## 4 Conclusions  
Raw jute fabric (J) was treated with 0.5, 1.0, or 2.0% chitosan solution (J0.5% CS, J1.0% CS, and J2.0% CS) to improve its sorption properties which are of great importance for the  
Figure 11: Adsorption of RO 16 onto J1.0% CS as a function of contact time, inset: Pseudo-first and pseudo-second-order kinetic models and calculated kinetic parameters (\(\zeta_{0}\) = 25 mg/L, \(t\) = 0–7 h, \(T\) = 25 \({}^{\circ}\)C, pH of 2.0 (for J, J0.5% CS, and J1.0% CS) and 4.0 (for J2.0% CS), the mass of adsorbent 0.25 g). utilization of such polysaccharide-based fabrics as water-binding geo-prebiotic supports that should provide the necessary water for the growth of cyanobacterial biocrusts. The fabrics' sorption properties were assessed by the determination of moisture sorption value and their ability to adsorb textile dye Reactive Orange 16 (RO 16). Chitosan-treated jute fabrics possessed up to 77.6% higher moisture sorption values than J, which is owed to the chitosan's greater capability to form hydrogen bonding with water. On the other hand, after the optimization of RO 16 adsorption in terms of the initial solution's pH (pH 4.0 was found optimal for J2.0% CS, while pH 2.0 was optimal for other fabrics) and adsorbent mass (0.25 g for all fabrics), the effect of dye initial concentration, temperature, and time on fabrics' adsorption potential was investigated. With the increase in initial RO 16 concentration from 25 to 100 mg/L, the amount of dye adsorbed per gram of J, J0.5% CS, and J1.0% CS increased by 1.5, 1.9, and 1.9, times, respectively. Furthermore, by increasing the chitosan percentage from 0 to 0.5, 1.0, fabric adsorption potential increased by 1.5, and 2.2 times (initial dye concentration of 100 mg/L), respectively. The adsorption of RO 16 onto all studied fabrics was represented by the Langmuir isotherm model with a calculated maximum adsorption capacity of 5.996-14.075 mg/g. In the studied temperature range (25 to 55 \({}^{\circ}\)C), the adsorption process under examination is spontaneous and thermodynamically feasible. With increasing the temperature to 30 \({}^{\circ}\)C, the adsorption potential of J, J0.5% CS, and J1.0% CS decreased by about 46, 33, and 39%, respectively;the adsorption process is exothermic and enthalpy driven. However, an inverse relationship between RO 16 adsorption onto J2.0% CS, initial dye concentration, and temperature was observed. Different behavior of J, J, J0.5% CS, and J1.0% CS, on one side, and J2.0% CS, on the other side, could be explained by the different dominant binding interactions. In the first case, governing mechanism is ascribed to electrostatic interactions between negatively charged dye and positively charged fabrics' surface, while in the case of J2.0% CS at pH 4, hydrogen bonds and stacking interactions play a major role in the adsorption of RO 16. Concerning the contact time, adsorption of RO 16 is rapid during the first 2 h, a slower rate of adsorption was observed between 2 and 4.5 h, after which the equilibrium was attained. The kinetic data followed the pseudo-second-order kinetic model. The findings of this paper confirm that the treatment with chitosan can improve the jute fabric sorption properties. The economic impact of the proposed approach can be considered beneficial for possible real-life applications of polysaccharide-based supports in biocarpet engineering since the associated costs are very low as jute can be obtained as waste material from the packaging industry while the low-cost chitosan was used in very low concentrations (up to 2.0%). Conceptualization, A.I. ; methodology, A.I. and M.M. ; formal analysis, A.I. and M.M. ; writing--original draft preparation, A.I. and J.L. ; writing--review and editing, J.L., L.P., Z.S., M.K. and J.M. ; visualization, A.I. and M.M. ; supervision, M.K. and J.M. ; funding acquisition, Z.S. All authors have read and agreed to the published version of the manuscript.