Nanostructured Al2O3/Graphene Additive in Bio-Based Lubricant: A Novel Approach to Improve Engine Performance

Personal and industrial use of internal combustion engines (ICEs) is projected to continue until 2050 and beyond. Yet demands to reduce global dependence on petrochemicals and fossil fuel-derived lubricants are increasing and environmentally necessary. New strategies for maintaining and enhancing ICE performance by reducing friction, wear, fuel consumption, and exhaust emissions will reduce the depletion of mineral and fossil fuel reserves and environmental pollution. This paper reports the tribological enhancement of nano-bio lubricants formulated using 2D nanocomposites of Al2O3/graphene as novel additives in coconut oil, whose performance as a lubricant compares favourably with the mineral-based engine oil 15W40. Structural, compositional, and morphological characterization of an Al2O3/graphene nanocomposite synthesized via thermal annealing revealed an ultra-fine particle size (<10 nm) with spherical/laminar morphology and a rich sp2 domain, exhibiting a consistent colloidal stability when formulated as nanofluid. Through the use of various characterisation techniques, including friction and wear analysis we gained valuable insight into the tribological mechanism. Our optimisation of 2D tribological system using coconut oil formulation resulted significant reductions in the coefficient of friction (28%), specific fuel consumption (8%), and exhaust pollutants (CO, SO2, and NOx) emissions. This work demonstrates the benefits of using nano-bio lubricant formulated using coconut oil and 2D based hybrids as base stock and additives, delivering solutions to global challenges such as improving fuel consumption while reducing environmental pollution; solutions that can be transferred to other areas where lubricants are a necessity

Maximizing Polypropylene Recovery from Waste Carpet Feedstock: A Solvent-Driven Pathway Towards Circular Economy

Here we propose a novel approach for the efficient recovery of polypropylene from waste carpet feedstock utilising a solvent based method operating at 160 °C. The findings contribute to advancing sustainable recycling practices for waste carpet materials and offer valuable insight into the recovery of PP which can also be utilised for other complex waste streams

Continuous Hydrothermal Flow Synthesis of Blue-Luminescent, Excitation-Independent N-doped Carbon Quantum Dots as Nanosensors

Blue-luminescent N-doped carbon quantum dots (NCQDs) exhibiting rarely observed excitation independent optical properties are synthesised from citric acid in the presence of ammonia via a Continuous Hydrothermal Flow Synthesis (CHFS) approach. CHFS is an eco-friendly, rapid synthetic approach (within fractions of a second) facilitating ease of scale-up industrialization as well as offering materials with superior properties. The synthesised CQDs readily disperse in aqueous solution, have an average particle size of 3.3 ± 0.7 nm, with highest emission intensity at 441 nm (and a narrow full width at half maximum, FWHM ~78 nm) under a 360 nm excitation wavelength. Carbon quantum dots, without any further modification, exhibited a high selectivity and sensitivity as a nano-sensor for the highly toxic and carcinogenic chromium(VI) ions. The nano-chemo-sensor delivers significant advantages including simplicity of manufacturing via a continuous, cleaner technology (using targeted biomass precursor), high selectivity, sensitivity and fast response leading to potential applications in environmental industry as well photovoltaics, bio-tagging, bio-sensing and beyond

Next frontiers in cleaner synthesis: 3D printed graphene-supported CeZrLa mixed-oxide nanocatalyst for CO2 utilisation and direct propylene carbonate production

A rapidly-growing 3D printing technology is innovatively employed for the manufacture of a new class of heterogenous catalysts for the conversion of CO2 into industrially relevant chemicals such as cyclic carbonates. For the first time, directly printed graphene-based 3D structured nanocatalysts have been developed combining the exceptional properties of graphene and active CeZrLa mixed-oxide nanoparticles. It constitutes a significant advance on previous attempts at 3D printing graphene inks in that it does not merely explore the printability itself, but enhances the efficiency of industrially relevant reactions, such as CO2 utilisation for direct propylene carbonate (PC) production in the absence of organic solvents. In comparison to the starting powder, 3D printed GO-supported CeZeLa catalysts showed improved activity with higher conversion and no noticeable change in selectivity. This can be attributed to the spatially uniform distribution of nanoparticles over the 2D and 3D surfaces, and the larger surface area and pore volume of the printed structures. 3D printed GO-supported CeZeLa catalysts compared to unsupported 3D printed samples exhibited higher selectivity and yield owing to the great number of new weak acid sites appearing in the supported sample, as observed by NH3-TPD analysis. In addition, the catalyst's facile separation from the product has the capacity to massively reduce materials and operating costs resulting in increased sustainability. It convincingly shows the potential of these printing technologies in revolutionising the way catalysts and catalytic reactors are designed in the general quest for clean technologies and greener chemistry

Engineering Nitrogen-Doped Carbon Quantum Dots: Tailoring Optical and Chemical Properties through Selection of Nitrogen Precursors

The process of N-doping is frequently employed to enhance the properties of carbon quantum dots. However, the precise requirements for nitrogen precursors in producing high-quality N-doped carbon quantum dots (NCQDs) remain undefined. This research systematically examines the influence of various nitrogen dopants on the morphology, optical features, and band structure of NCQDs. The dots are synthesized using an efficient, eco- friendly, and rapid continuous hydrothermal flow technique. This method offers unparalleled control over synthesis and doping, while also eliminating convention-related issues. Citric acid is used as the carbon source, and urea, trizma base, beta-alanine, L-arginine, and EDTA are used as nitrogen sources. Notably, urea and trizma produced NCQDs with excitation-independent fluorescence, high quantum yields (up to 40%), and uniform dots with narrow particle size distributions. Density functional theory (DFT) and time-dependent DFT modelling established that defects and substituents within the graphitic structure have a more significant impact on the NCQDs’ electronic structure than nitrogen-containing functional groups. Importantly, for the first time, this work demonstrates that the conventional approach of modelling single-layer structures is insufficient, but two layers suffice for replicating experimental data. This study, therefore, provides essential guidance on the selection of nitrogen precursors for NCQD customization for diverse applications

3D printed catalytic reactors for aerobic selective oxidation of benzyl alcohol into benzaldehyde in continuous multiphase flow

In this work, novel, patterned monolithic reactors were devised to explore more efficient routes for reactant conversion in order to investigate their potential to replace the packed bed and batch reactors conventionally employed in chemical industries. Well-defined bimetallic formulations were developed to substitute platinum group metals and critical raw materials such as palladium and cobalt, at least in part, by less active, but more sustainable and cost-effective metals such as earth-abundant iron. FePd and FeCo based monoliths were 3D printed and stacked in a continuous flow tubular reactor for testing the selective oxidation of benzyl alcohol (BA) into benzaldehyde (BZ) under mild conditions (80–100 °C and atmospheric pressure). The novel monolithic reactors were evaluated against current state-of-the-art reactor technologies, conventional packed bed and batch reactors. The FeCo- and FePd-Al2O3-supported monolithic catalyst beds showed higher conversion and TOF than their packed bed counterparts under the same operating conditions, revealing the impact of the novel design on both regular geometry and composition. What is of particular interest in the catalytic measurements shown is that the combined stacking of two monoliths in a flow reactor, Al2O3-supported Fe and GO-supported FePd catalysts, can significantly improve the performance with an increase in TOF of up to 90% in comparison to their FePd analogues. Mathematical modelling was used to obtain additional insights into the physical and chemical processes governing the rate of BA conversion. It was found that due to the flow regime inside the microchannels, an axial dispersion model was appropriate, which allowed for mapping the concentration profiles of the reactants and products within the respective monolith geometries

Towards High Capacity Li-ion Batteries Based on Silicon-Graphene Composite Anodes and Sub-micron V-doped LiFePO4 Cathodes

Lithium iron phosphate, LiFePO4 (LFP) has demonstrated promising performance as a cathode material in lithium ion batteries (LIBs), by overcoming the rate performance issues from limited electronic conductivity. Nano-sized vanadium-doped LFP (V-LFP) was synthesized using a continuous hydrothermal process using supercritical water as a reagent. The atomic % of dopant determined the particle shape. 5 at. % gave mixed plate and rod-like morphology, showing optimal electrochemical performance and good rate properties vs. Li. Specific capacities of >160 mAh g−1 were achieved. In order to increase the capacity of a full cell, V-LFP was cycled against an inexpensive micron-sized metallurgical grade Si-containing anode. This electrode was capable of reversible capacities of approximately 2000 mAh g−1 for over 150 cycles vs. Li, with improved performance resulting from the incorporation of few layer graphene (FLG) to enhance conductivity, tensile behaviour and thus, the composite stability. The cathode material synthesis and electrode formulation are scalable, inexpensive and are suitable for the fabrication of larger format cells suited to grid and transport applications

Controlled growth of titania nanospheres in supercritical carbon dioxide using a novel surfactant stabilised precursor

The titania nanospheres were synthesized from the controlled hydrolysis of a mixture of titanium(IV) isopropoxide and the precursor, [Ti(OPr i)3(Kry)]n in supercritical carbon dioxide. The use of sc-CO2 in the reaction , eliminates the need for organic solvents, optimizes manufacturing efficiency and produces materials with tailored properties. Simultaneous thermal analysis (STA) data for the nanospheres was carried out from room temperature (RT) to 800°C. The X-ray powder diffraction (XRD) pattern of the heat treated powder (600° C in air), reveals only phase anatase (TiO2)

Extra-esophageal symptoms in individuals with and without erosive esophagitis: a case-control study in Albania

IntroductionErosive reflux esophagitis caused a large clinical spectrum of symptoms. Our aim was to assess the prevalence of extra-esophageal symptoms in individuals with and those without erosive esophagitis in Albania.MethodsA case-control study was conducted at the Regional Hospital of Durres, the second main district in Albania, a transitional country in South Eastern Europe, including 248 patients with erosive esophagitis (aged 46.516.3 years) and 273 controls (aged 46.416.0 years; response rate: 70%) enrolled during the period January 2013-June 2014. Both cases and controls underwent upper endoscopy. Information on socio-demographic characteristics and lifestyle factors was also collected. Binary logistic regression was used to assess the association of erosive esophagitis and extra-esophageal symptoms.Results Patients with erosive esophagitis had a higher prevalence of excessive alcohol consumption, smoking, sedentarity, non-Mediterranean diet and obesity compared to their control counterparts (9% vs. 5%, 70% vs. 49%, 31% vs. 17%, 61% vs. 49% and 22% vs. 9%, respectively). Upon adjustment for all socio-demographic characteristics and lifestyle/behavioral factors, there was evidence of a strong association of erosive esophagitis with chronic cough (OR=3.2, 95% CI=1.7-5.8), and even more so with laryngeal disorders (OR=4.4, 95% CI=2.6-7.5). In all models, the association of erosive esophagitis with any extra-esophageal symptoms was strong and mainly consistent with each of the symptoms separately (fully-adjusted model: OR=4.6, 95% CI=2.9-7.3).Conclusion Our findings indicate that the prevalence of extra-esophageal symptoms is higher among patients with erosive esophagitis in a transitional country characterized conventionally by employment of a Mediterranean diet