Pseudo First-order Rate Research Articles

Phosphoramidate functionalization of hybrid chitosan/SiO2 beads for efficient sorption of ruthenium and application on seawater as a case study

Ruthenium removal from complex solutions (highly saline effluents, seawater) is a critical challenge. Herein, the sorption capacity of chitosan/SiO2 composite beads (Ch-Si) for ruthenium nitrosyl is increased three-fold after phosphoramidate grafting (DPA-Ch-Si, 1.6 mmol Ru g−1) at pH 5. Uptake kinetics and sorption isotherms are compared at pH0: 3, 5 and 10; playing with the mode of agitation (mechanical, MA, vs. ultrasonic treatment, UT). The sorbent maintains good sorption capacities at pH 3 and 10. Uptake kinetics modeled by pseudo-first order rate equation is boosted by functionalization. For Ch-Si, sorption isotherms are modeled by the Langmuir or Sips equations (depending on the pH), while for DPA-Ch-Si the best fits depend on pH, temperature and mode of agitation. Ruthenium sorption is spontaneous and endothermic for the two sorbents. For DPA-Ch-Si, the sorption capacity increases from 1.62 to 1.70 mmol Ru g−1 to 2.23–2.32 mmol Ru g−1 (T increasing from 21 to 50 °C). Nitric acid solution (0.3 M) reveals highly efficient for back extraction; ruthenium is completely released in <15 min. The functionalized sorbent can be reused for a minimum of 10 cycles, with limited loss in performance. Phosphoramidation improves sorption selectivity for the treatment of equimolar multicomponent solutions (Na, Ca, Mg, Fe, Al, U, and Nd). The effect of pH on sorption selectivity is evaluated in simple multi-metal solutions and complex environment. In seawater, the selective recovery of ruthenium is favored at pH close to 10. These tests confirm the promising perspectives offered for ruthenium removal from complex environments. Physicochemical characterizations of the sorbent (and their modes of interaction with ruthenium nitrosyl) included SEM, BET, TGA, FTIR, XPS, and elemental analyses.

Degradation of sulfamethoxazole in a falling film dielectric barrier discharge system: Performance, mechanism and toxicity evaluation

The ubiquitous presence of sulfonamides (SAs) in wastewater poses serious risks to human health and ecosystem safety. This study evaluated the performance of a falling film dielectric barrier discharge (DBD) system on the removal of five SAs, namely sulfamethoxazole (SMX), sulfisoxazole (SIZ), sulfathiazole (STZ), sulfadiazine (SDZ) and sulfamerazine (SMR). Removal efficiencies >99 % were observed for all target SAs within 30 min of treatment, with pseudo-first order rate constants varying between 0.17 and 0.27 min−1. Superior removal efficiencies were achieved under acidic conditions compared to neutral and alkaline conditions. Using SMX as a model compound, mechanistic investigations revealed that the synergy of reactive oxygen species (ROS) and reactive nitrogen species (RNS) led to its efficient degradation, with peroxynitrites (ONOO−/ONOOH) and hydroxyl radical (OH) playing pivotal roles. SMX degradation pathways encompassing nitration/nitrosation, hydroxylation, deamination, CS and SN bond cleavage were proposed. The toxicity evaluation results demonstrated that the solution toxicity diminished following the plasma treatment under specific conditions. In particular, the solution treated with air or oxygen discharge enhanced the growth of wheat seedlings, suggesting the potential for reusing plasma-treated wastewater in agriculture. This study enhances our understanding of the underlying mechanisms involved in the plasma degradation of SAs and reveals the significant potential of plasma technology as a sustainable approach for treating wastewater.

A new strategy toward synthesis of novel bifunctional N- and S-bearing sorbent for platinum(IV) removal from aqueous solutions and acidic leaching residue of Pt/Al2O3 catalyst

Strong incentive politics have been elaborated for promoting the recovery of precious metals from secondary resources. Solid leaching generates acidic effluents that can be pre-treated using precipitation steps for partial separation before applying sorption for metal recovery from mild acidic solutions. For this purpose, a new sorbent was designed bearing numerous N- and S-bearing reactive groups with good affinity for platinum (as chloroanionic species). Thiazole precursors were first reacted before being grafted (by free radical reaction) with triallyl cyanurate (to form CTTR sorbent). The material was characterized by a series of analytical tools (SEM, BET, FTIR, XPS, TGA, elemental analysis, and titration). The effect of pH combined with FTIR and XPS spectroscopy analyses allowed identifying the mechanisms involved in metal binding: (a) electrostatic attraction of chloroplatinate anions with protonated amine groups (especially in acidic conditions), (b) while at moderate acidic pH metal sorption proceeds through ligand exchange and chelation onto N-based and S-based groups. Optimum sorption was found at pH close to 4 (near pHpzc value). Under selected experimental conditions, the equilibrium was reached in 25–35 min. The pseudo-first order rate equation fitted well experimental profile (though the resistance to intraparticle diffusion contributes to the kinetic control). The maximum sorption capacity at room temperature reached up to 1.58 mmol Pt g−1 (at pH 4). The sorption isotherm was successfully fitted by the Temkin equation. The sorption is spontaneous and exothermic (with reduction in maximum sorption capacity reaching up to 25 %, when temperature increases to 50 °C). Optimum platinum desorption was obtained with 0.3 M HCl solution (with solid/liquid ratio 1.67 g L−1) for complete desorption and enrichment factor close to 4.6. Complete desorption was maintained over 5 cycles, while the sorption efficiency decreased by less than 3.5 % at the fifth cycle. The sorbent showed remarkable stability for PGMs (Pd(II) in addition to Pt(IV)) against alkali-earth elements or base metals (from equimolar synthetic solutions); the selectivity is driven by the preference of the reactive groups (soft base and intermediary base) for soft PGM metals against hard and borderline metal ions; this selectivity is also affected by metal speciation (formation of chloro-anionic species). The valorization of platinum from non-compliant Pt/Al2O3 catalyst was investigated after leaching with aqua regia. Platinum was precipitated from the leachate with ammonium chloride. In a second step, aluminum was removed by precipitation at pH 5. The residual solution was then treated by adsorption on CTTR: optimum separation between Pt and Al was achieved at pH ≈ 3.

ZVI-biochar granules for reactive chlorinated solvent filters generated by high temperature pyrolysis of iron(III) amended biomass

Reactive filters may replace activated carbon filters for degradation of chlorinated solvents in contaminated waters. Reactive porous filter materials with high hydraulic conductivity may be in form of millimeter sized zero valent iron (ZVI)-biochar granules produced via carbothermal reduction. We screened ZVI-biochar materials produced under different synthesis conditions including different iron sources, nitrogen additives and supplementary organic substrates followed by testing adsorption and dechlorination kinetics. Diatomaceous earth was used as an inorganic host reference material. The optimal product from the screening was identified as beech charcoal amended with Fe(III) chloride and urea followed by tube furnace pyrolysis at 1000 °C for 2 h. The millimeter sized granules have a high porosity of 79 %. This material resulted in fast trichloroethylene (TCE, 100–600 µM) sorption and complete dechlorination with acetylene as the main product. It also showed a 5 to 8.5-fold higher degradation capacity than the diatomaceous earth reference system. Fitted pseudo first-order dechlorination rate constants (0.114–0.281 h−1) were comparable to rates reported for powdered ZVI-activated carbon materials. In reactions with high TCE concentrations, Fe(0) consumption for TCE reduction reached up to 93.3 % demonstrating its high selectivity. Reactions with ground material demonstrated that intraparticle diffusion pose minor limitation to dehalogenation rates in the highly porous granules. Further tests demonstrated that the material was further highly reactive to tetrachloroethylene (PCE), cis-1,2-dichloroethyene (cis-DCE) and vinyl chloride (VC). The ZVI-BC material addresses the dual challenges of achieving both high hydraulic conductivity and dehalogenation reactivity, offering a cost-efficient and sustainable option for filter material selection in the remediation of CEs using reactive filters or permeable reactive barriers.

Unravelling charge carrier dynamics for enhancement of photocatalytic performance in Pd/MoS2 nanocomposites for water remediation of real-world pollutants

In this study, Pd/MoS2 nanocomposites were successfully synthesized incorporating Pd nanoparticles into three-dimensional (3D) flower-like MoS2 nanostructures. The controlled introduction of Pd was aimed to optimize the photocatalytic performance of the resulting nanocomposites, which exhibited exceptional efficiency in degrading various organic pollutants and antibiotic tetracycline (TC) under simulated solar light irradiation. The nanocomposites with an optimized Pd concentration of 2.5 % demonstrated outstanding photocatalytic efficiency, achieving the degradation of Rhodamine B (RhB), Methylene blue (MB), TC by 98 %, 98 %, and 96 %, respectively, with specific interval of 40, 30 and 60 min. The reaction rate constant of the Pd/MoS2 nanocomposites was measured to be 0.7798 min−1 using pseudo first-order rate kinetics. The value is about 19 times higher than that of pure MoS2 (0.00414 min−1) for degradation of RhB. The improved photocatalytic performance of these nanocomposites can be attributed to several factors. Firstly, the incorporation of Pd nanoparticles substantially enhanced their light absorption capabilities, leading to an overall increase in photocatalytic efficiency. Moreover, the presence of Pd contributed to a large surface area, further enhancing the nanocomposite's photocatalytic potential. Importantly, the formation of a built-in electric field at Pd/MoS2 interface facilitated the efficient separation of the electron-hole pairs, extending the life time of these photoinduced charge carriers. This study offers valuable insights into development of MoS2-based photocatalyst, which hold significant promise for addressing water pollution challenges and making substantial contributions to the field of water purification and environmental remediation.

Sodium thiosulfate modified graphitic carbon nitride for enhancing the photocatalytic production of aldehydes

The oxidation of alcohols to aldehydes is one of the most relevant reactions in organic chemistry. The currently implemented methods based on expensive noble metallic catalysts, toxic solvents, and high temperature and pressure conditions have released the seek for softer and cheaper alternatives such as photocatalysis. In this sense, graphitic carbon nitride has been modified with sodium thiosulfate as a source of S and Na+ incorporation in the structure, aimed at enhancing the photocatalytic performance on the oxidation of alcohols to aldehydes, i.e. cinnamaldehyde, benzaldehyde, and vanillin in aqueous solution. Three g-C3N4 samples synthesized from different precursors, i.e. melamine, thiourea, and urea, were treated with sodium thiosulfate. Urea led to the g-C3N4 with the highest mesoporosity (surface area, 69 m2 g−1) and photocatalytic activity. The modification with 5 % (wt.) of Na2S2O3 enhanced the pseudo-first order rate constant of cinnamyl alcohol oxidation from 0.265 h−1 (bare sample) to 0.792 h−1 (Na2S2O3-modified). The characterization of the material suggests a better charge separation of the photogenerated charges after S and Na+ incorporation in the structure, minimizing the recombination rate of photogenerated charges. The optimum photocatalyst, tested in aqueous solution, was most selective in the production of benzaldehyde (selectivity, >100 %) > cinnamaldehyde (>23 %) > vanillin (∼5 %). The selectivity was considerably boosted under acetonitrile as the solvent medium, raising in the case of cinnamaldehyde the 23 % recorded in water to 51 % in pure acetonitrile. The degradation mechanism suggests a strong influence of the photogenerated holes and the superoxide radical, the latter being more selective in the oxidation of the alcohol.

Trade-Off between Degradation Efficiency and Recyclability: Zeolite-Enhanced Ni3-xCoxS4 Catalyst for Photocatalytic Degradation of Methylene Blue.

We herein report successful syntheses of both nickel cobalt sulfide (NCS) and its composite with zeolite (NCS@Z) using a solvothermal method. Techniques such as EDX analysis, SEM, and molar ratio determination were used for product characterization. The incorporation of NCS significantly changed the surface roughness and active sites of the zeolite, improving the efficiency of methylene blue degradation and its reusability, especially under UV irradiation. In comparing the pseudo-first order rates, the highest degradation efficiency of methylene blue was achieved with NCS-2@Z, having a degradation extent of 91.07% under UV irradiation. This environmentally friendly approach offers a promising solution for the remediation of methylene blue contamination in various industries.

Photolytic decomposition of PFOS by electrospun nanofiber composites of Fe(III)/PVDF Under UV-C light

Per- and polyfluoro alkyl substances (PFAS) are emerging pollutants that have contaminated various water streams of the world. Besides polluting the environment, it is related to several human diseases, including cancer. Various methods have been proposed to remove PFAS from water streams including, photocatalytic or photolytic decomposition of PFAS which decomposes PFAS in a quasi-perpetual fashion and does not generate secondary pollution. In this work, perfluoroctane sulfonic acid (PFOS) is used as a model PFAS to study its photolytic decomposition by nanofiber composites (NFC) of Fe (III) and polyvinylidene fluoride (PVDF) under ultraviolet (UV)-C light. The nanofiber composite was fabricated using an electrospinning technique with PVDF and iron precursor on the conductive surface of indium tin oxide (ITO) coated polyethylene terephthalate (PET) film. The composite was characterized with SEM-EDX, AFM, XRD, and TGA. It was found that a significant amount, 70 % of aqueous PFOS solution is decomposed by the composites in the presence of traces of hydrogen peroxide and UV-C light. The kinetics of PFOS degradation was fit with pseudo-first order rate constant of 0.056 hr−1. It is proposed that PFOS binds with Fe(III) to form an unstable complex that is decomposed under UV-C light and Fe(III) is reduced Fe(II). Hydrogen peroxide provides the simultaneous benefits of further decomposing the PFOS complex and regenerating Fe(III). The overall results suggest that this nanofiber composite can be used for the photolytic decomposition of PFOS. It is also revealed that two composite mats showed the optimal performance and the increase in concentration of hydrogen peroxide increased the degradation of PFOS monotonically.

Overlooked role of protocatechuic acid in enhancing the selective elimination of sulfonamide antibiotics in Fe(III)/peroxymonosulfate process under actually neutral pH conditions

Protocatechuic acid (PCA) has been extensively employed as reducing agent to improve the Fenton-like processes under acidic pH conditions by accelerating the Fe(II)/Fe(III) redox cycle. Nevertheless, the potential of PCA as chelating agent to enable Fenton-like processes for contaminant elimination under neutral pH conditions has been overlooked. In this study, experiments and DFT calculations demonstrate that PCA can improve the elimination of sulfonamide antibiotics in Fe(III)/peroxymonosulfate (PMS) process under truly neutral pH conditions by improving the catalytic reactivity of Fe(III) with PMS, resulting in a 23.74-fold increase in the pseudo-first order rate constant (kobs) of sulfamethoxazole (SMX) removal at pH 7.0. Meanwhile, the kobs of SMX removal in PCA/Fe(III)/PMS process was 10–60 times higher than that in various previously reported strategies-enhanced Fe(III)/PMS processes at pH 7.0. The Fe(III)-peroxo intermediate (PCA-Fe(III)-OOSO3-), rather than •OH, SO4•-, Fe(IV)/Fe(V) and 1O2, was identified as the primary reactive species responsible for SMX removal in PCA/Fe(III)/PMS process under neutral pH conditions. DFT results indicate that PCA increased the oxidation potential of Fe(III)-OOSO3-. Meanwhile, PCA/Fe(III)/PMS process exhibited promising applicability in natural waters with strong anti-interference capability even with 5 μM Fe(III). Additionally, five potential elimination pathways of SMX were proposed, and the toxicity of treated SMX solution decreased. This study investigated the overlooked but crucial role of PCA in Fe(III)/PMS process under neutral pH conditions, which may provide novel insights into the underlying mechanism of PCA-enhanced Fenton-like processes and provide viable options for the application of Fe-catalyzed PMS processes in neutral waters.

Porphyrin photosensitizers compatible with both aqueous and non-aqueous conditions: Acid dependent spectral, solubility and photocatalytic properties of meso-tetra(pyridyl)porphyrins

The aerobic photooxidation of 1,3-diphenylisobenzofuran (DPBF) as a specific singlet oxygen quencher was studied in the presence of meso-tetra(aryl)porphyrins (aryl = 2-pyridyl, 3-pyridyl and 4-pyridyl) and their diprotonated and hexaprotonated derivatives to investigate the influence of the position of pyridine nitrogen atom, solvent, core protonation (with HCl or dichloroacetic acid) and full protonation of the porphyrins on their photocatalytic activity and photooxidative stability. The pseudo-first order rate constants (kobs) for the oxidation of DPBF with singlet oxygen were determined to compare the relative activity of the photosensitizers. 1,4-benzoquinone as a scavenger of superoxide anion radical provided evidence for the absence of this species in these photocatalytic systems. The singlet oxygen quantum yields (φΔ) of the porphyrin photosensitizers were estimated by determining the initial rate constants for the oxidation of DPBF. H4T(2-Py)P(Cl)2 and H4T(2-Py)P(CHCl2COO)2 were the most efficient photosensitizers of the series of the meso-tetra(2-, 3- or 4-pyridyl)porphyrins and the protonated derivatives.

Synthesis and Characterization of Ni based Metal Organic Framework for Enhancing the Removal of Typical Organic Dyes

In this report we present a simple synthesis of a nickel-based metal organic framework (MOF-Ni) at the room temperature using a solution of dimethylformamide (DMF), ethanol and distilled water. The MOF-Ni synthesized in various solvents displayed numerous different properties and advantages over other materials including easy synthesis procedure, good crystallinity, rigidity, and robust chemical stability. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), and thermal gravimetric analysis (TGA) were employed to analyze the as-synthesized MOF-Ni. The as-obtained MOF-Ni was used to investigate its adsorption kinetics of red telon dye (RTL) molecules. The effects of time (30–270 min), initial RTL concentration (20–300 mg/L), adsorbent dose (2–50 mg), solution pH (2–12), and temperature (10–80 °C) were investigated. The pseudo-first order rate equation was able to provide the best description of the adsorption kinetics data in the studied time scale. The Langmuir and Freundlich adsorption models were applied to describe the equilibrium isotherms, and the isotherm constants were also determined. Dye adsorption turned out to strongly depend on pH, and a low pH was found to increase the amount of adsorbed dyestuff. Compared with other samples, MOF-Ni synthesized in (DMF ​+ ​C2H5OH ​+ ​H2O) had a significantly enhanced adsorption ability for RTL dye. The MOF-Ni high adsorption capacity for RTL dye was attributed to the electrostatic attraction/repulsion phenomena. Moreover, MOF-Ni showed an improved stability at 370, 417, and 423 °C temperatures. The results obtained through our experiments suggested that our porous MOF-Ni microstructures synthesized in DMF ​+ ​C2H5OH ​+ ​H2O have potential applications for treating wastewaters containing RTL dyes.

Continuous-flow columns packed with zero-valent iron and iron sulfide as a feasible strategy to remediate the persistent contaminant nitroguanidine

The insensitive munitions compound nitroguanidine (NQ) is used by the U.S. Army to avoid unintended explosions. However, NQ also represents an emerging contaminant whose environmental emissions can cause toxicity toward aquatic organisms, indicating the need for effective remediation strategies. Thus, we investigated the feasibility of treating water contaminated with NQ in continuous-flow columns packed with zero-valent iron (ZVI) or iron sulfide (FeS). Initially, the impact of pH on NQ transformation by ZVI or FeS was evaluated in batch experiments. The pseudo first-order rate constant for NQ transformation (k1, NQ) by ZVI was 8–10 times higher at pH 3.0 compared to pH 5.5 and 7.0, whereas similar k1, NQ values were obtained for FeS at pH 5.5–10.0. Based on these findings, the influent pH fed to the ZVI- and FeS-packed columns was adjusted to 3.0 and 5.5, respectively. Both reactors transformed NQ into nitrosoguanidine (NsoQ). Further transformation of NsoQ by ZVI produced aminoguanidine, guanidine, and cyanamide, whereas NsoQ transformation by FeS produced guanidine, ammonium, and traces of urea. ZVI outperformed FeS as a reactive material to remove NQ. The ZVI-packed column effectively removed NQ below detection even after 45 d of operation (490 pore volumes, PV). In contrast, NQ breakthrough (removal efficiency <85%) was observed after 18 d (180 PV) in the FeS-packed column. The high NQ removal efficiency and long service life of the ZVI-packed column (>490 PV) suggest that the technology is a promising approach for NQ treatment in packed-bed reactors and in situ remediation.

Green synthesis and photocatalytic proficiency of tunable SnO2 nanostructures: unveiling environmental-friendly strategies for sustainable water remediation

This study demonstrates a proficient and eco-friendly synthesis of SnO2 nanostructures using a hydrothermal method, without the requirement of extra surfactants. The synthesis was systematically performed by adjusting the molar ratio of stannic chloride to sodium hydroxide and varying the pH settings. It was noted that the pH value rises according to the concentration of sodium hydroxide. A comprehensive analysis was performed to characterize the resulting nanostructures, which involved studying their structural features, chemical composition, morphology, and optical properties. An x-ray diffraction analysis showed that increasing the pH values resulted in a noticeable improvement in the crystalline structure and a decrease in the density of surface defects. The SnO2 nanostructures, synthesized using different pH settings, were subsequently assessed for their photocatalytic performance in the degradation of methylene blue dye under simulated solar irradiation. Surprisingly, the nanostructure produced at higher pH levels showed outstanding results, as 97% of the dye was broken down in just 70 min when exposed to simulated solar radiation. The analysis uncovered a maximum rate constant (k) value of 0.04 min−1, determined using pseudo first-order rate kinetics. In order to better understand the photodegradation process, scavenger experiments were performed to identify the active species involved. These investigations provided valuable insights into the complex mechanisms that drive the observed photocatalytic activity. This study not only enhances the progress of SnO2 nanostructures but also highlights their potential as strong and environmentally friendly materials for effective photocatalytic applications.

Impact of LaZnFe2O4 supported NiWO4@D400-MMT@CMS/MMA nanocomposites as a catalytic system in remediation of dyes from wastewater

Herein, a novel nanocomposite based on lanthanum zinc ferrite and nickel tungstate was created by incorporation between (MMT-jeffamine-400) nanoparticles (NPs), chloromethyl styrene as a binder and polymethyl methacrylate monomer using solution polymerization. The as-designed nanocomposites were employed to confiscate xylenol orange “X.O” as an acidic dye and rhodamine B “RhB” as “an amphoteric dye” from colored wastewater. The impact of several parameters such as solution pH, initial dye concentration, the effect of time, and the effect of temperature was explored. The consequences indicated that the pure organoclay had negligible adsorption while that composed of organoclay with PMMA@CMS-polymer incorporated with LaZnFe2O4@NiWO4 particles detached more than 90% for xylenol orange (XO) and 93% for “rhodamine B” molecules. Electrostatic interactions are the predominant factor in the adsorption of cationic and amphoteric adsorbates, as proven by zeta-potential measurement. Additionally, the adsorbent may be regenerate and utilized up to five times with good adsorption capabilities by adding sodium hydroxide. As a result, the removal can be effectively accomplished using the nanocomposite as an adsorbent. The actual and theoretical adsorption capacity values for both dyes at all doses were closely matched, which supported the adsorption kinetics data that fit the pseudo-first order rate model well. The adsorption data’s correlation values (0.995 for XO and 0.98 for RhB) indicated that both dyes’ Langmuir adsorption would perform well. Furthermore, the adsorption of XO and RhB dyes on the adsorbent is confirmed to be a viable reaction by the negative values of ΔGo. The enhanced adsorbent material for the removal of amphoteric and anionic dyes from waste water is the synthesized LaZnFe2O4 supported NiWO4@D400-MMT@CMS/MMA nanocomposites, which exhibits a reusability affinity of up to five cycles.

Oxidation of tryptophan by benzimidazolium dichromate

In order to determine a likely mechanism, tryptophan oxidation with benzimidazolium dichromate (BIDC) in an acid medium utilizing sulfuric acid has been investigated at 313 K. First order dependence is demonstrated by the calculated pseudo-first order rate constant, which is found to be independent of the oxidant’s initial concentration. Additionally, the reaction exhibits first order behavior for both sulfuric acid and tryptophan. The rate of reaction is unaffected by an increase in ionic strength and is lowered by a decrease in the medium’s dielectric constant. Since acrylonitrile is not polymerizing, there is no chance of a free radical mechanism. The two electron transfers involved in the mechanism are confirmed when the concentration of manganous sulphate increases because it slows down the rate of reaction. A suitable mechanism and rate law have been derived from the experimental observations. The oxidation reaction yields carbon dioxide, ammonia, and indole-3-acetaldehyde as its products.

Assessment of abiotic reduction rates of organic compounds by interpretable structural factors and experimental conditions in anoxic water environments

For organic contaminants in lake sediments, aquifers, and anaerobic bioreactors, their reduction is one of the primary transformation paths in these anoxic water environments. A simple model is introduced to predict pseudo-first order rate constants (kobs) for the abiotic reduction of organic compounds featuring diverse reducible functional groups. It utilizes the largest experimental dataset of –log kobs, encompassing 59 organic compounds (278 data points). Unlike available complex quantitative structure–activity relationship (QSAR) methods, the novel approach requires both experimental conditions and structural parameters. In comparison to one of the available general QSAR methods, the new model demonstrates favorable performance. The average absolute deviation (AAD), absolute maximum deviation (ADmax), average absolute relative deviation (AARD%), and R-squared (R2) values of the estimated outputs for 54/5 training/test data sets of the new model are 0.641/1.761, 1.761/1.417, 20.52/83.87, and 0.797/0.949, respectively. On the other hand, the available general comparative QSAR method shows the AAD: 1.311/2.301, ADmax: 3.795/3.732, AARD%: 641.0/821.2, and R2: 0.003/0.447. For the test set, AAD, AARD%, ADmax, and R2 values for the new/comparative models are 0.649/2.403, 62.20/190.5, 1.215/3.732 and 0.974/0.789, respectively. In summary, the new model offers a straightforward approach for the manual calculation of –log kobs, demonstrating excellent goodness-of-fit, reliability, precision, and accuracy.

Precious metal-based Catalytic Membrane Reactors for continuous flow catalytic hydrodechlorination

This work is focused on the development of Catalytic Membrane Reactors (CMRs) comprising precious metals as active phases for a comparative assessment in continuous-flow catalytic hydrodechlorination (HDC). HDC has proved its remarkable potential for application as polishing step in drinking water treatment plants, but studies operating in continuous mode are scarce. Preliminary experiments were conducted in batch operation using Pd/Al2O3, Rh/Al2O3 and Pt/Al2O3 powder catalysts to evaluate the influence of the active phase on the removal of prochloraz (PCZ) (100 μg L−1), a pesticide listed on the EU Watch List (2022/1307), by HDC. PCZ removal was successfully described by a pseudo-first order kinetic equation and reaction pathways were proposed. Among the catalysts tested, Pt-based suffered a significant deactivation, not warranting the elimination of this micropollutant. Pd/Al2O3 exhibited a faster removal of PCZ than Rh/Al2O3, while this catalyst resulted in further hydrogenation of the non-chlorinated reaction product. Accordingly, different CMRs were developed by decorating cylindrical inert porous alumina membranes with Pd, Rh, and a combination of Pd-Rh as active phases (∼1% wt.). All CMRs showed a remarkable stability along 100 h on stream, being Pd/CMR be the most effective, with a pseudo-first order rate constant value of 0.062 min−1. An assessment of the impact of operating conditions (aqueous flow rate, PCZ initial concentration, temperature and H2 flow rate) was conducted using the Pd/CMR, which notably remained stable for 450 h on stream. The versatility of the system was finally demonstrated in tap water, achieving a steady-state PCZ conversion close to 95 %.

Anthocyanins and phenolics content of Thai black soybean extracts and their prevention against myoglobin autoxidation

Anthocyanin and phenolics found in black soybean are known as active antioxidants and have been linked to a variety of health benefits. The purpose of this study was to determine total monomeric anthocyanins (TMA), total phenolics (TP), and the retardation ability of protein autoxidation of an ethanolic extract of black soybeans planted in Thailand. We investigated the optimal conditions for extraction conditions. The ultrasonic-assisted approach successfully extracted both TMA and TP using 85% v/v ethanol as the solvent. The 15-min extraction time and solvent-to-sample ratio of 20:1 (v/w), at 30°C resulted in the highest concentration of TMA at 3.232±0.04 mg cyanidine-3-Oglucoside equivalent per gram dry weight whereas the longer time and higher temperature resulted in significantly decreased TMA content (P&lt;0.05). The maximum TP concentration of 119.42±0.42 mg gallic acid equivalent per gram dry weight was obtained by using a method identical to that used to extract TMA, except that of the longer time, increased solvent consumption and temperature. The preventive effect of black soybean extracts on oxymyoglobin (oxyMb) autoxidation was investigated. The pseudo first-order rate constant of oxyMb oxidation is decreased in the presence of the extracts in comparison to oxyMb alone. Additionally, oxyMb's half -life was increased from 0.57 to 1.46 hrs in the presence of TMA-rich extracts and from 0.57 to 2.51 hrs in the presence of the highest concentration of TP extracts when compared to cyanidine-3- O-glucoside and gallic acid, respectively. The study revealed that the black soybean extract could stabilize the bound oxygen in the oxyMb lead to slow down autoxidation of the protein consumption of foods or products derived from black soybeans may help to reduce cellular oxidative stress and the risk of developing various diseases as the study's findings indicate.

Removal of Reactive Black 5 by UV-C assisted peroxydisulfate process: Effect of parameters, kinetic study, and phytotoxicity assessment

ABSTRACT Photochemical removal of Reactive Black 5 (RB5) was investigated by the UV-C assisted peroxydisulfate (UV-C/PDS) process. Parameters affecting the removal of RB5 were examined. Activation of PDS by UV-C light significantly improved the removal efficiency compared to direct photolysis or PDS alone. The removal of RB5 by UV-C/PDS process fitted well with the pseudo first-order kinetic model under all tested conditions. Almost complete removal of RB5 was achieved at the end of 120 min within the pH range of 3–7, whereas 90.7 and 89.4% removal efficiency values were observed at pH = 9 and 11, respectively. An increase in PDS dosage in the range of 0.25–1 mM led to a rise in removal from 48.5 to 97.3% after 120 min, and a complete removal was observed with a dosage higher than 2 mM. Pseudo firstorder rate constant (kobs) increased linearly with PDS dosage from 0.0058 to 0.0518 min−1 in the 0.25 mM − 2.3 mM concentration range. The removal efficiency decreased with an increase in the initial concentration of RB5 from 20 to 50 mg L−1 and an exponential correlation was observed between kobs and initial concentration of RB5. Scavenging experiments conducted using t-butyl alcohol and ethyl alcohol implied that both sulphate and hydroxyl radicals were involved in the removal of RB5. Adding HCO3 − decreased the removal of RB5 within the range of 1–30 mM. The presence of CI− showed a negative impact on the removal at low concentrations (1–15 mM) and NO3 − slightly inhibited the removal of RB5. With corresponding stoichiometric PDS dosage, almost a complete mineralisation was achieved for RB5 solution and simulated dyebath effluent after 720 min of reaction time. EE/O values were determined to be 91.0, 76.8, and 41.1 kWh m−3 order−1 for UV-C/H2O2, UV-C/PMS, and UV-C/PDS processes, respectively. The phytotoxicity tests indicated that the intermediates could be more toxic than the parent compound.

Microwave-assisted hydrothermal synthesis of ZnO@ZrO2 nanohybrid for biomedical and photocatalytic applications

The present study was conducted to synthesize zinc oxide decorated on zirconium oxide (ZnO@ZrO2) nanohybrid synthesized through microwave-hydrothermal (MW-HT) method. Various analytical techniques were used to analyze the morphology, surface properties, constitution of hybrid, and elemental composition. Additionally, the anti-microbial activity of ZnO@ZrO2 nanohybrid was assessed against Gram-positive and Gram-negative pathogenic bacteria, hemolytic, anti-oxidant as well as anti-inflammatory assay. The hexagonal wurtzite phase of the ZnO was revealed by the XRD analysis. The experimental results reveal that the synergetic effect between the Zn and Zr active sites results an excellent biomedical activity. The ZnO@ZrO2 nanohybrid was successfully applied to the photocatalytic degradation of basic fuchsin (BF) dye within short period of time under visible light (VL) radiation. Moreover, the ZnO@ZrO2 nanohybrid exhibited an extraordinary performance for photocatalytic degradation of BF with a pseudo-first order rate constant (k) of ca. 0.1702 min−1, which was 2.5 and 1.8 fold compared to ZnO and ZrO2 photocatalysts. These results indicated that the ZnO@ZrO2 nanohybrid can be used as a potential biomaterial for bioengineering and photocatalytic applications.