Gum Formation Research Articles

DFT-based computational analysis of 2,4-dimethyl-6-tert-butylphenol (DTBP) as an antioxidant in aviation fuels

Antioxidants are indispensable additives for ensuring the long-term stability, performance, and reliability of aviation fuels. They prevent the formation of gum and other insoluble deposits in the fuel which clog fuel systems, leading to engine problems. This is achieved by inhibiting free radical chain reactions involved in the oxidation of hydrocarbons in the fuel. The compound 2,4-Dimethyl-6-tert-butyl phenol (DTBP) is one of the widely used antioxidants in aviation fuels. In this report, the radical scavenging done by DTBP is analysed computationally by density functional theory (DFT) with the model chemistry X/6-31+G(d,p), where X represents certain Minnesota functionals such as MN15, M05-2X, M06-2X, M08-HX, and M11. Among the well-known modes of radical scavenging, namely HAT, SETPT, and SPLET, the HAT mode is preferred in the gaseous phase, while SPLET operates in non-polar solvents, as computations indicate. Fukui indices, global reactivity descriptors, electronic spectra, and natural bond orbitals (NBOs) are also generated to explain the results. Understanding the mechanism of radical scavenging is important in designing powerful and efficient antioxidants for aviation fuels such as jet fuel, aviation gasoline, Jet B, and bio-kerosene.

Tracking protein aggregation behavior and molecular interactions induced by conformational alterations in the formation of myofibrillar protein-Abelmoschus manihot gum mixed gels during heating process

The present study aimed to systematically investigate the effects of different Abelmoschus manihot gum (AMG) concentrations (0–0.5%, w/w) on the formation of myofibrillar protein (MP) gels during heating process (30–80 °C) based on conformational alterations, protein aggregation behavior and molecular interactions. With the increase of temperature, the fluorescence intensity and α-helix content significantly decreased, revealing conformational transition of MP molecular. Dynamic rheological results indicated that MP had completely denatured and formed temporary gel at 50 °C, and completely formed irreversible cross-linked three-dimensional network structure at 80 °C. Moreover, the addition of AMG decreased the fluorescence intensity, as well as induced the transition of MP from α-helix to β-sheet during the whole heating process. Furthermore, AMG addition significantly decreased the turbidity and improved solubility of MP (P < 0.05), especially for at 0.3% AMG concentration, indicating that AMG accelerated the early unfolding and aggregation of MP during heating process. This was verified by the dynamic rheological results. Additionally, hydrophobic interactions and disulfide bonds were the main molecular forces to induce the formation of MP-AMG mixed gel. Therefore, our present results provided the new insights into the formation of MP-AMG mixed thermal-induced gel, and also contributed to the practical application of AMG in meat processing.

Deasphalting and oxidative desulfurization of heavy fuel oil followed by liquid-liquid extraction

ABSTRACT Heavy fuels usually contain very high amounts of complex sulfur compounds such as benzothiophenes and dibenzothiophenes leading to emission of SOx and sulfate particulate matter, which cause environmental problems such as air pollution and acid rains. Using oxidative desulfurization (ODS) process, sulfur compounds can be oxidized to sulfoxides and sulfones that can be removed using liquid-liquid extraction due to their high polarity, under mild conditions. In this study, oxidative desulfurization of a heavy fuel (Mazut, 3.1 wt% S) has been studied, with hydrogen peroxide as the oxidant and acetic acid as the catalyst. Applying ODS to Mazut commonly results in high viscosity and gum formation in the fuel. Therefore, in this study, a novel ODS procedure was developed and combined with an upgrading method to avoid this problem. The appropriate extraction solvent and the adequate solvent-to-fuel and oxidant to fuel ratios were also determined. The oxidized sulfur compounds were extracted by liquid-liquid extraction using a solvent, dimethylformamide (DMF). By using a pre-treatment method followed by a desulfurization process involving two rounds of oxidation and extraction, viscosity of fuel decreased about 87% and the sulfur content of the heavy fuel was decreased to 0.91 wt%, which means achieving 70.83% desulfurization.

Biofuel upgrading via catalytic deoxygenation in trickle bed reactor: Crucial issue in selection of pressure regulator type

Trickle bed reactors (TBRs) are commonly used in various chemical and associated processes. The selection of a proper back pressure regulator (BPR) is crucial for maintaining the system's upstream pressure. In this study, we investigate the impact of BPR selection on deoxygenation reaction in a TBR with two typical types of BPR, including gas-phase type back pressure regulator (Gas-BPR) and multiphase type back pressure regulator (Multi-BPR). Notably, Gas-BPR introduces interruptions and pressure drops during the sampling step, impacting the hydrogen flow rate, while Multi-BPR ensures more consistent hydrogen flow. To examine the performance of BPR systems, hydrotreating experiments were conducted at 330 °C, 50 bar of hydrogen over Ni/γ-Al2O3 catalyst using crude Pongamia pinnata oil as a feedstock and refined palm olein as a benchmark. Insignificant difference in the reaction performance between Multi-BPR and Gas-BPR systems was observed when using refined palm olein. Interestingly, there was a significant difference between the two systems when feeding with crude Pongamia pinnata oil. The multi-BPR system demonstrated superior performance, achieving 100% conversion of the feedstock over a prolonged period compared to the interrupted hydrogen flow in the Gas-BPR system. Further characterization of fresh and spent catalysts using N2 sorption, XRD, SEM-EDS and TGA-DTG-DSC techniques revealed that a gum and coke formation was a reason for the rapid catalyst deactivation. Furthermore, the interrupted flow in the Gas-BPR system led to substantial gum production, ultimately causing a blockage in the reactor bed. Consequently, for feedstocks with high impurities, a robust continuous flow of hydrogen is essential. Thus, the study strongly recommends selecting Multi-BPR for continuous operation in TBRs to enhance efficiency and avoid catalyst deactivation.

Gum formation susceptibility of diesel oil cut in presence of oxygenates and blends thereof

Gum formation susceptibility of diesel oil cut in presence of oxygenates and blends thereof

Effects of oxidation degree and antioxidant addition on the carbon deposition tendency of jatropha biodiesel

ABSTRACT The residual carbon value and existent gum content were used to evaluate the carbon deposition tendency of the jatropha biodiesel with different oxidation degrees. The chemical components of residual carbon and existent gum of the jatropha biodiesel were analyzed before and after oxidation by Gas chromatography-mass spectrometry (GC-MS) and infrared spectrometer. The results showed that in the short-term oxidation process, both the residual carbon and existent gum content decreased first, and then increased with oxidation time. In the long-term oxidation process, these two indicators monotonically increased with oxidation time. The residual carbon and existent gum content increased from 1140 mg/100 mL to 11,300 mg/100 mL and from 0.0272% to 0.277%, respectively. After oxidation, the aromatic compounds in the residual carbon as well as the content in the existent gum such as cyclic ether, carboxylic acid, ketone carbonyl and some fat-soluble impurities significantly increased. The addition of antioxidants showed inhibitive effect on the formation of carbon residue and existent gum. Butylated hydroxytoluene reduced the gum content by 58.3%, and methyl gallate reduced the residual carbon value by 21.1%. These findings prove that the antioxidants can effectively inhibit the auto-oxidation of biodiesel, and thus, reduce the carbon deposition tendency of biodiesel.

Experimental study of the impact of metal (iron, copper and aluminum) surface and light exposure on gum formation in Iraqi automotive gasoline

In this study, the influence of various metals (iron, cast iron, copper, aluminum) and sunlight on the gum formation rate in Iraqi gasoline fuel (IGF) is studied. Gasoline has been doped with 5 g/100 mL of used metals and various concentrations (5, 10, 15, 20, 25, 30, 35, 40 g/100 mL) of iron metal. Washed gum content has been analyzed employing ASTM D 381 after storage period of 30 days. The results explain that gum formation at 5 μg mL −1 concentration of different metals obeys the following order: iron cost > aluminum > copper > iron. The results explain that the maximum gum content is 24.4 g/100 mL employing cast iron and the minimum content via using iron metal (6.4 g/100 mL). The results prove that the rate gum formation is higher affected by sunlight in comparing with iron, and weaker influence from other metals. The experimental data shows that gum content strongly enhances via increasing of iron content. The highest gum content (21.8 g/100 mL) is at the maximum iron content (40 g/100 mL) but the minimum rate (6.4 g/100 mL) is at minimum iron content (5 g/100 mL).

Techno-economic assessment of hydrotreated vegetable oil as a renewable fuel from waste sludge palm oil

To date, the development of renewable fuels has become a normal phenomenon to solve the problem of diesel fuel emissions and the scarcity of fossil fuels. Biodiesel production has some limitations, such as two-step processes requiring high free fatty acids (FFAs), oil feedstocks and gum formation. Hydrotreated vegetable oil (HVO) is a newly developed international renewable diesel that uses renewable feedstocks via the hydrotreatment process. Unlike FAME, FFAs percentage doesn't affect the HVO production and sustains a higher yield. The improved characteristics of HVO, such as a higher cetane value, better cold flow properties, lower emissions and excellent oxidation stability for storage, stand out from FAME biodiesel. Moreover, HVO is a hydrocarbon without oxygen content, but FAME is an ester with 11% oxygen content which makes it differ in oxidation stability. Waste sludge palm oil (SPO), an abundant non-edible industrial waste, was reused and selected as the feedstock for HVO production. Techno-economical and energy analyses were conducted for HVO production using Aspen HYSYS with a plant capacity of 25,000 kg/h. Alternatively, hydrogen has been recycled to reduce the hydrogen feed. With a capital investment of RM 65.86 million and an annual production cost of RM 332.56 million, the base case of the SPO-HVO production process was more desirable after consideration of all economic indicators and HVO purity. The base case of SPO-HVO production could achieve a return on investment (ROI) of 89.03% with a payback period (PBP) of 1.68 years. The SPO-HVO production in this study has observed a reduction in the primary greenhouse gas, carbon dioxide (CO2) emission by up to 90% and the total annual production cost by nearly RM 450 million. Therefore, SPO-HVO production is a potential and alternative process to produce biobased diesel fuels with waste oil.

Thermal stress stability of hydrocarbon fuels under supercritical environments

This study investigates the thermal stressing characteristics of hydrocarbon fuels to develop thermally stable fuels for supersonic vehicle applications. The thermal stability characteristics of two multicomponent hydrocarbon fuels, namely F-1 and F-2 fuels, under subcritical and supercritical conditions, are examined for a wide range of temperatures (30–500 °C) and pressures (15–50 bar) using a semi-batch reactor. Various analysis techniques, such as UV-Vis spectrophotometry, ASTM D86 distillation, gas chromatography, scanning electron microscopy (SEM), etc., are used to characterize the feed and product properties. The study showed that the fuels are reasonably stable up to around 400 °C and above 40 bar pressure. The stability of the fuels is relatively less under subcritical pressure at elevated temperatures. The amount of gum formation increased with the increase of both temperature and pressure parameters. Further, the SEM analysis showed oval-shaped and ribbon-like structures in the solid deposits. The present investigation may be useful in developing an appropriate fuel for regenerative cooling in supersonic applications.

Challenges of oxidative/extractive desulphurization of heavy fuel oil

AbstractOxidative desulphurization (ODS) of heavy fuel oil (HFO) has some challenges such as gum formation and a high level of waste hydrocarbons. Simple calculations show that, assuming dibenzothiophene (DBT) as a representative component of sulphur‐containing components in the cut, about 20% of hydrocarbons are lost within the extraction process. An experimental investigation has been conducted in a three‐neck glass flask with a mechanical stirrer to obtain more insight about the gum formation during ODS of HFO. The gum formation process was investigated in diluted forms of fuel oil. It was observed that the fuel oil converted to the gum increases by decreasing the hydrogen/carbon (H/C) content of the diluting solvents. The main reason for gum formation during ODS is some polymer formation reactions induced by peroxide radicals. At an oxidant to sulphur ratio (O/S) ratio of 0.25, no gum was formed, while at O/S = 5.0, all of the fuel oil was converted to gum. Finally, a simple and efficient extractive desulphurization procedure has been proposed as an alternative method. At the best condition, about 84% desulphurization was obtained with dimethylformamide (DMF) solvent extraction of HFO. It can be assumed as a potential method to use mild mixing conditions with low contact time for extractive desulphurization of HFO on an industrial scale.

Synthesis, antioxidant properties, and oil solubility of a novel ionic liquid [UIM0Y2][C6H2(OH)3COO] in biodiesel

To promote the practical applications of biodiesel, an antioxidant of biodiesel is designed and synthesized in this study. The antioxidant is a 1-(2-cyanoethyl)-2-undecyl imidazole gallate ionic liquid, referred to as [UIM0Y2][C6H2(OH)3COO], which is synthesized from gallic acid (GA) and 1-(2-cyanoethyl)-2-undecyl imidazole. The synthesized samples are characterized by proton nuclear magnetic resonance (1H NMR) and Fourier transform infrared (FTIR) spectroscopy. The effects of [UIM0Y2][C6H2(OH)3COO] on the oxidation stability, metal corrosion, gum formation of Jatropha biodiesel, and oil solubility in biodiesel are also explored. The results reveal that [UIM0Y2][C6H2(OH)3COO] has an excellent oil solubility of 0.0425 g·(100 mL)−1 at 25 °C because of its non-polar structure, which is 85 times that of GA. The oxidation stability of Jatropha biodiesel is significantly improved by [UIM0Y2][C6H2(OH)3COO]. After adding 0.2‰ [UIM0Y2][C6H2(OH)3COO], the induction period of Jatropha biodiesel is enhanced by 76% and reaches the European standard (6 h). In addition, [UIM0Y2][C6H2(OH)3COO] can also inhibit the corrosion of copper and galvanized iron sheets by Jatropha biodiesel as well as the formation of gum. The amount of gum formation decreases by 37% when the concentration of [UIM0Y2][C6H2(OH)3COO] is 0.5‰. These findings indicate that [UIM0Y2][C6H2(OH)3COO] is a promising material for enhancing the oxidation stability of biodiesel.

The identification, etymology and uses of Bombax ceiba (semal) sold by street vendors as Semarkanda: a review

The paper deals with the identification of a taproot sold by the street vendors under the name ‘semar-kanda,’ ‘semar-musalī’ or ‘Ram-kanda’ as Bombax ceiba (semala). The nomenclatural history, botanical description, chemical composition and uses of the plant parts of Bombax ceiba (semala) along with folk-uses and a report of Yellow flower by Charles McCann is also been reviewed. The Sanskrit names given in Amarakośa and their etymology are discussed. The formation of gum (moca-rasa) and its chemical analysis and the myths associated with the plant by the tribals are discussed. It is concluded that ‘semar-musalī’ or ‘semar-kanda’ and ‘moca-rasa’ sold in the bazaar are the products of Bombax ceiba. The mystery of the formation of the gum moca-rasa has also been discussed as to whether it is of fungal or insect origin?

Integrated transcriptomic and metabolic analyses reveal that ethylene enhances peach susceptibility to Lasiodiplodia theobromae-induced gummosis.

Gummosis, one of the most detrimental diseases to the peach industry worldwide, can be induced by Lasiodiplodia theobromae. Ethylene (ET) is known to trigger the production of gum exudates, but the mechanism underlying fungus-induced gummosis remains unclear. In this study, L. theobromae infection triggered the accumulation of ET and jasmonic acid (JA) but not salicylic acid (SA) in a susceptible peach variety. Gaseous ET and its biosynthetic precursor increased gum formation, whereas ET inhibitors repressed it. SA and methyl-jasmonate treatments did not influence gum formation. RNA-seq analysis indicated that L. theobromae infection and ET treatment induced a shared subset of 1808 differentially expressed genes, which were enriched in the category "starch and sucrose, UDP-sugars metabolism". Metabolic and transcriptional profiling identified a pronounced role of ET in promoting the transformation of primary sugars (sucrose, fructose, and glucose) into UDP-sugars, which are substrates of gum polysaccharide biosynthesis. Furthermore, ethylene insensitive3-like1 (EIL1), a key transcription factor in the ET pathway, could directly target the promoters of the UDP-sugar biosynthetic genes UXS1a, UXE, RGP and MPI and activate their transcription, as revealed by firefly luciferase and yeast one-hybrid assays. On the other hand, the supply of SA and inhibitors of ET and JA decreased the lesion size. ET treatment reduced JA levels and the transcription of the JA biosynthetic gene OPR but increased the SA content and the expression of its biosynthetic gene PAL. Overall, we suggest that endogenous and exogenous ET aggravate gummosis disease by transactivating UDP-sugar metabolic genes through EIL1 and modulating JA and SA biosynthesis in L. theobromae-infected peach shoots. Our findings shed light on the molecular mechanism by which ET regulates plant defense responses in peach during L. theobromae infection.

Continuous Valorization of Glycerol into Solketal: Recent Advances on Catalysts, Processes, and Industrial Perspectives

With the global biodiesel production growing as never seen before, encouraged by government policies, fiscal incentives, and emissions laws to control air pollution, there has been the collateral effect of generating massive amounts of crude glycerol, a by-product from the biodiesel industry. The positive effect of minimizing CO2 emissions using biofuels is jeopardized by the fact that the waste generated by this industry represents an enormous environmental disadvantage. The strategy of viewing “waste as a resource” led the scientific community to propose numerous processes that use glycerol as raw material. Solketal, the product of the reaction of glycerol and acetone, stands out as a promising fuel additive capable of enhancing fuel octane number and oxidation stability, diminishing particle emissions and gum formation, and enhancing properties at low temperatures. The production of this chemical can rely on several of the Green Chemistry principles, besides fitting the Circular Economy Model, once it can be reinserted in the biofuel production chain. This paper reviews the recent advances in solketal production, focusing on continuous production processes and on Process Intensification strategies. The performance of different catalysts under various operational conditions is summarized and the proposed industrial solketal production processes are compared.

Development of pH-Responsive Interpenetrating Polymer Networks of Polyacrylamide-g-Gum Arabica and Sodium Alginate for Gastroprotective Delivery of Gabapentin

In the present work, a grafted polymer of polyacrylamide with gum arabica was synthesized as Gum acacia-g-polyacrylamide using microwave-assisted synthesis with ceric ammonium nitrate as a reaction initiator. The polymer was utilized in combination with sodium alginate to prepare interpenetrating polymer network hydrogel beads to effectively deliver gabapentin in gastrointestinal tract. The formulated interpenetrating polymer network microbeads showed pH-responsive release in a different medium. The interpenetrating polymer network hydrogel beads were processed for different analytical characterization like Fourier transform infrared spectroscopy, differential scanning calorimetry, X-ray powder diffraction and scanning electron microscopy. The Fourier transform infrared spectroscopy study confirms the formation of gum acacia-g-polyacrylamide whereas differential scanning calorimetry, X-ray powder diffraction studies confirm the appearance of gabapentin in the interpenetrating polymer network microbead formulations. The release of the drug from the interpenetrating polymer network structured hydrogel beads was found higher in pH 6.8 as compared to pH 1.2 and pH 7.4 indicating the effective delivery of gabapentin from the interpenetrating polymer network beads to upper duodenum for better absorption.

Proton Nuclear Magnetic Resonance (1H-NMR) Methodology for Monolefin Analysis: Application to Aquaprocessing-Upgraded Bitumen

Olefins are problematic components of petroleum products responsible for gum formation, polymers, and solid deposition in oil facilities. This work presents a methodology developed for monolefin an...

Neutral hydrocolloids promote shear-induced elasticity and gel strength of gelatinized waxy potato starch

Shear forces are important during food processing, food consumption, and food digestion, and often are estimated to evaluate their effects on product quality. However, few studies have been done on shear-induced structure changes of starch/hydrocolloid systems. Our previous work showed that gelatinized waxy potato starch forms a strong viscoelastic gel under the application of long-term low shear at low temperatures, a phenomenon that is not noted in other waxy starches such as rice and corn. In the present study, the rheological properties of gelatinized waxy potato starch in the presence of neutral (guar gum and konjac glucomannan) and anionic hydrocolloids (gum arabic, xanthan gum, sodium alginate, and pectin) were investigated. Results showed that gelatinized starch dispersions containing hydrocolloids with flexible polymer chains (guar gum, konjac glucomannan, sodium alginate, and pectin) or a highly-branched structure (gum arabic) were able to produce gels with a more liquid-like behaviour when compared to gels produced by dispersions containing hydrocolloids with rigid chains (i.e., xanthan gum). Phase separation in starch/xanthan gum system and formation of a 3D-network in the xanthan gum phase may be responsible for the strengthened gel structure resulting in high elasticity. When shearing the gelatinized waxy potato starch/hydrocolloid dispersions at 5 °C for 24 h at 20 s−1, the presence of neutral and highly viscous hydrocolloids drastically increased the gel strength, while anionic and low viscous hydrocolloids decreased it. Such decrease in gel strength was attributed to the electrostatic repulsion between anionic hydrocolloids and the naturally negatively charged phosphorylated chains of waxy potato starch.

A review on cold flow properties of biodiesel and their improvement

The depletion of petroleum derivatives and expanded contamination caused by the consuming of fossil fuel is a driving component to consider the renewable source. Biodiesel is considered as most promising fuel to use in diesel engines. Biodiesel obtains from animal fats, Straight vegetable oils and waste by transesterification and esterification process. The properties of biodiesel oil meet the requirement of fuels and it can build a huge positive impact on pollution and make the fuel eco-friendly. Biodiesel with its points of interest undergoes a notable downside in the low-temperature properties. Due to inferior low-temperature properties of biodiesel, fuel crystallization and gum formation occur at low-temperature which leads to stopping of channels and tubes. It indicated higher pour point and cloud point, higher nitrogen oxide (NOx) which cuts down engine speed and power, injector coking. The present study review is done on low-temperature properties and Impact of different actions taken to improve these properties.

Optimization of Colon Specific Drug Delivery System for Ornidazole using Modified Gum

The present study aimed to optimize a colon-specific formulation of ornidazole for the treatment of Crohn's disease and intestinal amoebiasis. Firstly carboxymethyl xanthan gum was prepared from xanthan gum reacting with monochloroacetic acid in alkaline conditions using the Williamson synthesis method. Fourier transform infrared spectrophotometer (FTIR) spectroscopy confirmed the formation of carboxymethyl xanthan gum. The differential scanning calorimetry (DSC) revealed the crystalline nature of carboxymethyl xanthan gum. A 32 full factorial design was used for optimization. The independent variables employed were the amount of Carboxymethyl Xanthan gum and the amount of hydroxy propyl methyl cellulose (HPMC), each at three levels. Drug release studies were carried out in various media [pH 1.2, 7.4, and 6.8]. The optimized formulation consisting of Carboxymethyl Xanthan gum (66 %) and HPMC (22%) released a small fraction of drug at pH 1.2 and pH 7.4, whereas significant drug release was observed at pH 6.8. The results of the study established Carboxymethyl Xanthan gum compression coated tablet to be a promising system for the colon-specific delivery of ornidazole to treat active Crohn's disease and intestinal amoebiasis.

Evaluation of Red Onion Skin Extract as Inhibitor for Gum Formation in Gas Condensates

In the upstream sector, gum in condensate causes significant erosion in value worth millions of dollars per annum and increases operational cost due to high injection concentration of conventional antioxidants. Phenolic compounds are commonly used at low concentrations in the downstream sector to inhibit gum formation in refined petroleum products. However, gum inhibition in condensates, in the upstream sector, requires high concentrations of phenolic antioxidant. Therefore, there is need for cheaper and more effective antioxidants for gas condensates. The present study investigates the use of Red Onion Skin Extract (ROSE) as a natural inhibitor for gum formation in condensate based on ASTM D381. Treatments with ethanolic extracts of red onion skin were carried out on seven gas condensate samples with gum formation tendency. At a dosage of 200ppm red onion skin extract caused a reduction of 17.4% to 99.6% in washed gum content of the condensate samples. The performance of ROSE was comparable to, and in some condensates better than, commercially available catechol. The result obtained using ROSE highlights the need to explore the commercial viability of this application in oil &amp; gas upstream operations.