## 1 Introduction  
One of the greatest environmental problems today is the presence of harmful and hazardous substances in industrial wastewater. Pollution in the ecosystem significantly affects the quality of water, and thus the life of plants and animals [1]. Some of the worst pollutants are heavy metals, which are released into the environment through natural process and anthropogenic activities. Due to accumulation, even small concentrations can significantly worsen the condition of the environment [2]. The increasing contamination of these substances necessitates their removal from wastewater and post-process water [3]. Examples of such metals are copper and silver. In recent years, the above-mentioned metals have been widely used in utility products (cosmetics, cleaning agents and impregnated functional coatings, among others) as biocidal agents. The elements occur in products as nanoparticles as well as ions, which affects their concentration in wastewater [4]. Small-sized nanoparticles demonstrate increased reactivity, which simultaneously reduces a particle's lifetime in the environment. The reactivity of the particles may cause an increased degree of aggregation, changes in an oxidation state or a tendency to precipitate. Modifications of the structure of particles occurring in the environment strongly affect their surface properties and, consequently, transport and behaviour in water systems, soils, and their impact on organisms [5].  
Conventional methods for removing heavy metals from aqueous solutions include filtration, chemical precipitation, coagulation and ion exchange [6; 7]. These methods are not effective unless the concentration of a metal in the sewage is relatively high. Adsorption is one of the alternative technologies for removing metal ions, which is an efficient method even for low metal ion concentrations. Recently, research has been focused on \"green adsorption\". This method places particular emphasis on the natural origin of sorbents, lower acquisition costs and the possibility of using materials of waste origin, for example, from agricultural and food industries [8; 9; 10]. Examples of natural adsorbents are biosorbents, aluminosilicates, zeolites and fly ash [11]. Clay minerals are an increasingly important group of natural adsorbents [12; 13]. The main advantage of using clay minerals are their relatively easy availability and natural origin, low production cost, and high thermal and mechanical resistance. An example of clay minerals is vermiculite, which is a hydrated mineral magnesium and iron silicate [14; 15]. Vermiculite is a good adsorbent for removing ions from aqueous solutions because of an insufficient electron charge. Cations are exchanged at planar sites, resulting from the interactions between metal ions and the negative permanent charge (outer-sphere complexes) [16; 17].  
This work investigated the possibility of using vermiculite as an adsorbent of silver and copper ions. The adsorption process was carried out in a continuous system that evaluated the efficiency of the removal of copper and silver ions from aqueous solutions. The influence of process parameters and the effectiveness of the applied sorption method were studied. In addition, a mathematical description of the dynamics of the adsorption process analysis was presented.