English English

Keywords: adsorption

Adsorption of methylene blue by activated pyrolysis products of sunflower seed husks

https://doi.org/10.58224/2619-0575-2025-8-3-1
, ,
Abstract
In the context of the global environmental crisis caused by the rapid growth of industrial and household waste, the search for effective methods of their recycling is becoming a key task of sustainable development. Traditional disposal methods, such as burial or incineration, not only require significant resources, but also lead to atmospheric pollution with negatively biologically active gases. In this context, pyrolysis of carbon-containing waste represents a promising alternative combining environmental safety and economic feasibility. Unlike combustion, pyrolysis takes place in an environment with a limited oxygen content, which minimizes CO and CO2 emissions, and also allows for the production of valuable secondary products — pyrolysis gases, liquid and solid carbon materials. The latter are suitable for use as adsorbents. Activation of pyrolysis products by chemical reagents (alkalis, acids, or steam) is used to increase the adsorption capacity, which significantly increases their porosity and adsorption capacity. In this work, the adsorption properties of sunflower husk pyrolysis products activated with an aqueous 2 M solution of potassium hydroxide (KL-21(A)), sunflower husk pyrolysis products combined with bentonite clay (KL-21(A)) and pyrolysis products of crushed worn car tires (KR-21(A)) were determined. Their effectiveness in terms of adsorption of methylene blue (MG), a model cationic dye widely used in assessing the absorption capacity of adsorbents, has been studied by spectrophotometric method. Kinetic dependences of adsorption have been established, and the maximum adsorption capacities of experimental materials have been determined depending on MG concentration. The results of experimental studies allow us to conclude that the activation of pyrolysis products of crop and communal waste with potassium hydroxide improves the adsorption characteristics of the developed material.
Objectives: to identify the adsorption properties of pyrolysis products of sunflower seed husk KL-21(A) activated with an aqueous 2 M solution of potassium hydroxide, pyrolysis products of sunflower seed husk combined with bentonite clay KL-21(A) and pyrolysis products of worn-out automobile tires KR-21(A).
Methods. A Nabi MicroDigital spectrophotometer (South Korea), laboratory instruments and reagents were used to study the adsorption properties by the spectrophotometric method.
Results. Graphical dependences of the absorption capacity on the duration and rate of adsorption are revealed, and adsorption isotherms are constructed and analyzed.
Conclusions. An adsorption-active material based on pyrolysis products of sunflower seed husks and pyrolysis products of worn-out automobile tires was obtained. The adsorption capacity of CL-21(A) samples was 474 mg/g, CLG-21(A) – 131 mg/g, and KR-21(A) – 351 mg/g. The obtained isotherms are determined by the Langmuir model.
It was found that the adsorption equilibrium occurs after 6 hours in KL-21(A) and a day later in KL-21(A) and KR-21(A).
It was found that the highest rate of adsorption is characteristic of the KL-21(A) sample and amounted to 0.00094 mmol/min or 0.300 mg/min in the first 15 minutes of exposure.
PDF

Bentonite from the Nalchik deposit and the possibilities of its use as a cationic adsorbent

https://doi.org/10.58224/2619-0575-2025-8-2-2
, , , ,
Abstract
Chemical, mineralogical, granulometric and structural-morphological characteristics of bentonite clays of the Nalchik deposit have been established. The elemental composition contains B (trace amounts), Al, Si, K, Ca, Ti, Fe. It has been revealed that the mineralogical composition of the studied clay is complex of montmorillonite, clinoptilolite and low-temperature trigonal quartz. The montmorillonite content is 53.0 ± 1.1 wt.%. The maximum particle size is 198.7-210.1 μm, the proportion of such particles is 0.69 wt.%. The minimum particle size is 0.6-0.9 μm, the proportion of such particles is 1.22 wt.%. According to the results of differential thermal analysis, 4 endoeffects were recorded, the total mass loss on sample calcination was 16.5%, taking into account the loss of free water - 9.5 wt.%. The adsorption characteristics of the analyzed bentonite were studied using “model” pollutants – nickel (II) cations and methylene blue dye. It was found that the adsorption isotherm of nickel (II) ions belongs to class L type 3, and the adsorption isotherm of methylene blue belongs to class L type 2 according to the Gils classification. The results of the study showed that bentonite clay from the Nalchik deposit is capable of purifying wastewater to the maximum permissible concentration of cationic pollutants.
Objectives: to investigate the material composition and adsorption properties of bentonite clay from the Nalchik deposit.
Methods. To determine the elemental, phase and granulometric composition, the following equipment was used: transmission electron microscope JEM-2100 (Jeol, Japan), diffractometer Ultima IV (Rigaku, Japan), combined analyzer TG/DTG/DTA SDT Q600 (TA Instruments, Inc., USA), particle size analyzer Microtrac S3500 (USA), as well as laboratory instruments and reagents.
Results. The mineralogical composition of the clay sample from the Nalchik deposit was established; the mass content of montmorillonite was determined. The granulometric composition was studied. The adsorption processes of the clay sample in relation to the organic dye methylene blue and nickel (II) ions were investigated.
Conclusions. The mineralogical composition of the clay sample from the Nalchik deposit was determined: montmorillonite, clinoptilolite and low-temperature trigonal quartz. The montmorillonite content is 53.0 ± 1.1 wt.%. The maximum particle size of the fraction in the studied clay sample is 198.7-210.1 μm, the proportion of such particles is 0.69 wt.%. The minimum particle size of the fraction is 0.6-0.9 μm, the proportion of particles is 1.22 wt.%. The adsorption processes of the clay sample in relation to the organic dye methylene blue and nickel (II) ions were studied. It was shown that the clay of the Nalchik deposit is capable of purifying wastewater from the specified cationic pollutants to the regulatory requirements.
PDF

Study of temperature and salinity effect on encapsulated surfactants ability to alter wettability and decrease interfacial tension

https://doi.org/10.58224/2619-0575-2024-7-4-87-103
, , , ,
 87-103 p.
Abstract
In recent decades, the task of increasing the oil recovery factor from productive formations has not lost its relevance. Today, there is a rapidly growing interest in the use of chemical methods to increase oil recovery to enhance production, in particular, using surfactants. To overcome the problem of high adsorption, which prevents the widespread introduction of surfactant flooding in carbonate formations, it is proposed to use the technology of encapsulating surfactants in a solid shell. Thus, the active substance can cover a large part of the reservoir, and therefore more oil can be extracted by injecting surfactants. In this work, the influence of typical reservoir conditions (high temperature and salinity) on the main properties of the dispersions of encapsulated surfactants, namely, a decrease in interfacial tension and a change in wettability, was studied. It is shown that the application of the encapsulation method preserves the necessary properties of surfactants, at which low interfacial tension is observed, and the surface of the carbonate rock becomes more hydrophilic.
PDF

Overview of surfactant flooding as a method of increasing oil recovery and the applicability of microcapsulation technology to improve the efficiency of surfactant flooding

, , , , , ,
 28-47 p.
Abstract
The problem of increasing the degree of oil recovery from reservoir formations has remained relevant over the past few decades.
Currently, there is a rapid increase in interest in chemical methods of increasing oil recovery to intensify oil production, in particular, flooding with surfactants (surfactants).
This article describes the factors affecting the efficiency of self-winding and the effect of adsorption on the eco-nomic component of the technology. To solve the problem of adsorption, preventing the large-scale introduction of surfactant, it is proposed to use the technology of microencapsulation of surfactants in a solid shell.
PDF

NICKEL IONS ADSORPTION BY THERMOMODIFIED FALLEN LEAVES OF CHESTNUT

, ,
 48-59 p.
Abstract
In recent years, the attention of researchers has been attracted by industrial and agricultural waste, which can be used as sorption materials. A special group is made up of lignocellulose-containing components of woody biomass (leaves, bark, needles, fruits, etc.) and wood processing products (sawdust, shavings, chips, etc.). Advantages of using the latter as reagents for wastewater treatment include simple technique, small processing, good adsorption capacity, selective adsorption of heavy metal ions, low cost, free availability and easy regeneration. Trees foliage attracts attention аmong the components of the woody biomass, it has a large specific surface area and falls annually under the conditions of the Russian Federation, which facilitates its collection and use.
Nickel ions are one of the most toxic pollutants that enter water bodies with industrial wastewater. The infor-mation on the nickel compounds toxic effect on living organisms is briefly presented. In this work, we studied the sorption properties of chestnut fallen leaves (CFL) in relation to nickel ions. The sorption capacity maximum value of the thermally modified CFL at a temperature of 250° C (CFL250) is 1.3 mmol / g for nickel ions. By processing the obtained isotherm within the framework of the Langmuir, Freundlich, BET, Dubinin-Radushkevich sorption models, it was found that the adsorption process is most accurately described by the Langmuir model (R2 = 0.9912). The calculated Gibbs energy is equal to -7.86 kJ / mol, it indicates the occurrence of spontaneous physical adsorption of Ni2 + ions on the CFL250 surface.
PDF

PURIFICATION OF WASTE WATER FROM THE PRODUCTION OF LIPID CONCENTRATE OF HERMETIA ILLUCENS GARVES WITH WASTE FROM PROCESSING OF BIOMASS PISUM SATIVUM

, ,
 93-104 p.
Abstract
The possibility of using the crushed biomass of the pods of the common pea (Pisum sativum) as a sorption material for purifying model waters from the production of lipid concentrate from the larvae of the fly of the species Hermetia illucens has been investigated. Information on the composition and amount of lipids and saturated and unsaturated fatty acids in insect larvae is briefly presented. The effect of the particle size of the sorption material on the efficiency of the adsorptive extraction of the lipid concentrate emulsion from the model wastewater was investigated and an increase in the degree of purification with an increase in the dispersion of the dried biomass of pea pods was revealed. The dependence of the efficiency of removal of emulsion particles on the dosage of the sorption material and the time of contact of the latter with the sorbate was also investigated. The optimal pa-rameters of adsorption purification have been determined.
PDF

ADSORPTION OF HEAVY METAL IONS BY BENTONITE MODIFIED WITH CARBON NANOTUBES AND ACTIVATED WITH ACID

, , , ,
 56-66 p.
Abstract
At present, there is no doubt about the need to search for new, more advanced methods and means of treating industrial wastewater. The adsorption method is one of the effective methods for purifying the aquatic environment. One of the sorption materials is bentonite, modified in different ways (by roasting, adding organic components, etc.). Laboratory studies were carried out on the bentonite of the Sarigyukh deposit (Republic of Armenia). The adsorption capacity of bentonite modified with carbon nanotubes with roasting at a temperature of 550°C and subjected to activation with HCl acid was investigated experimentally. It was found that acidic (HCl) activation of bentonite modified with carbon nanotubes and calcined at 550°C promotes an increase in its adsorption activity towards nickel (II) and cadmium (II) ions. The degree of adsorptive extraction of nickel (II) ions after activation of the specified adsorbent with HCl increases by 10%, and the degree of adsorptive extraction of cadmium (II) ions after a similar activation increases by 11%. The characteristics of the efficiency of adsorption of nickel (II) and cadmium (II) ions under static conditions were found with bentonite modified with carbon nanotubes and fired at 550°C, subjected to acid activation with HCl and without it. Bentonite modified with carbon nanotubes, calcined at 550°C and activated with HCl acid showed the greatest adsorption effect with respect to the ions of these metals. Its parameters: in relation to Ni 2+ ions: СОЕ = 852.0 mg-eq/g, Kd = 243.42 mg/dm3, S = 95.4%; to Cd2+ ions: COE = 950 mg-eq/g, Kd = 263.89 mg/dm3, S = 92.0%. The results of laboratory studies made it possible to recommend bentonite modified with carbon nanotubes, fired at 550° C and activated with HCl acid as a sorption material for purifying wastewater from nickel (II) and cadmium (II) ions.
PDF

STUDY OF AGGREGATIVE STABILITY OF LIPID CONCENTRATE PRODUCTION MODEL WASTE WATER AND POSSIBILITY OF ITS PURIFICATION BY SORPTION METHOD

,
 17-28 p.
Abstract
In the Belgorod region, work is underway to create the first high-tech large-scale production of lipid concentrate and animal protein from the larvae of the Black Soldier fly Hermetia illucens in Russia. The lipid concentrate emulsifies well in tap water, which indicates the presence of substances in it that do not belong to triglycerides of fatty acids. Obviously, it contains impurities of compounds present in the larval biomass - protein compounds and their decay products, phospholipids, etc., which can play the role of surfactants. This paper presents the results of studies on the possibility of fat-containing wastewater purification using a sorption material obtained by leaf litter of the horse chestnut genus (Aésculus hippocastanum L.) carbonization. It was found that the lipid concentrate is easily emulsified, both in pure form and in the presence of sodium lauryl sulfate. The resulting emulsions are highly resistant to degradation. It was found that the presence of the surfactant in an amount of 0.01 g/l improves the purification efficiency in the process of the model emulsion adsorption treatment. The addition of 0.6 g of the material allows to reach 92% purification, and with the addition of 1.5 g the efficiency is 98%. Similar amounts of sorbent in a pure emulsion make it possible to achieve values of only 35% and 88%, respectively. When finely dispersed particles of inorganic substances are added to an aqueous medium, the suspension effect is often observed, which manifests itself in the difference between the pH values of the suspension and the filtrate. The results of studies of the amount of added sorbent effect on pH changes in suspensions and filtrates showed that the complex «lipid micelle + sorbent» has a positive charge, and in the presence of the surfactant the charge retains a positive value, but is very close to neutral. An approach to the isoelectric point is observed.
PDF

ADSORPTION OF 4-NITROPHENOL AND DYES ON SILVER-DOPED TiO2, TiO2-ZrO2, ZrO2 XEROGELS UNDER UV IRRADIATION

,
 56-62 p.
Abstract
Nanoscale and composite materials containing titanium and zirconium oxides are of the greatest theoretical and practical interest. Their advantages are low cost, availability of production, the choice of source components and matrices of different nature. This work is an immersion in the subject of research at the Peoples' Friendship University of Russia. The research topic is extremely relevant, because silver appears only once in the list of previously used modifiers, and it is possible to study this issue. The production of TiO2 and ZrO2 nanopowders with dopants using gel technology is a simple and well-studied method for the synthesis of photocatalysts, but the effect of powder irradiation on adsorption has not been studied much, especially for irradiation of dry material with its subsequent introduction into an adsorption solution. It is of interest to study the effect on the adsorption of para-nitrophenol (the state of the molecule - anion or molecule), depending on the pH of the environment, on synthesized xerogels of titanium dioxide and zirconium. It is also necessary to conduct a study to understand the effect of silver on the adsorption of various types of dyes. Model dyes of the cationic type (methylene blue) and anionic type (methylorange) can be used to determine the charged surface centers of materials based on TiO2 and ZrO2 that do not contain or contain a dopant component.
PDF

SORPTION PROPERTIES OF SYCAMORE LEAF LITTER IN RELATION TO METHYLENE BLUE DYE

, , ,
 5-13 p.
Abstract
Dyes are one of the widespread and hazardous contaminants that enter water bodies with wastewater. Reagent precipitation, ion exchange, coagulation, flotation, and other methods are used to remove dyes from aqueous environment. At the same time, sorption treatment is one of the most effective. The authors proposed to use sycamore leaves biomass for the dye "Methylene blue" extraction from aqueous environment. To investigate the process of adsorption of methylene blue by the leaves biomass, the sorption capacity of the material has been es-tablished; it is shown that the adsorption process is best described by the Freundlich model with a correlation co-efficient R2 = 0.9537.
PDF