The sorption of Cu(II) ions onto natural (clinoptilolite) and synthetic (Na-X and Na-P1) zeolites was investigated. The synthetic zeolite samples were obtained from coal fly ash under hydrothermal crystallization conditions. The following issues were studied under batch conditions: the influence of the initial concentration of the Cu(II) ions, dose of zeolites, anion kind, and pH of solution. The experimental data were modelled with the Freundlich, Langmuir, and Dubinin-Radushkevich adsorption isotherms and their goodness-of-fit levels were compared. The affinity of the Cu(II) ions for synthetic zeolites was much higher than for the natural ones. The maximum sorption capacity of the synthetic zeolites (Na-P1 and Na-X) was 256 mg·g^-1 and 141 mg·g^-1, respectively. It was 10.6 and 6 times higher, respectively, than the clinoptilolite sorption capacity (24 mg·g^-1). The uptake of the Cu(II) ions occurred in two processes, i.e. the ion exchange and adsorption/precipitation in accordance with the initial concentration of the Cu(II) ions in the solution. Study of the pH and anion kind influence on the zeolite sorption capacity shows that the synthetic zeolites were effective sorbents of the Cu(II) ions, also in the acidic solutions. The Freundlich and Dubinin-Radushkevich equations provided the best description of the sorption for the Cu(II) ions onto the synthetic zeolite systems when the initial Cu(II) ion concentration was 500-1,000 mg·L^-1. On the other hand, the Langmuir and Dubinin-Radushkevich isotherms described the sorption most properly when the concentrations were above 1,000 mg·L^-1.

Silver nanoparticles are one of the most commonly used forms of silver (Ag) in nanotechnology applications due to their antibacterial properties and electrical and thermal resistance. The increasing production and use of products containing nanoparticles has led to their release into and contamination of soil and water. This review summarizes the literature on the fate, behavior (adsorption/desorption, precipitation/oxidative dissolution, transformation), and transport/mobility of Ag forms in soils (Ag⁺ ions and Ag nanoparticles—AgNPs). The behavior of Ag⁺/AgNPs in soil is a complex process. It depends on many factors, including the characteristics of the Ag forms (ions, nanoparticle size, ligand type used for coating, surface charge, initial Ag concentration), the soil properties (organic matter and clay mineral content, textural properties, point of zero charge, cation exchange capacity, surface functional groups), and the solute properties (pH–Eh, ionic strength, cation type, oxygen content). The binding of Ag⁺ and AgNPs is significantly positively correlated with Al/Fe/Mn oxide and SOM content and depends on the surface charge of the minerals and CEC, which controls adsorption processes. Very important parameters to consider are the pH and Eh of the solution, which determine the durability of the ligands, the aggregation rate and the oxidation process of AgNPs, as well as the presence of sulfide and chloride and the Cl/Ag ratio, which determine the stability/mobility of Ag. Since AgNPs can be oxidized to Ag⁺ ions during their life cycle, it is necessary to consider the behavior of both forms of Ag in soils. Understanding the transport and behavior of Ag in soil is essential for the environmental risk assessment and management of wastes containing Ag.

The aim of this paper is to present characteristics, toxicity and environmental behavior of nanoparticles (NPs) (silver, copper, gold, zinc oxide, titanium dioxide, iron oxide) that most frequently occur in consumer products. In addition, NPs are addressed as the new aquatic environmental pollutant of the 21^stcentury. NPs are adsorbed onto particles in the aquatic systems (clay minerals, fulvic and humic acids), or they can adsorb environmental pollutants (heavy metal ions, organic compounds). Nanosilver (nAg) is released from consumer products into the aquatic environment. It can threaten aquatic organisms with high toxicity. Interestingly, copper nanoparticles (Cu-NPs) demonstrate higher toxicity to bacteria and aquatic microorganisms than those of nanosilver nAg. Their small size and reactivity can cause penetration into the tissues and interfere with the metabolic systems of living organisms and bacterial biogeochemical cycles. The behavior of NPs is not fully recognized. Nevertheless, it is known that NPs can agglomerate, bind with ions (chlorides, sulphates, phosphates) or organic compounds. They can also be bound or immobilized by slurry. The NPs behavior depends on process conditions, i.e. pH, ionic strength, temperature and presence of other chemical compounds. It is unknown how NPs behave in the aquatic environment. Therefore, the research on this problem should be carried out under different process conditions. As for the toxicity, it is important to understand where the differences in the research results come from. As NPs have an impact on not only aquatic organisms but also human health and life, it is necessary to recognize their toxic doses and know standards/regulations that determine the permissible concentrations of NPs in the environment.