Effects of Cerium Oxide and Ferrocene Nanoparticles Addition As Fuel-Borne Catalysts on Diesel Engine Particulate Emissions: Environmental and Health Implications

Development and evaluation of thiosalicylic-modified/ion-imprinted chitosan for selective removal of cerium (III) ion

Chitosan was used in this study as the bio-based product for the development of microparticles for the specifically targeted removal of cerium ions (Ce3+) by ion-imprinting technology. A thiosalicylic hydrazide-modified chitosan (TSCS) is produced via cyanoacetylation of chitosan, followed by hydrazidine derivatization to finally introduce the thiosalicylate chelating units. Ion-imprinted Ce-TSCS sorbent microparticles were prepared by combining the synthesized TSCS with Ce3+, crosslinking the polymeric Ce3+/TSCS complex with glutaraldehyde, and releasing the chelated Ce3+ using an eluent solution containing a mixture of EDTA and HNO3. Ce-TSCS had a capacity of 164 ± 1 mg/g and better removal selectivity for Ce3+ because it was smart enough to figure out which target ions would fit into the holes made by Ce3+ during the imprinting process. The kinetic data were well suited to a pseudo-second-order model, and the isotherms were well described by the Langmuir model, both of which pointed to chemisorption and adsorption through Ce3+ chelation. XPS and FTIR analyses demonstrate that the predominant adsorption mechanism is the coordination of Ce3+ with the -NH-, -NH2, and -SH chelating units of the thiosalicylic hydrazidine. These findings provide fresh direction for the development of sorbent materials that can effectively and selectively remove Ce3+ from aqueous effluents.

Behavior of the particulate matter (PM) emitted by trackless rubber-tyred vehicle (TRTV) at an idle speed under different movement conditions and ventilation optimization

The particulate matter (PM) emitted by a trackless rubber-tyred vehicle (TRTV) in coal mines can seriously threaten the health and safety of the exposed workers underground. In this paper, in order to effectively reduce the PM concentration and improve the underground working environment, a combination of numerical simulations and field measurements was adopted to study the migration distribution of the PM emitted by a TRTV at an idle speed for 60 s under different movement conditions, and the dilution effects of the ventilation rate on the PM. The results showed that under different movement conditions, the PM mainly moved along the floor of the roadway, but upward diffusion trends were shown overall, which meant that the chambers are in high-risk areas. Field measurements were then performed under the two conditions to verify the effectiveness of the simulations. Furthermore, the dilution effects of the increased ventilation rate on the PM were analyzed. It was concluded that the optimal dilution ventilation rate under condition 1 was 4600m³/min, and that under condition 2 was 2800m³/min. Accordingly, the driver of the TRTV should try to move forward when entering the chamber.

Most Recent Advances in Diesel Engine Catalytic Soot Abatement: Structured Catalysts and Alternative Approaches

Diesel engine emissions are typically composed of several hundred chemical compounds, partly present in the gas phase and partly in solid phase as particles, the so-called particulate matter or soot. The morphology of the catalyst is an important characteristic of soot particles’ abatement, since a good contact between catalyst and soot is mandatory. For practical purposes, the active species should be supported as a film on the structured carrier, in order to allow simultaneous soot filtration and combustion. This review focuses on the most recent advances in the development of structured catalysts for diesel engine catalytic soot combustion, characterized by different active species and supports, as well as by different geometric configurations (monoliths, foams, ceramic papers, or wire mesh); the most important peculiar properties are highlighted and summarized. Moreover, a critical review of the most recent advances in modeling studies is also presented in this paper. In addition, some highlights on some of the most recent alternative approaches proposed for limiting the soot emissions from diesel engines have been given, delineating feasible alternatives to the classical strategies nowadays used.

Exhaust emissions from diesel engines fueled by different blends with the addition of nanomodifiers and hydrotreated vegetable oil HVO

Diesel emissions have a significant impact on the atmosphere, contributing to air pollution, smog and global warming. As a result, diesel exhaust is dangerous to human health. While emissions reduction efforts have often focused on changing engine design or improving aftertreatment, diesel fuel modifications can also play an important role in improving engine efficiency and reducing exhaust emissions. The aim of this work was to examine the potential for emissions reductions under real-world conditions when employing fuel additives. Three different additives were examined, consisting of hydrotreated vegetable oil (HVO) and two commercial additives containing nanoparticles of cerium dioxide and ferrocene. HVO was selected as a renewable fuel, an alternative to commonly used biodiesels with competitive advantages. The new European driving cycle (NEDC) procedure was used to measure emissions of regulated compounds: carbon monoxide, nitrogen oxides, hydrocarbons and particulates (by mass and number) from an 11-year-old passenger car equipped with a diesel engine powered by fuel blends. The fuel blends prepared met the quality requirements for diesel fuel. The results obtained confirm that the application of both HVO and nano-additives to diesel can achieve a significant reduction of carbon monoxide (52%) and hydrocarbon (47%) emissions compared to the B7 base fuel. Particulate emissions (up to 10% by mass of particulates and 7% by number of particulates) were found to be best reduced by adding nanoparticles of cerium dioxide to the B7 fuel (with 30% HVO), while the best results in reducing nitrogen oxide emissions were obtained by adding ferrocene nanoparticles to the B7 fuel with 30% HVO.

Synthesis and Characterization of Bismuth-Cerium Oxides for the Catalytic Oxidation of Diesel Soot

In this paper, the syntheses of a set of cerium-bismuth mixed oxides with the formula Ce_1−xBi_xO_2−x/2, where the range of x is 0.0 to 1.0 in 10 mol% steps, via co-precipitation methods is described. Two synthesis routes are tested: The “normal” and the so called “reverse strike” (RS) co-precipitation route. The syntheses are performed with an automated synthesis robot. The activity for Diesel soot oxidation is measured by temperature programmed oxidation with an automated, serial thermogravimetric and differential scanning calorimetry system (TGA/DSC). P90 is used as a model soot. An automated and reproducible tight contact between soot and catalyst is used. The synthesized catalysts are characterized in terms of the specific surface area according to Brunauer, Emmett and Teller (S_BET), as well as the dynamic oxygen storage capacity (OSC_dyn). The crystalline phases of the catalysts are analysed by powder X-ray diffraction (PXRD) and Raman spectroscopy. The elemental mass fraction of the synthesized catalysts is verified by X-ray fluorescence (XRF) analysis. A correlation between the T₅₀ values, OSC_dyn and S_BET has been discovered. The best catalytic performance is exhibited by the catalyst with the formula RS-Ce_0.8Bi_0.2O_x which is synthesized by the reverse strike co-precipitation route. Here, a correlation between activity, OSC_dyn, and S_BET can be confirmed based on structural properties.

Diesel exhaust particle and dust mite induced airway inflammation is modified by cerium dioxide nanoparticles

Cerium dioxide nanoparticles (CeO₂NPs) have been used as diesel fuel-borne catalysts for improved efficiency and pollutant emissions. Concerns that such material may influence diesel exhaust particle (DEP) effects within the lung upon inhalation, prompted us to examine particle responses in mice in the presence and absence of the common allergen house dust mite (HDM). Repeated intranasal instillation of combined HDM and DEP increased airway mucin, eosinophils, lymphocytes, IL-5, IL-13, IL-17A and plasma IgE, which were further increased with CeO₂NPs co-exposure. A single co-exposure of CeO₂NPs and DEP after repeated HDM exposure increased macrophage and IL-17A levels above DEP induced levels. CeO₂NPs exposure in the absence of HDM also resulted in increased levels of plasma IgE and airway mucin staining, changes not observed with repeated DEP exposure alone. These observations indicate that CeO₂NPs can modify exhaust particulate and allergen induced inflammatory events in the lung with the potential to influence conditions such as allergic airway disease.

Simulated biological fluid exposure changes nanoceria's surface properties but not its biological response

Nanoscale cerium dioxide (nanoceria) has industrial applications, capitalizing on its catalytic, abrasive, and energy storage properties. It auto-catalytically cycles between Ce³⁺ and Ce⁴⁺, giving it pro-and anti-oxidative properties. The latter mediates beneficial effects in models of diseases that have oxidative stress/inflammation components. Engineered nanoparticles become coated after body fluid exposure, creating a corona, which can greatly influence their fate and effects. Very little has been reported about nanoceria surface changes and biological effects after pulmonary or gastrointestinal fluid exposure. The study objective was to address the hypothesis that simulated biological fluid (SBF) exposure changes nanoceria's surface properties and biological activity. This was investigated by measuring the physicochemical properties of nanoceria with a citric acid coating (size; morphology; crystal structure; surface elemental composition, charge, and functional groups; and weight) before and after exposure to simulated lung, gastric, and intestinal fluids. SBF-exposed nanoceria biological effect was assessed as A549 or Caco-2 cell resazurin metabolism and mitochondrial oxygen consumption rate. SBF exposure resulted in loss or overcoating of nanoceria's surface citrate, greater nanoceria agglomeration, deposition of some SBF components on nanoceria's surface, and small changes in its zeta potential. The engineered nanoceria and SBF-exposed nanoceria produced no statistically significant changes in cell viability or cellular oxygen consumption rates.

Effect of sulphur and vanadium spiked fuels on particle characteristics and engine performance of auxiliary diesel engines

Particle emission characteristics and engine performance were investigated from an auxiliary, heavy duty, six-cylinder, turbocharged and after-cooled diesel engine with a common rail injection system using spiked fuels with different combinations of sulphur (S) and vanadium (V) spiking. The effect of fuel S content on both particle number (PN) and mass (PM) was clearly observed in this study. Higher PN and PM were observed for fuels with higher S contents at all engine load conditions. This study also found a correlation between fuel S content and nucleation mode particle number concentration which have more harmful impact on human health than larger particles. The highest PN and PM were observed at partial load conditions. In addition, S in fuel resulted in higher viscosity of spiked fuels, which led to lower engine blow-by. Fuel V content was observed in this study, evidencing that it had no clear effect on engine performance and emissions. Increased engine load also resulted in higher engine blow-by. The lower peak of in-cylinder pressure observed at both pre-mixed and diffusion combustion phases with the spiked fuels may be associated with the lower energy content in the fuel blends compared to diesel fuel.

Douglas-Fir ( Pseudotsuga menziesii (Mirb.) Franco) Transcriptome Profile Changes Induced by Diesel Emissions Generated with CeO2 Nanoparticle Fuel Borne Catalyst

It is important to understand molecular effects on plants exposed to compounds released from use of products containing engineered nanomaterials. Here, we present mRNA sequencing data on transcriptome impacts to Douglas-fir following 2 weeks of sublethal exposure to 30:1 diluted airborne emissions released from combustion of diesel fuel containing engineered CeO₂ nanoparticle catalysts (DECe). Our hypothesis was that chamber exposure to DECe would induce distinct transcriptome changes in seedling needles compared with responses to conventional diesel exhaust (DE) or filtered DECe Gas Phase. Significantly increased uptake/binding of Ce in needles of DECe treated seedlings was 2.7X above background levels and was associated with altered gene expression patterns. All 225 Blast2GO gene ontologies (GOs) enriched by up-regulated DECe transcripts were nested within GOs for DE, however, 29 of 31 enriched GOs for down-regulated DECe transcripts were unique. MapMan analysis also identified three pathways enriched with DECe down-regulated transcripts. There was prominent representation of genes with attenuated expression in transferase, transporter, RNA regulation and protein degradation GOs and pathways. CeO₂ nanoparticle additive decreased and shifted molecular impact of diesel emissions. Wide-spread use of such products and chronic environmental exposure to DECe may adversely affect plant physiology and development.

TiO₂, SiO₂ and ZrO₂ Nanoparticles Synergistically Provoke Cellular Oxidative Damage in Freshwater Microalgae

Metal-based nanoparticles (NPs) are the most widely used engineered nanomaterials. The individual toxicities of metal-based NPs have been plentifully studied. However, the mixture toxicity of multiple NP systems (n ≥ 3) remains much less understood. Herein, the toxicity of titanium dioxide (TiO₂) nanoparticles (NPs), silicon dioxide (SiO₂) NPs and zirconium dioxide (ZrO₂) NPs to unicellular freshwater algae Scenedesmus obliquus was investigated individually and in binary and ternary combination. Results show that the ternary combination systems of TiO₂, SiO₂ and ZrO₂ NPs at a mixture concentration of 1 mg/L significantly enhanced mitochondrial membrane potential and intracellular reactive oxygen species level in the algae. Moreover, the ternary NP systems remarkably increased the activity of the antioxidant defense enzymes superoxide dismutase and catalase, together with an increase in lipid peroxidation products and small molecule metabolites. Furthermore, the observation of superficial structures of S. obliquus revealed obvious oxidative damage induced by the ternary mixtures. Taken together, the ternary NP systems exerted more severe oxidative stress in the algae than the individual and the binary NP systems. Thus, our findings highlight the importance of the assessment of the synergistic toxicity of multi-nanomaterial systems.