## 1 _Acticle_
In the last decade, the emphasis has been placed on the application of cheap alternative carbonaceous sorbents, such as biochar (BC) produced from waste biomass [22]. BC has recently gained an interest for its potential application in agriculture due to great carbon sequestration [23; 24]. The physical and chemical properties of BC are dictated by the feedstock and production processes [23; 24; 25]. As [PERSON] et al. [25] reported, a wide range of fixed carbon (0-47.8%), volatile matter (28-74.1%) and ash contents (1.5-65.7%) were observed among tested samples of BC. A high variability in the surface area (0.1-155.1 g m\({}^{2}\)) and PAH and heavy metal contents of the solid phase was also detected (0.7-83 mg kg\({}^{-1}\)) [25]. Detailed characterizations and descriptions of BC are presented in several research works [23; 24; 25]; for a graphical representation of the BC structure, see ref. [26]. Due to relatively high cation exchange capacities and low cost, the utilization of a clay sorbent, such as bentonite (BT) or montmorillonite (MTM), is also one of the alternative sorption techniques applicable for the removal of organic pollutants from wastewater [27; 28; 29]. BT/MTM consists chiefly of crystalline clay minerals belonging to the smectic group, which are hydrated aluminum silicates containing iron and magnesium. Two types of BT--sodium or calcium--are recognized, and the uses of each depend on specific physical properties [28; 29]. The main constituents of BT clay, SiO\({}_{2}\), Al\({}_{2}\)O\({}_{3}\), K\({}_{2}\)O, Fe\({}_{2}\)O\({}_{3}\), MgO, Na\({}_{2}\)O and TiO\({}_{2}\), reach approx. 50%, 15%, 0.3%, 12%, 3%, 3% and 0.269%, respectively, with the rest of the impurities [30; 31]. The further descriptions, physical and chemical characteristics and structures of BT clay are detailed in refs. [28; 30; 31]. These clay materials find many applications, e.g., in the construction industry or as cat litter [28]. Despite several different applications of BC and BT (in agriculture, construction industry, etc. ), many authors have previously published options for the adsorption of different types of dyes on BC [32; 33; 34; 35; 36] as well as on BT [27; 29; 37; 38; 36]. However, BC and BT provided lower adsorption capacities and removal efficiencies (in comparison with AC action) [32; 33; 34; 35; 36; 37]. The applicable improvement of removal efficiencies serves the co-action of BC or BT together with appropriate ionic liquids (ILs) [32; 38]. ILs are usually defined as compounds completely composed of ions with melting points below 100 \({}^{\circ}\)C [39]. Some authors reported the application of ILs in the separation of acid dyes from aqueous solutions. [PERSON] et al. [39], for the first time in 2006, reported on the effective extraction of selected acid azo dyes from wastewater using ILs. Since 2006, other authors [40; 41; 42; 43] introduced efficient methods applicable for acid dye separation using ILs. As we previously published, anionic drugs [44] or anionic azo dyes [45] can be effectively separated from aqueous solutions using ILs based on quaternary ammonium salts (R\({}_{4}\)NX). This method consists in the addition of commercially available and inexpensive ILs, which is accompanied by the ion exchange of inorganic anions X\({}^{-}\) of R\({}_{4}\)NX with anions of acid dyes (according to Equation (1)), producing low-polar ion pairs (\(\text{dye-SO}_{3}\text{NR}_{4}\)) insoluble in aqueous solution and separable by sedimentation and/or filtration. \[\text{dye-SO}_{3}{}^{-}+\text{Na}^{+}+\text{R}_{4}\text{N}^{+}+\text{X}^{-} \rightarrow\text{dye-SO}_{3}\text{NR}_{4}\downarrow\text{Na}^{+}+\text{X}^{-} \tag{1}\]  
In this paper, the removal of the chromium complex of reactive azo dye RB8 using alternative sorbents such as BC or BT alone or in the co-action of IL benzalkonium chloride (BAC) or Aliquat 336 (A336) (for chemical drawings, see Figure 2) and the action of sole BAC or A336 was studied in model and real wastewater produced in the dye manufacturing process.