# A New Route for Low Pressure and Temperature
## 3 Results
### Catalyst Performance  
First of all, to analyze the behavior of the neat resin it was tested in the operating conditions: 95 \({}^{\circ}\)C, phenol concentration 4000 mg/L, resin concentration 0.4 g/L. The tests evidence the capability of the system to remove more than 60% of the phenol in 30 min, see Figure 7.  
Figure 5: Nitrogen adsorption (filled symbols) and desorption (empty symbols) isotherms at 77 K (**a**) and DFT pore size distribution (**b**) of the HCL resin and HCL nanocomposites. Figure 6: TG-DTGA analysis of PtRu/MoS\({}_{2}\) nanoparticles, HCL resin, and HCL nanocomposite. In particular, the removal ability of the resin reached a plateau of \(\sim\)88% phenol removal after 240 min. To distinguish between adsorption and catalytic behavior, in Figure 8a the UV-vis spectra at 180 min and 420 min of the solution media, showing the adsorption of phenols (i.e., reduction of the intensity of the absorbance peaks) and the absence of chemical reactions, were reported. This result was further analyzed by GC-MS, which shows, for the tests up to 420 min, a single peak at 19.95 min retention time, attributable to phenol. Following this experiment, neat and catalytic resins were tested in the same operating conditions but after saturation with phenol, evidencing a significant phenol removal efficiency for the nanocomposites in comparison with an almost total absence of catalytic activity for the unloaded resin, see Figure 9a. Although, after 10 min, in the case of catalyst loaded resins, see the blue profile in Figure 8b, no significant catalytic activity is observed, at 240 min the formation of acetic acid at lower wavelengths and of hydroquinone at higher wavelengths can be seen, see the green spectrum in Figure 8b. In this case, the analysis by GC evidence, e.g., that at 300 min the phenol content was 30.01%; the remaining 69.99% consists of hydroquinone 2.98%, \(p\)-benzoquinone 0.41%, and acetic acid 96.61%, see the scheme in Figure 10. Because of the maximum phenols content in the solution, at this time, is equal to 5.43%, see Figure 9a, the total phenols content still presents in the solution after 300 min account for a maximum of 217 mg/L, which gives a total carbon content of 727 mg/L, which means a carbon removal of 81.8%. After 300 min, TOC conversion (\(\Delta\)T  
Figure 8: UV-spectra of the reaction media (reaction solutions at specific times) at 95 \({}^{\circ}\)C, 4000 mg/L phenol concentration, 0.4 g/L of HCL resin (**a**) and HCL nanocomposite (**b**). Figure 7: Phenol adsorption performance at Cphenol = 4000 mg/L with HCL resin CSolid = 0.4 g/L. result equal to 83.8%. The slight difference in the carbon removal efficiency obtained with GC/UV-vis and TOC evaluations is probably because of other species--e.g., hydroquinone--contribute, although weakly [65], to the 5.43% phenol residue evaluated through UV-vis. After 420 min a phenol removal of 99.9% was achieved indicating a quasi-complete depletion of phenol. In these conditions, a TOC conversion (\(\Delta\)TOC) of 86.5%, with a mineralization degree of 84.2%, was measured. At this time the phenol content in the reaction mixture was about 6.1% and the remaining \(\sim\) 93.9% consists of acetic acid. During phenol CWAO, hydroquinone is the primary intermediate, which is quickly oxidized to \(p\)-benzoquinone. It evolves mainly towards CO\({}_{2}\), while a lower amount oxidized in short-chain acids to, finally, give acetic acid and CO\({}_{2}\). We believe that we found for a longer time the presence essentially of acetic acid because it is a very refractory compound in CWAO conditions, even more at the soft conditions of our study, as it requires drastic conditions to be oxidized at some extent. Indeed, acetic acid can be considered a product in CWAO together with CO\({}_{2}\)[66; 67]. In Figure 9b, the results of catalytic tests for the abatement of phenol at a concentration of 4000 mg/L, and after 180 min reaction time, carried out in the presence of the nano-catalysts alone are reported.