## 4 Conclusions
Additionally, sorption with the proposed BC + BAC or BT + BAC systems proceeds smoothly from 30 to 60 min, in contrast with adsorption using conventional PAC (3-4 h is necessary for effective removal of RB8 dye using PAC). The application of BAC + B also saves energy and further reduces economic costs joined with waste treatment (compared with conventional sorption using active carbon). The optimized method of direct combination of BAC with BT for RB8 dye from wastewater is rapid, economically acceptable and almost as effective as that based on expensive PAC application. The following supporting information can be downloaded at [[https://www.mdpi.com/article/10.3390/app14020673/s1](https://www.mdpi.com/article/10.3390/app14020673/s1)]([https://www.mdpi.com/article/10.3390/app14020673/s1](https://www.mdpi.com/article/10.3390/app14020673/s1)), File S1: Figure S1. Report from EDXRF analysis of commercial RB8 sample; Scheme S1. The experimental scope of RB8 separation using alternative sorbents with presence/absence of benzalkonium chloride; Figure S2. Absorption spectrum of RB8 in model and real wastewater (A) and calibration curve of model aq. solutions of RB (B); Figure S3. The experimental layout of the RB8 separation using alternative sorbents with presence/absence of benzalkonium chloride; Figure S4. The comparison of decolorization efficiency and COD removal of RB8 dye using PAC and MTM (40 g L\({}^{-1}\)) and alternative sorbents (40 g L\({}^{-1}\)) after 5 h of action; Figure S5. Report from EDXRF analysis of alternative BC sorbent saturated with RB8 dye; Figure S6. The comparison of octan-1-ol/water partition coefficients (log P\({}_{\text{ow}}\)) for RB8 and RB8-based ion pairs (R\({}_{4}\)N)\({}_{4}\)-RBS; Figure S7. The removal of AOX from model aq. solutions of RBS (1 g L\({}^{-1}\) aq. model solution) using optimal doses of BAC and BC or BT after 30 min of action; Figure S8. The dependencies of adsorption capacity on time within adsorption of RB8 (1 g L\({}^{-1}\) aq. model solution) on (A) different sorbents (40 g L\({}^{-1}\)) or (B) co-action of BC (2 g L\({}^{-1}\)) with BAC (1.5 g L\({}^{-1}\)) or BT (2 g L\({}^{-1}\)) with BAC (2 g L\({}^{-1}\)); Figure S9. Report from EDXRF analysis of alternative BC sorbent saturated with (BAC)\({}_{4}\)RB8 ion pair; Table S1. A comparison of economic costs of tested separation methods of RB dye from model (1 g L\({}^{-1}\)) or real (7 g L\({}^{-1}\)) wastewater; Scheme S2. The proposed mechanisms of separation of RB8 dye from wastewaters. File S2: Measured data from chemical analysis and VIS spectroscopy. Conceptualization, B.K. and T.W. ; methodology, T.W. ; validation, B.K. and M.P. ; formal analysis, B.K. ; investigation, B.K., T.W. and K.M. ; resources, B.K. and K.M. ; data curation, B.K., M.P. and K.M. ; writing--original draft preparation, B.K. ; writing--review and editing, T.W. ; visualization, B.K. ; supervision, T.W. All authors have read and agreed to the published version of the manuscript. This research received no external funding. Not applicable. The data presented in this study are available in Supplementary Materials, further inquiries can be directed to the corresponding author. The authors declare no conflicts of interest.