Madhu Singh

Differences in lamellae length, stacking, and particularly a difference in the core-to-shell radial structure are observed for carbon blacks produced using different feedstocks. Carbon black (CB) produced using a coal tar (CT) feedstock formed particles with amorphous cores exhibiting a sharp transition to extended lamellae oriented about the periphery of the particle. In contrast, the carbon black produced from fluidized catalytic cracker (FCC) decant oil as feedstock formed particles with a single nucleated core possess a rather uniform radial transition—reflecting the presence of ordered, concentric lamellae across most of the particle radius. Minimal disorder was observed in the core while the undulations in perimeter lamellae were fewer. Our interpretation for these structural dissimilarities is premised on differences in fuel composition, specifically component classes as found by saturate, aromatic, resin, asphaltene (SARA) analysis. These in turn lead to variation in the relative rates of particle nucleation and particle growth by pyrolysis products, moderated by temperature. Electron energy loss spectroscopy reveals radial variation in the sp² content between the different feedstocks consistent with observed nanostructures. Collectively these results are interpreted in terms of an offset in nucleation and growth—dependent upon the relative contributions of feedstock aromatic content and pyrolysis processes to particle nucleation and growth. To further test the postulate of different formation conditions for the two carbon blacks pulsed laser annealing was applied. The high temperature heating accentuated the dissimilarities in nanostructure and chemistry—leading to stark dissimilarities. These differences were also manifested by comparing oxidative reactivity.

Utilization of biopolymers to form graphitic carbons is challenged by their high oxygen content and resulting curved and defective carbon lamellae upon high-temperature heat-treatment. Two composites, one with graphene-oxide (GO) and the other with reduced graphene-oxide (rGO) as fillers, respectively, in a matrix of sugar, each for the same added 2.5 wt.%, exhibited different degrees of graphitization compared to pure sugar on its own. Reactive oxygen groups on GO contribute to reactive templating and crystallite formation. Under high-temperature heat-treatment, sugar, a well-known non-graphitizing precursor, is converted to graphitic carbon in the presence of GO. Possessing fewer oxygen groups, rGO forms two phases in the sugar matrix—a non-graphitic phase and a graphitic phase. The latter is attributed to the remaining oxygen on the rGO.

Air pollution has become the world’s single biggest environmental health risk of the past decade, causing millions of yearly deaths worldwide. One of the dominant air pollutants is fine particulate matter (PM_2.5), which is a product of combustion. Exposure to PM_2.5 has been associated with decreased lung function, impaired immunity, and exacerbations of lung disease. Accumulating evidence suggests that many of the adverse health effects of PM_2.5 exposure are associated with lung inflammation and oxidative stress. While the physical structure and surface chemistry of PM_2.5 are surrogate measures of particle oxidative potential, little is known about their contributions to negative health effects. In this study, we used functionalized carbon black particles as surrogates for atmospherically aged combustion-formed soot to assess the effects of PM_2.5 surface chemistry in lung cells. We exposed the BEAS-2B lung epithelial cell line to different soot at a range of concentrations and assessed cell viability, inflammation, and oxidative stress. Our results indicate that exposure to soot with varying particle surface composition results in differential cell viability rates, the expression of pro-inflammatory and oxidative stress genes, and protein carbonylation. We conclude that particle surface chemistry, specifically oxygen content, in soot modulates lung cell inflammatory and oxidative stress responses.

Air pollution has become the world’s single biggest environmental health risk of the past decade, causing about 7 million yearly deaths worldwide. One of the dominant air pollutants is fine particulate matter (PM2.5), a product of combustion. Exposure to PM2.5 has been associated with decreased lung function, impaired immunity, and exacerbations of lung disease. Accumulating evidence suggests that many of the adverse health effects of PM2.5 exposure are associated with lung inflammation and oxidative stress. While the physical structure and surface chemistry of PM2.5 are surrogate measures of particle oxidative potential, little is known about their contributions to negative health effects. In this study, we used functionalized carbon black particles as surrogates for atmospherically aged combustion formed soot to assess the effects of PM2.5 surface chemistry in lung cells. We exposed the BEAS-2B lung epithelial cell line to different soot at a range of concentrations, and assessed cell viability, inflammation, and oxidative stress. Our results indicate that exposure to soot with varying particle surface composition results in differential cell viability rates, expression of pro-inflammatory and oxidative stress genes, and protein carbonylation. We conclude that particle surface chemistry, specifically oxygen content, in soot modulates lung cell inflammatory and oxidative stress responses.

Laser derivatization is proposed as a diagnostic technique towards identifying the sources contributing to combustion produced soot. Fuel chemistry and the resultant oxygen content in nascent soot have been shown to influence the evolution of soot nanostructure upon laser derivatization. This is illustrated using the spectroscopic and microscopic characterization of biodiesel soot, with a systematic variation in fuel chemistry used to generate the soot. Functionalized carbon black is used as the control to independently verify the influence of material chemistry on nanostructure upon laser heat treatment. Results track with those observed for biodiesel soot. Reciprocally, the similarity in soot nanostructure observed after laser heating is tied to the likeness in fuel chemistry of biomass-fueled sources. Understanding the origin of differences or similarities in soot nanostructure upon laser heat treatment can help differentiate sources based on their contribution, thereby aiding in effective air quality control.

In the present study, Calcium oxide (CaO) obtained from eggshells has been used as a heterogeneous catalyst for biodiesel production from highly viscous non-edible rubber seed oil (RSO). Characterization of synthesized catalyst was done with the help of scanning electron microscope equipped with Energy dispersive spectrometry (SEM-EDS), X-ray diffraction (XRD) and Fourier transform Infrared spectroscopy (FTIR). Response surface methodology (RSM) with central composite design (CCD) was used to optimize the process parameters and ¹ H-NMR (Nuclear Magnetic Resonance) spectroscopy analysis was performed to find the conversion of RSO to biodiesel. A conversion of 99.7% of RSO to biodiesel was obtained at 12:1 methanol to oil molar ratio, 4 (wt%) of catalyst, and 3 hour reaction time with a quadratic regression model of R ² of value 0.9566 was obtained. The composition of prepared biodiesel is estimated with the help of Gas Chromatogram-Mass Spectroscopy (GC-MS) analysis. Artificial Neural Network (ANN) with Levenberg-Marquardt algorithm was also trained to predict biodiesel conversion and the value of R ² obtained was 0.9976. It was observed that predicted conversion values from ANN were better when compared to prediction using RSM.

Carbon blacks are an extensively used manufactured product. There exist different grades by which the carbon black is classified, based on its purpose and end use. Different properties inherent to the various carbon black types are a result of their production processes. Based on the combustion condition and fuel used, each process results in a carbon black separate from those obtained from other processes. These carbons differ in their aggregate morphology, particle size, and particle nanostructure. Nanostructure is key in determining the material’s behavior in bulk form. A variety of carbon blacks have been analyzed and quantified for their lattice parameters and structure at the nanometer scale, using transmission electron microscopy and custom-developed fringe analysis algorithms, to illustrate differences in nanostructure and their potential relation to observed material properties.