Catalytic activity of Zr/CeO2-Al2O3 catalyst for diesel soot oxidation: synthesis, characterization, and performance evaluation.

Diesel soot is a significant contributor to air pollution. Soot particles present in diesel engine exhaust have a negative impact on the environment and human health. Diesel oxidation catalysts (DOCs) and diesel particulate filters (DPFs) currently use noble metal-based catalysts for soot oxidation. Due to the use of noble metals in the catalyst, the cost of diesel after-treatment systems is steadily rising. As a result, diesel vehicles have become commercially less viable than gasoline vehicles and electronic vehicles. The study focuses on an alternative diesel oxidation catalyst with efficiency similar to that of a noble metal catalyst but with a much lower cost. CeO2-Al2O3 catalysts are known for their oxygen storage capacity and high redox activity, making them suitable for soot oxidation. Adding Zr to these catalysts has been shown to influence their structural and chemical properties, significantly affecting their catalytic behavior. Therefore, the current study is focused on using Zr/CeO2-Al2O3 as a substitute for noble metal-based catalysts to enhance its performance for diesel soot oxidation in automotive exhaust. Evaporation-induced self-assembly (EISA) was used to prepare 1, 3, and 5 weight (wt) % Zr supported mesoporous CeO2-Al2O3 catalysts. Morphological, structural, and physicochemical properties of the synthesized catalysts were examined using Brunauer-Emmett-Teller (BET) absolute isotherm, Scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Temperature programmed reduction (TPR), and Temperature-programmed desorption of ammonia (NH3-TPD). XRD, BET, and SEM data confirmed that the catalysts were mesoporous and low-crystalline with a high surface area. The soot oxidation activity of the catalysts was evaluated using a thermogravimetric analysis (TGA) technique. The loose contacts soot oxidation activity test suggested that 50% oxidation of soot occurred at 390 °C in the absence of a catalyst. T50 of CeO2-Al2O3 catalyzed soot oxidation was 296 °C. Adding Zr to the catalyst significantly improved catalytic activity for diesel soot oxidation. We observed a further drastic change in T50 of soot over 1, 3, and 5% Zr/CeO2-Al2O3, which were 220 °C, 210 °C, and 193 °C, respectively. According to these results, incorporating Zr into the CeO2-Al2O3 catalyst significantly improved the oxidation process of soot.

Bioproduction of yeast single cell oil with acute oral toxicity study intended for edible oil application.

Human nutrition and health rely on edible oils. Global demand for edible oils is expanding, necessitating the discovery of new natural oil sources subjected to adequate quality and safety evaluation. However, in contrast to other agricultural products, India's edible oil supply is surprisingly dependent on imports. The microbial oil is generated by fermentation of oleaginous yeast Rhodotorula mucilaginosa IIPL32 MTCC 25056 using biodiesel plant byproduct crude glycerol as a fermentable carbon source. Enriched with monounsaturated fatty acid, nutritional indices mapping based on the fatty acid composition of the yeast SCO, suggested its plausible use as an edible oil blend. In the present study, acute toxicity evaluation of the yeast SCO in C57BL/6 mice has been performed by randomly dividing the animals into 5 groups with 50, 300, 2000, and 5000 mg/Kg yeast SCO dosage, respectively, and predicted the median lethal dose (LD50). Detailed blood biochemistry and kidney and liver histopathology analyses were also reported. The functions of the liver enzymes were also evaluated to check and confirm the anticipated toxicity. To determine cell viability and in vitro biocompatibility, the 3T3-L1 cell line and haemolysis tests were performed. The results suggested the plausible use of yeast SCO as an edible oil blend due to its non-toxic nature in mice models.

Selective production of phenolic monomer via catalytic depolymerization of lignin over cobalt-nickel-zirconium dioxide catalyst.

The utilization of lignin, an abundant and renewable bio-aromatic source, is of significant importance. In this study, lignin oxidation was examined at different temperatures with zirconium oxide (ZrO2)-supported nickel (Ni), cobalt (Co) and bimetallic Ni-Co metal catalysts under different solvents and oxygen pressure. Non-catalytic oxidation reaction produced maximum bio-oil (35.3 wt%), while catalytic oxidation significantly increased the bio-oil yield. The bimetallic catalyst Ni-Co/ZrO2 produced the highest bio-oil yield (67.4 wt%) compared to the monometallic catalyst Ni/ZrO2 (59.3 wt%) and Co/ZrO2 (54.0 wt%). The selectively higher percentage of vanillin, 2-methoxy phenol, acetovanillone, acetosyringone and vanillic acid compounds are found in the catalytic bio-oil. Moreover, it has been observed that the bimetallic Co-Ni/ZrO2 produced a higher amount of vanillin (43.7% and 13.30 wt%) compound. These results demonstrate that the bimetallic Ni-Co/ZrO2 catalyst promotes the selective cleavage of the ether ß-O-4 bond in lignin, leading to a higher yield of phenolic monomer compounds.

Effective utilization of discarded reverse osmosis post-carbon for adsorption of dyes from wastewater.

In this study, the deployment of post Reverse Osmosis (RO)-carbon as a adsorbent for dye removal from water has been investigated. The post RO-carbon was thermally activated (RO900), and the material thus obtained exhibited high surface area viz. 753 m2/g. In the batch system, the efficient Methylene Blue (MB) and Methyl Orange (MO) removal was obtained by using 0.08 g and 0.13 g/50 mL adsorbent dosage respectively. Moreover, 420 min was the optimized equilibration time for both the dyes. The maximum adsorption capacities of RO900 for MB and MO dyes were 223.29 and 158.14 mg/g, respectively. The comparatively higher MB adsorption was attributed to the electrostatic attraction between adsorbent and MB. The thermodynamic findings revealed the process as spontaneous, endothermic, and accompanied by entropy increment. Additionally, simulated effluent was treated, and >99% dye removal efficiency was achieved. To mimic an industrial perspective, MB adsorption onto RO900 was also carried out in continuous mode. The initial dye concentration and effluent flow rate were among the process parameters that were optimized using the continuous mode of operation. Further, the experimental data of continuous mode was fitted with Clark, Yan, and Yoon-Nelson models. Py-GC/MS investigation revealed that dye-loaded adsorbents could be pyrolyzed to produce valuable chemicals. The cost and low toxicity associated benefits of discarded RO-carbon over other adsorbents reveal the significance of the present study.

Characterization of slow pyrolysis products from three different cashew wastes.

A huge amount of waste is generated by the cashew processing industries. This study aims to valorise these cashew wastes generated at different levels while processing cashew nuts in factories. The feedstocks include cashew skin, cashew shell and cashew shell de-oiled cake. Slow pyrolysis of these three different cashew wastes was performed at varying temperatures (300-500℃) at a heating rate of 10℃/min in a lab scale glass-tubular reactor under inert atmosphere of nitrogen with flow rate of 50 ml/min. The total bio-oil yield for cashew skin and the de-oiled shell cake was 37.1 and 48.6 wt% at 400℃ and 450℃, respectively. However, the maximum bio-oil yield obtained for cashew shell waste was 54.9 wt% at 500℃. The bio-oil was analysed using GC-MS, FTIR, and NMR. Along with the various functionalities observed in bio-oil through GC-MS, phenolics were observed to have maximum area% for all the feedstocks at all temperatures. At all the slow pyrolysis temperatures, cashew skin led to more biochar yield (40 wt%) as compared to cashew de-oiled cake (26 wt%) and cashew shell waste (22 wt%). Biochar was characterized by various analytical tools such as XRD, FTIR, Proximate analyser, CHNS, Py-GC/MS and SEM. Characterization of biochar revealed its carbonaceous and amorphous nature along with porosity.

Water footprint and wastewater quality assessment of yeast single cell oil production: Gate to gate approach for industrial water sustainability.

Effective water resource utilization and sustainability for industrial operations is a growing concern. With increased industrial water demand, abstraction and water quality changes are rising. In India, distilleries generate more than 40.4 billion litres of effluent daily within the fermentation industry. Water, a public good with market and opportunity costs, needs effective mapping and management. Emerging distillery processes such as yeast lipid fermentation, if developed along with water sustainability, could aid in advancing water resource management. In the scope of this idea, the present study focuses on assessing the water footprint and water quality mapping for Rhodotorula mucilaginosa IIPL32 lipid production using crude glycerol, a by-product of the biodiesel industry. The assessment was based on primary data generated during the 500 L plant scale operation. The process's blue water footprint was assessed by applying a chain-summation approach, and the grey water requirement was determined by measuring water quality parameters for the effluent streams. The process's net blue and grey water footprint were estimated to be 3.87 and 23.66 m3 water/kg of lipid, respectively. Water quality index ratings were identified for all the respective water streams within the processing system, and human risk factors were estimated. The results suggested proper treatment of the spent broth, whereas the secondary effluent stream from cleaning operations could be reutilized within the system. Quality mapping also suggested that the effluent's high organic and mineral load can be processed for water and material recovery, which may significantly reduce the process's grey water and pollution load.

Bio-oil and biochar from the pyrolytic conversion of biomass: A current and future perspective on the trade-off between economic, environmental, and technical indicators.

Over the years, the transformation of biomass into a plethora of renewable value-added products has been identified as a promising strategy to fulfil high energy demands, lower greenhouse gas emissions, and exploit under-utilized resources. Techno-economic analysis (TEA) and life-cycle assessment (LCA) are essential to scale up this process while lowering the conversion cost. In this study, trade-offs are made between economic, environmental, and technical indicators produced from these methodologies to better evaluate the commercialization potential of biomass pyrolysis. This research emphasizes the necessity of combining LCA and TEA variables to assess the performance of the early-stage technology and associated constraints. The important findings based on the LCA analysis imply that most of the studies reported in literature focussed on the global warming potentials (GWP) under environmental category by considering greenhouse gases (GHGs) as evaluation parameter, neglecting many other important environmental indices. In addition, the upstream and downstream processes play an important role in understanding the life cycle impacts of a biomass based biorefinery. Under upstream conditions, the use of a specific type of feedstock may influence the LCA conclusions and technical priority. Under downstream conditions, the product utilization as fuels in different energy backgrounds is crucial to the overall impact potentials of the pyrolysis systems. In view of the TEA analysis, investigations towards maximizing the yield of valuable co-products would play an important role in the commercialization of pyrolysis process. However, comprehensive research to compare the conventional, advanced, and emerging approaches of biomass pyrolysis from the economic perspective is currently not available in the literature.

Jute sticks biomass delignification through laccase-mediator system for enhanced saccharification and sustainable release of fermentable sugar.

Jute sticks obtained after the extraction of jute fiber are an excellent biomass feedstock with a significant amount of carbohydrates that makes it an attractive resource for sustainable energy generation. However, the high lignin content in the jute stick hinders the cellulosic component of the cell wall from enzymatic hydrolysis.This work demonstrates the lignin degradation of jute stick biomass by Trametes maxima laccase in the presence of mediator Hydroxybenzotriazole and improvement in its subsequent saccharification. Lignin component in jute stick is reduced by 21.8% in a single reaction treatment with laccase-mediator compared to the untreated jute stick sample used as control. The yield of fermentable sugar is increased by 19.5% that verifies enhanced saccharification after lignin removal. Delignification of jute stick was corroborated through different analytical techniques. The Pyrolysis gas chromatography/mass spectrometry results further confirms abundance of S lignin unit in the jute stick compared to the H and G unit and modification in lignin polymer as a change in the syringyl-to-guaiacyl ratio. Hence, this work demonstrates that jute stick can be effectively delignified using biocatalyst-mediator system and utilized as biomass source, thus contributing in circular bio-economy through waste valorization.

Scale-up strategy for yeast single cell oil production for Rhodotorula mucilagenosa IIPL32 from corn cob derived pentosan.

This work was aimed to strategically scale-up the yeast lipid production process using Reynolds number as a standard rheological parameter from 50 mL to 50 L scale. Oleaginous yeast Rhodotorula mucilaginosa IIPL32 was cultivated in xylose rich corncob hydrolysate. The fermentation process for growth and maturation was operated in fed-batch with two different C/N ratios of 40 and 60. The hydrodynamic parameters were used to standardize and represent the effect of rheology on the fermentation process. The growth pattern of the yeast was found similar in both shake flask and fermenter with the maximum growth observed at 48 h. The lipid yield increased from 0.4 g/L and 0.5 g/L to 1.3 g/L and 1.83 g/L for 50 mL to 50 L for C/N ratio 40 and 60 respectively. The increase in productivity during the growth phase and lipid accumulation during the maturation phase showed that the scale-up strategy was successful.

Catalytic pyrolysis of soda lignin over zeolites using pyrolysis gas chromatography-mass spectrometry.

Catalytic fast pyrolysis of soda lignin was examined at different temperatures (500,600,700,800 and 900 °C) in the presence of three zeolites with different Si/Al ratio using the Py-GC/MS in order to investigate best catalytic system. The three zeolites are y-zeolite (8-9), mordenite (15-17), ZSM-5 (30-40), which have static pore sizes 0.74, 0.65, and 0.59 nm respectively. The shape and acidity of zeolites, as well as pyrolysis temperature, have a significant effect on product distribution in catalytic fast pyrolysis. Y-zeolite was the most effective catalytic system among all catalysts for deomethoxylation and dehydroxylation of small oxygenates as well as bulky oxygenates to produce aromatics. However, mordenite and ZSM-5 could not convert the large oxygenates due to size exclusion and pore blockage. Highest yield of aromatics with significant amount of aromatic dimers was obtained over y-zeolite and then yield of aromatics followed in order by mordenite and ZSM-5 at 800 °C.

Optimization of process parameters for hydrothermal conversion of castor residue.

Castor plant (Ricinus communis) is a fast-growing shrub from Euphorbiaceae family. India ranks first in the world for the production of castor seeds. The generation of residue from its leaves and stems is more than 50% of the whole plant. This research work involves the estimation of the optimum condition for the production/value addition by hydrothermal liquefaction of castor residue using factorial design. Temperature (T) and residence time (RT) are the key parameters that affect the bio-oil yield. A 32 full factorial design was employed to understand the affects the bio-oil yield and conversion with key parameters. The key parameter and its interaction effects were analyzed by analysis of variance (ANOVA); F-test and p-values were used to rank the process variable affecting the total bio-oil yield. It was observed that the temperature imparts significant effect on total bio-oil yield. The optimum conditions to obtain maximum total bio-oil yield are T = 300 °C and RT = 60 min. The statistical model was best fitted with high coefficient of determination (R2) of 0.9994 and 0.9473 for total bio-oil yield and conversion respectively.

Pyrolysis of azolla, sargassum tenerrimum and water hyacinth for production of bio-oil.

Pyrolysis of azolla, sargassum tenerrimum and water hyacinth were carried out in a fixed-bed reactor at different temperatures in the range of 300-450°C in the presence of nitrogen (inert atmosphere). The objective of this study is to understand the effect of compositional changes of various aquatic biomass samples on product distribution and nature of products during slow pyrolysis. The maximum liquid product yield of azolla, sargassum tenerrimum and water hyacinth (38.5, 43.4 and 24.6wt.% respectively) obtained at 400, 450 and 400°C. Detailed analysis of the bio-oil and bio-char was investigated using 1H NMR, FT-IR, and XRD. The characterization of bio-oil showed a high percentage of aliphatic functional groups and presence of phenolic, ketones and nitrogen-containing group. The characterization results showed that the bio-oil obtained from azolla, sargassum tenerrimum and water hyacinth can be potentially valuable as a fuel and chemicals.

Pyrolysis of Mesua ferrea and Pongamia glabra seed cover: characterization of bio-oil and its sub-fractions.

In the present study, pyrolysis of Mesua ferrea seed cover (MFSC) and Pongamia glabra seed cover (PGSC) was performed to investigate the characteristics of bio-oil and its sub fractions. In a fixed bed reactor, the effect of temperature (range of 350-650 °C) on product yield and quality of solid product were monitored. The maximum bio-oil yield of 28.5 wt.% and 29.6 wt.% for PGSC and MFSC respectively was obtained at 550 °C at heating rate of 40 °C/min. The chemical composition of bio-oil and its sub fractions were investigated using FTIR and (1)H NMR. GC-MS was performed for both PGSC and MFSC bio-oils and their corresponding n-hexane fractions. The results showed that bio-oil from the feedstocks and its sub-fractions might be a potential source of renewable fuel and value added chemicals.

TG-MS investigation of brominated products from the degradation of brominated flame retardants in high-impact polystyrene.

The thermal degradation of flame retardant containing high-impact polystyrene (HIPS-Br), one of the most commonly employed plastics in electric and electronic appliances, was examined by thermogravimetry coupled with mass spectroscopy (TG-MS) in order to understand the threat that is posed by the release of hazardous brominated compounds. The HIPS samples contained decabromodiphenylether (DPE) and decabromodibenzyl (DDB) as the flame retardants as well as Sb2O3 as the synergist. The largest number of brominated compounds was obtained in the presence of DPE and Sb2O3 and DDB without Sb2O3. From the degradation of DPE, brominated benzenes, phenols, diphenylethers, and dibenzofurans were identified, and from the degradation of DDB, brominated benzenes, dibenzyls, and phenanthrenes were formed. The interaction between the flame retardant and the polymer matrix resulted in α-bromoethylbenzene. The formation of brominated dibenzodioxins was not observed, probably, due to the low phenol concentration in the polymer melt. No other report has, to our knowledge, ever reported on the formation of brominated phenanthrenes from flame retardants. Because they share similar steric features, it may well be that brominated phenanthrenes are similar in their carcinogen and mutagen potential to dibenzofurans and dibenzodioxins. A plausible mechanism for the formation of the observed compounds is presented, and the role of the synergist is considered.

Effect of decabromodiphenyl ether and antimony trioxide on controlled pyrolysis of high-impact polystyrene mixed with polyolefins.

The controlled pyrolysis of polyethylene/polypropylene/polystyrene mixed with brominated high-impact polystyrene containing decabromodiphenyl ether as a brominated flame-retardant with antimony trioxide as a synergist was performed. The effect of decabromodiphenyl ether and antimony trioxide on the formation of its congeners and their effect on distribution of pyrolysis products were investigated. The controlled pyrolysis significantly affected the decomposition behavior and the formation of products. Analysis with gas chromatograph with electron capture detector confirmed that the bromine content was rich in step 1 (oil 1) liquid products leaving less bromine content in the step 2 (oil 2) liquid products. In the presence of antimony containing samples, the major portion of bromine was observed in the form of antimony bromide and no flame-retardant species were found in oil 1. In the presence of synergist, the step 1 and step 2 oils contain both light and heavy compounds. In the absence of synergist, the heavy compounds in step 1 oil and light compounds in step 2 oils were observed. The presence of antimony bromide was confirmed in the step 1 oils but not in step 2 oils.

The individual and cumulative effect of brominated flame retardant and polyvinylchloride (PVC) on thermal degradation of acrylonitrile-butadiene-styrene (ABS) copolymer.

Acrylonitrile-butadiene-styrene (ABS) copolymers without and with a polybrominated epoxy type flame retardant were thermally degraded at 450 degrees C alone (10 g) and mixed with polyvinylchloride (PVC) (8 g/2 g). Gaseous and liquid products of degradation were analysed by various gas chromatographic methods (GC with TCD, FID, AED, MSD) in order to determine the individual and cumulative effect of bromine and chlorine on the quality and quantity of degradation compounds. It was found that nitrogen, chlorine, bromine and oxygen are present as organic compounds in liquid products, their quantity depends on the pyrolysed polymer or polymer mixture. Bromophenol and dibromophenols were the main brominated compounds that come from the flame retardant. 1-Chloroethylbenzene was the main chlorine compound observed in liquid products. It was also determined that interactions appear at high temperatures during decomposition between the flame retardant, PVC and the ABS copolymer.