Currently, the key challenge of the oil-refining industry worldwide is to produce environmentally friendly fuel in large volumes to meet market demand, which is due to strict environmental standards governing the permissible sulfur content in fuel. Natural gas, refinery gas, and coal gas contain acid gases such as hydrogen sulfide and carbon dioxide. These compounds must be removed from the gas stream because of the toxicity of H₂S and to prevent the acid gas-induced corrosion of pipelines and facilities. Hydrogen sulfide is released as a result of various industrial processes, and its removal is critical because this compound can cause corrosion and environmental damage even at low concentrations. Sulfur compounds are also present in natural gas, biofuels and other fuel gases used in power plants. This article proposes new adsorbents of natural and waste origin and presents the results of their testing for the removal of acid gases. This paper also considers methods for the preparation of adsorbents from waste and procedures for the removal of sulfur-containing compounds. Using agricultural, industrial waste to produce activated sorbents not only solves the problem of waste disposal but also reduces the cost of desulfurization, contributing to the creation of sustainable and environmentally friendly technologies. The Review Section comprehensively summarizes current research on hydrogen sulfide removal in gas cleaning processes using agricultural and industrial waste as highly efficient adsorbents. In the Experimental Section, 10 composite materials based on natural raw materials and wastes, as well as 6 commercial adsorbents, were synthesized and tested under laboratory conditions. The choice of materials for the adsorbent production was based on the principles of environmental friendliness, availability, and cost-effectiveness. The developed materials based on modified sludge from water treatment plants of thermal power plants are effective sorbents for the purification of gas emissions from petrochemical enterprises. For industrial use, it is necessary to solve the problems of increasing the economic attractiveness of sorbents from waste, the ability of regeneration, the competitive adsorption of pollutants, the use of indicator sorbents, the optimization of operating conditions, and safe waste disposal.

Fuel gas desulfurization is an important technological step toward achieving environmental neutrality in industrial production. The presence of sulfur compounds in fuel not only significantly increases the rate of corrosion processes, but also increases the amount of sulfur oxides in flue gases. Adsorption technologies are actively used to purify fuel. Materials that are mainly chosen as sorbents are determined by economic feasibility. These materials include bentonite clays. The paper presents an analysis of scientific works on the possible methods of using bentonite clays in industry. Due to its natural properties, this material has high adsorption properties. The authors present experimental laboratory studies to determine the adsorption efficiency of bentonite clay with a carbon substrate. Results on the adsorption capacity after regeneration of the composition are also presented. Based on the data obtained, the adsorption unit was calculated, and the process flow diagram was designed.

The study addresses the problem of imparting electrical conductivity to conventional polymer materials for 3D printing by means of surface modification. Polylactide, polyethylene terephthalate glycol, and thermoplastic polyurethane were used as the polymer matrices. The conductive polymer complex poly(3,4-ethylenedioxythiophene) poly(styrene sulfonate) (PEDOT:PSS) was applied as a surface modifier. The modification procedure consisted of impregnating polymer samples with an aqueous PEDOT:PSS dispersion followed by thermal treatment. Electrical properties of the obtained composites were evaluated by measuring resistance and calculating specific electrical conductivity. Surface modification was shown to increase the conductivity of the polymers by 12–14 orders of magnitude compared to the initial dielectric materials. The highest specific conductivity was achieved for the polyethylene terephthalate glycol + PEDOT:PSS composite and reached 9.26×10^-2 S/m. The conductivity of the polylactide-based composite was 2.73×10^-3 S/m, while thermoplastic polyurethane exhibited the lowest value of 3.97×10^-6 S/m, which is attributed to the structural features and reduced wettability of the elastomer surface. Optimal processing parameters were established as 30 minutes of ultrasonic treatment and a drying temperature of 100 ℃. Dispersion dilution with water was found to reduce electrical conductivity, whereas the addition of organic solvents to the modifier was ineffective. A synergistic effect was revealed when combining bulk filling of polylactide with multiwalled carbon nanotubes and subsequent surface modification with PEDOT:PSS, with maximum conductivity observed at a nanotube content of 7 %. The results demonstrate the practical potential of the proposed method for manufacturing electrically conductive functional components using additive manufacturing technologies.

The paper presents the results of a comprehensive study of the functional properties of electrically conductive composites obtained by surface modification of polymer materials for 3D printing – polylactide (PLA), polyethylene terephthalate glycol (PETG), and thermoplastic polyurethane (TPU) – with a conducting polymer complex of poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS). The piezoresistive response of the samples was studied under mechanical bending deformation in the range of 0–2%. The gauge factor (GF) was calculated. The PETG + PEDOT:PSS composite demonstrated the highest sensitivity with a maximum GF of ≈ 47, which is due to the formation of a rigid and well-adhered conductive layer that is prone to cracking during deformation. For the PLA + PEDOT:PSS and TPU + PEDOT:PSS composites, the maximum GF values were ≈ 19.5 and ≈ 13.5, respectively. A study of the Joule heating effect under a constant voltage of 70 V revealed a slight increase in the sample temperature (ΔT = 0.5–1.9 °C), which is due to the high resistivity of the surface layer. It was shown that, despite their limited effectiveness for active heating purposes, the materials exhibit stability when subjected to current flow. These findings demonstrate the potential of these composites for the development of passive strain sensors and flexible electronic components using additive manufacturing techniques in nuclear power plants (NPPs).

Sulfide-alkaline wastewater (SAW) from petrochemical plants, particularly from pyrolysis and hydrotreating units, presents a significant environmental challenge due to its high toxicity, extreme alkalinity (pH > 12), and high concentrations of sulfides and organic pollutants. Traditional treatment methods like acid neutralization or air oxidation are often inefficient, generate secondary waste, or fail to recover valuable components. This study investigates the effectiveness of a novel electrochemical system for the simultaneous treatment of SAW and recovery of valuable products. A lab-scale four-chamber bipolar electrolyzer, equipped with cation-exchange membranes and nickel electrodes, was designed and tested using real industrial wastewater. The wastewater was characterized by a pH of 13.06, chemical oxygen demand of 12600 mg/l, and a sulfide content of approximately 5000 mg/l. The process leverages anodic oxidation to convert sulfide ions into elemental sulfur, while sodium cations migrate through cation-exchange membranes to the cathodic compartments. There, water reduction generates high-purity hydrogen (≥99.9%) and a concentrated, purified sodium hydroxide solution. The results demonstrate the ineffectiveness of conventional electrodialysis with anion-exchange membranes due to rapid membrane degradation. In contrast, the proposed bipolar membrane electrolysis achieved excellent performance: a caustic soda solution with a concentration of 2.3–2.5% was recovered with a current efficiency of 83–85%, containing only trace amounts of sulfides (0.0052%) and organic impurities (0.053%). The process completely removed the original sulfide alkalinity. The study confirms the chemical and mechanical stability of the cation-exchange membranes under harsh SAW conditions. The proposed technology offers a path towards a closed-loop system in refineries by enabling the reuse of recovered caustic, utilization of hydrogen, and potential recovery of sulfur, aligning with the principles of green chemistry and circular economy.

Sulfide-alkaline wastewater (SAW) from petrochemical plants, particularly from pyrolysis and hydrotreating units, presents a significant environmental challenge due to its high toxicity, extreme alkalinity (pH > 12), and high concentrations of sulfides and organic pollutants. Traditional treatment methods like acid neutralization or air oxidation are often inefficient, generate secondary waste, or fail to recover valuable components. This study investigates the effectiveness of a novel electrochemical system for the simultaneous treatment of SAW and recovery of valuable products. A lab-scale four-chamber electrodialyzer, equipped with cation-exchange membranes and nickel bipolar electrodes, was designed and tested using real industrial wastewater. The wastewater was characterized by a pH of 13.06, chemical oxygen demand of 12,600 mg/L, and a sulfide content of approximately 5000 mg/L. The process leverages anodic oxidation to convert sulfide ions into elemental sulfur, while sodium cations migrate through cation-exchange membranes to the cathodic compartments. There, water reduction generates high-purity hydrogen (≥99.9%) and a concentrated, purified sodium hydroxide solution. The results demonstrate the ineffectiveness of electrodialysis with anion-exchange membranes due to rapid membrane degradation. In contrast, the proposed electrodialyzer with bipolar electrodes achieved excellent performance: a caustic soda solution with a concentration of 2.3–2.5% was recovered with a current efficiency of 83–85%, containing only trace amounts of sulfides (0.0052%) and organic impurities (0.053%). The process completely removed the original sulfide alkalinity. The study confirms the chemical and mechanical stability of the cation-exchange membranes under harsh SAW conditions. The proposed technology offers a path towards a closed-loop system in refineries by enabling the reuse of recovered caustic, utilization of hydrogen, and potential recovery of sulfur, aligning with the principles of green chemistry and circular economy.