Search Results (20,116)

Microplastics (MPs), defined as synthetic polymer particles ranging from 1 μm to 5 mm, originate from various sources, including synthetic textiles, tire wear, degraded plastic waste, etc. Their small size and chemical stability make them challenging to remove, collect and degrade, posing significant adverse effects to both ecosystems and human health. While efforts to develop sustainable alternatives and removal methods are ongoing, effective solutions remain limited. Catalytic degradation and upcycling present a promising route to mitigate MP pollution by enabling efficient breakdown into less harmful molecules and potential upcycling into valuable products with lower energy requirements. This review provides a comprehensive overview of recent advances in catalyst design and development specifically for MP degradation, highlighting photochemical, thermal, biological, electrochemical, and hybrid approaches. Key challenges, reaction mechanisms, and future directions are discussed, offering a timely reference for researchers in this emerging field. Full article

Graphene Nano-Carbons (GNCs) have a huge potential, but current production methods limit their exploration and use. Many GNCs will be explored here with a focus on CNTs (Carbon NanoTubes) (which have some of the highest strengths of any known material, conductivity, EMF absorptivity, and many other useful properties. Manufacturing them abundantly, inexpensively, and in eco-friendly ways remains a significant challenge. Two CNT/GNCs production methods are compared and reviewed. Traditional Chemical Vapor Deposition (CVD) production heats organic reactants with metal catalysts to form GNC/CNTs. As of now, the CVD CNT production has been limited by the high-energy costs, costs per weight comparable to precious metals, and a high CO₂-footprint. C2CNT is an electrochemical methodology that overcomes the constraints of CVD, while producing high-quality CNT/GNCs. C2CNT is a molten carbonate CO₂-electrolysis that makes GNCs. The C2CNT process also selectively produces a wider variety of CNTs (including helical, magnetic, and doped) and GNCs with higher product specificity than CVD by fine-tuning electrolysis parameters. The wide variety of CNTs/GNCs that can be produced by each of these methods is reviewed and discussed. The goal of this perspective is to compare GNC production methods. Full article

A series of porous carbons (PPC) derived from pomegranate peel were synthesized as catalyst supports for Pd/PPC catalysts via hydrothermal-carbonization and incipient wetness impregnation in an acetylene hydrochlorination reaction. The optimal Pd/PPC (500) catalyst with more than 99% of acetylene conversion and vinyl chloride monomer (VCM) selectivity was obtained using an orthogonal experimental design (OED) and single-factor experiments. Based on the catalytic performance and characterization of the Pd/PPC catalyst, the deactivation mechanism of the catalysts, which was attributed to carbon deposition on the catalysts’ surface, and the loss of active Pd species have been studied, which provides insights for the rational design of high-performance biomass-based acetylene hydrochlorination catalysts. Full article

Non-precious catalysts for alkaline hydrogen evolution reaction (HER) face a fundamental multi-scale challenge: lack of synergy between electronic structure tuning for balancing H adsorption and water dissociation, active site stabilization for boosting intrinsic turnover frequency (TOF), and mass transport. Even Pt loses 2–3 orders of magnitude activity in alkaline media due to inefficient water dissociation, a synergistic gap unresolved by the Sabatier principle alone. Existing strategies only address isolated aspects: phase engineering optimizes electronic structure but not active site stability; heteroatom doping introduces defects unlinked to mass transport; and nanostructuring enhances mass transfer but not atomic-level activity. None of them address multi-scale mechanistic synergy. Herein, we design a hierarchically porous P-doped NiCo alloy (hpP-NiCo) with an aim of achieving this synergy via integrating α-FCC/ε-HCP phases, P-induced defects, and 3D porosity. The formed α/ε interface tunes the d-band center to balance H adsorption and water dissociation; and the doped P stabilizes metal-vacancy sites to boost TOF. In addition, porosity matches mass transport with active site accessibility. In 1 M KOH, hpP-NiCo reaches 1000 mA cm⁻² at 185 mV overpotential and has a Tafel slope of 43.1 mV dec⁻¹, corresponding to electrochemical desorption as the rate-limiting step and verifying Volmer acceleration. Moreover, it also exhibits bifunctional oxygen evolution reaction (OER), achieving 100 mA cm⁻² at potential of 1.55 V. This work establishes a mechanistic synergy model for non-precious HER catalysts. Full article

A multiscale 3D CFD model of CO₂ methanation over Ni/Al₂O₃ was developed in COMSOL Multiphysics 6.3 for a lab-scale isothermal fixed-bed Sabatier reactor and validated against published data. The multiscale approach integrated bulk convection–diffusion, fluid flow, and pressure distribution with intraparticle diffusion–reaction phenomena coupled with Langmuir–Hinshelwood–Hougen–Watson-based kinetics, thus solving mass-transfer limitations without empirical effectiveness factors. Model validation was carried out by (i) kinetics, (ii) reactor performance, and (iii) hydrodynamics. Simulation results showed strong diffusion-dominated species transport at the bed entrance that lessened downstream as partial pressures decreased and products accumulated, resulting in a diffusion-relieved regime near the outlet. Sensitivity studies identified 320–350 °C and up to 10 bar as favorable conditions for high CH₄ yield. Additionally, slightly H₂-rich feed accelerated approach to equilibrium, while lower flow rates achieved near-complete conversion within the first half of the reactor bed. Simulations were carried out in COMSOL Multiphysics 6.3 on a dual Intel Xeon Platinum 8168 (48 cores at 2.7 GHz) workstation with 512 GB RAM to solve a 12-million-element mesh. The developed framework identifies a practical operating window and quantifies the conversion–throughput trade-off with flow rate, guiding operating condition selection and providing a basis for process intensification and lab-to-pilot scale-up of CO₂ methanation. Full article

This article reviews recent advances in heterogeneous hydroformylation, with a particular focus on rhodium-based catalysts supported on oxide surfaces. The hydroformylation reaction is a vital industrial process for producing aldehydes from petrochemicals. This reaction involves the addition of carbon monoxide (CO) and hydrogen (H₂) to alkenes, resulting in the formation of aldehydes. Aldehydes serve as essential building blocks for various downstream products in the chemical industry, including alcohols, esters, and amines. Although homogeneous catalysts such as rhodium complexes coordinated with phosphorus-based ligands (e.g., [RhCl(PPh₃)₃]) are highly active and selective, their separation and recovery remain significant challenges. This has fueled growing interest in the development of heterogeneous catalysts, which offer advantages in terms of sustainability, reusability, and catalyst recovery process. This review highlights recent progress in the design of heterogeneous hydroformylation catalysts, with emphasis on rhodium-based systems on oxide supports. Key challenges and emerging strategies for enhancing catalytic performance and stability are also discussed. Full article

Photocatalytic oxidation technology harnesses solar energy for pollutant mineralization, presenting significant potential for environmental applications. A critical bottleneck remains the development of high-performance photocatalysts. This study centers on the non-metallic semiconductor material graphitic carbon nitride (g-C₃N₄). To overcome the inherent limitations of pristine g-C₃N₄, including limited surface area, rapid charge carrier recombination, and inadequate active sites, it implements surface engineering strategies employing acidic (H₂SO₄) or basic (K₂CO₃) agents to modulate microstructure, introduce defect sites (cyano/amino groups), and optimize bandgap engineering. These modifications synergistically enhanced photogenerated charge carrier separation efficiency and surface reactivity, leading to efficient dye degradation. Notably, the K₂CO₃-modified catalyst (g-C₃N₄-OH), synthesized with a mass ratio of m(g-C₃N₄):m(K₂CO₃) = 1:1, achieved 92.2% Rhodamine B degradation within 50 min under visible light, surpassing pristine g-C₃N₄ (20.6%), the optimized H₂SO₄-modified sample (g-C₃N₄-HS, 60.9%), and even template-synthesized g-C₃N₄-SBA (79.6%). The g-C₃N₄-OH catalyst demonstrated exceptional performance under both visible light and natural solar illumination. Combining facile synthesis, cost-effectiveness, superior activity, and robust stability, this work provides a novel approach for developing high-efficiency non-metallic photocatalysts applicable to dye wastewater. Full article

This study introduces nitrogen- and silicon-containing carbon quantum dots (N,Si-CQDs), synthesized hydrothermally from the sustainable bioresource stinging nettle (Urtica dioica L.), as chemically active supports for Pt, Pd, and Pt₃Pd₁ electrocatalysts. The N,Si-CQDs were characterized by a high concentration of N/O surface functionalities and the presence of biogenic Si. A significant finding is that, with this support, biogenic Si acts as a nucleation template: Pd forms in situ as orthorhombic Pd₉Si₂ nanorods alongside spherical particles, whereas Pt predominantly develops as cubic/quasi-cubic crystals. This templating process promotes faceted (cubic) Pt₃Pd₁ alloy nanoparticles with robust interfacial contact with the support and a log-normal size distribution (14.2 ± 4.3 nm) on N,Si-CQDs (4.7 ± 1.4 nm). This configuration enhanced the electrochemically active surface area to 181 m² gPt⁻¹, significantly exceeding those of commercial Pt₁Pd₁/XC-72 (27.7 m² gPt⁻¹) and monometallic Pt/N,Si-CQDs (14.3 m² gPt⁻¹). Consequently, the catalyst demonstrated superior methanol oxidation performance, evidenced by a low onset potential (0.17 V), approximately 10-fold higher mass activity compared to Pt₁Pd₁/XC-72, and 53% activity retention after a 16 h accelerated durability test. The enhanced performance is attributed to the strong nanoparticle anchoring by N,Si-CQDs, the bifunctional/ligand effects of the Pt–Pd alloy that improve CO tolerance, and the templating role of biogenic Si. Full article

In 2024, the global average temperature reached 1.55 °C above the pre-industrial level for the first time. However, we could still keep the long-term global average temperature below 2 °C if all possible measures are taken to mitigate greenhouse gases. It is widely accepted that methane (CH₄) mitigation can slow global warming in the near term. Among all approaches toward this goal, the utilization of aerobic methanotrophs, which are natural catalysts for the conversion of CH₄, emerges as a promising solution. Previously, we identified a candidate for CH₄ mitigation, Methylotuvimicrobium buryatense 5GB1C, which exhibits a greater growth rate and CH₄ consumption rate than other known methanotrophs at 500 ppm CH₄. In this study, we address aspects of the practical applications of this methanotroph for CH₄ mitigation. We first examined temperature and medium conditions to optimize M. buryatense 5GB1C growth at 500 ppm CH₄. The results show that M. buryatense 5GB1C has a broad optimal temperature range for growth at 500 ppm, from 15 °C to 30 °C, and that its growth rate is consistently improved by 20–30% in 10-fold-diluted medium. Next, to demonstrate the feasibility of CH₄ removal at low concentrations by this methanotroph, we applied it in a laboratory-scale packed-bed column reactor for the treatment of 500 ppm CH₄ and tested different packing materials. The column reactor experiments revealed a maximum elimination capacity of 2.1 g CH₄ m⁻³ h⁻¹ with 2 mm cellulose beads as the packing material. These results demonstrate that with further technological innovation, this methanotroph has the potential for real-world methane mitigation. Full article

The transition to a circular economy depends on the widespread adoption of sustainable products by consumers. However, the point-of-sale purchase decision is a complex process, influenced not only by ethical arguments but also by sensory cues. This study investigates how the aesthetics (visual design) and materiality (tactile sensation) of green products shape value perception and purchase intention. Using a qualitative methodology based on a focus group, the research directly compares consumer reactions to green products (e.g., a bamboo toothbrush) versus their conventional alternatives (e.g., plastic). Thematic analysis of the data reveals a fundamental dichotomy among consumers: while one segment associates high-tech aesthetics and perfect finishes with quality and hygiene, another segment values natural materials and their “imperfections” as signs of authenticity and responsibility. The results demonstrate that there is no single, universally accepted “sustainable aesthetic” and highlight the need for designers and marketers to align the visual and tactile language of products with the value system of the target consumer segment. The study provides a framework for understanding how design can act as either a barrier to or a catalyst for the adoption of sustainable products. Full article

Biodiesel is an alternative to conventional diesel. The use of heterogeneous catalysts in biodiesel production is promising, as it is easier to separate them from the product than homogeneous ones. It was determined that the calcined grape snail (Helix pomatia) shells show good catalytic efficiency in the rapeseed oil transesterification process with methanol. It was determined that the CaO concentration in calcined grape snail (Helix pomatia) shells was 97.74 ± 0.12%. Using the response surface methodology, the biodiesel production process was optimized. The influence of the interaction of independent variables and optimal conditions for the synthesis of rapeseed oil methyl ester was determined: an alcohol-to-oil molar ratio of 10.6:1, a catalyst concentration of 5.7 wt%, and a reaction duration of 7.8 h at a temperature of 64 °C. The physical and chemical properties of the produced biodiesel at optimal process conditions are presented, and their compliance with the requirements of the biodiesel standard is discussed. The produced biodiesel using snail shells, which are food processing waste, meets the requirements of the standard and can be used in diesel engines during the summer period. Full article

The COVID-19 pandemic forced European Union member states to accelerate the digitalization of public services, turning a gradual policy priority into an urgent necessity. This study examines the pandemic’s impact on the digital transformation of public administrations, assessing the effectiveness of digital-oriented interventions implemented during this period. Using a Difference-in-Differences (DiDs) methodology, the analysis compares treatment and control groups based on 2019 Digital Economy and Society Index (DESI) scores, with digital public services as the dependent variable. Independent variables include pre-filled forms, service transparency, design and data protection, e-government usage, internet penetration, total population, and governance quality, covering all 27 EU member states from 2016 to 2023. Data sources include DESI, Eurostat, and the World Bank. The analysis shows that countries with lower digitalization achieved the largest post-pandemic gains, with transparency, service design, and data protection significantly enhancing digital service quality. Pre-existing governance and infrastructure shaped the magnitude of these improvements, highlighting the combined role of preparedness and reactive policy measures. The findings underscore the critical role of citizens as end-users and accountability drivers in digital governance. By providing empirical evidence on pandemic-driven digitalization trends, this study contributes to policy discussions on resilience, strategic planning, and the future of inclusive, transparent e-government services in the EU. Full article

The CO₂ emission issue has raised global concern as the sea level increase it caused can threaten human activity. The utilization of CO₂ as a building block for value-added chemicals can be an effective approach for the mitigation of the greenhouse effect. As one of the potential valuable products, formic acid (HCOOH) has been recognized as an effective hydrogen carrier. For thermal CO₂-to-HCOOH conversion, molecular catalysts and metal nanoparticles are prominent choices for the initial conversion. The conventional catalyst substrates have been shown to have issues of deactivation and product selectivity. The metal–organic framework (MOF), as a novel catalyst substrate, showcases its potential for solving the problem. Herein, this review intends to provide an overview of recent progress of metal nanoparticles and molecular catalysts stabilized by conventional catalyst substrates and MOFs for thermal CO₂-to-HCOOH conversion, including perspectives on further research. Full article

The many uses of biochar extend to microbial enhancement in fermentation processes because it acts as a catalyst and a support medium in agricultural industries, particularly for biofertilizer production. This study explores how three key biochar parameters, concentration (0.05–0.25% w/v), temperature (30–50 °C), and particle size (250 μm–1.40 mm) affect hyper-ammonia-producing bacteria (HAB) growth during fermentation using commercially sourced pine wood-derived biochar. Fermentation experiments utilized enriched cow rumen fluid under controlled conditions, monitoring bacterial growth via optical density (OD₆₀₀) over 48 h. Microbial proliferation was strongly influenced by all tested parameters (concentration, temperature, particle size). Highest growth occurred at 0.15% biochar concentration, 45 °C, and 250 μm particle size within the tested parameter ranges. Lower concentrations and smaller particles promoted microbial adhesion and colonization. Higher biochar levels hindered growth due to surface saturation and reduced pore accessibility. SEM imaging supported these findings by revealing structural changes on the biochar surface at different concentrations. Regression analysis demonstrated strong correlation between biochar parameters and microbial activity (R² = 0.9931), though multicollinearity limited individual variable significance. These findings support biochar optimization for enhanced microbial processing in biotechnological applications. Full article

The indiscriminate use of antibiotics in food-producing animals serves as a major catalyst for the emergence of antibiotic-resistant infections. This study aimed to assess the genetic diversity and antibiotic resistance of Enterobacterales in animal-derived foods. A total of 905 animal-derived food samples, including meat, dairy, poultry, fish, and environmental sources, were collected from various locations in Pakistan. Isolates were confirmed through selective subculturing, morphological, biochemical, and MALDI-TOF analysis, followed by antibiotic susceptibility testing. Subsequently, PCR-based detection of antibiotic resistance genes and virulence-associated genes. Overall, a total of 263 (29.06%) Enterobacterales were identified, as follows: 58.55% (154/263) E. coli, 6.84% (18/263) K. pneumoniae, 21.29% (56/263) P. mirabilis, and 13.30% (35/263) Salmonella spp. Isolates showed a varying resistance pattern against different studied antibiotics, e.g., beta-lactams and inhibitors, ciprofloxacin, and tetracycline, while colistin and tigecycline remained most effective. All the isolates displayed an array of antibiotic resistance and virulence-associated genes. Particularly significant (<0.05) co-existence of bla_NDM and mcr-1 was observed among the Enterobacterales isolated from various animal-derived foods. This study underscores the need to monitor Enterobacterales in animal-derived foods, especially in developing countries, to curb the spread of resistant pathogens and ensure effective food safety measures. Full article