α-terpinene, linalool, carvone, citral, and α-phellandrene over a 48 h period. Our study indicates that the lengthened reaction period enhanced activity from several dozen to several hundred percent. The obtained results also revealed an explicit high correlation of the increase in the activity of compounds with the increase in monoterpene concentration. Due to the hydrophobic character of monoterpenes, the FRAP method was modified by the addition of Tween 20. The highest activity was obtained for α-terpinene and γ-terpinene.

Biodiesel-Derived Waste Glycerol as a Green Template for Creating Mesopores in the ZSM-5 Catalyst for Aromatics Production Applications.

The present study provides a novel sustainable approach for the synthesis of the ZSM-5 catalyst using biodiesel-derived waste glycerol as a green template as well as a mesopore creator, which is here reported for the first time, to the best of our knowledge. The use of bioglycerol in the preparation of ZSM-5 (Zn-Z-G and Zn-Z-T) materials exhibited a typical MFI zeolite structure, indicating glycerol played a similar role to that of a typical (TPA+) template in the formation of the ZSM-5 zeolite structure. The Zn-Z-G material also exhibited a large mesopore in the ZSM-5 pore structure, suggesting that glycerol played both template and mesopore creator roles. Interestingly, Zn-Z-GT prepared by the dual-template route using bioglycerol along with typical TPA+ showed a MFI zeolite structure with special catalytic features such as hierarchical micromesopores and well-balanced acid sites. These results reveal that the use of bioglycerol along with a typical TPA+ template had a promotional effect on creating such special properties in the Zn-Z-GT material. The Zn-Z-GT catalyst exhibited excellent catalytic performance in the naphtha aromatization reaction, resulting in achieving ∼58 wt % of the aromatic product and useful gas byproduct (14 wt %) with a minimum coke content (∼4 wt %) in a 12 h reaction period ascribed to its combined effect of hierarchical micromesopores and well-balanced acidity with optimum Lewis acid sites. The liquid product possessing high alkyl-aromatics with a high octane value (RON ∼ 109) produced in the present study can be used as an octane booster for liquid gasoline. The high alkyl-aromatics (>50 wt %) content of the liquid product also attracts various petrochemical applications. The effective utilization of waste bioglycerol as a green template and mesopore creator for the preparation of Zn-Z-GT can exhibit sustainability in the resultant material.

Evaluating the photocatalytic degradation efficacy of 2,4,6-trichlorophenol: performance evaluation and influencing factors

Abstract Chlorophenols are organic compounds that have garnered considerable attention in recent years because of their prevalent occurrence in the environment and associated harmful effects on ecosystems and human health. The current work investigated the photocatalytic oxidation of 2,4,6-trichlorophenol as a potential treatment option. The effects of different process-conditioning parameters were studied. Analytical-grade commercially available TiO2 reported 80% degradation, whereas nano-grade TiO2 resulted in complete removal in the same time duration. Furthermore, the study assessed the use of Degussa P-25 nano-TiO2 at varying doses for the optimization of treatment. Under the optimal dose of 250 mg/L of nano-TiO2, the complete removal of 2,4,6-trichlorophenol was observed within 210 min of the reaction period. The addition of H2O2 to further increase the rates of treatment did not yield any benefit. Under solar irradiation, almost 95% degradation of 2,4,6-trichlorophenol was observed in 315 min at an optimized photocatalyst dose. Moreover, the comparison of the operational cost of UV-photocatalysis (UV/nano-TiO2), photocatalysis with H2O2 (UV/nano-TiO2/H2O2) and solar-photocatalysis revealed costs of US$0.27 per litre, US$0.30 per litre and US$0.16 per litre, respectively, during the experimentation, thus making solar-photocatalysis the best option.

Isochoric pressure-temperature behavior of lactalbumin+water reactive mixtures under subcritical conditions

This study examines the pressure-temperature (P-T) behavior of reactive mixtures composed of lactalbumin and water under subcritical and isochoric conditions. The impact of density on the P-T behavior was investigated for an initial lactalbumin composition of 5%, covering a density range of 0.7597 g/mL to 0.85620 g/mL. Additionally, the effect of varying lactalbumin concentrations, ranging from 3% to 15% (w/w), at a constant initial density of 0.831 g/mL, was also studied. Isochoric lines and density values of the reactive mixtures were compared to those of pure water under identical pressure and temperature conditions in all experiments. Furthermore, the total soluble solids (TSS) content was analyzed after each experiment, along with the thermal stability of amino acids subjected to prolonged reaction periods and high temperatures.

Continuous ammonia synthesis from water and nitrogen via contact electrification

We synthesized ammonia (NH3) by bubbling nitrogen (N2) gas into bulk liquid water (200 mL) containing 50 mg polytetrafluoroethylene (PTFE) particles (~5 µm in diameter) suspended with the help of a surfactant (Tween 20, ~0.05 vol.%) at room temperature (25 °C). Electron spin resonance spectroscopy and density functional theory calculations reveal that water acts as the proton donor for the reduction of N2. Moreover, isotopic labeling of the N2 gas shows that it is the source of nitrogen in the ammonia. We propose a mechanism for ammonia generation based on the activation of N2 caused by electron transfer and reduction processes driven by contact electrification. We optimized the pH of the PTFE suspension at 6.5 to 7.0 and employed ultrasonic mixing. We found an ammonia production rate of ~420 μmol L-1 h-1 per gram of PTFE particles for the conditions described above. This rate did not change more than 10% over an 8-h period of sustained reaction.

Insights into the Structural Evolution Process of Na/ZnFe2O4 Spinel Catalyst in CO2 Hydrogenation

AbstractThe CO2 hydrogenation to olefins process over Fe‐based catalysts offer a promising route for the production of high‐value chemicals from non‐fossil route. Herein, we present a Na promoted ZnFe2O4 spinel catalyst and their structural evolution from fresh state to reduction and to reaction period was elucidated. The clear phase segregation between Fe and Zn occurred after reduction/reaction because of crystalline phase transformation in the order of ZnFe2O4→ZnO+Fe7C3+χ‐Fe5C2→FeO+ZnO+Fe7C3+χ‐Fe5C2. The formation of iron carbide phases (Fe7C3 and χ‐Fe5C2) was enhanced dramatically by Na promoter. The adjacent Na promoter increase the electron density in Fe−Zn interfaces and enhance its ability to dissociate CO* to form adsorbed CHx* species, thus promoting the formation of olefins. This Na promoted rich electronic Fe−Zn interfaces alters the balance between iron oxides and iron carbides on the catalyst surface, which accelerate the chain growth reaction and facilitate the coupling efficiency of tandem reaction. The various catalysts were characterized by N2 physisorption, SEM, HR‐TEM, HAADF‐STEM, ex‐situ /in situ XRD, Mössbauer spectra, ICP, in situ XPS, and operando DRIFTs.

Development of novel heterogeneous cobalt acylpyrazolone catalyst: Synthesis, characterization and selective oxidation of styrene to benzaldehyde

Cobalt acylpyrazolone complex was prepared and characterized using various spectral methods, FT-IR, TGA, UV–visible, DRS, magnetic study, and single crystal XRD. A heterogeneous catalyst consisting of neutral alumina and cobalt complex was synthesized and characterized using various physicochemical methods and successfully applied to styrene oxidation without a solvent. The effects of the reaction variables (mole proportion of the reactantto hydrogen peroxide and TBHP, quantity of the catalyst, reaction period and reaction temperature) were investigated. No appreciable catalytic activity reduction occurred when the catalyst was utilised again. The catalyst's recycling is verified by infrared and diffuse reflectance spectra confirming that the catalyst was intact and notdestroyed following the process. The work's unique feature is its benzaldehyde selectivity under benign reaction circumstances.

Bismuth Nanoparticles Modified Indium Tin Oxide-Coated with Polyethene Terephthalate Electrode Using Hydrothermal Method for Pb Detection

Heavy metal elements are elements with comparatively high density and are dangerous even in a minimal quantity as they can persist in the environment. The electrochemical sensor can play an essential role in detecting heavy metals. However, the electrochemical sensor has drawbacks, such as low sensitivity and a high detection limit. Bismuth nanoparticles (BiNPs) can improve the sensitivity and lower the detection limit of an electrochemical sensor by modifying the working electrode. In this study, BiNPs produced by the hydrothermal method were drop-casted on the indium-tin-oxide (ITO) coated with polyethene terephthalate (PET) film (BiNPs/ITO-PET). The effect of the hydrothermal reaction was studied by varying the hydrothermal reaction period (5, 6, 7, and 8 h). X-ray Diffraction (XRD) was used to characterize the phase presence, and the morphology of BiNPs was characterized using a transmission electron microscope (TEM). The BiNPs/ITO-PET electrode was subjected to electrochemical characterization using cyclic voltammetry (CV) and the detection of Pb(II) using differential pulse anodic stripping voltammetry (DPASV). The BiNPs/ITO-PET electrode showed good electrochemical performance in detecting Pb(II).

Controlled and automatic fabrication of ultra small SnO2-CdS nano-heterojunction via continuous flow method designed for photochemical treatment of dye contaminated natural water resources

Contaminated organics such as dyes represent a most important and rising source of environmental pollution. A capable approach to remedy this utilizes semiconductors to catalytically photodegrade the stable bonds in these toxic dye molecules. Heterostructured photocatalysts composed of two dissimilar semiconductors can conquer difficulties of rapid electron-hole recombination and inefficient light harvesting whilst reducing dependency on either constituent independently. At present fabrication of scalable, non-agglomerated, and monodispersed semiconductor photocatalysts by using continuous flow microreactor technology pays severe concern since it presents a range of advantages compared to the conventional batch reactor technology. In this contribution, we advance the prior art by introducing a simplistic, commercial, and environmentally benign continuous flow microreactor synthetic approach for designing a SnO2-CdS nano-heterojunction at a reasonably low reaction temperature and very short reaction period. Up-to-date, very few researchers are able to prepare the heterojunction nanocomposites such as SnO2-CdS through a microfluidic approach and as well the corresponding ultra-low particle size is not reported either. A PTFE (polytetrafluoroethylene)-based helical tubular microreactor is being exploited that comprises a compact structure and offers improved heat and mass transport as well as better intermixing among the reactants. Heterostructure formation is confirmed by X-ray diffraction (XRD), FTIR spectroscopy, and transmission electron microscopy (TEM) analysis. Mott-Schottky (M−S) and Diffused Reflectance (DRS) analyses jointly demonstrate that the heterostructured nanomaterial, comprising a narrow bandgap semiconductor (CdS) and a wide band-gap semiconductor (SnO2), possesses significant potential as a photocatalyst. Furthermore, when applied in the degradation of Congo red (CR) dye under simulated solar conditions, it clearly exhibits superior photocatalytic activity compared to its individual SnO2 and CdS components. The efficient charge separation in this heterostructure is confirmed by the time resolved spectroscopic study. It is monitored that a strong type-II interaction is exhibited in the heterostructure and a plausible mechanism has been utilized to clarify this behaviour.

Low-temperature dissociation of CO2 molecules on vicinal Cu surfaces.

The reaction of carbon dioxide on the vicinal Cu surfaces at low temperatures was investigated by infrared reflection absorption spectroscopy, scanning tunneling microscopy, X-ray photoelectron spectroscopy, and quadrupole mass spectrometry. Dissociation of CO2 molecules into CO on the Cu(997) and Cu(977) surfaces was observed at temperatures between 80 K and 90 K, whereas it did not occur on Cu(111) under a similar condition. CO and physisorbed CO2 were the main adsorbates during the reaction. In contrast, the amount of atomic oxygen on the surface was small. The dissociation of CO2 was promoted by the small amount of oxygen produced by the CO2 dissociation on the Cu surfaces. This leads to the induction period in the CO2 reaction; the initial reaction rate on the clean Cu surfaces was low, and the coadsorbed oxygen enhanced the dissociation reactivity of CO2. Mass analysis of desorption species during the reaction revealed that the observed CO formation on the vicinal Cu surface is mainly caused by an oxygen-exchange reaction with residual CO in an ultra-high vacuum chamber.

A strategy for the controllable generation of organic superbases from benchtop-stable salts.

Organic superbases are a distinct class of strong base that enable numerous modern reaction applications. Despite their great synthetic potential, widespread use and study of superbases are limited by their air sensitivity and difficult preparation. To address this, we report air-stable carboxylate salts of BTPP and P2-t-Bu phosphazene superbases that, when added to solution with an epoxide, spontaneously generate freebase. These systems function as effective precatalysts and stoichiometric prereagents for superbase-promoted addition, substitution and polymerization reactions. In addition to improving the synthesis, shelf stability, handling and recycling of phosphazenes, this approach enables precise regulation of the rate of base generation in situ. The activation strategy effectively mimics manual slow addition techniques, allowing for control over a reaction's rate or induction period and improvement of reactions that require strong base but are also sensitive to its presence, such as Pd-catalyzed coupling reactions.

A two dimensional Co(OH)2 catalytic gravity-driven membrane for water purification: a green and facile fabrication strategy and excellent water decontamination performance.

Cobalt-based materials are reported to be the most efficient catalysts in sulfate radical advanced oxidation processes (SR-AOPs). A green and facile method was developed in this work to prepare uniform Co(OH)2 hexagonal nanosheets, which was void of any organic solvents via mere ambient temperature stirring. The obtained nanosheets were assembled into a catalytic gravity-driven membrane, through which the removal efficiency of a typical pharmaceutical contaminant, ranitidine (RNTD), could reach ∼100% within 20 min. Meanwhile, the catalytic membrane also demonstrated effective removal performance towards various pollutants. In order to augment the long-term stability of catalytic membranes, Co(OH)2/rGO composites were fabricated using the same strategy, and a Co(OH)2/rGO catalytic membrane was prepared correspondingly. The Co(OH)2/rGO membrane could maintain a ∼100% removal of RNTD over a constant reaction period lasting for up to 165 hours, which was approximately 11 times that of the sole Co(OH)2 membrane (15 h). Analysis of element chemical states, metal ion concentration in filtrates, and quenching experiments suggested that the combination with rGO could promote the electron transfer to accelerate the Co(II) regeneration, restrain the cobalt dissolution to alleviate the active site loss, and contribute to the production of 1O2via synergistic effects of oxygen-containing groups in rGO. Toxicity assessment was performed on RNTD and its degradation intermediates to confirm the reduction in ecotoxicity of the treated feed. Overall, this work not only offered guidance for the application of nanosheets in AOP membranes, but also had implications for the environmentally-friendly preparation protocol to obtain functional metal hydroxides.

Facile preparation of Fe2O3 catalyst and assessment of its photodegradation performance for industrial effluent purification

This study focuses on synthesizing nano-scaled Fe2O3 particles using Araucaria columnaris (Cook's pine) leaf extract under atmosphere circumstances. These extracts serve as both a reductant and a stabilizer. Fe2O3 nanoparticle synthesis was confirmed through a comprehensive characterization process using many analytical techniques. The analysis of XRD patterns indicated that the examined samples consisted of nanoparticles of γ-Fe2O3, exhibiting a cubic crystal structure with a high degree of crystallization. Furthermore, the calculated crystallite size was resolute to be 24.5 nm. The scanning electron microscopy pictures revealed that the created samplesexhibited a combination of spherical and polyhedral morphologies. The investigation of optical characteristics, such as light absorption and bandgap width, was conducted usingUV–visible spectroscopy, employing a bandgap energy value of 3.78 eV. The study aimed to assess the removal effectiveness of Eosin yellow, Malachite green, Reactive black, and Rhodamine 6G dyes using Fe2O3 nanoparticles synthesized as a photocatalyst which exhibited remarkable photocatalytic efficacy in the breakdown of dyes when exposed to sunlight, and the reaction period of 90 min resulted in a maximum degradation rate of 97.4 %. Considering the promising results, utilizing Fe2O3 nanoparticles as a photocatalyst for degrading dyes in wastewater is feasible. Additionally, Araucaria columnaris leaf extract can be an environmentally friendly and economically viable method for synthesizing Fe2O3 nanoparticles.

Slatted floor reduces the welfare and increases the foot pad dermatitis and growth performance of Turkeys under Egyptian conditions.

When Turkeys' legscome in contact with their dropping during the growing stage results in footpad dermatitis condition which affects the poult's welfare and productivity. Our experiment aimed to detect the impact of various bedding substrates on the wellbeing, and performance of growing Turkey under Egyptian conditions. 180-day-old Turkey poults were allocated into three treatments. In treatment I, the poults [60 each with three replicates (n = 20 birds)] were kept on wood shavings (WS); in the second treatment, the poults were housed on chopped wheat straw (CWS). However, in the third treatment, they kept on a plastic slatted floor (PSF). The greater feed intake and body weight were recorded in poults reared in PSF compared with those kept in other treatments (WS and CWS). Feed conversion ratio did not show any significant difference. The mortality percentage was higher in the PSF group than in the WS one. The frequency of feeding and drinking behavior was higher in poults reared on WS treatment compared with other treatments CWS and PSF. On the other hand, resting behavior showed the highest frequency in poults kept in PSF. Contrary, the lowest frequency of walking behavior was recorded in poults reared in PSF treatment. In addition, the poults kept in WS had a longer tonic immobility reaction period followed by those kept in PSF and CWS. Concerning foot-pad dermatitis, the highest score of 0 was observed in the CWS group, while the highest score of 1 was recorded among poults kept in the WS group. On the other side, the highest score 2, 3, and 4 was observed in the poults reared in the PSF group. Heterophil/Lymphocyte ratio of Turkey poults was higher in PSF. While T3 and T4 concentrations in blood were not affected by using different bedding materials. It is concluded that the slatted floor was good for Turkey producers from the point of performance but, it is the worst from the point of welfare.

Tailored sulfonated carbons: unraveling enhanced catalytic dynamics for fructose dehydration under conventional and microwave heating

Cooperation among active sites within a strongly acidic carbon allowed 80% conversion at 120 °C within a 5-minute reaction period.

Insight into the long-term nonoxidative immobilization of thallium on birnessite

Birnessite has been considered as a potential thallium (Tl)-oxidizing mineral and Tl scavenger in natural and engineered systems. However, the birnessite aging that occurs during Tl sorption may severely limit the long-term effectiveness of Tl immobilization on birnessite. In this study, kinetic experiments were performed in batch coupled stirred-flow systems to investigate the effects of Tl(I) loading and pH on Tl(I) retention during short- and long-term Tl-birnessite interactions. Spectral analysis, microscopic observations, and theoretical calculations revealed a change in the Tl(I) binding mode to birnessite with time. In the short term, low levels of Tl(I) could be effectively immobilized through adsorption to birnessite vacancies. Structural disruption and vacancy occupation in birnessite resulted in the migration of adsorbed Tl(I) toward the edges of the mineral during a 24-d reaction period. Under acidic to neutral conditions, the migration of vacancy-bound Tl(I) induced sustained Tl(I) release (10–45%) from birnessite over the long-term. Under alkaline conditions, hydroxide ions contributed to the formation of Tl(I)–OH species with double edge sharing, which enhanced the binding ability (α ≈ 7 × 10−4 min−1) and stable retention of Tl(I) on birnessite. Understanding Tl(I) retention dynamics during long-term Tl-birnessite interactions elucidates the Tl cycle in Mn oxide-containing systems.