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This analytical review is aimed at identifying and analysing a variety of factors affecting the low oil recovery factor. The study covers a wide range of parameters, from the mining and geological conditions of deposits to the physical and mechanical properties of rocks and hydrocarbons. Attention is also paid to such important aspects as geological features, including fracturing of rocks, waterlogging of formations and folding of deposits, which can significantly complicate oil production. Statistical data on current oil recovery rates from different regions and countries were collected and analysed, which helped to identify the most common problems and typical oil recovery rates. The review highlights that, along with well-known factors such as high oil viscosity and low rock permeability, oil recovery factor is significantly influenced by resistance to extraction by gravity, and complex tectonic conditions such as the presence of folds and faults. In addition, the problems related to the modelling and representation of the oil reservoir are considered, which can lead to errors in the assessment of oil reserves and, consequently, to an underestimated oil recovery factor. In conclusion, the review suggests possible areas for the development of oil production technologies that can help to overcome the identified obstacles. Suggestions are given for improving methods of increasing oil recovery, such as the introduction of new technologies, improvement of existing methods, and conducting more accurate geological studies.

The engine oil contamination caused by various chemical elements and fuel is an important problem. As a consequence, the engine oil loses its tribological properties, engine lubrication worsens and may lead to potential problems such as excessive wear, corrosion, etc. For that reason, the study of oil degradation and contamination due to the replacement strategies is of special interest to the engine operators and engine manufacturers. In this paper, the chemical elements and fuel dilution of engine oil are analyzed under real engine operating conditions. This research is focused on the fundamental question: how is the chemical performance of lubricant components impacted by diesel dilution? Various tribological tests were performed on regularly collected samples from the fuel injection pump of a Pielstick PA4 V185 marine diesel engine. These tests assessed the influence of fuel on the lubricating oil chemistry performance and useful residual life. Tests included variations in lubricant density, viscosity, flash point temperature and chemical components for 10 samples taken in the following hours of engine operation. Results suggest that diesel dilution only slightly affects chemical additive performance. Most of the examined chemical elements remained at a negligible level (below 1 ppm) in the case of elements whose content was greater, and the changes were either negligible (Al, Fe, MG, Si) in the grits from 1 to 5 ppm or higher (Ca, P, Zn, C), ranging from tens to several hundred ppm. On the other hand, the kinematic viscosity changed significantly from 89.8 to 12.0 cSt at 40 °C or from 9.8 to 2.9 cSt at 100 °C. The change in flash point, although significant from 236 (for fresh oil) to a value below 100, does not exceed the limit values. To sum up, the study concluded that the reduction in oil change intervals for this engine is worth considering under the given operating conditions.

The article presents the impact of ecological additives on selected parameters and the microbiological distribution of marine engine oil (Marinol). With the development of industry and the automotive sector in general, it has become apparent that the problem of microbial contamination is still relevant and is becoming increasingly widespread. The author decided to investigate the impact of additives, namely silver and effective microorganisms with a 2% percentage share in marine engine oil (Marinol), on selected parameters and on slowing down the growth of bacteria and fungi. The article presents the impact of additives on selected engine oil parameters, including flash point, water content, acid and base numbers, density and kinematic viscosity. In addition, the oil was also tested for the effect of additives on the inhibition of microbial decomposition in the tested oil. It was found that the best additive with a positive effect on engine oil parameters and microbial decomposition was a silver solution and effective microorganisms in the form of ceramics. The addition of effective microorganisms in liquid form and silver solution to used oil resulted in an increase in temperature of approximately 1 °C compared to the ignition temperature of oil without additives. For the addition of colloidal nanosilver, a temperature of 225.22 °C was obtained. For used oil, the water content increased to 0.16% from 0.1% for new oil. The addition of liquid effective microorganisms caused the largest increase in water content to 0.58%, while EM in the form of ceramics did not contribute to the increase in water content due to its composition. The addition of silver solution contributed to an increase in water content to 0.47% and colloidal silver to 0.53%. The base number of used motor oil without additives decreased from 11.82 mgKOH/g for fresh oil to 11.52 mgKOH/g. After the application of ceramic effective microorganisms, a lower base number was obtained compared to oil without additives, which is 11.34 mgKOH/g, while liquid effective microorganisms reduced the base number the most, to 11.27 mgKOH/g. Each of the additives caused a decrease in bacteria and fungi compared to used oil without additives. The use of these additives is an original solution that has a positive effect on the microbial degradation process, while maintaining the original performance parameters of the engine oil. In the next stage, it would be desirable to confirm the results obtained under actual operating conditions.

Fuel contamination of engine lubricating oil has been previously determined to arise from two independent phenomena: the effect on oil flash point, and the effect of changing lubrication conditions on tribological pairs. This paper combines these effects and holistically analyzes the consequences of fuel in the lubricating oil of a trunk piston engine on the risk of crankcase explosion. The author hypothesized that diesel fuel as an oil contaminant increases the risk of an explosion in the crankcase of an engine due to the independent interaction of two factors: (1) changes in the oil’s combustible properties, and (2) deterioration of the lubrication conditions of the engine’s tribological nodes, such as main bearings, piston pins, or crank bearings. An experiment was performed to evaluate the rheological, ignition, and lubrication properties of two oils (SAE 30 and SAE 40) commonly used for the recirculation lubrication of marine trunk piston engines for different levels of diesel contamination. The hypothesis was partially confirmed, and the results show that contamination of the lubricating oil with diesel fuel in an amount of no more than 10% does not significantly affect the risk of explosion in the crankcase. However, diesel concentrations above 10% call for corrective action because the viscosity index, lubricity, coefficient of friction and oil film resistance change significantly. Deterioration of the tribological conditions of the engine bearings, as seen in the change in viscosity, viscosity index, and lubricity of the oil, causes an increase in bearing temperature and the possibility of hot spots leading to crankcase explosion.

The rheological, ignition, and tribological properties of lubricating oils diluted with biodiesel were analyzed. The flash point tFP, calculated cetane index CCI, density ρ, coefficient of the temperature density change ε, kinematic viscosity ν, dynamic viscosity η, viscosity index VI, and lubricity during a High-Frequency Reciprocating Rig (HFFR) test (x, y, WSD, and WS1.4) and lubricating conditions during an HFFR test (oil film resistance FILM and friction coefficient μ) were determined. The test was performed for the oil mixtures of the lubricating oil of the SAE 30 and SAE 40 viscosity grades, which were diluted with the biodiesel blend (D93B7—diesel oil with 7% v/v fatty acid methyl esters, FAME) at concentrations of diesel oil in the mixture equal to 0% (pure lubricating oil), 1%, 2%, 5%, 10%, 20%, 30%, 50%, and 75% m/m, respectively. The experiment confirmed the existence of clear relationships between the increase in the dilution of lubricating oil with tested biodiesel blend and tFP, ρ, ε, ν, η, and VI, and the deterioration of lubrication conditions. It is recommended to take remedial action even in the case of low diesel oil concentration (<5% m/m) in the lubricating oil due to tFP, ν, and η changes. Simultaneously, the tests showed no significant effect on the lubricity and the CCI. The critical contamination of oil with fuel in the range of 2–5% by weight, as indicated in the literature, still allowed for a certain “safety margin” regarding these parameters. However, when the concentration of diesel fuel in the lubricating oil exceeded 5–8% m/m, the deterioration of the lubrication was expressed by a decrease in FILM and an increase in μ was observed; hence, such a contamination should be considered excessive. When the concentration of diesel fuel exceeds 10% by weight, there is a serious risk of engine damage during operation.

The growing world population necessitates the implementation of appropriate processing technologies for edible insects. The objective of this study was to examine the impact of distinct drying techniques, including convective drying at 70 °C (70CD) and 90 °C (90CD) and freeze-drying (FD), on the drying kinetics, physical characteristics (water activity, color), chemical characteristics (chemical composition, amino acid profile, oil properties, total polyphenol content and antioxidant activity, mineral composition, FTIR), and presence of hazards (allergens, microorganisms) of blanched yellow mealworm larvae. The freeze-drying process results in greater lightness and reduced moisture content and water activity. The study demonstrated that the freeze-dried insects exhibited lower contents of protein and essential amino acids as compared to the convective-dried insects. The lowest content of total polyphenols was found in the freeze-dried yellow mealworm larvae; however, the highest antioxidant activity was determined for those insects. Although the oil isolated from the freeze-dried insects exhibited the lowest acid and peroxide values, it proved to have the lowest PUFA content and oxidative stability. All the samples met the microbiological criteria for dried insects. The results of the study demonstrate that a high temperature during the CD method does not result in the anticipated undesirable changes. It appears that freeze-drying is not the optimal method for preserving the nutritional value of insects, particularly with regard to the quality of protein and oil.

Fossil fuel reserve depletion and environmental concerns have spurred substantial research to find alternative energy sources. Bio-oil derived from biomass pyrolysis has great potential to substitute fossil fuels. However, bio-oil physicochemical properties are far below the requirements for biofuels due to several issues such as low heating value, and high-water content, acidity, and viscosity. Bio-oil is unstable and tends to polymerize due to the high content of reactive oxygenates and molecular compounds, even during storage. Therefore, bio-oil without quality upgrading is not suitable for use as a fuel. A promising method to improve bio-oil properties is through catalytic hydrodeoxygenation (HDO) — a hydrogenolysis process for removing oxygen from the oxygen-containing compounds. However, the complex mixture of organic components in bio-oil renders the complexity of HDO, and the significant issues in HDO are coking and decreasing catalyst performance. Therefore, various approaches to overcome these issues have been developed. The final product distribution of HDO can be customized by tuning the experimental parameters such as catalyst acidity, pressure, temperature, types of solvents, and even reaction duration. In this review, the parameters of catalytic HDO are elaborated as functions to provide comprehensive options for constructing the strategy in practicing HDO of bio-oil.

This paper presents the effect of environmentally friendly additives on selected parameters and microbial degradation of Marine Diesel Oil (MDO). Microbiological contamination is a serious problem in MDO and other petroleum products. For this reason, it was decided to investigate the effects of environmentally friendly additives such as silver solution and colloidal nanosilver, as well as effective liquid microorganisms and ceramic tubes with different percentages of them in diesel oil (MDO) on its selected parameters and inhibition of bacterial and fungal growth. The tests were conducted on a mixture of fuel with four types of environmentally friendly additives at concentrations of 2% and 5%, and on fuel without any additives. The effect of the additives on selected diesel parameters, including flash point, water content and acid number, as well as density and kinematic viscosity, is presented. The diesel oil was also subjected to microbiological tests. It was found that the most beneficial additive that positively influenced diesel parameters and microbial degradation was a silver solution at a concentration of 2%. The lowest ignition temperature was obtained when ionic silver was used, i.e. 60 °C, which is closest to the value for pure diesel fuel. The addition of effective microorganisms in liquid form to the fuel in an amount of 2%, increases the ignition temperature to 62.2 °C and this is the highest value obtained in comparison with other additives. The lowest water content in the test samples was obtained for the effective microorganisms in ceramic form at − 0.0068%, while the highest value was obtained for the silver solution at 0.0123%. At 100 °C, the highest kinematic viscosity was obtained for EM in ceramic, at 1.11 mm 2 /s. While for pure oil it was 1.03 mm 2 /s. For pure diesel, a value of 1.1 × 106 cfu/1 dm 3 for bacteria and 7.3 × 103 cfu/1 dm 3 was obtained. For each type of mixture, a value of less than 1 × 102 cfu/1 dm 3 for bacteria was obtained, while in terms of fungal counts in the mixtures, a decrease of 73 times is also observed for diesel mixed with effective microorganisms in liquid form and ceramics, 48 times less was recorded after the use of non-ionic silver. The use of these additives is an innovative solution that has a positive effect on slowing down microbial degradation, without any loss of diesel performance.

Edible insects may solve the current problem of the greater demand for food for the world’s growing human population. This work aimed to examine the impact of blanching (BL) and ultrasound (US) at 20 and 50 °C as a pretreatment method on the chemical composition, mineral composition, FTIR spectra, presence of allergens and microorganisms, and properties of the isolated oil of freeze-dried superworm larvae. The US treatment resulted in significantly lower protein content (31.65–33.34 g/100 g d.m.) compared to untreated (36.38 g/100 g d.m.) and BL (37.72 g/100 g d.m.) samples. The study demonstrated that the US-treated insects exhibited a lower content of crustacean and mollusk allergens than the BL insects, and the lowest content of tested allergens was found in the US_50°C superworm larvae. Furthermore, oil isolated from US_50°C insects exhibited the lowest SFA and the highest PUFA content and the best prospective nutritional properties expressed through theoretical health indices. The presence of Enterobacteriaceae and anaerobic spore-forming bacteria was not detected in the tested insects, proving suitable microbiological quality. It appears that using US treatment is a promising alternative to traditional blanching of insects before drying.

Abstract Aromatic oils obtained during lubricant production (DAE) have high value as rubber extenders in tire manufacturing, but they have high carcinogenic potential due to the content of polycyclic aromatic compounds (PCAs). Legislation on PCA content requires additional treatment to reach treated oils (TDAE) with a PCA content lower than 3% according to the IP 346 method. IP 346 is a highly time-consuming and high uncertainty method, and several proposals have tried to replace it, but nowadays, there is no standard alternative. In this work, an extensive collection of samples covering a broad PCA content were obtained and characterized by physical properties, NMR, and aromatic and PCA content. Several correlations were tested to establish an optimum procedure to estimate the aromatic and the PCA content according to the requirement of high accuracy and low time and effort. The combination of several properties does not improve the accuracy of the correlation, and simpler equations were preferred. Integrated spectra appear as an acceptable characterization method as NMR percent of the total aromatic proton and polycyclic aromatic proton correlates satisfactory with the number of aromatic carbons and PCA content, respectively. The refractive index yields the best results for the correlation to PCA content. Obtained deviations compare favorably with methods previously described in the literature and with the uncertainty involved in the experimental method. They can be considered adequate methods to analyze such magnitudes routinely.