# Effect of Washing Temperature on Adsorption of Cationic Dyes by Raw Lignocellulosic Biomass
## 3 Results and Discussion
### Results of Methylene Blue and Crystal Violet Adsorption on Raw Materials
#### 3.2.1 The Effect of Various Physico-Chemical Parameters
Effect of Temperature on the Adsorption Isotherm  
The results of the adsorption isotherms for MB and CV on the raw materials are shown in Figure 11.0 For all the studied materials, the adsorption isotherms initially show a steeper inclination at lower concentrations, indicating the presence of many easily accessible sites [87]. Each curve eventually reaches a plateau, indicating that the sorbent is saturated at this level. This plateau can be influenced by the concentration of the biosorbent. By altering the amount of the utilized biosorbent, the number of active sites available for adsorption changes, which can affect the saturation point. According to [PERSON]'s classification of adsorption isotherms [46], these isotherms are of type I, demonstrating a high affinity between the dyes and the biosorbents. The maximum adsorption capacity of MB and CV varied depending on the nature of the biosorbents, being significantly higher for MPC than for CC (twice as high). The high adsorption capacity of _Maclura pomifera_ (MPC) is logically linked to its developed structure and high content of basic functional groups compared to those of wild carob (CC). These characteristics enhance its ability to retain cationic dyes. Furthermore, the temperature of the wash water significantly affected the adsorption capacity of MP. The maximum adsorbed quantity of MB and CV decreased, respectively, from 133.4 and 136.6 mg g\({}^{-1}\) for MPC to 117.2 and 117.7 mg g\({}^{-1}\) for MPW and 67.1 and 90.5 mg g\({}^{-1}\) for MPH. This reduction could be attributed to the destruction of the structure or the breaking of certain chemical bonds at high temperatures. These findings are consistent with the textural and chemical properties of the materials. In contrast, the temperature of the wash water had no significant effect on the performance of the wild carob biosorbents. The maximum values of the equilibrium adsorption capacity for CC, CW, and CH were very close, indicating that the effect of wash water temperature depended on the nature of the used material. Figures 17-22 show the influence of temperature on the adsorption isotherms of MB and CV on raw MP and C. From these figures, we can see that for all the materials and for low initial concentrations, temperature had no influence on the quantity of MB and CV adsorbed. However, it did have a significant effect at high initial concentrations. Figures 17-19 show that MB and CV behaved differently. We observed that the quantity of MB adsorbed on MPC, MPW, and MPH decreased with increasing temperature, reflecting the exothermic nature of the adsorption. For CV, on the other hand, it increased with increasing temperature, in agreement with an endothermic process. Figures 20-22 show that temperature had a positive effect on the adsorption of both dyes by CC, CW, and CH. This indicated an endothermic nature of adsorption. The influence of temperature on the adsorption of cationic dyes has been examined in numerous studies, most of which noted a  
Figure 11.1 Adsorption isotherms for MB and CV on raw materials (natural pH, T = 20 \({}^{\circ}\)C, V = 250 rpm, r = 1 g L\({}^{-1}\), 10 \(\leq\) C\({}_{0}\)\(\leq\) 300 mg L\({}^{-1}\)). positive effect of temperature on adsorption capacity [71; 88; 89]. This is due to the fact that increasing temperature facilitates the diffusion of adsorbate molecules through the outer boundary layer and into the pores of the adsorbent particles by reducing the viscosity of the solution [90]. Figure 11.2 Adsorption isotherms for MB and CV on MPC (natural pH, V = 250 rpm, r = 1 g L\({}^{-1}\), \(10\leq\) C\({}_{0}\leq\) 300 mg L\({}^{-1}\)). Figure 11.3 Adsorption isotherms for MB and CV on MPW (natural pH, V = 250 rpm, r = 1 g L\({}^{-1}\), \(10\leq\) C\({}_{0}\leq\) 300 mg L\({}^{-1}\)). Figure 11.4 Adsorption isotherms for MB and CV on CW (natural pH, V = 250 rpm, r = 1 g L\({}^{-1}\), 10 \(\leq\) C\({}_{0}\)\(\leq\) 300 mg L\({}^{-1}\)).