## 3 Results and Discussion
### Removal of CR and MG by Activated Carbon and Dry Biomass of T. virens and T. viriide  
Figure 4 shows removal efficiencies for CR (Figure 4A) and MG (Figure 4B), for the more representative dye concentrations, as a function of stirring times ranging from 1.5 to 48 h. It is important to note that removal by activated carbon is very fast for both dyes and remained almost unchanged during the experimentation time, indicating that it reaches the equilibrium faster than the mycelium of both _Trichoderma_ isolates. As it can be seen, during the first 24 h, the activated carbon showed the highest CR removal capacity. In absorption processes, activated carbon is a highly effective and versatile material. However, both chemical and thermal regeneration of the used carbon produces effluent, is expensive, and is impractical on a large scale. On the other hand, after 24 h, the dry biomass of both _Trichoderma_ species showed higher CR removal capacity than activated carbon (Figure 4A). In addition, the CR removal obtained by the dry biomass of _T. virens_ (88%) was higher than that reported for the fungus _Aspergillus niger_ (72%) [73]. In contrast, MG removal by the dry biomass of both fungi was lower than that observed by activated carbon during the first 24 h, although, at 48 h, the \begin{table}
\begin{tabular}{c c c c c} \hline
**Adsorbent** & **Dye** & **K\({}_{2}\) (g mg\({}^{-1}\) h\({}^{-1}\))** & **\(q_{\text{e}}\) (mg g\({}^{-1}\))** & **\(q_{\text{exp}}\) (mg g\({}^{-1}\))** & **R\({}^{2}\)** \\ \hline _T. virens_ dead mycelium & CR & \(-\)0.0234 & 22.15 & 23.39 & 0.999 \\ _T. virens_ living mycelium & CR & 0.0116 & 20.74 & 21.97 & 0.998 \\ _T. viriide_ dead mycelium & CR & \(-\)0.0422 & 21.28 & 22.44 & 0.999 \\ _T. viriide_ living mycelium & CR & \(-\)0.0275 & 19.56 & 20.65 & 0.999 \\ _T. virens_ dead mycelium & MG & 0.0543 & 22.66 & 23.36 & 0.999 \\ _T. virive_ living mycelium & MG & 0.1062 & 23.60 & 22.36 & 0.999 \\ _T. viriide_ dead mycelium & MG & 0.0067 & 20.29 & 18.64 & 0.998 \\ _T. viriide_ living mycelium & MG & \(-\)0.0181 & 16.87 & 17.62 & 0.998 \\ \hline \end{tabular}
\end{table} 
Table 2: Pseudo-second-order kinetic parameters for the removal of Congo red and malachite green by fungal fresh biomass of _T. virens_ and _T. viriide_. Figure 4: Removal efficiency of Congo red (row **A**) and malachite green (row **B**) (60, 75, and 90 mg L\({}^{-1}\)) by activated carbon and fungal dry biomass of _T. virens_ and _T. viriide_. removal of MG by the dry fungal biomass was similar to that observed for activated carbon (Figure 4B). Equilibrium adsorptions data of CR and MG onto activated carbon and dry biomass of the two _Trichoderma_ species were analyzed using the Freundlich (Equation (2)) and Langmuir (Equation (3)) adsorption isotherms. The isothermal plots were found to be linear, and the linear correlation coefficients were slightly higher for the Langmuir model (Figure 5); all the calculated isotherm model parameters are given in Table 2.  
Additionally, we calculate the equilibrium parameter, \(R_{\rm L}\), which represent an important characteristic in the Langmuir model and is defined by  
\[R_{\rm L}=\frac{1}{1+K_{\rm L}C_{0}}, \tag{6}\]  
where \(C_{0}\) stands for the initial concentration of dye. The value of \(R_{\rm L}\) indicates favorable absorption if 0 \(<R_{\rm L}<\) 1. In addition, \(R_{\rm L}\) = 0 denotes irreversible absorption, \(R_{\rm L}\) = 1 indicates linear absorption, and \(R_{\rm L}\) >1 reveals unfavorable absorption [74]. Then, higher correlation coefficients for the Langmuir model and \(R_{\rm L}\) values between 0 and 1 (last column in Table 3) suggest that the adsorption of CR and MG by activated carbon and dry biomass of _T. virens_ and _T. viride_ could be well described by the Langmuir model. Parameters found through the Freundlich model could give information about the heterogeneous nature of adsorption (\(n>\) 1). That is the case of CR adsorption by activated carbon and _T. virens_, and MG adsorption by _T. virens_.