Lignocellulosic biomass contains lignin, an aromatic and oxygenated substance and a potential method for lignin utilization is achieved through catalytic conversion into useful phenolic and aromatic monomers. The application of monometallic catalysts for lignin hydrogenolysis reaction remains one of the major reasons for the underutilization of lignin to produce valuable chemicals. Monometallic catalysts have many limitations such as limited catalytic sites for interacting with different lignin linkages, poor catalytic activity, low lignin conversion, and low product selectivity. It is due to lack of synergy with other metallic catalysts that can enhance the catalytic activity, stability, selectivity, and overall catalytic performance. To overcome these limitations, works on the application of bimetallic catalysts that can offer higher activity, selectivity, and stability have been initiated. In this review, cutting-edge insights into the catalytic hydrogenolysis of lignin, focusing on the production of phenolic and aromatic monomers using bimetallic catalysts within an internal hydrogen donor solvent are discussed. The contribution of this work lies in a critical discussion of recent reported findings, in-depth analyses of reaction mechanisms, optimal conditions, and emerging trends in lignin catalytic hydrogenolysis. The specific effects of catalytic active components on the reaction outcomes are also explored. Additionally, this review extends beyond current knowledge, offering forward-looking suggestions for utilizing lignin as a raw material in the production of valuable products across various industrial processes. This work not only consolidates existing knowledge but also introduces novel perspectives, paving the way for future advancements in lignin utilization and catalytic processes.
The widespread consumption of pharmaceutical drugs and their incomplete breakdown in organisms has led to their extensive presence in aquatic environments. The indiscriminate use of antibiotics, such as sulfonamides, has contributed to the development of drug-resistant bacteria and the persistent pollution of water bodies, posing a threat to human health and the safety of the environment. Thus, it is paramount to explore remediation technologies aimed at decomposing and complete elimination of the toxic contaminants from pharmaceutical wastewater. The review aims to explore the utilization of metal-oxide nanoparticles (MONPs) and graphitic carbon nitrides (g-C3N4) in photocatalytic degradation of sulfonamides from wastewater. Recent advances in oxidation techniques such as photocatalytic degradation are being exploited in the elimination of the sulfonamides from wastewater. MONP and g-C3N4 are commonly evolved nano substances with intrinsic properties. They possessed nano-scale structure, considerable porosity semi-conducting properties, responsible for decomposing wide range of water pollutants. They are widely applied for photocatalytic degradation of organic and inorganic substances which continue to evolve due to the low-cost, efficiency, less toxicity, and more environmentally friendliness of the materials. The review focuses on the current advances in the application of these materials, their efficiencies, degradation mechanisms, and recyclability in the context of sulfonamides photocatalytic degradation.
In response to the escalating global issue of microbial contamination, this study introduces a breakthrough photocatalyst: bismuth ferrite-activated carbon (BFO-AC) for visible light-driven disinfection, specifically targeting the Gram-positive bacterium Staphylococcus aureus (S. aureus). Employing an ultrasonication method, we synthesized various BFO-AC ratios and subjected them to comprehensive characterization. Remarkably, the bismuth ferrite-activated carbon 1:1.5 ratio (BA 1:1.5) nanocomposite exhibited the narrowest band gap of 1.86 eV. Notably, BA (1:1.5) demonstrated an exceptional BET surface area of 862.99 m2/g, a remarkable improvement compared to pristine BFO with only 27.61 m2/g. Further investigation through FE-SEM unveiled the presence of BFO nanoparticles on the activated carbon surface. Crucially, the photocatalytic efficacy of BA (1:1.5) towards S. aureus reached its zenith, achieving complete inactivation in just 60 min. TEM analysis revealed severe damage and rupture of bacterial cells, affirming the potent disinfection capabilities of BA (1:1.5). This exceptional disinfection efficiency underscores the promising potential of BA (1:1.5) for the treatment of contaminated water sources. Importantly, our results underscore the enhanced photocatalytic performance with an increased content of activated carbon, suggesting a promising avenue for more effective microorganism inactivation.
Metal-Organic Frameworks (MOFs) have exceptional inherent properties that make them highly suitable for diverse applications, such as catalysis, storage, optics, chemo sensing, and biomedical science and technology. Over the past decades, researchers have utilized various techniques, including solvothermal, hydrothermal, mechanochemical, electrochemical, and ultrasonic, to synthesize MOFs with tailored properties. Post-synthetic modification of linkers, nodal components, and crystallite domain size and morphology can functionalize MOFs to improve their aptamer applications. Advancements in AI and machine learning led to the development of nonporous MOFs and nanoscale MOFs for medical purposes. MOFs have exhibited promise in cancer therapy, with the successful accumulation of a photosensitizer in cancer cells representing a significant breakthrough. This perspective is focused on MOFs' use as advanced materials and systems for cancer therapy, exploring the challenging aspects and promising features of MOF-based cancer diagnosis and treatment. The paper concludes by emphasizing the potential of MOFs as a transformative technology for cancer treatment and diagnosis.
Dealing with the current defaults of environmental toxicity, heating, waste management, and economic crises, exploration of novel non-edible, toxic, and waste feedstock for renewable biodiesel synthesis is the need of the hour. The present study is concerned with Buxus papillosa with seeds oil concentration (45% w/w), a promising biodiesel feedstock encountering environmental defaults and waste management; in addition, this research performed simulation based-response surface methodology (RSM) for Buxus papillosa bio-diesel. Synthesis and application of novel Phyto-nanocatalyst bimetallic oxide with Buxus papillosa fruit capsule aqueous extract was advantageous during transesterification. Characterization of sodium/potassium oxide Phyto-nanocatalyst confirmed 23.5 nm nano-size and enhanced catalytic activity. Other characterizing tools are FTIR, DRS, XRD, Zeta potential, SEM, and EDX. Methyl ester formation was authenticated by FTIR, GC-MS, and NMR. A maximum 97% yield was obtained at optimized conditions i.e., methanol ratio to oil (8:1), catalyst amount (0.37 wt%), reaction duration (180 min), and temperature of 80 °C. The reusability of novel sodium/potassium oxide was checked for six reactions. Buxus papillosa fuel properties were within the international restrictions of fuel. The sulphur content of 0.00090% signified the environmental remedial nature of Buxus papillosa methyl esters and it is a highly recommendable species for biodiesel production at large scale due to a t huge number of seeds production and vast distribution.
Carbon-integrated binary metal oxide semiconductors have gained prominence in the last decade as a better material for photocatalytic wastewater treatment technology. In this regard, this research describes the investigation of the binary metal oxide TiO2@Fe3O4 embedded on reduced graphene oxide (rGO) nanosheets synthesized through a combination of sol-gel, chemical precipitation, and Hummer's processes. Besides, the catalyst is applied for the photocatalytic degradation of organic chlorophenol pollutants. The characterized diffraction results showed the peak broadening of the rGO-TiO2@Fe3O4 composite formed with tetragonal and cubic structures having small crystallite sizes. The TEM observation shows an enormous miniature of TiO2@Fe3O4 nanospheres spread on the folded 2D-rGO nanosheets with a large BET surface area. The XPS result holds the mixed phases of Fe3O4 and Fe2O3. Finally, the catalyst demonstrated a low band gap with extended light absorption towards visible light irradiation. The synergistic interactions between Fe3+ and Fe2+ improved the visible light activity due to the incorporation of rGO, and also possessed good recycling capacity. The increased mobility of electrons at the interfaces of TiO2 and Fe3O4 due to the mixing of rGO results in the separation of charge carriers by elevating the photocatalytic degradation efficiency of chlorophenol.
Semiconductor metal oxide with TiO2 nanoparticles removes hazardous compounds from environmental samples. TiO2 nanoparticles have shown potential as an efficient photocatalyst by being employed as a nano-catalyst for the breakdown of organic contaminants in wastewater samples. To separate substances from contaminated samples, combined UV and visible light irradiation has been used. Sol-gel synthesis was used to produce a copper chromite-titanium nanocomposite, which was then evaluated using analytical methods, such as XRD, BET, DRS-UV, and FT-IR. Using visible light, the photocatalytic activity of a nanocomposite made of CuCr2O4 and TiO2 was investigated for its role in the breakdown of malachite green. The effects of several parameters, including pH change, anions presence, contact time, catalyst amount, concentration variation, and the kinetics of photocatalytic degradation were investigated. The magnitude of transition energy calculated using UV-DRS spectra was found to be 3.1 eV for CuCr2O4-TiO2 nanocomposite. Maximum degradation was observed at pH 7.0. The surface area and pore volume of the co-doped samples of Cr2O4 - TiO2 obtained from BET were found to be 6.1213 m2/g and 0.045063 cm3/g respectively. The average particle size of the catalyst of the nano-catalysts calculated from XRD was found to be 8 nm for TiO2 and 66 nm for TiO2-CuCrO4. The peaks obtained in FTIR between the range of 900-500 cm-1 were due to the presence of an aromatic compound. The binding mechanism of a dye molecule to the surface of CuCr2O4-TiO2 nanocomposite was analysed using quantum chemical calculations with the self-consistent reaction field technique employing integral equation formalism for the polarized continuum method and the UFF atomic radii set.
The present study highlights the treatment of industrial effluent, which is one of the most life-threatening factors. Herein, for the first time, two types of NiO (green and black) photocatalysts were prepared by facile chemical precipitation and thermal decomposition methods separately. The synthesized NiO materials were demonstrated with various instrumental techniques for finding their characteristics. The X-ray diffraction studies (XRD) and X-ray photoelectron spectroscopy (XPS) revealed the presence of Ni2O3 in black NiO material. The transmission electron microscopic (TEM) images engrained the nanospherical shaped green NiO and nanoflower shaped black NiO/Ni2O3 materials. Further, the band gap of black NiO nanoflower was 2.9 eV compared to green NiO having 3.8 eV obtained from UV-vis spectroscopy. Meanwhile, both NiO catalysts were employed for visible light degradation, which yields a 60.3% efficiency of black NiO comparable to a 4.3% efficiency of green NiO within 180 min of exposure. The higher degrading efficiency of black NiO was due to the presence of Ni2O3 and the development of pores, which was evident from the Barrett-Joyner-Halenda (BJH) method. Type IV hysteresis was observed in black NiO nanoflowers with high surface area and pore size measurements. This black NiO/Ni2O3 synthesized from the thermal decomposition method has promoted better photocatalytic degradation of 4-chlorophenol upon exposure to visible light and is applicable for other industrial pollutants.
Vanadia (V2O5)-incorporated fibrous silica-titania (V/FST) catalysts, which were successfully synthesized using a hydrothermal method followed by the impregnation of V2O5. The catalysts were then characterized using numerous techniques, including X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy, nitrogen adsorption-desorption analyses, ultraviolet-visible diffuse reflectance spectroscopy, Fourier-transform infrared, X-ray photoelectron spectroscopy, and photoluminescence (PL) analyses. The study found that varying the amount of V2O5 (1-10 wt%) had a significant impact on the physicochemical properties of the FST, which in turn improved the photodegradation efficiency of two organic compounds, ciprofloxacin (CIP) and congo red (CR). 5V/FST demonstrated the best performance in degrading 10 mg L-1 of CIP (83%) and CR (100%) at pH 3 using 0.375 g L-1 catalyst under visible light irradiation within 180 min. The highest photoactivity of 5V/FST is mainly due to higher crystallinity and the highest number of V2O5-FST interactions. Furthermore, as demonstrated by PL analysis, the 5V/FST catalyst has the most significant impact on interfacial charge transfer and reduces electron-hole recombination. The photodegradation of both contaminants follows the Langmuir-Hinshelwood pseudo-first-order model, according to the kinetic study. The scavenger investigation demonstrated that hydroxyl radicals and holes dominated species in the system, indicating that the catalyst effectively generated reactive species for pollutant degradation. A possible mechanism was also identified for FST and 5V/FST. Interestingly, V2O5 acts as an electron-hole recombination inhibitor on FST for selective hole oxidation of ciprofloxacin and congo red photodegradation. Finally, the degradation efficiency of the catalyst remained relatively stable even after five cyclic experiments, indicating its potential for long-term use in environmental remediation.
Photocatalysis utilizing semiconductors offer a cost-effective and promising solution for the removal of pollutants. MXene and perovskites, which possess desirable properties such as a suitable bandgap, stability, and affordability, have emerged as a highly promising material for photocatalytic activity. However, the efficiency of MXene and perovskites is limited by their fast recombination rates and inadequate light harvesting abilities. Nonetheless, several additional modifications have been shown to enhance their performance, thereby warranting further exploration. This study delves into the fundamental principles of reactive species for MXene-perovskites. Various methods of modification of MXene-perovskite-based photocatalysts, including Schottky junction, Z-scheme and S-scheme are analyzed with regard to their operation, differences, identification techniques and reusability. The assemblance of heterojunctions is demonstrated to enhance photocatalytic activity while also suppressing charge carrier recombination. Furthermore, the separation of photocatalysts through magnetic-based methods is also investigated. Consequently, MXene-perovskite-based photocatalysts are seen as an exciting emerging technology that necessitates further research and development.
Burkholderia pseudomallei is a highly versatile pathogen with ~25% of its genome annotated to encode hypothetical proteins. One such hypothetical protein, BPSL1038, is conserved across seven bacterial genera and 654 Burkholderia spp. Here, we present a 1.55 Å resolution crystal structure of BPSL1038. The overall structure folded into a modified βαββαβα ferredoxin fold similar to known Cas2 nucleases. The Cas2 equivalent catalytic aspartate (D11) pairs are conserved in BPSL1038 although B. pseudomallei has no known CRISPR associated system. Functional analysis revealed that BPSL1038 is a nuclease with endonuclease activity towards double-stranded DNA. The DNase activity is divalent ion independent and optimum at pH 6. The concentration of monovalent ions (Na+ and K+) is crucial for nuclease activity. An active site with a unique D11(X20)SST motif was identified and proposed for BPSL1038 and its orthologs. Structure modelling indicates the catalytic role of the D11(X20)SST motif and that the arginine residues R10 and R30 may interact with the nucleic acid backbone. The structural similarity of BPSL1038 to Cas2 proteins suggests that BPSL1038 may represent a sub-family of nucleases that share a common ancestor with Cas2.
The current research concentrated on the Co-precipitation synthesis of g-C3N4 (CN), ZnO, ZnO/CN, and Co-doped ZnO/CN nanocomposite, as well as the solar light enhanced photocatalytic treatment of Reactive Red 120 (RR120) from genuine wool textile effluent. The 3D flower-like structure of Co-doped ZnO distributed on the surface of CN thin sheets, according to structural studies employing XRD and SEM examinations Electrochemical experiments exhibited that the Co-doped ZnO/CN nanocomposite has a large electroactive surface area. The optical band-gap values of CN, ZnO, ZnO/CN, and Co-doped ZnO/CN nanocomposites were 2.68, 3.13, 2.38, and 2.23 eV, respectively, according to optical characterizations. The synergistic effects and heterojunction produced by Co-doped ZnO and CN can be linked to the narrow gap in nanocomposites. After 75, 60, 50, and 40 min of exposure to solar light, photocatalytic degradation assays for 250 mL of 20 mg/L RR120 solution in the presence of CN, ZnO, ZnO/CN, and Co-doped ZnO/CN nanocomposites demonstrated 100% dye treatment. The applicability of photocatalysts for decolorization of 250 mL of 10 mg/L RR120 prepared from actual wool textile wastewater was investigated, and the results showed that Co-doped ZnO/CN nanocomposites for treatment of RR120 from actual wool textile wastewater were highly efficient at photocatalytic degradation.
UV and solar-based photocatalytic degradation of 2,4-dichlorophenol (2,4-DCP) as an organic contaminant in ceramics industry wastewater by ZnS and Fe-doped ZnS NPs was the focus of this research. Nanoparticles were prepared using a chemical precipitation process. The cubic, closed-packed structure of undoped ZnS and Fe-doped ZnS NPs was formed in spherical clusters, according to XRD and SEM investigations. According to optical studies, the optical band gaps of pure ZnS and Fe-doped ZnS nanoparticles are 3.35 and 2.51 eV, respectively, and Fe doping increased the number of carriers with high mobility, improved carrier separation and injection efficiency, and increased photocatalytic activity under UV or visible light. Doping of Fe increased the separation of photogenerated electrons and holes and facilitated charge transfer, according to electrochemical impedance spectroscopy investigations. Photocatalytic degradation studies revealed that in the present pure ZnS and Fe-doped ZnS nanoparticles, 100% treatment of 120 mL of 15 mg/L phenolic compound was obtained after 55- and 45-min UV-irradiation, respectively, and complete treatment was attained after 45 and 35-min solar light irradiation, respectively. Because of the synergistic effects of effective surface area, more effective photo-generated electron and hole separation efficiency, and enhanced electron transfer, Fe-doped ZnS demonstrated high photocatalytic degradation performance. The study of Fe-doped ZnS's practical photocatalytic treatment capability for removing 120 mL of 10 mg/L 2,4-DCP solution made from genuine ceramic industrial wastewater revealed Fe-doped ZnS's excellent photocatalytic destruction of 2,4-DCP from real industrial wastewater.
This work aimed to study an integrated pretreatment technology employing p-toluenesulfonic acid (TsOH)-catalyzed liquid hot water (LHW) and short-time ball milling for the complete conversion of poplar biomass to xylooligosaccharides (XOS), glucose, and native-like lignin. The optimized TsOH-catalyzed LHW pretreatment solubilized 98.5% of hemicellulose at 160 °C for 40 min, releasing 49.8% XOS. Moreover, subsequent ball milling (20 min) maximized the enzymatic hydrolysis of cellulose from 65.8% to 96.5%, owing to the reduced particle sizes and cellulose crystallinity index. The combined pretreatment reduced the crystallinity by 70.9% while enlarging the average pore size and pore volume of the substrate by 29.5% and 52.4%, respectively. The residual lignin after enzymatic hydrolysis was rich in β-O-4 linkages (55.7/100 Ar) with less condensed structures. This lignin exhibited excellent antioxidant activity (RSI of 66.22) and ultraviolet absorbance. Thus, this research suggested a sustainable waste-free biorefinery for the holistic valorization of biomass through two-step biomass fractionation.
The presence of phenolic compounds in the aquatic environment has posed severe risks due to their toxicity. Among the phenolic families, nitro- and alkyl-phenolic compounds have been categorized as precedence contaminants by the United States Environmental Protection Agency (US EPA). Therefore, efficient treatment methods for wastewater containing nitro- and alkyl-phenolic compounds are urgently needed. Due to the advantages of creating reactive species and generating efficient degradation of hazardous contaminants in wastewater, advanced oxidation processes (AOPs) are well-known in the field of treating toxic contaminants. In this review paper, the recent directions in AOPs, catalysts, mechanisms, and kinetics of AOPs are comprehensively reviewed. Furthermore, the conclusion summarizes the research findings, future prospects, and opportunities for this study. The main direction of AOPs lies on the optimization of catalyst and operating parameters, with industrial applications remain as the main challenge. This review article is expected to present a summary and in-depth understanding of AOPs development; and thus, inspiring scientists to accelerate the evolution of AOPs in industrial applications.
Palm olein (POL) was modified by enzymatic interesterification with different degrees of acyl migration in a solvent-free packed bed reactor. The fatty acid and acylglycerol composition, isomer content, thermodynamic behavior, and relationship between crystal polymorphism, solid fat content (SFC), crystal microstructure, and texture before and after modification were studied. We found that the increase in sn-2 saturation interesterification was not only due to the generated tripalmitin (PPP) but also caused by acyl migration, and the SFC profiles were changed accordingly. The emergence of high melting point acylglycerols was an important factor accelerating the crystallization rate, further shortening the crystallization induction time, leading to the formation of large crystal spherulites, thereby reducing the hardness. The transformation from the β' to the β form occurred during post-hardening during storage. The isomer content also affected the physicochemical properties of the modified POL.
This study investigated the effect of different Co3O4-based catalysts on the catalytic decomposition of nitrous oxide (N2O) and on nitric oxide (NO) conversion. The experiments were carried out using various reaction temperatures, alkaline solutions, pH, mixing conditions, aging times, space velocities, impregnation loads, and compounds. The results showed that Co3O4 catalysts prepared by precipitation methods have the highest catalytic activity and N2O conversion, even at low reaction temperatures, while the commercial nano and powder forms of Co3O4 (CS) have the lowest performance. The catalysts become inactive at temperatures below 400 °C, and their activity is strongly influenced by the mixing temperature. Samples without stirring during the aging process have higher catalytic activity than those with stirring, even at low reaction temperatures (200-300 °C). The catalytic activity of Co3O4 PM1 decreases with low W/F values and low reaction temperatures. Additionally, the catalyst's performance tends to increase with the reduction process. The study suggests that cobalt-oxide-based catalysts are effective in N2O catalytic decomposition and NO conversion. The findings may be useful in the design and optimization of catalytic systems for N2O and NO control. The results obtained provide important insights into the development of highly efficient, low-cost, and sustainable catalysts for environmental protection.
Pyrolysis oil from oil palm biomass can be a sustainable alternative to fossil fuels and the precursor for synthesizing petrochemical products due to its carbon-neutral properties and low sulfur and nitrogen content. This work investigated the effect of applying mesoporous acidic catalysts, Ni-Mo/TiO2 and Ni/Al2O3, in a catalytic co-pyrolysis of oil palm trunk (OPT) and polypropylene (PP) from 500 to 700 °C. The obtained oil yields varied between 12.67 and 19.50 wt.% and 12.33-17.17 wt.% for Ni-Mo/TiO2 and Ni/Al2O3, respectively. The hydrocarbon content in oil significantly increased up to 54.07-58.18% and 37.28-68.77% after adding Ni-Mo/TiO2 and Ni/Al2O3, respectively. The phenolic compounds content was substantially reduced to 8.46-20.16% for Ni-Mo/TiO2 and 2.93-14.56% for Ni/Al2O3. Minor reduction in oxygenated compounds was noticed from catalytic co-pyrolysis, though the parametric effects of temperature and catalyst type remain unclear. The enhanced deoxygenation and cracking of phenolic and oxygenated compounds and the PP decomposition resulted in increased hydrocarbon production in oil during catalytic co-pyrolysis. Catalyst addition also promoted the isomerization and oligomerization reactions, enhancing the formation of cyclic relative to aliphatic hydrocarbon.
Natural enzymes possess several drawbacks which limits their application in industries, wastewater remediation and biomedical field. Therefore, in recent years researchers have developed enzyme mimicking nanomaterials and enzymatic hybrid nanoflower which are alternatives of enzyme. Nanozymes and organic inorganic hybrid nanoflower have been developed which mimics natural enzymes functionalities such as diverse enzyme mimicking activities, enhanced catalytic activities, low cost, ease of preparation, stability and biocompatibility. Nanozymes include metal and metal oxide nanoparticles mimicking oxidases, peroxidases, superoxide dismutase and catalases while enzymatic and non-enzymatic biomolecules were used for preparing hybrid nanoflower. In this review nanozymes and hybrid nanoflower have been compared in terms of physiochemical properties, common synthetic routes, mechanism of action, modification, green synthesis and application in the field of disease diagnosis, imaging, environmental remediation and disease treatment. We also address the current challenges facing nanozyme and hybrid nanoflower research and the possible way to fulfil their potential in future.
Air gasification of the Wood-Plastic Composite (WPC) was performed over Ni-loaded HZSM-5 catalysts to generate H2-rich gas. Increasing SiO2/Al2O3 ratio (SAR) of HZSM-5 adversely affected catalytic activity, where the highest gas yield (51.38 wt%) and H2 selectivity (27.01 vol%) were acquired using 20 %Ni/HZSM-5(30) than those produced over 20 %Ni/HZSM-5(80) and 20 %Ni/HZSM-5(280). Reducing SAR was also favorably conducive to increasing the acyclic at the expense of cyclic compounds in oil products. These phenomena are attributed to enhanced acid strength and Ni dispersion of 20 %Ni/HZSM-5(30) catalyst. Moreover, catalytic activity in the terms of gas yield and H2 selectivity enhanced with growing Ni loading to 20 %. Also, the addition of promoters (Cu and Ca) to 20 %Ni/HZSM-5(30) boosted the catalytic efficiency for H2-rich gas generation. Raising temperature indicated a positive relevance with the gas yield and H2 selectivity. WPC valorization via gasification technology would be an outstanding outlook in the terms of a waste-to-energy platform.