An important goal in environmental research for industrial activity and sites is the investigation and development of effective adsorbents for chemical pollutants that are widespread, inexpensive, unharmful to the environment, and have the required adsorption selectivity. Organoclays are adsorption materials that can be obtained by modifying clays and clay minerals with various organic compounds through intercalation and surface grafting. Organoclays have important practical applications as adsorbents of a wide range of organic pollutants and some inorganic contaminants. The traditional raw materials for the synthesis of organoclays are phyllosilicates with the expanding structural cell of the smectite group, such as montmorillonite. Moreover, other phyllosilicates and inosilicates are used to synthesize organoclay to a limited extent. The purpose of this review was to analyze the possibility of using minerals of other groups with different abilities to expand the structure and structural charge for the adsorption of chemical environmental pollutants. The structural characteristics of various groups of phyllosilicates and chain minerals that affect their ability to modify organic surfactants and the adsorption properties of prepared organoclays were reviewed.

The use of widespread and inexpensive clay minerals as adsorptive agents, as well as materials obtained by their chemical modification, can contribute to the solution of the problem of environmental pollution with antibiotics. This review considers the structural features of various natural clay minerals and the effect of these features on their sorption capacity. Based on the analysis of available papers (over the last 15 years, also including some fundamental basics over the last 20–30 years), it has been established that the main property of an antibiotic molecule affecting the ability to be adsorbed by a clay mineral is the hydrophilicity of the organic substance molecule. The leading properties that determine the ability of clays to adsorb antibiotics are the charge and area of their surfaces. The ability of antibiotic molecules to protonate and a partial change in the edge charge of mineral layers is determined by the acidity of the sorption solution. In addition, empirical evidence is provided that the most important factors affecting adsorption are the ionic strength of the sorption solution, the concentration of the adsorbent and adsorbate, and the interaction temperature. The diversity of the composition, structure, and properties of clay minerals allows them to be effective sorbents for a wide range of antibiotics.

The rapid industrial development of civilization has led to the need for the development of new materials to clean up chemically contaminated wastewater and soils. Organoclays, based on smectite minerals and various types of surfactants, are one of the most effective sorbents for adsorbing organic and inorganic pollutants. Organoclays are clay minerals that have been modified by the intercalation or grafting of organic molecules. The main mechanism of interaction between organic substances and organoclays involves the adsorption of the substances onto the surface of the clay mineral, which has an expanded structural cell. Various types of surfactants can be used to synthesize organoclays, including cationic, anionic, and amphoteric surfactants. Each type of surfactant has different properties that affect the clay’s ability to sorb. Cationic forms of trace elements, such as heavy metals, can also be adsorbed by organoclays. Data on the adsorption of these substances by organoclays are provided, along with information on how to synthesize them using various surfactants. This review also discusses the main mechanisms of interaction between these substances and clays and the various methods used to create organoclays. It is clear that the adsorption of heavy metals by organoclays is not influenced by their structure or properties, as they belong to the category of surfactant, but rather by their overall chemical structure and characteristics. The wide variety of surfactant types leads to different effects on the adsorption properties of trace elements.

In real soils the interaction of humic substances with clay minerals often occurs with the participation of metal cations. The adsorption of fulvic acids (FA) solution and their solutions in the presence of heavy metal ions (Pb or Zn) on two clay minerals (kaolinite and bentonite) was investigated by measurement of the optical density changes in the of equilibrium solutions. The FA adsorption by bentonite at the concentrations 0.05–1 g/L proceeds according to the polymolecular mechanism and has a stepwise character. The adsorption of FA on kaolinite can be described by the mechanism of monomolecular adsorption. In three-component systems, including FA, trace element ions and a clay mineral, complex processes occur, including the formation of complexes and salts and their adsorption. The sorption of colored complexes of FA with Pb on the surface of kaolinite and bentonite increases with increasing metal concentrations (0.5–2 mmol/L). The interaction of the FA-Zn²⁺ compounds with bentonite is a more complicated process—adsorption takes place at the lowest concentration used only. Thus, binding of FA by clay minerals in the presence of metal cations is a complex phenomenon due to the chemical heterogeneity of FA, different properties of metals, characteristics of mineral surfaces and the variability of environmental conditions.

For many decades, natural and modified clay minerals have been used as adsorbents to clean up aquatic and soil ecosystems contaminated with organic and inorganic pollutants. In this study, organoclays based on bentonite and various amphoteric and nonionic surfactants were synthesized and tested as effective sorbents for lead ions. The maximum values of R were obtained when describing the sorption processes using the Langmuir model, which ranged from 0.97 to 0.99. The adsorption of lead ions by these organoclays was investigated using different sorption models including the Langmuir, Freundlich, and BET. It was found that, according to the values of limiting adsorption to the Langmuir equation, the synthesized organoclays formed an increasing series: organoclay with cocamide diethanolamine < bentonite < organoclay with lauramine oxide < organoclay with sodium cocoiminodipropionate < organoclay with disodium cocoamphodiacetate < organoclay with alkyl polyglucoside. The Gibbs energy for all of the analyzed samples was calculated and found to be negative, indicating the spontaneity of the cation adsorption process in the forward direction. The maximum value of the adsorption capacity of lead cations on organoclay-based bentonite with alkyl polyglucoside was 1.49 ± 0.05 mmol/g according to the Langmuir model, and 0.523 ± 0.003 mmol/g as determined by the BET model. In the process of modifying bentonite, there was an increase in negative values of the zeta potential for organoclays compared to the initial mineral, which clearly enhanced their electrostatic interactions with the positively charged lead ions. It was hypothesized, based on the physicochemical principles, that exchange adsorption is the main mechanism for lead absorption. Based on chemical approaches, organoclays based on amphoteric surfactants absorb lead mainly through the mechanisms of electrostatic attraction, ion exchange, and complexation as well as the formation of insoluble precipitates. Organoclays based on nonionic surfactants, on the other hand, absorb lead through mechanisms of complexation (including chelation) and the formation of insoluble chemical precipitates. The comparison of isotherms from different models allows us to find the most accurate match between the model and the experimental data, and to better understand the nature of the processes involved.

The use of nature-like technologies, leading to acceleration of the processes of natural destruction of pollutants, is one of the promising directions for oil and petroleum product degradation in the environment. The joint use of oil-degrading bacteria and natural polymers with the properties of surfactants and humic acids (HAs) in bioorganic compositions is effective. In this study, humic acids from reed peat, which have a critical micelle concentration (CMC) of 0.6 g/L, were used as an organic component. Oil-degrading bacteria of the genera Rhodococcus and Pseudomonas, which have an increased biodegrading ability in relation to crude oil and waste engine oil, were used as a bacterial component. Mono- and polybacterial bioorganic compositions based on these components are proposed. The emulsification index is maximum (94% ± 2%) using a bioorganic composition based on the association of strains of three bacteria. Analysis of films of model petroleum products in vitro showed a high degree of their destruction after 7 days using monobacterial bioorganic compositions (up to 80%) and after 2 days using a bioorganic composition based on 3 strains (almost 90%). A high ability to stabilize emulsions of humic acids and develop bioorganic compositions has been established, which indicates a significant potential for their use for cleaning the environment from oil pollution. The use of a combination of humic acids and oil-degrading bacteria (all strains) makes it possible to achieve the maximum stabilizing effect of emulsions: the transmission coefficients of emulsions are 37–75% lower relative to control (oil-polluted water) and 50% lower in relation to humic acids.