Fossil Raw Materials Research Articles

A life cycle assessment of CCU process to produce a nanocomposite from ethanol plant CO2 emission

The use of rubber septa for controlled release of semiochemicals has raised important discussions about their efficiency and environmental impact since they are composed of fossil raw material. The life cycle assessment (LCA) of the synthesis of a nanocomposite type calcium nanocarbonate/Kraft lignin (NC-CN-KL) obtained from CO2 capture aimed to quantify the environmental loads involved in the production process. The synthesis evaluated by the LCA was performed on a laboratory scale, since it is a synthetic route classified as technological readiness level 4 (TRL-4) and is in the study and development stage. The LCA was performed according to the principles of the ISO 14044/2006 series of standards, from 101.854 g of nanocomposite as a functional unit. The limitations of the study arose from its synthesis scale, absence of LCA data on the rubber septa and other nanocomposites. The results obtained in the LCA identified electricity and other energy generation processes as the largest contributors to environmental loads for all environmental impact categories studied and suggest that research should focus on these inputs when choosing the sources used in energy nanocomposite formulation processes. LCAs for this synthesis to obtain NC-CN-KL should be carried out on a pilot scale, and it is expected that this work will contribute to the formulation of the material and decision-making, especially regarding the choice of the energy matrix.

История забытой экспедиции

This article delves into a little-studied aspect of the history of the Russian exploration of the North – one of the first Arctic expeditions of the Russians in the early XIX century. The appeal to the historical experience of the discovery and study of the New Siberian Islands archipelago is determined by the growing interest in it on the part of world powers in connection with the development of coastal shelf resources and the resumption of the Northern Sea Route. In the Russian historiography the name of M.M. Gedenstrom remained a figure of silence for a long time in comparison with such explorers as F.P. Wrangel, P.F. Anju, G.A. Sarychev, E.V. Toll, who were engaged in the study of this region of the Arctic. However, the expedition of M.M. Gedenstrom is marked not only by the connection with specific tasks of Russian foreign policy and attempts to solve scientific problems relevant for that time, but also with the interests of business development on the islands, the subsoil of which is still rich in valuable fossil raw materials. M.M. Gedenstrom was the first to create a general map of the Novosi-birsk Islands, described them and the coast between the mouths of the Yana and Kolyma rivers, and corrected inaccuracies on previously compiled maps.

Characteristics of granulated activated carbon from a mixture of plant raw material waste

Relevance. The need to increase the use of renewable energy sources in the economy to reduce the harmful effects on the environment. Aim. To assess the possibility of obtaining by the thermochemical method high-quality carbon adsorbents from a granular mixture of various wastes of plant origin. Objects. Samples of illiquid lumpy birch wood, walnut shells, sunflower seed husks, flax fires, anthracite coal. Methods. Physical experiments: conductive pyrolysis, water-steam activation and differential thermal analysis. The ash content and moisture content of the samples were determined according to SS R 56881-2016 and SS 33503-2015. Nitrogen adsorption isotherms were measured using a NOVA-1200e analyzer. The equilibrium activity for toluene was determined according to SS 8703-74, the adsorption activity for iodine was determined according to SS 6217-74. The determination of the density of the granules was carried out according to SS 15139-69. Results. The authors have established rational parameters for obtaining carbon adsorbents from granules of vegetable raw materials. The specific yield of pyrolysis products of a mixture of vegetable raw materials with pyrolysis resin was determined. The specific yield of carbonization products of the granular compacted mass showed an increase of 25% in comparison with the non-compacted mixture of vegetable raw materials. Rational parameters for obtaining activated carbon with the highest adsorption capacity are granules with a density of 1200 kg/m3 with a degree of burnout of the carbonization product of 70%. It was established that the obtained samples of adsorbents from granules of plant raw materials have high adsorption characteristics comparable to activated carbons obtained from fossil raw materials.

Determining the Reactivity of Selected Biomass Types Considering Their Application in Pyrometallurgical Processes of Metal Production.

In this paper, results of research on the reactivities of selected biomass types considering their application in pyrometallurgical processes of metal production are presented. Walnut shells, sunflower husk pellets and spent coffee grounds were selected as biomass materials. Their use as potential reducers in the process of metallurgical slag decopperisation is an innovative approach to this subject. The thermogravimetric findings show that all three tested biomass types are classified as highly reactive. The time to reach maximum reactivity ranges from 1.5 to 3 min and, the lowest value is recorded for the sample of spent coffee grounds. The sample hold time of two hours enables copper content reduction to approx. 1 wt% for practically all the reducers tested. A longer duration of liquid slag contact with the reducer results in a decreased copper content in the slag to a value below 1 wt%. Copper concentrations of 0.5 wt% and lower are observed with a hold time of 4 h. The preliminary results indicate that there is great potential for the use of this type of material in non-ferrous metallurgy, which may translate into replacing fossil raw materials and thus introducing the principles of a sustainable process in this case of metal production.

A Study of the Influence of Cement Addition and Humidity on the Mechanical Strength and Microstructure of Flue Gas Desulfurization Gypsum-Cement Plasters.

Over the last 20 years, flue gas desulfurization gypsum (FGD gypsum) has become a valuable and widely used substitute for a natural raw material to produce plasters, mortars, and many other construction products. The essential advantages of FGD gypsum include its high purity and stability, which allow for better technical parameters compared to natural gypsum, and, until recently, its low price and easy availability. This FGD gypsum is obtained in the process of desulfurization of flue gases and waste gases in power plants, thermal power plants, refineries, etc., using fossil fuels such as coal or oil. The gradual reduction in energy production from fossil raw materials implemented by European Union countries until its complete cessation in 2049 in favor of renewable energy sources significantly affects the availability of synthetic gypsum, and forces producers of mortars and other construction products to look for new solutions. The gypsum content in commonly used light plaster mortars is usually from 50 to 60% by mass. This work presents the results of tests on mortars wherein the authors reduced the amount of gypsum to 30%, and, to meet the strength requirements specified in the EN 13279-1:2008 standard, added Portland cement in the amount of 6-12% by mass. Such a significant reduction in the content of synthetic gypsum will reduce this raw material's consumption, thus extending its availability and developing other solutions. The study presented the test results on strength, density, porosity, pore size distribution, and changes in the microstructure of mortars during up to 180 days of maturation in conditions of increased relative humidity. The results show that decreased porosity and increased mechanical strength occur due to the densification of the microstructure caused by the formation of hydration products, such as C-S-H, ettringite, and thaumasite.

Chitosan-derived large surface area porous carbon via microphase separation engineering of pore-regulation and nitrogen-doping coupling for high-performance supercapacitors

In the face of the contradiction between the shortage of fossil raw materials, global warming and growing energy demand, it is of great practical significance to apply biomass, which is widely available in nature, environmentally friendly and renewable, to energy storage. Based on the coupling mechanism of pore-regulation and N-doping, this study implements pre-carbonization through microphase separation engineering in the chitosan (CS) and aniline (AN) co-hydrothermal. Using hydrochar as the precursor, porous carbon with good electrochemical properties has been prepared by a multi-step process consisting of KOH activation, pyrolysis, pickling and water washing. The CS/AN co-doped porous carbons (1830.08–2576.53 m2/g) show an enhancement of 8.48%–52.73 % in specific surface area compared to the CS porous carbon (1687.02 m2/g). The hierarchical network structure of the micro-mesoporous interconnects enables fast ion transport and the ultra-micropores further increase the specific capacitance of the electrodes. Theoretical calculation shows that N doping can effectively activate the chemically inert carbon structure and enhance the adsorption capacity of electrolyte ions, thus increasing the specific capacitance. Using 6 M KOH as the electrolyte, CS-AN60-220-800 exhibits a specific capacitance of 368.6 F/g (1.0 A/g) in the three-electrode system. In the two-electrode system, the supercapacitor device constructed with CS-AN60-220-800 demonstrates a capacitance retention of 95.32 % (after 10,000 cycles) along with an energy density of 14.16 Wh/kg (with a power density of 125 W/kg), which is at a high level among similar biomass symmetric supercapacitors. The preparation strategy provides a valuable reference for the preparation of other biomass-based porous carbon, as well as for applications in energy storage.

Phenol and formaldehyde alternatives for novel synthetic phenolic resins: state of the art

Since their appearance and commercialization, phenolic resins have been widely used and adopted in many sectors of activity. Produced from phenol and formaldehyde, these thermosetting materials are now being singled out because of the dangerousness of their precursors as well as the fossil raw material from which they are produced. To address and deal with the current general issue on the reduction of the impact of human activity on the environment, this review details and evaluates current studies on alternative molecules that can be used instead of phenol and formaldehyde in the synthesis of phenolic resins. After a contextualizing introduction and a quick review of what phenolic resins are and how these materials are obtained, two main parts are devoted to the platform molecules likely to replace phenol, first, and formaldehyde, second. Finally, the author gives his opinion on the future potential of research concerning the substitution of these molecules and the future of phenolic resins.

A Study on the Pyrolysis Behavior and Product Evolution of Typical Wood Biomass to Hydrogen-Rich Gas Catalyzed by the Ni-Fe/HZSM-5 Catalyst

The thermo-chemical conversion of biomass wastes is a practical approach for the value-added reclamation of bioenergy in large quantities, and pyrolysis plays a core role in this process. In this work, poplar (PR) and cedar (CR) were used as staple wood biomasses to investigate the apparent kinetics of TG/DTG at different heating rates. Secondly, miscellaneous wood chips (MWC), in which PR and CR were mixed in equal proportion, were subjected to comprehensive investigations on their pyrolysis behavior and product evolution in a fixed bed reactor with pyrolysis temperature, catalyst, and the flow rate H2O steam as influencing factors. The results demonstrated that both PR and CR underwent three consecutive pyrolysis stages, the TG/DTG curves shifted to higher temperatures, and the peak temperature intervals also enhanced as the heating rate increased. The kinetic compensation effect expression and apparent reaction kinetic model of CR and PR pyrolysis were obtained based on the law of mass action and the Arrhenius equation; the reaction kinetic parameter averages of Ea and A of its were almost the same, which were about 72.38 kJ/mol and 72.36 kJ/mol and 1147.11 min−1 and 1144.39 min−1, respectively. The high temperature was beneficial for the promotion of the pyrolysis of biomass, increased pyrolysis gas yield, and reduced tar yield. This process was strengthened in the presence of the catalyst, thus significantly increasing the yield of hydrogen-rich gas to 117.9 mL/g-biomass. It was observed that H2O steam was the most effective activator for providing a hydrogen source for the whole reaction process, promoted the reaction to proceed in the opposite direction of H2O steam participation, and was beneficial to the production of H2 and other hydrocarbons. In particular, when the flow rate of H2O steam was 1 mL/min, the gas yield and hydrogen conversion were 76.94% and 15.90%, and the H2/CO was 2.07. The yields of H2, CO, and CO2 in the gas formation were significantly increased to 107.35 mL/g-biomass, 53.70 mL/g-biomass, and 99.31 mL/g-biomass, respectively. Therefore, H2 was the most dominant species among gas products, followed by C-O bond-containing species, which provides a method for the production of hydrogen-rich gas and also provides ideas for compensating or partially replacing the fossil raw material for hydrogen production.

Multiple approaches to exploit ferulic acid bio-based epoxy monomer for green thermoset

Bio-based monomers are under investigation to replace fossil-based materials due to the concerns regarding climate change and depletion of fossil raw materials. Lignin, cellulose and hemicellulose represent the main interesting platform to use for developing new monomers due to their significant abundance. Ferulic acid is one of the moieties derived from lignin which can be suitable for many applications. In this study, the ferulic acid was epoxidated and it was investigated in cationic UV-curing. Due to the limited performance obtained during UV-curing, two alternative strategies were developed to overcome the initial problem of poor material properties. A thiol-ene epoxy system based on the ferulic epoxy derivative and a commercially available thiol as well as a thermally cured system based on pure cationic curing of ferulic acid diepoxy were chosen as alternative methods. The different curing processes were thoroughly investigated by means of FTIR (Fourier transform infrared spectroscopy) and photo-DSC (differential scanning calorimetry). The thermo-mechanical properties of the thermosets employing DMA- (dynamic mechanical analysis) and tensile analysis were deeply evaluated. Finally, the possibility to use the best cured system as an adhesive was raised investigating the shear strength of metallic and composite joined samples using the single lap offset (SLO) test under compression.

On Search for Unconventional Energy Sources for Harvesting

Energy transformation requires replacing power plants based on fossil raw materials with renewable energy. Energy harvesting plays an important, although not fully appreciated, role here. Distributed, local power supply systems for small receivers, based on various sources which previously dissipated energy, may contribute to changing the current energy paradigm. This article presents an overview of energy harvesting technologies and various energy sources used in this process. Particular attention was paid to sources of a less conventional nature. The aim of this article is to encourage and direct scientists with the potential to explore this topic to look for new, previously unexploited energy sources and innovative and effective methods of obtaining useful energy in the harvesting process.

Production of Chestnut Coppice Biomass in a Framework of Low Mechanization and High Expectations to Combat Climate Change and Other Social Expectations

Climate change has become one of the most critical problems facing modern society. Sustainable forest management can be an important solution to counter the increasing concentration of carbon dioxide in the atmosphere. In particular, management of the chestnut forest could prove to be an effective strategy to absorb carbon dioxide as this species is characterized by sustained growth, so it has a high capacity to store carbon, and through the use of wood products, it is possible to sequester it for a considerable period. Chestnut (Castanea sativa Mill.) forests cover an area of about 800,000 ha in Italy, most of which is managed as coppice. It plays a central role in the Latium Region where its productive function is very important, as it provides timber of excellent quality. The purpose of this paper is to verify whether the current management of chestnut is efficient, as well as whether retractable wood products can contribute to the fight against climate change. The chestnut coppice located in the municipality of Tolfa (Lazio region, Italy) produces timber for 352 m3/ha and stores about 390,000 kg of CO2. Wood residues and losses during woodworking, together with emissions for the use of machineries, generate emissions of 368,000 kg of CO2. The chestnut semi-finished products, with long-term use prospects, retain a net volume of 22,000 kg of CO2. Although this is good for combating climate change, the amount of CO2 stored is very low, less than 6% of the CO2 stored by functional unit. Chestnut wood has a high versatility of use, so it could replace several products generated by fossil raw materials. Moreover, the implementation of precision forestry, the adoption of forest management more oriented to favor larger plants, the development of local economies and the reduction in the carbon footprint of the wood supply chain through the use of sustainable technologies would increase the capacity for climate change mitigation and increase the added value of its products.

Investigations on Ways to Improve the Scuffing and Wear Behavior of Oil-Free Water-Based Lubricants for Gear Applications

Abstract Today, mineral or synthetic oils that are made out of fossil raw materials are the most common lubricants in gear drive applications. Most of them are nonbiodegradable and may pose a risk to the environment. An important step to minimize the risk and the ecological footprint is the use of biodegradable and eco-friendly lubricants. Former research shows the potential of water-based lubricants in gear applications. Therefore, an oil-free, water-based lubricant was developed for this study. The base lubricant contains plant-based thickeners to generate an appropriate viscosity for a sufficient lubricant film thickness in the tooth contact. In experimental investigations, the sliding wear and scuffing performance has been examined under variation of the added polymers and additives. The scuffing tests A/8.3/RT are performed according to DIN ISO 14635-1. The wear test procedure is based on DGMK 377-01. In both scuffing tests with the sample, the failure load stage = 8 was achieved. For case-carburized gears, a “medium” to “high” amount of wear can be detected. Additional tests with nitrided gears show a “low” amount of wear. This article aims to show the great potential of water-based oils for gear lubrication and suggests operating conditions for maximum wear and scuffing carrying capacity.

New gentle extraction method of hemp bast strips for use as bio-based reinforcing fibers in highly loaded fiber composites

Nowadays, fiber composites are among the most important construction materials in lightweight design. Increasingly, attempts are being made to replace fossil raw materials with bio-based materials in order to improve their recyclability and reduce greenhouse gas emissions. While processes suitable for industrial use already exist for the production of biopolymers as matrix materials, there is still a considerable need for research in the production of bio-based reinforcing fibers. For hemp bast strips (HBS), promising utilization options arise due to very good mechanical properties. However, current processes for extracting such raw materials from bast fiber plants result in damage to the fiber structure because they use biochemical decomposition processes and/or squeeze and crush large disordered amounts of stalk along their entire length. This strongly reduces the application potential of the raw materials. A newly developed principle extracts the HBS with minimal impact by dividing single hemp stalks only at one end and then isolating them from the wood core by pulling on the resulting wood fragments. In this manner, the fiber structure and the good mechanical properties are largely retained and the HBS obtained can be stored in parallel alignment for further processing with little effort.

Energy aspects of automobile transport development

Problem. Improving automobile transport means increasing fuel economy and environmental indicators. Fuel, in a broad sense, means energy used to activate the car's power plant. Potential energy is dispersed in the earth’s interior, on its surface, in the atmospheric air, and even in space. Moreover, some of them exist in different substances. On the one hand, the efficiency of an energy product use is assessed by its energy intensity; on the other hand, it is evaluated by the costs of its production (transportation) and the quality of its transformation into a consumer type of energy. Special attention is paid to renewable and unlimited kinds of energy sources. Goal. The purpose of the study is a qualitative analysis of the road transport development direction from the standpoint of the alternative energy sources use, taking into account the factors that comprehensively determine the economic and environmental indicators at the stages of production and processing of fossil raw materials, production of power plants and conversion, transformation, and transportation of energy in the field of transport technologies. Methodology. The first direction consists of the adaptation (conversion) of the design of thermal internal combustion engines for alternative liquid or gaseous fuel types. The advantage of this approach is minimal costs for engine conversion and fuel production. The second approach involves using hybrid power plants, consisting of a main and auxiliary engine, an energy source or accumulator, an energy converter, and a braking recuperation system. The third direction is the use of non-traditional energy sources. Results. The directions of the development of power plants for motor vehicles related to the increase in the energy density of hydrocarbon fuels, the use of hybrid power plants, and the use of alternative energy sources have been determined. A qualitative assessment of the considered approaches is given. Originality. A comprehensive approach to evaluating the effectiveness of using alternative types of energy in road transport is considered in terms of energy, economic, and environmental indicators. Practical value. The obtained results can be regarded as recommendations when drawing up plans for the evolution of industries of fossil extraction and transformation of other energy resources, the development of motor vehicles, and transport infrastructure technologies, taking into account the natural and industrial potential of the country

SIMPLIFIED HYDRAULIC CALCULATION OF THE CRYOGENIC PIPELINE OF EXTERNAL FACILITIES FOR FILLING LIQUEFIED NATURAL GAS

Natural gas is a mineral that is the most environmentally friendly energy fossil raw material. In recent decades, proven natural gas reserves have equaled oil reserves in terms of their indicators and, moreover, continue to grow actively. In this regard, the issue of transportation and storage of natural gas becomes relevant. One actively developing area has become the industry of natural gas liquefaction, transportation and distribution.The paper discusses the issues of shipment of liquefied natural gas (LNG) to gas tankers during its large-tonnage production. The authors propose the use of remote filling systems (VSN) for LNG in a similar way to similar devices for filling oil into tankers. However, the main feature of the VSN LNG is the cryogenic pipeline from the onshore facilities to the VSN. In this regard, it is necessary to make a simplified mathematical model of a cryogenic pipeline taking into account heat exchange with the environment and heat release during energy dissipation due to viscous friction forces.In the course of numerical simulation, the dependence of the maximum pumping distance was obtained for a given difference between the temperature of LNG on shore facilities and the maximum required temperature of LNG loading into a gas carrier. The influence of each component of the heat flow equation — heat exchange with the environment and LNG heating due to viscous friction forces was also evaluated.As an example, a section with a length of 10 km was selected and a simulation of the temperature distribution, as well as the required pressure on shore structures necessary to ensure a given loading speed of the gas carrier and the temperature of the supplied LNG was carried out.

Green Solvent-Based Antifouling Polymer Brushes Demonstrate Excellent Hemocompatibility.

Medical devices are crucial for patient care, yet even the best biomaterials lead to infections and unwanted activation of blood coagulation, potentially being life-threatening. While hydrophilic polymer brushes are the best coatings to mitigate these issues, their reliance on fossil raw materials underscores the urgency of bio-based alternatives. In this work, we introduce polymer brushes of a green solvent-based monomer, prohibiting protein adsorption, bacterial colonization, and blood clot formation at the same level as fossil-based polymer brushes. The polymer brushes are composed of N,N-dimethyl lactamide acrylate (DMLA), can be polymerized in a controlled manner, and show strong hydrophilicity as determined by thermodynamic analysis of the surface tension components. The contact of various challenging protein solutions results in repellency on the poly(DMLA) brushes. Furthermore, the poly(DMLA) brushes completely prevent the adhesion and colonization of Escherichia coli. Remarkably, upon blood contact, the poly(DMLA) brushes successfully prevent the formation of a fibrin network and leukocyte adhesion on the surface. While showcasing excellent antifouling properties similar to those of N-hydroxypropyl methacrylamide (HPMA) polymer brushes as one of the best antifouling coatings, the absence of hydroxyl groups prevents activation of the complement system in blood. We envision the polymer brushes to contribute to the future of hemocompatible coatings.

The oxygen-tolerant reductive glycine pathway assimilates methanol, formate and CO2 in the yeast Komagataella phaffii

The current climatic change is predominantly driven by excessive anthropogenic CO2 emissions. As industrial bioprocesses primarily depend on food-competing organic feedstocks or fossil raw materials, CO2 co-assimilation or the use of CO2-derived methanol or formate as carbon sources are considered pathbreaking contributions to solving this global problem. The number of industrially-relevant microorganisms that can use these two carbon sources is limited, and even fewer can concurrently co-assimilate CO2. Here, we search for alternative native methanol and formate assimilation pathways that co-assimilate CO2 in the industrially-relevant methylotrophic yeast Komagataella phaffii (Pichia pastoris). Using 13C-tracer-based metabolomic techniques and metabolic engineering approaches, we discover and confirm a growth supporting pathway based on native enzymes that can perform all three assimilations: namely, the oxygen-tolerant reductive glycine pathway. This finding paves the way towards metabolic engineering of formate and CO2 utilisation to produce proteins, biomass, or chemicals in yeast.

Prediction of the Growth of Renewable Energies in the European Union using Time Series Analysis

The whole world is affected by climate change and renewable energy plays an important role in combating climate change. To add to the existing precarious situation, the current political events such as the war in Ukraine mean that fossil raw materials such as oil and gas are becoming more and more expensive in the raw material markets. This paper presents the current state of renewable energies in Germany and Europe. Using data from the past 56 years, the predictive models ARIMA and Prophet are used to find out if the conversion to renewable energies and the elimination of fossil raw materials in the energy sector can be achieved in the EU. The results are compared with the target of the EU in 2030 and a long-term outlook until 2050 will be provided.

Solar Corn Sheller Machine Design Based on Ergonomics Principles

The existing sheller machine on the market still uses diesel fuel and electricity, even though diesel fuel has increased. Solar is a non-renewable energy. In addition, there is a new modification of the corn sheller machine with solar power to replace diesel fuel. The fuel replacement is focused on the utilization of sunlight. This corn sheller machine can replace the use of fossil raw materials and electricity with solar power and obtain faster, more ergonomic product results. The data required in this study are body dimension data or shoulder height anthropometry in an upright standing position to determine the height of the corn sheller that will be done standing when the farmer does the corn shelling process. With the existence of a solar-powered corn sheller machine, it is expected to be more productive than before. The transition to the use of environmentally friendly (pollution-free) corn sheller machines so as to reduce air pollution that previously used motor engines with fossil fuels, namely diesel, corn farmers can understand about work comfort, are able to operate environmentally friendly corn sheller machines and can carry out maintenance procedures for solar corn sheller machines.

Ligninsulfonate-based hydrogel films for ion sensing

The manufacturing of sensors based on sustainable and renewable materials is becoming increasingly important to achieve independence from fossil raw materials. It is known that hydrogels based on lignin, the polyphenolic biopolymer in lignocellulosic biomass, are able to react to environmental influences such as pH value, temperature or ion concentration. This effect can be used for sensor applications. For this purpose, ligninsulfonate hydrogel was simultaneously generated and bound to glass surfaces via a two-step synthesis. First, the etched oxide substrates were silanized using (3-acryloxypropyl)methyldimethoxysilane (APMDMS). Thereafter, the hydrogel was bound to the surface via a radical polymerization process. Here, the lignosulfonate solution, which included the crosslinker polyethyleneglycoldiacrylate (PEGDA) and ascorbic acid, was applied directly to the functionalized surface.The functionalized surface was analyzed using XPS, AFM, SEM, ATR-IR, profilometer, contact angle, and QCM. The layer thickness was found to vary between 1.8–8.6 µm as a function of the amount of precursor lignin solution applied. The porous structure exhibited pore sizes of 4–6 µm.For the sensor tests, solutions of sodium(I) and magnesium(II) salts at different concentrations were used. The hydrogels reacted with shrinking and swelling processes, depending on the selected cation and its concentration. This effect was reproducible over several cycles and the initial state could be reestablished at the end of the tests.