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.

THE PURPOSE. Determination of effective methods of carbon dioxide capture and utilization, search for promising solutions and testing of carbon dioxide capture methods at a laboratory facility. The most popular absorption methods of CO₂ capture, in which the gas reacts with a liquid absorbent.METHODS. The laboratory setup includes the CO₂ source itself (gas cylinder), an absorber, and a flask with sodium hydroxide solution to analyze absorption efficiency. Efficiency is evaluated by the titrimetric method, where a solution of hydrochloric acid is used as a titrant, phenolphthalein and methyl orange act as indicators.RESULTS. For the analysis, available absorbents were selected, which are available at most thermal power plants. As a result of a laboratory experiment, it was found that a quicklime suspension of 6% has the highest sorption capacity.CONCLUSION. The decarbonization of the industrial energy sector is a complex process that requires global changes in fuel policy, namely the transition to carbon-free energy resources. An alternative energy resource is hydrogen energy, but even here carbon dioxide emissions are present. Capture and disposal will help decarbonize the main sources of pollution. Industrial carbon dioxide capture has great potential, which lies in the variety of uses of sorption materials.

Development of sorbent compositions from industrial waste is a promising and economically feasible method for solving environmental problems. Power industry enterprises experience an acute need for the development of new environmentally friendly and cheap sorbents for gaseous fuel desulfurization purposes. Owing to removal of sulfur compounds from the fuel, the latter becomes less corrosive in nature, due to which it becomes possible to increase the equipment’s service life and also to decrease the deposits of sulfides on the surfaces of power installations. Based on a review of literature sources, the most important developments for sorbents consisting of industrial waste were determined. The waste of a thermal power plant (TPP) water-treatment facility (WTF) in the form of sludge water is of the greatest interest for removing sulfur compounds from fuel. Sludge water has a complex composition, which depends directly on the source water quality and water-treatment technology. Sludge water is produced at the natural water pretreatment stage, during which suspended matter is removed from source water by adding coagulants, flocculants, and other chemical agents that are specified by the process regulation. The article presents the composition of a sorbent produced from the WTF sludge at one of the Kazan combined heat and power plants (CHPP) for gaseous fuel desulfurization. Laboratory experiments were carried out with this sorbent, as a result of which the sulfur compound absorption efficiency and the strength characteristics of the prepared and formed sorbent were determined. A new method for indicating the extent to which the adsorbent absorption efficiency is decreased by using an indicating sorbent is also proposed. It is very difficult to monitor the level of sulfur compounds in purified gas by means of automatic sensors in view of a high measurement error, due to which an inaccurate result is obtained. An indicating sorbent composition that makes it possible to detect nonadsorbed sulfuric compositions by showing a color change from light to deep yellow is proposed. A method for using this indicating sorbent is described, and experimental data on its ability to absorb sulfur compounds are given.

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.

It is possible at present to reduce the emission of harmful substances into the environment during the operation of industrial enterprises by cleaning emissions and modernizing existing technological equipment. A survey of purification plants showed that sorption technologies are more accessible and simpler. Adsorption is an effective physical and chemical process for capturing carbon dioxide. The modern market offers a wide range of adsorbents that can be used to capture harmful substances, but, as a rule, for reasons of economic efficiency, it is more profitable to use secondary resources: production waste. At energy sector enterprises, various wastes are generated during the generation of thermal and electrical energy. Thus, when preparing a heat carrier at water-treatment plants, wastewater after clarifiers and ion exchange filters can be utilized to create a sorption material capable of capturing carbon dioxide, one of the main greenhouse gases. Obtaining adsorbents from waste from water-treatment plants will reduce the volume of sludge-storage facilities or eliminate their use altogether. Industrial waste is a secondary raw material and, as a rule, is inferior in its original form to traditional industrial adsorbents in terms of the activity indicator, which characterizes the ability to capture carbon dioxide. Therefore, to obtain high absorption capacity, waste is combined and activated. An adsorbent obtained from waste from water-treatment plants of thermal power plants is presented. The waste used was sludge water discharges and spent regeneration solutions after the softening filter. The component composition of the adsorbent and the method of its preparation by activation and preparation of waste are described. The efficiency of the developed adsorbent was tested on a laboratory setup. Comparative results of laboratory studies with the most frequently used adsorbents are presented. The results of determining the strength, porosity, permeability coefficient, and specific surface area of the studied adsorbents are presented.

Adsorption materials based on natural minerals are considered in the world literature as inexpensive hydrogen sulfide adsorbents capable of completely replacing commercial products such as synthetic zeolites. The global demand for inexpensive, accessible, safe materials is growing, including in the field of cleaning industrial and agricultural gas emissions from hydrogen sulfide. The article presents an analysis of literary data on natural clays, activated sludge and other materials and methods of their use for hydrogen sulfide adsorption. Data on the composition of activated sludge, clays and limestone rocks are provided. The composition studies were carried out on an infrared spectrophotometer. The inorganic component of activated sludge includes iron oxide, aluminum, calcium, magnesium compounds, and silicates. Limestone consists of carbonates, iron oxide, silicates, and when calcined at high temperatures, it mainly forms calcium oxide. Various clays contain aluminosilicates, iron oxides, copper, cobalt, and manganese. Due to the content of metal oxides, natural materials have a chemisorption mechanism, and due to the content of aluminum and silicon compounds, they have a physical sorption mechanism. 17 compositions of composite materials from natural minerals were developed and their sulfur content was studied. A study was also conducted on the absorption capacity of activated sludge in a liquid state. It was shown that all natural materials have a high potential for use as adsorbents with minimal preparation (dehydration, calcination). Compositions that do not contain expensive additives, consisting mainly of сalcined limestone rock and clays, showed sulfur capacity from 10 to 40 %.