This research focuses on the development of a highly effective monolithic Metal-Organic Framework (MOF) photocatalyst, a monoZIF-8 supported ZnO (ZnO@monoZIF-8) heterostructure, for the photocatalytic degradation of toxic dyes. The synthesis of ZnO@monoZIF-8 photocatalyst capitalizes on the synergistic effects of zinc oxide (ZnO) and zeolitic imidazolate framework-8 (ZIF-8), resulting in a catalyst that demonstrates exceptional photocatalytic activity. The lowering of the bandgap of ZIF-8 from 5.03 eV to 2.9 eV confirmed the proper anchoring of ZnO@monoZIF-8. The photocatalyst was exhaustively characterized by XRD, FT-IR, XPS, TGA, BET, SEM-EDX, UV-Vis DRS, and ICP-OES. Under UV radiation, the photocatalyst exhibits remarkable efficiency in the degradation of methylene blue (MB), achieving 95.13% degradation within a short time of 50 min. The monolithic photocatalyst could be recycled upto five times without significantly losing its degradation ability by a simple gravimetric filtration technique. In this study, we present a comprehensive bibliometric analysis of photocatalysis, alongside a detailed cost analysis for the synthesized photocatalyst. These insights shed light on the advancements and significance of research in this domain, offering valuable guidance for future developments.

The rising cost of biodiesel production is mainly driven by the high price of conventional oil feedstocks and the operational drawbacks of homogeneous catalysts. While microwave assistance accelerates transesterification, low-activity waste limits industrial scalability. This study addresses this gap through novel papaya leaf activation of inert fly ash, creating PLFC catalyst which achieved 96.6% waste cooking oil (WCO) biodiesel yield in 60 min vs 4-8 h required by conventional biomass catalysts. This work introduces a novel heterogeneous base catalyst derived from Carica papaya leaves combined with coal fly ash, an abundant and inexpensive industrial by-product. The catalyst was prepared by calcining the papaya-leaf/coal fly ash mixture at 700 degrees C for 4 h, producing a mesoporous material with a BET surface area of 4.586 m(2)/g, total pore volume of 0.0144 cm(3) g(-1), and an average pore diameter of 2.491 nm. Structural and elemental analyses using XRD, SEM-EDX, and XPS confirmed the presence of SiO2, Al2O3, Fe2O3 (T, total iron oxide content), K2O, P2O5, and MgO, which impart basicity and thermal stability. Catalytic activity was evaluated for the transesterification of WCO under microwave assistance. Formation of fatty acid methyl esters (FAMEs) was verified by H-1 and C-13 NMR spectroscopy as well as GC-MS profiling. Optimized reaction conditions were 50 W microwave power, 100 psi pressure, 700 rpm agitation, 85 degrees C temperature, 10 wt% catalyst loading, and a methanol-to-oil molar ratio of 24:1, which yielded 96.6% biodiesel within 60 min. Kinetic studies revealed a pseudo-first-order reaction with a low activation energy of 20.76 kJ mol(-1), while thermodynamic parameters (Delta H double dagger > 0, Delta S double dagger < 0, negative Delta G double dagger) indicated an endothermic process. Overall, this low-cost papaya-leaf/coal-fly-ash catalyst offers a sustainable and industrially scalable alternative to conventional catalysts, supporting economical biodiesel production and reduced reliance on fossil fuels.

The rapid growth of biodiesel production has resulted in an oversupply of glycerol, necessitating sustainable and efficient valorization. While biomass-derived sulfonated carbon catalysts have shown potential for glycerol acetalization, conventional sulfonation techniques suffer from active site leaching and poor stability. To address these limitations, we have developed a novel biomass-derived solid acid catalyst via arylation-based sulfonation of pine cone activated carbon using 4-benzenediazonium sulfonate. This environmentally friendly catalyst helps turn glycerol into solketal, a valuable fuel additive. TGA, XRD, BET, XPS, FT-IR, and SEM-EDX confirmed the structural integrity and surface acidity of the catalyst, while the final solketal product was validated using NMR and GC analysis. Process optimization revealed ideal conditions at a glycerol-to-acetone molar ratio of 1:5, 80 degrees C temperature, 20 min reaction time, and 8 wt% catalyst loading, achieving an impressive 93.69 % selectivity toward solketal. The catalyst exhibited a high surface area of 623.90 m2g-1 with a pore diameter of 1.804 nm and also an excellent recyclability up to six cycles. Life cycle cost analysis indicated a competitive solketal production cost of $1.20 per kg. This study presents a stable, reusable, and economically viable approach for glycerol valorization using biomass-derived solid acid catalysts.

The electronic and optical properties of silicon-doped tetragonal hafnium dioxide (t-HfO2) have been investigated by using the meta-generalized gradient approximation (MGGA-TB09 + c) approach within the framework of density functional theory (DFT). Silicon (Si) is assumed to be the most effective dopant among all other investigated dopants to support the t-HfO2 phase as well as it improves the required properties of high-k gate dielectric oxides. The unique characteristics of this material are closely associated with the inclusion of dopants within the supercell. The primary objective of this study is to examine and compare various features distinguished by their doping percentages of Si as 0%, 6.25%, 12.50%, and 18.75% respectively. Ground state features such as lattice parameters and volume are computed and compared to existing experimental and theoretical data. A comprehensive theoretical investigation of bandgap, and dielectric properties is also computed here. This analysis not only yielded an experimental bandgap of the material as 5.83 eV but also revealed a notable reduction in the bandgap of Si-doped crystal structures. Further, the optical properties are also computed which reveals a visible isotropic spectrum phenomenon, that is attributed to the inherent electronic configuration of the Si dopant. A significant increase in the static dielectric constant is seen for the Si-doped structures, accompanied by a shift in the absorption spectra at a specific wavelength, which enables optical absorption within the visible range. The experimental results demonstrated a simultaneous rise in the real component of the refractive index and a significant enhancement in optical conductivity. These findings indicate that Si-doped t-HfO2 can be a promising material for applications as negative capacitance field effect transistors and in future-generation memory devices.

The electronic and optical properties of Si-doped t-HfO2 have been investigated using the MGGA-TB09+c method within the DFT framework. Silicon is considered the most efficient dopant among all examined dopants for stabilizing the t-HfO2 phase. This work primarily aims to investigate the optoelectronic properties of t-HfO2 with 6.25, 12.50, and 18.75

The transition toward renewable fuels requires robust, recyclable, and eco-friendly catalysts for biodiesel synthesis. Here, we reported the synthesis process of a sulfonated covalent triazine framework-based porous organic polymer (CTF-POP-SO3H) and the microwave-assisted esterification of oleic acid with methanol using a heterogeneous CTF-POP-SO3H catalyst. The catalyst exhibited a high biodiesel conversion of 96.61% under optimized conditions (methanol-to-oil ratio, 20 : 1; catalyst loading, 8 wt%; reaction time, 50 min; temperature, 100 °C) with product formation confirmed by 1H NMR, 13C NMR, and GC analyses. Comprehensive characterization of the catalyst was conducted using FTIR, BET, TGA, XRD, XPS, and SEM-EDX-MAPPING. The presence of acidic sites (-SO3H) is confirmed by acid-base titration, which is well aligned with SEM-EDX-MAPPING. Kinetic evaluation revealed a low activation energy of 24.52 kJ mol-1, while thermodynamic analysis indicated an endothermic process. Importantly, the catalyst retained over 80% of its activity after five successive cycles, confirming its durability and reusability. These results highlight that the sulfonated porous organic polymer is an efficient and sustainable catalyst for biodiesel production, providing an eco-friendly pathway aligned with global clean energy targets.

The global energy crisis and growing environmental alarms have hastened the search for renewable energy sources. This study explores a novel approach to biodiesel synthesis using microwave-assisted transesterification with a composite catalyst derived from snail shell-derived calcium oxide (CaO) supported on coal fly ash. The synthesized catalyst exhibits FAME conversion of 98.03 % under optimal conditions. Diverse analytical techniques were utilized to characterize the catalyst using TGA, XRF, BET, CO2-TPD, XRD, XPS, SEM, ICP-OES, and TEM analysis. Kinetic and thermodynamic parameters resulted in an activation energy of 36.6 kJ mol-1, an activation enthalpy of 33.62 kJ mol-1, and an entropy of-0.173 kJ mol-1 K-1, respectively. The cost analysis effectively demonstrated the economic viability of this method. A comprehensive bibliometric analysis also provided insights into the research trends and developments in biodiesel production from waste materials regarding feedstock and catalysts. The findings indicate that microwave-assisted biodiesel production with ecofriendly catalysts offers a promising alternative for sustainable energy, meeting economic and environmental objectives as the Sustainable Development Goals (SDGs).

The effect of silver (Ag) and gold (Au) doping at a concentration of 8.33% on the electronic and optical properties of the LiNbO3 crystal was theoretically analyzed using density functional theory (DFT). The results showed that LiNbO3 exhibits a non-magnetic semiconductor property, which is consistent with experimental evidence described in the literature. Ag and Au doping at a concentration of 8.33% had no impact on the semiconductor behavior. However, a significant decrease in band gap energy was found when compared to pure LiNbO3. The results of this study show that LiNbO3 can be successfully used in a variety of technical fields, including spintronic. This can pave the way for additional studies and research into these materials.

The electronic and optical properties of pure and Ag-Au co-doped lithium niobate crystals are calculated by using density functional theory (DFT). The obtained results indicate that lithium niobate exhibits a non-magnetic semiconducting nature. The co-doping percentage of 8.33% did not change the semiconducting nature of the crystal. However, a significant reduction in the band gap was found in the co-doped structure. For both pure and co-doped structures, the optical properties including dielectric function, refractive index, extinction coefficient, and reflectivity were calculated and thoroughly examined.

The effect of lanthanum (La) and Scandium (Sc) doping on the structural, electronic, and optical properties of cubic hafnium oxide (c-HfO2) has been thoroughly investigated using density functional theory (DFT). The spin-polarized calculations have been performed using the MGGA-TB09 + c exchange–correlation functional. In this study, 6.25

Fly ash-Ag2O nanoaggregates photocatalyst (FA-Ag2O NAP) has been effectively synthesized by a green technique using silver nitrate and F-type fly ash. The physico-chemical properties of synthesized FA-Ag2O NAP were studied by a number of techniques such as field emission-scanning electron microscopy (FE-SEM), energy dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), Fourier-transform infrared (FT-IR) and ultraviolet-visible (UV-Vis) spectroscopy. The photocatalytic activity of the synthesized FA-Ag2O NAP has been evaluated by performing the degradation of malachite green (MG) dye in aqueous solution under solar irradiation. The photocatalyst was associated with a band gap energy of 3.84 eV. The ash provided a strong support of the silver oxides accountable for the photocatalytic degradation. FA-Ag2O NAP was associated with excellent photocatalytic activity towards the degradation of malachite green dye, in aqueous solution, within only 75 min under direct sunlight. The photocatalyst could be effectively regenerated and reused up to four runs. The synthesized FA-Ag2O NAP may be used for purification of polluted water released from various textile, dye and pharmaceutical industries. Copyright (C) 2022 Elsevier Ltd. All rights reserved. Selection and peer-review under responsibility of the scientific committee of the XII th Biennial National Conference of Physics Academy of North East (PANE 2021).

A magnetic nano-sized solid catalyst derived from bio-waste Citrus sinensis peel ash (CSPA)@Fe3O4 was developed for the synthesis of biodiesel from waste cooking oil (WCO). The core-shell structure of the catalyst enhanced the surface properties and maintained a controlled size and shape of the catalyst, thus improved the catalyst stability to a great extent. The synthesized catalyst was characterized by several analysis techniques. The high amount of potassium and calcium in the Citrus sinensis peel ash (CSPA) catalyst makes it extremely basic and played an important catalytic role in the transesterification of WCO. The CSPA@Fe3O4 catalyzed transesterification afforded a maximum biodiesel yield of 98% under the optimized reaction conditions such as 6:1 methanol/oil molar ratio, 6 wt% catalyst loading, 65 degrees C temperature and 3 h time. The activation energy of the reaction was found to be 34. 41 KJ mol(-1), which indicated that the transesterification of WCO using the present catalyst is chemically controlled reaction. Beneficially, the magnetic iron oxide core endorsed easily recoverable of the catalyst from the reaction mixtures by using an external magnet. Moreover, the catalyst showed high physical stability and reactivity up to the 9 consecutive cycles, demonstrating it as a promising solid base catalyst for sustainable production of biodiesel.

A robust, magnetically recoverable Fe3O4@SiO2-SO3H core@shell nanoparticulate acid catalyst was successfully synthesized by a stepwise co-precipitation, coating, and functionalization. It was utilized as a heterogeneous catalyst for the transesterification and esterification of triglycerides and free fatty acids in Jatropha curcas oil (JCO) to a fatty acid methyl ester (FAME) mixture. This product conformed to ASTM standards for biodiesel. The as-prepared catalyst had a magnetic saturation of 30.94 emu g-1, surface area of 32.88 m2g- 1, acidity of 0.76 mmol g-1, and pore diameter of 3.48 nm. The catalyst showed 98 +/- 1% conversion using the optimized reaction conditions of methanol:oil molar ratio of 9:1, 8 wt% catalyst loading, 80 degrees C, and 3.5 h. The transesterification of JCO to FAME using the present catalyst benefitted from a very low activation energy of 37.0 kJ mol-1. The solid acid catalyst exhibited excellent chemical and thermal stability, and also reusability based on easy separation from the reaction mixture due to its inherently magnetic nature. Modest deterioration in oil conversion after multiple uses was offset by one-pot, quantitative regeneration of catalyst active sites. This enabled identical performance in JCO methyl transesterification and esterification in the 1st and 10th catalytic cycles.

Low carbon coal ash—a solid air pollutant from super thermal power plant using pulverized fuel combustor—has been characterized in respect of its physico-chemical, mineralogical, and morphological features. Size-classified fractions with their magnetic and non-magnetic components have also been characterized. Low loss on ignition and particle size distribution profile shows fly ash has high utility. The magic number,10 µm, is attained by greater % of particles. The particles with diameter 50 µm occupy population density of 93%. SEM-EDS reveals that particles are mostly globular with high surface enrichment of Al/Si indicating that it will act as un-reactive inert fillers. In magnetic components, various types of Fe bearing phase are present with less porous and more regular shape than non-magnetic components. Finer fractions have high content of magnetite which is expected to help in coal beneficiation. The finer non-magnetic fraction is a source of alumino-siliceous material for synthesizing a novel solid acid or base catalyst for catalyzing industrially important organic reactions.

Fly ash modified copper oxide photocatalyst (FA/CuO) has been successfully synthesized via a green method using copper sulphate pentahydrate and F-type fly ash. The physico-chemical properties of prepared FA/CuO were examined by various techniques such as FEG-SEM, XRD, FT-IR and UV-visible spectroscopy. The photocatalytic activity of the synthesized FA/CuO has been evaluated by performing the degradation of methyl orange (MO) dye in aqueous solution under direct sunlight irradiation. The photocatalyst was associated with band gap energy of 2.09 eV. The ash provided a strong support of the copper oxides responsible for photocatalytic degradation. A rapid MO dye degradation (99.1%) occurred at 40 min over the surface of FA/CuO photocatalyst.

In the present work, the physicochemical, mineralogical, and morphological characteristics of coal combustion residues (CCRs) collected from two different Pulp and Paper Mills of Assam, India, have been investigated. CCRs from both the sources were mechanically sieved to obtain various size-classified fractions and their physical properties were determined using standard methods. X-ray diffraction (XRD), Fourier Transformation Infrared (FTIR) Spectroscopy, Scanning Electron Microscopy (SEM) etc. techniques were employed to study the mineralogical and morphological characteristics of each size classified fraction. The loss on ignition (LOI) values of the coarser fractions were found to be unexceptionally high, implying the presence of a huge amount of unburned carbon, and indicating the incomplete combustion of feed coal. From the utilization point of view, coarser fractions may be recycled (as domestic fuels) and less-coarse fractions may be used as adsorbents of toxic organic chemicals. Due to the larger water-holding capacities (WHCs), the coarser fractions may be used for soil amendment.

Coal combustion power stations generate huge quantities of ash annually; thus, utilization of such waste residues is an important and essential component for sustainable disposal and management. This paper summarizes an investigation carried out on the coal combustion residues (CCRs) collected from Cachar Paper Mill, Assam, India. A thorough characterization of ash has been carried out with respect to its physicochemical, mineralogical, and morphological features by using density determination, loss on ignition (LOI) determination, Fourier transform infrared, X-ray diffraction, X-ray fluorescence, scanning electron microscopy with electron dispersive X-ray, etc. . The coarser fraction appears to contain a high percentage of char, semi-coked/coked carbonaceous particles, and exceptionally high LOI (86%) values. The carbonaceous matters contain some aliphatic carbon, which implies incomplete combustion. For correlating the total characteristic features, various experiments were performed based on which a number of possible potential utilization directions were suggested. Furthermore, the coarser particles showed excellent water-holding capacities (WHCs, 400%) and good adsorption capabilities, due to the presence of micro- and macropores.

A green and efficient solid acid catalyst (SAC) has been synthesized upon modification of F-type fly ash using ortho-phosphoric acid (35 wt. %). Catalyst characterization has been accomplished using different analytical techniques, such as FT-IR, XRD, SEM-EDS, and BET surface area analysis. SAC possessed excellent catalytic activity for Fischer esterification reaction between 4-aminobenzoic acid and methanol at 95 degrees C to produce methyl 4-aminobenzoate (MAB), an important precursor for the synthesis of pharmaceutical drugs, (+/-) martinelline, and (+/-) martinellic acid. This investigation suggests the utilization of fly ash to develop novel solid acid catalyst system for catalyzing industrially important esterification reaction. (C) 2015 The Korean Society of Industrial and Engineering Chemistry. Published by Elsevier B.V. All rights reserved.

The objective of the investigation was to evaluate the catalytic efficiency of a solid base catalyst (SBC) derived from coal combustion fly ash to synthesize dibenzylideneacetone (DBA, 94% yield). The catalyst was produced using potassium hydroxide (30 wt.%) on thermally activated F-type fly ash. The physicochemical, mineralogical and morphological characterization of the fly ash and catalyst were performed using XRF, FT-IR, BET surface area analyser, XRD and SEM-EDS. The results of such analysis revealed that the catalyst obtained was associated with strong basic hydroxyl (-OH) sites that were highly suited to produce DBA by crossed aldol condensation reaction. (C) 2015 The Korean Society of Industrial and Engineering Chemistry. Published by Elsevier B.V. All rights reserved.