## 3 Results and Discussion
### Photocatalytic Performance Analysis  
#### 3.3.1 Photodegradation of the TCH Aqueous Solution  
This study prepared composite photocatalysts by combining porous g-C\({}_{3}\)N\({}_{4}\) and CdS in varying mass ratios (1:1, 1:2, and 1:3) to examine their effectiveness in degrading TCH. The performance of the prepared catalysts was assessed by examining TCH degradation under light exposure, emphasizing the synergy between CdS and porous g-C\({}_{3}\)N\({}_{4}\). Prior to light exposure, equilibrium adsorption showed a 0.89% TCH reduction in standard g-C\({}_{3}\)N\({}_{4}\) and 3.50% for porous g-C\({}_{3}\)N\({}_{4}\), attributed to its larger surface area. Following adsorption equilibrium, TCH concentrations for the CdS/g-C\({}_{3}\)N\({}_{4}\)-1, CdS/g-C\({}_{3}\)N\({}_{4}\)-2, and CdS/g-C\({}_{3}\)N\({}_{4}\)-3 composites were reduced by 17.33%, 24.26%, and 19.06%, respectively (Figure 8a). The improvement in adsorption performance can be credited to the addition of CdS, but an excess of CdS particles led to pore clogging, reducing both the  
Figure 7: Photoluminescence spectra comparison for porous g-C\({}_{3}\)N\({}_{4}\) and CdS/g-C\({}_{3}\)N\({}_{4}\)-2 under 350 nm excitation. specific surface area and adsorption capacity. Therefore, an appropriate CdS loading level is crucial for maximizing adsorption efficiency. Upon visible light exposure, significant photodegradation of TCH was observed for all three composites, with degradation rates of 77.12%, 81.46%, and 77.99% within 60 min. The increase in photocatalytic efficiency, relative to pure CdS and g-C3N4, stems from the synergy between CdS and porous g-C3N4. This interaction facilitates improved charge carrier separation and enhances light absorption capacity. The photodegradation properties were further analyzed by calculating the kinetic rate constant (\(k\)) using ln (\(C_{0}/C_{\text{f}}\)) vs. \(t\). Figure 8b presents the linear kinetic fitting for TCH degradation over a duration of 30 min. The rate constants (\(k\) values) for CdS/g-C3N4-1, CdS/g-C3N4-2, and CdS/g-C3N4-3 are 0.0407, 0.0516, and 0.0357 min\({}^{-1}\), respectively. As shown in Table 1, the \(k\) values for the CdS/g-C3N4 composites are significantly higher than those for other photocatalytic systems, suggesting the superior performance of the CdS/g-C3N4 heterojunction. The correlation coefficients (0.9981, 0.9933, and 0.9979) indicate a good fit, demonstrating that the composites exhibit quasi-first-order kinetics in TCH degradation. Optimal catalytic efficiency was achieved at a 1:2 mass ratio of g-C3N4 to CdS, with a 9.64-fold higher degradation rate than pure porous g-C3N4 within 30 min. CdS/g-C3N4-2 showed a higher k value than CdS alone, highlighting that the enhanced catalytic performance arises from the interaction between CdS and g-C3N4 rather than from CdS itself. This improvement can be ascribed to the larger surface region and effective charge carrier separation facilitated by the heterojunction, which minimizes electron-hole recombination and thereby boosts overall activity. Porous g-C3N4 also provides a suitable substrate for improved light absorption and mass transport, enhancing interactions between TCH molecules and catalytic sites. In summary, the preferred mass ratio of CdS to porous g-C3N4 is 2:1, as it provides the optimal balance between increased adsorption sites and minimal pore-blocking effects, thereby maximizing photocatalytic efficiency. This synergy between CdS and g-C3N4, at the optimized mass ratio, is crucial for achieving superior photocatalytic performance. \begin{table}
\begin{tabular}{c c c} \hline \hline
**Target Pollutant** & **k Value (min\({}^{-1}\))** & **Ref.** \\ \hline RhB & 0.0055 & [42] \\ RhB & 0.0189 & [43] \\ MO & 0.0231 & [44] \\ RhB & 0.0032 & [45] \\ MB & 0.01 & [46] \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Photocatalytic Properties of CdS.