Universal Journal of Green Chemistry

Systematic Multivariate Analysis for Optimizing Active and Selective AuPd-Based-Nanocatalyts towards Benzyl Alcohol Oxidation

2024-06-03T10:39:16+08:00

Supported bimetallic gold-palladium (AuPd) nanomaterials have been extensively studied as highly active and selective nanocatalysts for oxidation reactions. For long-term viability, optimizing synthesis and reaction parameters is essential for utilizing noble-based materials once they are expensive to produce on a large scale. For that reason, using a performance-focused strategy like a multivariate experimental design is an optimal solution for simultaneously investigating the effects of different parameters and implementing such materials in business activities. Therefore, herein, we report a systematic multivariate optimization of model AuPd/SiO2 nanocatalysts for selective benzyl alcohol oxidation in solvent-free sustainable conditions, which allows for the evaluation of the impact of the material synthesis and reaction conditions on the process and optimization of reaction and calcination temperatures. Our multivariate analysis shows that the calcination temperature has considerably impacted the structural properties of gold nanoparticles; still, these changes did not produce a pronounced effect on the material’s catalytic properties. On the other hand, the physical variables of reaction time and temperature had a more significant influence on both conversion and selectivity. An 18% conversion of benzyl alcohol with a benzaldehyde selectivity of 93% was achieved under a 562 ◦C catalyst calcination temperature, 100 ◦C reaction temperature, and 4 h of reaction time.

Use of Group Contribution Methods, Hansen’s Solubility Theory and Microsoft Excel in Solvents Selection for Extraction of Natural Products

2024-09-24T09:54:02+08:00

Usually, Hansen’s theory and the COSMO continuous solvation models have been used for the selection
of solvents related to a solute, using the HSPiP and COSMO-RS computational tools, respectively. Those tools are not
always available to many researchers; for this reason, Microsoft Excel (ME) has been used for the estimation of good
solvents in the extraction of natural products of high value and interesting for the food, pharmaceutical and cosmetic
industries. This method is applicable to cases where there is little, or practically no information about the compound of
interest, for which functional group contribution methods are used, among them, the Joback method for the estimation of
properties necessary for the determination of solubility models, and Van Krevelen method for the initial estimation of the
Hansen solubility parameters for solubility estimates, the Flory-Hugging model is used, from which and its classification,
according to the North American Pharmacopeia, the good and bad solvents are defined in the selected database for
the final estimation of Hansen’s parameters and the solubility region. The methodology was validated with ten study
cases reported in the literature. The results of this study showed that other green solvents, not reported in the literature
consulted, are suggested as good solvents for polyphenols, such as diacetone alcohol, diethylene glycol monobutyl ether
and tetrahydrofurfuryl alcohol. In the consulted literature there are no references on the use of a structured methodology
in Microsoft Excel (ME) for the estimation of good solvents for the extraction of natural products from the estimation
of solubility with existing models. All the consulted papers refer the use of various professional computer programs for
this purpose, specifically HSPiP, and COSMO-RS, which are not accessible to all researchers. With these estimates and
an initial classification based on pharmacopoeia criteria, a first classification of good and bad solvents is made, which is
refined by means of optimization methods in ME.

Waste to Wealth Catalyzed Synthesis of 3-methyl-4-(hetero)arylmethyleneisoxazole- 5(4H)-ones and pBR 322 DNA Cleavage Studies

2024-04-30T10:27:01+08:00

Herein, we demonstrated the synthesis of pharmacologically significant 3-methyl-4-(hetero)arylmethylene isoxazole-5(4H)-one by employing the water extract of lemon fruit shell ash (WELFSA) and glycerol as a solvent medium. The present method explored WELFSA as an eco-friendly catalyst to obtain 3-methyl-4-(hetero)aryl methyleneisoxazole-5(4H)-one derivative by the reaction of substituted aryl/heterocyclic aldehyde, hydroxylamine hydrochloride and ethyl acetoacetate at 60 ◦C on oil bath stirring condition. The completion of the reaction was monitored by thin-layer chromatography, and then the reaction mixture was quenched with ice-cold water, the separated solid was filtered, recrystallized in ethanol, and confirmed by various spectroscopic techniques. Some of the selected derivatives are subjected to DNA cleavage studies against pBR322, and showed comparable activities.

Removal of Phosphate and Ammonium Ion from Domestic Wastewater Using Clay Feldspar in Wupa Sewage Treatment Plant Abuja

2024-05-22T09:36:06+08:00

The aim of this study is centered on the sustainability of feldspar as an adsorbent as opposed to other clay minerals such as plastic clay, red clay and barite. Brauner-Emmert-Teller (BET) analysis of the clay minerals considered in this study revealed that raw feldspar had the highest surface area and pore volume of 332.8 m²/g and 0.218 cc/g respectively. Similarly, the clay minerals were used in adsorption study with feldspar producing the best removal efficiency of 90.00%and 73.96% for ammonium and phosphate ions respectively. The BET results and the adsorption test showed that feldspar was a better adsorbent than the other adsorbents. Thermal activation of feldspar was carried out at temperatures of 500–700 ◦C using muffle furnace. The BET results of the thermal activation revealed that feldspar activated at 600 ◦C has the highest surface area and pore volume of 533.9 m²/g and 0.272 cc/g respectively. The Fourier’s transformed infrared (FT-IR) results indicated that several functional groups were involved in the adsorption process of the phosphate and ammonium ions some of which were O-H, N-H and C-O groups. The results showed that irregular-layered structures of the raw feldspar became smooth and regular after thermal activation. The effects of pH, adsorbent dosage, temperature, contact time and initial PO₄3− and NH₄⁺ concentrations on the adsorption of phosphate ions and ammonium ions were investigated using atomic adsorption spectroscopy (ASS). The adsorption studies of phosphate ion and ammonium ion onto feldspar increased with contact time, adsorbent dosage and temperatures until optimum values were reached.

Evaluation of Gerbera jamesonii Derived Silver Nanoparticles for Photocatalysis, Antibacterial Activity and Detection of Melamine Adulteration in Milk

2024-09-29T11:58:14+08:00

Nanotechnology plays a crucial role in today’s world in fields of food technology and textile. The present study focuses on green synthesis of silver nanoparticles using 5 petal extracts of Gerbera jamesonii and assessing its photocatalytic and antibacterial activity. The petal extracts were subjected to 30-min incubation at 90 ◦C for AgNP synthesis. Qualitative and quantitative analysis of antioxidants were carried out and results were statistically analysed in order to determine the highest incorporation of antioxidants in AgNP synthesis. The shape and size of synthesised AgNP were analysed using SEM, which showed spherical AgNPs with a diameter of 50–60 nm. Photocatalytic activity with Malachite Green (MG) in the presence of NaBH4 confirmed a higher rate constant with AgNP diluted at 267 ppm. Antibacterial activity tested using well diffusion technique against Escherichia coli showed a higher growth inhibition in red (GerR), white (GerW) and yellow (GerY) petal extracts and Staphylococcus aureus showed a higher growth inhibition in AgNPs synthesised with pink (GerP) and yellow (GerY) petal extracts. Melamine adulteration in Milk was assessed using raw milk and 2 mM melamine spiked milk samples. A clear colour change was observed, and absorption peak was visible at 500–540 nm confirming the ability to detect melamine using AgNPs synthesised using GerP extracts. The results therefore suggests that green synthesised AgNPs can be utilised for various applications which will play a crucial role in quality assurance purposes in the food technology and textile industries.

Optimization of Batch Adsorption Study Parameters of Acid Dyes onto Spent Brewery Grains

2024-03-19T16:51:31+08:00

The exploration of economical and nature friendly adsorbents for dye elimination from effluent is a promising area of research, driven by the need for sustainable and economically viable solutions. This work deals with the adsorption features of Acid Blue 25 (AB25) and Acid Green 25 (AG25) dyes from aqueous solutions using spent brewery grains (SBG). After brewing process, the obtained residue consists of spent grains. Optimum conditions for AB25 & AG25 removal were found to be at pH 2, adsorbent dosage as 0.8 and 1 g/L of solution respectively and equilibrium time was found to be 60 mins. In order to adjudicate the adsorption process, analysis was carried out with kinetic and isothermal two parameter and three parameter models. The results were discovered to fit most with the pseudo-second-order (R2 = 0.990) for the kinetics and the Langmuir isotherm (R2 = 0.993) for the adsorption isotherms. The isotherms and kinetics verified that SBG had a high value of adsorption capacity. Experiment results pointed out SBG is one of the best adsorbent that eco-friendly, economical, readily accessible, and efficient on the removal of AB25 and AG25 dyes from aqueous solution.

Fluoride Removal in Water Using Kaolin and Eggshell Powder Blend Adsorbents

2024-05-29T17:00:06+08:00

Fluoride contamination in water has emerged as a significant global concern due to its adverse health effects when consumed in excess. This study is focused on developing an eco-friendly, cost-effective adsorbent for fluoride removal using eggshells and kaolin. Adsorbent blends were prepared by mixing kaolin and eggshell powder in six different ratios, namely; 100:0, 80:20, 65:35, 50:50, 35:65, and 20:80. Cylindrical-shaped pellets were produced from each of the blends and subjected to the thermal treatment at 950 ◦C. Fluoride adsorption capacities of the pellets were investigated at different pH conditions (from pH 2 to pH 10) for a 5 mg/L fluoride solution with 1 g of adsorbent dosage and 60 min of contact time. Pellets with a 50:50 ratio (CKE3) were found to be the most effective adsorbent considering the adsorption capacity and stability at all the studied pH conditions. At pH 6, CKE3 showed an adsorption capacity of 0.06 mg/g compared to 0.02 mg/g of kaolin-only pellets. XRD, TGA-DSC, EDX and SEM analysis were used to characterize the adsorbent. XRD analysis showed that the raw adsorbent contained phases of CaCO3 and kaolinite, whereas the calcined material comprised Ca(OH)2 and metakaolinite. Batch experiments were carried out with CKE3 for adsorbent dosage, pH, contact time, and initial fluoride concentration. An adsorbent dosage of 4 g was capable of resulting in a 53% removal of fluoride for a 5 mg/L solution after 60 min of contact time. Pseudo-first-order and pseudo-second-order kinetic models were applied in the study, and pseudo-second-order exhibited the best fit. The isotherm data were studied for Langmuir and Freundlich models, and the results were satisfactorily fitted with Langmuir isotherm.

Two Principles for Colorimetric Detections of Cr6+ Using Polyurethane Foam—Gold Nanoparticles Composite

2024-06-17T10:20:47+08:00

Two principles of leaching and precipitating for colorimetric sensing of hexavalent chromium using a composite of polyurethane foam with gold nanoparticles (PUF-AuNPs) with a smartphone and image processing were reported. The PUF-AuNP composites were exposed to different concentrations of hydrobromic acid (HBr) before taking a one-shot image and processing it to obtain a color value with ImageJ for a sample with triplicate results. In 0.05 M HBr, the leaching of AuNPs by oxidation would provide a linear calibration with yellow value = 0.021[Cr6+, mM] + 0.078 (R2 = 0.998) for 0.5–5 mM with a limit of quantitation (LOQ) of 0.3 mM. In 1 M HBr, the amount of precipitate of Cr3+-bromide was proportional to the concentration of Cr6+ with a linear range of 2–20 mM and a green value = −2.5[Cr6+, mM] + 210 (R2 = 0.981) with a limit of detection (LOD) of 0.6 mM. The precision was lower than 4% RSD with a good accuracy by % relative error. Various techniques, such as FT-IR, SEM, TEM, and EDS, confirmed the presented principles, and PUF-AuNPs. The PUF was readily synthesized in a lab using simple apparatuses like plastic cups and stirrer rods. AuNPs sorbed on PUF were obtained from the reduction of hydrogen tetrachloroaurate (III), which would be obtained from a low-cost gold leaf. Preliminarily, two proposed colorimetric sensors were tested for Cr6+ assay in known aqueous samples with calculations in a calibration graph and the naked eye.

Reduced Graphene Oxide Decorated with Cu Nanoparticles as an Efficient Catalyst for Ullmann-Type N -Arylation Reactions

2024-10-09T11:20:12+08:00

Ullmann-type aryl amination of aryl halides catalyzed by reduced graphene oxide decorated with copper nanoparticles was investigated. The reduced graphene oxide-supported copper nanoparticles were prepared via simultaneous electrodeposition of copper nanoparticles and reduction of graphene oxide by a facile cyclic voltammetry method in the absence of any reducing agent or volatile solvents. The proposed method is simple, general, ligand-free, and efficient to afford N-arylated compounds in high yield. The hot filtration test suggests the present reaction would proceed via heterogeneous nature. The catalyst showed high stability and could easily be recovered and reused without any considerable loss of its catalytic activity.

Nickel Oxide Based Nanoparticles: Green Synthesis, Morphological Assessment, and Their Biological Properties

2024-06-24T15:40:41+08:00

Nanotechnology has been successfully implemented for improved applications in biological activities and environmental remediation. Nickel oxide nanoparticles (NiO-NPs) are effectively synthesized from bio-inspired sources, and their effectivity is higher than that of chemically synthesized NiO-NPs. Biogenic synthesis is mostly favored due to its low cost and eco-friendliness. Properties of NiO-NPs, such as wide bandgap, semi-conductivity, good electrochemical performance, etc., have proved to be superior to those of other Metal Oxide Nanoparticles. Phytochemicals present in various medicinal plant materials act as chelating agents, capping agents, and stabilizers for the green synthesis of NiO-NPs. While various organic molecules present in microorganisms reduce metal salts to Metal Oxide Nanoparticles as they act as reductants or dispersants, distinct characterization techniques such as XRD, SEM, TEM, UV-VIS, FTIR, EDS, etc. are used to confirm the formation of NiO-NPs and for their morphological studies. Green chemistry is witnessing rapid progress by virtue of its ease of synthesis, inexpensiveness, non-toxicity, and renewability. NiO-NPs have a wide range of applications. Biochemical applications such as antifungal, antibacterial, antidiabetic, anticancer, and anti-larvicidal are discussed with their plausible mechanisms. Photocatalytic activities of NiO-NPs are also studied in detail, in which a light-activated catalyst is used for the reduction or oxidation of organic dyes. The present review systematically represents various routes for green synthesis of NiO-NPs, morphological elucidation through well-known quantitative techniques, and potential applications with respect to catalytic and biological fields.