Reducing ecological damage to flora and fauna through the use of waste from oil production as porous fillers in manufacturing

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Introduction
Ecological-economic systems are the subject of study in industrial or industrial ecology. The subject of study in industrial ecology is the relationship between production activities and the environment, in which not only humans but all living organisms exist. The main task of industrial ecology is to significantly reduce environmental pollution by renewing outdated facilities and bringing them into compliance with new requirements and standards, technical conditions, and quality indicators.
Industrial ecology studies waste-free technologies, which is when the waste of one production facility is used as raw materials at another facility, which allows for achieving either zero-waste production or maximum utilization of multi-ton waste. Industrial ecology studies chemical, biological, and physical relationships (interactions) both within and between ecological and industrial systems, i.e., when raw materials and waste that are in relationships and connections with each other form a certain integrity and unity.
Currently, the impact of industry on the environment is relevant, as the activities of fuel and energy complexes, metallurgical, chemical, engineering, and many other enterprises cause significant and irreversible damage to nature.
The aim of the work is to 1) use waste from oil production (oil sludge) to obtain a porous filler based on liquid-glass composition; 2) study the structure of the porosity of the porous filler.

Materials and methods
It should be noted that one of the main "polluters" of the natural environment is the fuel and energy complex, which includes atmospheric emissions (48% of all atmospheric emissions), wastewater discharges (36% of all discharges), as well as the formation of solid waste (30% of all solid pollutants) [1,2].
The waste of the fuel and energy complex includes oil sludge (waste from oil production), waste from coal enrichment, shale fuel waste, which are obtained during the extraction, enrichment, and combustion of solid fuel [3].
Long-term storage of waste in oil production (oil sludge pits) and thermal power plants in ash dumps contributes to the entry of harmful substances and heavy metal ions into water and soil, therefore it is necessary to reduce the anthropogenic load by implementing regional norms, changing the fees for pollution of water bodies, and using them in the production of building materials.
Effective utilization of large-tonnage industrial waste is one of the current environmental problems [4]. The industry producing thermal insulation materials stands out for its unlimited possibilities for waste utilization [5]. This is due to the large scale of the construction complex, its material intensity, and the range of products.
Thermal insulation materials include porous filler and lightweight brick. One of the current challenges for the thermal insulation industry is the production of products with high efficiency, with a thermal conductivity of no more than 0.25 W/(m•°C). The production and consumption of such thermal insulation materials in Russia is much lower than in European and North American countries, despite the fact that the climate there is much milder [6,7].
The work uses empirical, experimental research methods, computational and analytical methods of data processing.

Results
The Samara region is a region with a developed oil refining industry. In this work, waste from oil production was studied -oil sludge that is formed at an oil production plant in the town of Neftegorsk. The sludge is a finely dispersed powder of dark brown color [8]. The main characteristics of the oil sludge are presented in     will manifest against the backdrop of no less widespread natural flows of these substances, which can also bring HC into soils [9]. As a result, a certain complex of HC of various classes accumulates in the soils, which are in different aggregate states, which adversely affects the fauna and flora of this region. It should be noted that the complex of oil HC is very complex in composition and contains thousands of individual components that differ in physical, chemical, and toxicological properties [10]. Heavy oil fractions are immobile and can create a stable pollution hotspot, and cleaning the natural environment from them is difficult. Studies have shown that the oil part of the oil sludge has an increased content of heavy fractions (80.4% heavy oils, Table 2), which not only have a toxic effect on organisms but also significantly change the water-physical properties of soils. They deteriorate the water-physical properties of soils due to the cementation of the soil pore space.

Discussion
Resins, asphaltenes (Table 2), and total petroleum hydrocarbons in Western literature are considered as a complex of diverse substances that include chain and cyclic molecules of HC -heteroatom compounds and high molecular weight polycondensation compounds [11]. Asphaltenes and resins, like heavy oils, deteriorate the water-physical properties of soils due to the cementation of the soil pore space.
In the work [12], the authors believe that low (C10-C16) and high molecular weight (C16-C34) petroleum hydrocarbons need to be investigated separately. Studies have shown that paraffins make up 9% of the petroleum fraction of oil sludge ( Table 2). The penetration of paraffinic oil into the soil leads to a long-term disruption of soil moisture exchange. They are hazardous to the soil because, having a low freezing point, they firmly block the pores and channels of the soil through which metabolic exchange occurs between the soil and adjacent environments.
In assessing the risk of contamination to human health, the authors of work [13] believe that total petroleum hydrocarbons are divided into groups based on their physicochemical and toxicological properties, for example, by belonging to aromatic or aliphatic compounds. Despite their low solubility in water, a small amount of oil is enough to significantly deteriorate water quality. Usually, oil components form an emulsion with water that is difficult to break. Oil often floats on the surface of the water in the form of a film, enveloping suspended particles and settling to the bottom.
Technogenic hydrocarbons penetrate the soil after its surface is contaminated with oil, petroleum products, wastewater, and other substances containing hydrocarbons [9].
When entering the soil, petroleum hydrocarbons undergo sorption by organic and mineral substances in the soil [14]. When the organic matter content is high, sorption processes are intensified, and the availability of petroleum hydrocarbons for biodegradation is significantly reduced [15,16]. The intensity of accumulation of petroleum hydrocarbons in soils is also related to the particle size distribution of soils. Weak levels of accumulation of these compounds have been found in sandy soils. At the same time, petroleum hydrocarbons can penetrate into nanoscale pores in soils, where their availability to microorganisms is reduced [17].
The decomposition of petroleum hydrocarbons in soil occurs with the obligatory participation of oxidoreductases. Oxidoreductases are enzymes that catalyze oxidation and reduction reactions, i.e., the transfer of electrons from a donor to an acceptor. Enzymes in this work refer to protein molecules or RNA molecules (ribozymes) or their complexes that accelerate (catalyze) chemical reactions in living systems.
One representative of oxidoreductases is catalase, which is secreted by microorganisms into the surrounding environment [18]. Catalase is an enzyme of the oxidoreductase class that catalyzes the decomposition of hydrogen peroxide into water and molecular oxygen. At low concentrations of hydrogen peroxide, catalase also exhibits peroxidase activity, oxidizing lower alcohols and polyphenols. One of the main functions of catalase is to protect cell membranes from hydrogen peroxide, which is formed during lipid peroxidation. Oxidation is the removal of hydrogen atoms from the substrate, while reduction is the addition of hydrogen atoms to the acceptor.
Catalase has high stability, can accumulate and persist in the soil for a long time, and can also serve as an indicator of the ability of the soil bacterial complex to survive under conditions of oil pollution. Insufficient stability leads to slow plant growth, chlorosis, necrosis, and disruption of photosynthesis and respiration function. Heavy oils and petroleum products, when coating plant roots, significantly reduce the flow of water, leading to plant death. These substances are poorly accessible to microorganisms, and the process of their destruction is very slow, sometimes taking decades. Stunted plant growth can occur up to the absence of generative organs.
The influx of gaseous alkanes such as methane, propane, butane, and many other volatile compounds from deep parts of the lithosphere, including oil and gas deposits and waste from oil refining plants, has long been known, but research on this topic continues to be relevant [19]. Large accumulations of waste from oil production release a large number of substances of different hazard classes into the air. The most dangerous of them is 3,4benz(a)pyrene. An increase in its content in the environment leads to severe environmental consequences. Dangerous amounts of 3,4-benz(a)pyrene are present in the soils of oilproducing regions of Russia in the early stages after pollution.
Wastes from oil production with high organic content (carbon, Table 4) can be used as a fuel and as a burning additive for the production of heat-insulating materials, including porous fillers. Various types of solid fuels, including anthracite, coke fines, and others, belong to the group of burning additives [20]. They are added to the mixture in a volume of up to 5%, i.e., up to 50-80% of the total fuel needs for firing the products. Their purpose is to intensify the firing process, improve the fusibility of the mass, and increase the porosity of the products.
Exhaustion of natural resources, as is the case in the European territory of Russia and many other countries around the world, is a result of the intensive use of natural resources in expanding the volume of public production. By utilizing industrial waste, it is possible to significantly alter the parameters of Russia's raw material base. The use of technogenic raw materials in the production of thermal insulation materials contributes to a significant reduction in the use of natural traditional raw materials and a reduction in environmental stress in the regions [21]. At the same time, costs for geological exploration, construction, and operation of quarries are eliminated, and significant land areas are freed from the impact of negative anthropogenic factors.
Using waste from the fuel and energy complex as raw materials for producing ceramic building materials allows for a reduction in the cost of products. For example, the cost of raw materials in the production of building materials sometimes reaches 40-50% [22][23][24]. Therefore, the issue of reducing the price of raw materials in the production of building materials is becoming particularly relevant.
In addition, about 70% of thermal power plant waste and coal enrichment waste have an increased content of unburned residues, which significantly reduces the need for fuel when firing ceramic materials [24,25]. For example, the carbon content in oil sludge and its heating value are correspondingly equal to C (carbon) -16.02% (Table 4) and (θp) -3300 kcal/kg (Table 6) [14,15]. The total content of such residues can satisfy the fuel demand for 1/4 of the entire ceramic demand for producing lightweight bricks (thermal insulation materials), and the mineral part of energy waste can satisfy up to one-third of the demand for clay raw materials, binders, and fluxes.
Thus, due to the increased contents of carbon (Table 4) and calorific value (Table 6) in oil sludge (ppm = 30-32%, Table 3), which burn or promote combustion (calorific value) during firing, a porous structure is created in the ceramic material, resulting in a lightweight porous material [25,26].
Liquid glass. Commercial sodium liquid glass with a density of 1.41 g/cm3 was used as a binder. Liquid glass refers to aqueous alkaline solutions of silicates, which are thick liquids. The chemical composition can be represented by the formula: R2OnSiO2 + mH2O, where R is an alkali cation (Na+, K+, Li+ or NH4+); n is the silicate modulus of liquid glass (the ratio of the siliceous component to the alkaline); m is the number of water molecules [2,27].
The prevalence of the raw material base for the production of porous fillers based on liquid glass compositions is provided by nature itself, where the closest analog of carbonsilicon -is the third most common element (after oxygen and hydrogen) in the earth's crust, accounting for 16.7% of the total number of atoms [2,27]. If carbon can be considered the main element for all organic life, then silicon plays a similar role with respect to the solid earth's crust.
Studying the state diagrams of Na2O-SiO2 and Na2O-SiO2-H2O, P.N. Grigoryev and M.A. Matveev established that the content of hydrated water is reflected in the melting temperature of the alkaline silicate [28]. Thus, when the silicate contains 20% of hydrated water, it melts at 100°C. When such a hydrated silicate is rapidly heated to 200°C, it becomes diluted, and the hydrated water quickly turns into steam. Due to the high viscosity of the molten silicate, water vapor is retained in it, forming bubbles with thin walls.
The results of the study on obtaining a porous filler based on liquid glass systems showed that swelling begins at 50°C. Similar studies conducted by V.I. Konev and Danilov showed that the melting of the Na2O-SiO2-H2O triple system begins at a temperature above 48°C [29]. The authors explain the obtained results by stating that the cations and anions (Na2SiO3•H2O) are connected only by electrostatic interactions and weak hydrogen bonds between water molecules. Therefore, at a temperature of 48°C, the crystalline structure breaks down and the crystal hydrate melts in its own water.
Due to the high viscosity of the melted silicate, water vapor is trapped in it, forming bubbles with thin walls. Adding fillers to liquid glass compositions leads to the structuring of the system, which allows for more homogeneous structures to be obtained [2,27].
Sodium chloride (GOST 13830-97, produced by OAO "Bassol") was used as a coagulant additive, ground to a size of less than 0.3 mm.
Porous fillers. Currently, about one-third of the energy in Russia's heating systems is lost. In Russia, 2-3 times more energy is used for heating residential areas than in European countries. For example, 600-800 kW/(m2⋅ year) is used for individual houses in Russia, while in Germany it is 250 kW/(m2⋅ year), and in Sweden it is 139 kW/(m2⋅ year).
The use of porous fillers significantly reduces heat loss in heated buildings and reduces fuel consumption, which is particularly relevant at present.
Compositions (Table 7) for the production of a porous filler were prepared by carefully mixing all components. The mixture was prepared in a high-shear mixer in the following order: first, oil sludge and sodium chloride were loaded into the mixer and thoroughly mixed. Then, while the mixer was running, sodium silicate was added slowly in a thin stream to the dry mixture. Mixing was continued until a homogeneous mass was obtained, but for no less than 5 minutes. The obtained mixture was cut into separate granules by a knife system and then thermally treated at 250-300°C in a pelletizing oven, swelling and forming spherical highporosity granules. The resulting granules were placed in an electric furnace heated to a temperature of 1000°C and held there for 10 minutes. After the isothermal hold, the granules were cooled at a cooling rate of 40°C/min. The technology presented in this work is patented in Russia [30]. The physical and mechanical properties of the porous filler are shown in Table 8. As shown in Table 8, the porous fillers made from the proposed compositions have high compressive strength and softening coefficient, while the bulk density grade does not exceed 400 and the thermal conductivity is less than 0.20 W/(m•°C). The optimal composition can be considered as composition #2, which has a bulk density grade of no more than 350 kg/m3 (grade 300) and an increased strength compared to composition #1 ( Table 8). The resulting sample is shown in Fig. 1.   Fig. 1. Photo of the porous filler (composition 2), view: a) -external; b) -internal.
As seen in Fig. 1a, the porosity is not prominent in the external view, unlike in the internal view. This means that the petroleum sludge contributes to the formation of closed pores in the porous filler. Figure 2 shows an electron photo of the porous filler of composition #2, where the porosity is represented by small, large, and closed pores.

Conclusion
A porous filler with high physical and mechanical properties was obtained based on a liquid glass composition and oil sludge.
Oil sludge is advisable to use as a burn-out additive. Due to the increased content of heat capacity, organics (>25%), and carbon in the oil sludge, which burns or contributes to combustion (heat capacity) during firing, porosity is created in the ceramic material, and a porous material with low density is obtained.
The use of oil sludge based on a liquid glass composition in the production of a porous filler, without using natural traditional material, contributes to the reduction of the anthropogenic component in the formation of ecology.