Wet Peroxide Oxidation Research Articles

Lignin conversion into C4 dicarboxylic acids by catalytic wet peroxide oxidation using titanium silicalite-1

Lignin valorisation towards added-value products has become a relevant topic to consolidate a future circular bioeconomy. In this context lignin oxidation to C4 dicarboxylic acids (C4-DCA) by catalytic wet peroxide oxidation is emerging as a value-added strategy, supported by the extensive use of these building blocks in several industrial fields. In this work, lignins from different sources and processes (Indulin AT, Lignol, alkali and E. globulus kraft lignins) were oxidised using H2O2 and titanium silicalite-1 catalyst (TS-1) under different operating conditions (temperature, pH, time, H2O2, and TS-1 load). Indulin AT was the lignin leading to the highest succinic acid yield (11.3 wt%), and TS-1 catalyst enhanced its production four times over the non-catalysed reaction. Malic acid was also produced at high yields, especially for Lignol lignin. The other lignins (E. globulus kraft, and alkali lignins) also produced these C4 acids but at lower yields. The catalyst remained stable at the used experimental conditions, and showed potential to be reused for several cycles without being deactivated. Overall, the catalytic conversion of lignin to C4-DCA can help to guide the pathway to renewable chemicals production.

Characterization of microplastics in sediment using stereomicroscopy and laser direct infrared (LDIR) spectroscopy

The analysis of microplastics (MP) becomes more difficult for smaller sizes, especially in complex matrices such as sediment of natural waters. In this work, we analyzed MPs in sediment using laser direct infrared (LDIR) imaging, a relatively new technique in environmental MP studies. Sediment samples were spiked with analytical surrogates (polyethylene spheres), and subjected to density separation, wet peroxide oxidation, calcite removal, and filtration. The extracted particles were coated on to a low-emissivity glass slide which was first examined on a stereomicroscope. Six slides (two sediment samples and four different blanks) were further analyzed using an Agilent LDIR system. Approximately 520 and 430 MP/g were found in the two samples, with diameter ranging 20–3384 μm and 84% being smaller than 100 μm. The increase in particle count with decreasing particle sizes followed a power law curve, suggesting that a large portion of the smaller MPs was generated by the breakdown of larger plastic pieces. Major polymers found in this work included polyamide, polyester, polytetrafluoroethylene, and polyacetal. Most MPs were fragments, while beads and fiber were also found. In the two sediment samples, 14% and 46% of the total particles, respectively, were composed of non-plastic micro-sized particles, including natural polyamide, cellulose, chitin, rubber, and “unknown”. Challenges, potential biases, and uncertainties are discussed. This work is the first application of LDIR imaging on MPs in natural sediment.

Regeneration of odorous sulphur compound-exhausted activated carbons using wet peroxide oxidation: The impact of chemical surface characteristics

The efficiency of hydrogen peroxide in the regeneration of dimethyl sulphide (DMS) exhausted-activated carbons (ACs) is assessed in this study. Moreover, the influence of chemical surface composition is evaluated using six ACs (two commercial ACs and four chemically modified ACs) with different surface features. Chemical surface composition of ACs before and after different adsorption-regeneration cycles is assessed by temperature-programmed desorption coupled with mass spectroscopy (TPD-MS) and by diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). Results reveal that up to a 60% of regeneration efficiency is attained, being more effective in the presence of ACs derived from Filtrasorb 300 AC sample. Experimental findings show that ACs with high content of basic oxygen–containing functional surface groups and mineral fraction are responsible to promote the catalytic decomposition of hydroxide peroxide, leading to a higher formation of hydroxyl radicals and to the observed increase in the regenerative oxidation of adsorbed DMS. However, a decrease in removal efficiency is related to an increase in the amounts of oxygen functionalities mainly in the form of strong acidic surface groups such as carboxylic acid anhydrides and carboxylic acids that shift the reaction mechanism from promoting the initiation of radical chain reactions to termination. Additionally, DRIFTS analyses indicate that after successive adsorption-regeneration cycles the fraction of organic molecules that remains adsorbed limits the access to active surface sites responsible for radical generation, reducing drastically the catalytic activity of ACs.

Catalytic wet peroxide oxidation of phenolic wastewater on novel Cu/Mn-UiO-66@Al2O3 ceramic tube membrane catalysts

Novel Cu and Mn supported UiO-66@Al2O3 ceramic tube (UiO-66CT) membrane catalysts were synthesized by solvothermal method combined with secondary incipient wetness impregnation method and used for efficient catalytic wet peroxide oxidation (CWPO) of phenolic wastewater. Synthesis conditions of UiO-66CT were optimized by investigating the secondary soaking times and UiO-66 content. The experimental set-up based on a novel membrane reactor was designed for the catalytic activity evaluation of the ceramic tube catalysts. Results indicated that solvothermal time of 24 h and secondary soaking time of 1 h in the UiO-66 (12.8 g/L) can effectively shorten the synthesis time with a UiO-66 loading ratio about 2.0 wt% obtained. The SEM and EDS mapping results certificated the loading of UiO-66 in the macro-pores of the ceramic tube and the successfully supporting of Cu species on the UiO-66CT. The Cu-UiO-66CT catalysts exhibited good catalytic activity (Xphenol > 99% without toxic by-products detected in the final treated wastewater). By contrast, the Mn-UiO-66CT catalysts exhibited lower catalytic activity because of the fast decomposition of H2O2 on the MnO2 catalysts. The Cu-UiO-66CT catalyst showed excellent stability with phenol conversion (initial concentration of 500 ppm) kept above 90% after reused for 5 times. The immobilization of UiO-66 into the macro-pores of Al2O3 ceramic tube and the supporting of Cu species in the UiO-66CT can not only keep the high activity of MOFs catalysts but also enhance the stability of Cu-UiO-66 in the CWPO process. This research provides a promising strategy to solve the unstability of MOFs catalysts when used for the CWPO process of wastewaters.

Treatment of cork boiling wastewater by thermal wet oxidation processes

This work explores the feasibility of Fenton oxidation and Catalytic Wet Peroxide Oxidation (CWPO) at high temperature for the treatment of a complex cork-boiling wastewater (CBW) characterized by a high organic load (COD = 4906 mg/L) and substantial content of phenolics. Since CBW leaves the process at 100 °C, working at high temperature favors the integration of an on-site thermal water treatment, as explored in this work. Fenton oxidation of CBW at 100 °C employing 100 mg/L Fe2+ and the stoichiometric dose of H2O2 for complete mineralization (H2O2 = 9795 mg/L), yielded around 70% TOC removal after 180 min reaction. In CWPO, four different catalysts were tested, 0.5wt.%Fe/SiC, 4wt.%Fe/SiC, AC (activated carbon) and 4wt.%Fe/AC also at 100 °C. The Fe catalysts exhibited significant activity that makes possible the disposal of the treated water to the environment. Nonetheless, the occurrence of significant iron leaching jeopardizes their stability and the process implementation. On the contrary , AC showed a great stability as evidenced by the well maintained COD and TOC removal efficiencies of 78 and 58%,respectively, in a long term run (72 h) at 100 °C. Based on these results, CWPO at 100 °C using AC as catalyst can be considered a promising alternative for the integration of an on-site CBW treatment.

Insights of emerging contaminants removal in real water matrices by CWPO using a magnetic catalyst

The study was focused on the application of catalytic wet peroxide oxidation (CWPO) with a synthesized magnetic catalyst (Fe3O4/MWCNTs) for the treatment of real water matrices spiked with pharmaceutical compounds. CWPO was carried out by modifying the initial pH of surface water (SW), wastewater treatment plant (WWTP) effluent, brewery wastewater (BW) and hospital wastewater (HW), and the effect of the addition of the emerging pollutants naproxen (NAP) and diclofenac (DCF). From the experimental results, pH and concentration of NAP and DCF in CWPO were crucial factors in the successful pollutants removal from water matrices. The lab-prepared catalyst showed high removal rates of NAP and DCF from different water matrices spiked with the NAP-DCF mixture at pH 5.0. The highest average removal rate of TOC (75%), NAP (66%), DCF (76%), TN (39%) and aromaticity (68.39%) was obtained for SW matrix using 1.0 g L−1 of catalyst, pH ≈ 5.0, 5 mM of H2O2 and 60 °C. The mineralization decreased with the increase of the initial TOC concentration of the tested matrix. By CWPO tests of the real water matrices it was demonstrated that DCF removal was higher than NAP. From the recyclability tests, the catalyst demonstrated high activity and stability along three consecutive CWPO cycles of 8 h each one. The pseudo-second order model well-described the degradation of NAP and DCF. Finally, aromaticity and toxicity of the effluents were greatly reduced after CWPO treatment. This work demonstrated that CWPO with the magnetic catalyst is an efficient method to remove DCF-NAP mixtures from real aqueous matrices.

Degradation of ranitidine and changes in N-nitrosodimethylamine formation potential by advanced oxidation processes: Role of oxidant speciation and water matrix

This study investigated the effects of thirteen (photo/electro) chemical oxidation processes on the formation potential (FP) of N-nitrosodimethylamine (NDMA) during the chloramination of ranitidine in reverse osmosis (RO) permeate and brine. The NDMA-FP varied significantly depending on the pretreatment process, initial pH, and water matrix types. At higher initial pH values (> 7.0), most pretreatments did not reduce the NDMA-FP, presumably because few radical species and more chloramine-reactive byproducts were generated. At pH < 7.0, however, electrochemical oxidation assisted by chloride and Fe2+/H2O2, catalytic wet peroxide oxidation and peroxydisulfate-induced pretreatments removed up to 85% of NDMA-FP in the RO brine. Ultraviolet (UV) irradiation or prechlorination alone did not reduce the NDMA-FP effectively, but combined UV/chlorine treatment effectively reduced the NDMA-FP. In contrast, after UV irradiation (2.1 mW cm−2 for 0.5 h) in the presence of H2O2 and chloramine, NDMA formation increased substantially (up to 26%) during the post-chloramination of the RO permeate. Mass spectrometric analysis and structural elucidation of the oxidation byproducts indicated that compared with the reactive nitrogen species generated by UV/NH2Cl, sulfate radicals and (photo/electro)chemically generated reactive chlorine species were more promising for minimizing NDMA-FP. Unlike, the hemolytic •OH driven by UV/H2O2, the •OH from Fe(IV)-assisted pretreatments showed a significant synergistic effect on NDMA-FP reduction. Overall, the results suggest the need for a careful assessment of the type of radical species to be used for treating an RO water system containing amine-functionalized compounds.

Optimization of catalytic wet peroxide oxidation of carbofuran by Ti-LaFeO3 dual photocatalyst

In this study, a robustly dual catalyst of Ti-substituted LaFeO 3 (Ti-LaFeO3) was synthesized in a quest for developing a simultaneous photocatalytic wet peroxide oxidation (photo-CWPO). In this feature, Ti-LaFeO3 was utilized to degrade carbofuran (CBF) by photocatalysis and photo-Fenton processes under UV and visible light. EDX and XRD analyses confirmed the partial substitution of La by Ti in the lattice of LaFeO3. Other analyses such as SEM, TEM, HRTEM, SAED, and FTIR characterized the structure and morphology of the catalyst. Furthermore, the reflectance spectra indicated a remarkable bandgap of the modified catalyst (1.96 eV). Compared to pristine LaFeO3, Ti-LaFeO3 showed higher degradation of CBF due to the reduced bandgap. A central composite design was utilized for the optimization of the experimental parameters such as the CBF initial concentration, loading of Ti-LaFeO3, H2O2 dose, and pH. Under the optimal conditions (initial CBF concentration = 7.0 mg/L, catalyst loading = 700 mg/L, H2O2 dose = 480 mg/L, and pH 3.0), CBF removal was 90.6% after 180 min of the CWPO process. Furthermore, the catalyst was reused in five consecutive cycles to evaluate its stability. The leaching of iron was measured to assess its role in the degradation of CBF. The oxidation pathway of CBF was proposed according to the identified transformation products by tandem mass spectrometry. The mechanism investigation indicated an enhanced degradation of CBF by both photocatalytic and Fenton-like reactions using Ti-LaFeO3.

Efficient degradation of 4-chlorophenol over zirconium, nitrogen and sulphur doped cobalt nanoferrite catalysts

Cobalt ferrite and zirconium doped cobalt ferrite were prepared by coprecipitation method. Nirogen and sulphur ions were doped to it by wet impregnation and co precipitation techniques. The efficiency of the samples towards catalytic wet peroxide oxidation of 4-chlorophenol was checked. Doping increased the catalytic efficacy of cobalt ferrites towards the reaction; zirconium being the most efficient dopant. Complete conversion of 4-chlorophenol with appreciable reduction in chemical oxygen demand(COD) was noted at 50 °C with pollutant to hydrogen peroxide ratio of 1:15. Surface area and nature of the catalyst active surface played deciding role in the oxidation rreaction. The mechanism followed a heterogenous free radical catalysed path as evidenced from metal leaching and radical scavenging studies. The catalysts were magnetically recoverable and stable on repeated uses.

Catalytic wet peroxide oxidation degradation of magenta wastewater and preparation of FeOCl/montmorillonite.

The iron oxychloride/pillared montmorillonite (FeOCl/MMT) catalyst was prepared by wet impregnation method and solid melting method. Various characterization techniques were used to analyze the microscopic morphology and structure of a series of catalysts. Moreover, the catalysts were used to treat magenta-simulated dye wastewater through catalytic wet peroxide oxidation (CWPO) degradation. The magenta removal rate and chemical oxygen demand (COD) removal rate of the magenta-simulated dye wastewater were used to evaluate the catalytic performance of the catalyst, and the optimal catalyst preparation conditions were selected. The results showed that the solid melting method was more favorable to the preparation of the catalyst, and the COD removal rate of wastewater can reach 70.8% when the FeOCl load was 3%. Moreover, 96.2% of the magenta in the solution was removed. The COD removal rate of the magenta wastewater decreased by only 12.4% after the catalyst was repeatedly used six times, indicating that the catalyst has good activity and stability. The Fermi equation can simulate the reaction process of the catalyst treating magenta wastewater at high temperature.

Innovative iron oxide foams for the removal of micropollutants by Catalytic Wet Peroxide Oxidation: Assessment of long-term operation under continuous mode

This work aims to develop highly stable iron oxide foams for the continuous Catalytic Wet Peroxide Oxidation (CWPO) of micropollutants in a structured fixed-bed reactor. Homogeneity and adhesion of the active phase were achieved by adjusting the preparation methodology. Three structured catalysts based on Al2O3, SiC and ZrO2 foams were obtained with Fe content of 2.5%, 2.1% and 0.90% wt., respectively. The catalytic foams were tested in the CWPO of a mixture of three pharmaceuticals (metronidazole (MNZ), sulfamethoxazole (SMX) and carbamazepine (CBZ)), with a concentration of 100 µg L−1 each. The catalysts resulted active and stable up to 200h of CWPO carried out at ambient conditions, with the exception of Fe/ZrO2, which showed a progressive deactivation due to the iron leaching from the solid. An increase in space time led to an enhanced performance achieving remarkable conversion levels of 73%, 83% and 90% for MNZ, SMX and CBZ, respectively. The effect of H2O2 dose was also evaluated revealing the development of competing side reactions for supra-stoichiometric dosages. Moreover, the scavenging effect of the water matrix was assessed operating in presence of humic acid as representative natural organic matter (NOM). In this case, the conversion levels for SMX and CBZ resulted alike to the ones obtained for ultrapure water and only a slight decrease in MNZ removal rate was detected. After 400h of usage at different steady-state conditions, the outstanding catalytic performance of Fe/Al2O3 and Fe/SiC was sustained in the long-term operation.

Catalytic wet peroxide oxidation to remove natural organic matter from real surface waters at urban and rural drinking water treatment plants

Al/Fe-pillared-clay-activated catalytic wet peroxide oxidation (CWPO) of dissolved natural organic matter (NOM) in real surface water streams at both urban drinking water treatment plants (DWTPs) and rural plants (R) was investigated. The clay-catalyst prepared from technical-grade reagents exhibited textural properties quite comparable to those of the one obtained from analytical-grade, costly reagents. The mineralization of dissolved organic carbon (DOC) was improved to around 90 % under ambient conditions of temperature (10–19 °C) and pH (6.07–8.12), and not governed by adsorption of the complex on the catalyst’s surface. Optimal dose of hydrogen peroxide per unit mass of DOC and Fe in the solid was found to be 0.037 mg H2O2/mg C.mg Fe. The maximal efficiency of hydrogen peroxide consumption in the degradation of a synthetic surrogate of NOM (0.437 mg C/mg H2O2) was significantly enhanced in comparison with recent studies on phenol spiked solutions (≤0.124 mg C/mg H2O2), but also when real water samples were treated (0.176 mg C/mg H2O2), while the selectivity to DOC mineralization remained close to 90 %. Sulfates and chlorides in real surface waters showed the most detrimental effect on the DOC mineralization. The more cost-effective couplings of the Al/Fe-PILC-catalyzed CWPO treatment to improve urban drinking water treatment plants by promoting both DOC mineralization and improved H2O2 consumption as a function of the input SUVA254 were (raw water → CWPO → physicochemical treatment) for values < 2.0 dm3/mg DOC.m, and (raw water → physicochemical treatment → CWPO) for values > 2.0 dm3/mg DOC.m.

Corrigendum to Catalytic wet hydrogen peroxide oxidation of isoeugenol to vanillin using microwave-assisted synthesized metal loaded catalysts [Molecular Catalysis 506 (2021) 111537

Corrigendum to Catalytic wet hydrogen peroxide oxidation of isoeugenol to vanillin using microwave-assisted synthesized metal loaded catalysts [Molecular Catalysis 506 (2021) 111537

Alkali-Activated Materials as Catalysts for Water Purification

In this study, novel and cost-effective alkali-activated materials (AAMs) for catalytic applications were developed by using an industrial side stream, i.e., blast furnace slag (BFS). AAMs can be prepared from aluminosilicate precursors under mild conditions (room temperature using non-hazardous chemicals). AAMs were synthesized by mixing BFS and a 50 wt % sodium hydroxide (NaOH) solution at different BFS/NaOH ratios. The pastes were poured into molds, followed by consolidation at 20 or 60 °C. As the active metal, Fe was impregnated into the prepared AAMs by ion exchange. The prepared materials were examined as catalysts for the catalytic wet peroxide oxidation (CWPO) of a bisphenol A (BPA) aqueous solution. As-prepared AAMs exhibited a moderate surface area and mesoporous structure, and they exhibited moderate activity for the CWPO of BPA, while the iron ion-exchanged, BFS-based catalyst (Fe/BFS30-60) exhibited the maximum removal of BPA (50%) during 3 h of oxidation at pH 3.5 at 70 °C. Therefore, these new, inexpensive, AAM-based catalysts could be interesting alternatives for catalytic wastewater treatment applications.

Visible-Light Enhanced Catalytic Wet Peroxide Oxidation of Natural Organic Matter in the Presence of Al/Fe-Pillared Clay

An Al/Fe-pillared clay catalyst (Al/Fe-PILC) prepared from low cost technical-grade reagents has been investigated in the photocatalytic Wet Peroxide Oxidation (photo-CWPO) of dissolved Natural Organic Matter (NOM) under circumneutral pH. The successful pillaring of the layered clay material was confirmed by X-ray diffraction (XRD), N2 adsorption at −196 °C, cation exchange capacity (CEC) and simultaneous thermal analysis (TGA/DSC). High levels of mineralization of the dissolved organic carbon and color removal of a synthetic NOM surrogate solution were achieved even under natural lab’s lighting and ambient temperature and pressure, whereas the absence of radiation (in dark) was found to strongly affect the performance of the degradation. The photo-CWPO of NOM activated by the Al/Fe-PILC clay catalyst under visible light irradiation (LED lamp, 450 and 550 nm peaks) displayed a DOC mineralization of 72% and color removal of 73% in just 210 min of irradiation at neutral pH, whereas both responses decayed under ultraviolet lightning (λ: 365 nm) to 41% and 58%, respectively. This behavior is ascribed to formation of triplet states of natural organic matter (3NOM*) by absorption of visible light, which seems to synergistically improve the rate-determining step of the heterogeneous Fenton process, namely reduction of Fe3+ into Fe2+ on the surface of the clay catalyst. Interestingly, experiments performed at neutral and pH 3.0 showed very similar efficiencies under visible light irradiation; these findings may really facilitate the application of the photo-CWPO process to assist conventional drinking water treatment plants in the removal of NOM before the typical disinfection by chlorine to produce safer drinking water.

Delafossite-alumina nanocomposite for enhanced catalytic wet peroxide oxidation of anionic pollutants

Mass transfer efficiency and catalytic reactivity are the two major hurdles for heterogeneous catalytic wet peroxide oxidation (CWPO) technologies. To address these issues, nanocomposite CuFeO2/Al2O3 was synthesized and assessed as a novel catalyst for enhanced adsorption and oxidation of anionic pollutants (catechol and reactive red 195 (RR195)) in waters. With a positive charge on the nanocomposite by introducing Al2O3, the adsorption of anionic pollutants was promoted. The surface complexation reaction on CuFeO2/Al2O3, which fits well to the Langmuir isotherm, has engined the mass transfer of pollutants to the nanocatalyst that demonstrated 96.46% and 99.75% removal of catechol and RR195 at pH 3, respectively. CuFeO2/Al2O3 also showed good performance in various reaction media including binary pollutants system and real wastewaters. The hydroxyl radical in aqueous solution played a major role in the pollutants degradation. The CWPO, which followed the Haber-Weiss mechanism, has been accelerated by the Cu and Fe redox cycles. The robustness of the catalyst was verified by negligible amount of metal leaching from the catalysts along with stable catalytic performance after five cycles. Upon the observed results, CuFeO2/Al2O3 with the synergistic effect has shown to be a promising catalyst for removal and degradation of anionic pollutants in CWPO.

Preparation of Supported Perovskite Catalyst to Purify Membrane Concentrate of Coal Chemical Wastewater in UV-Catalytic Wet Hydrogen Peroxide Oxidation System.

The effective treatment of membrane concentrate is a major technical challenge faced by the new coal chemical industry. In this study, a supported perovskite catalyst LaCoO3/X was prepared by a sol–impregnation two-step method. The feasibility of the supported perovskite catalyst LaCoO3/X in the UV-catalytic wet hydrogen peroxide oxidation (UV-CWPO) system for the purification of concentrated liquid of coal chemical wastewater was investigated. The effects of catalyst support, calcination temperature, calcination time, and re-use time on catalytic performance were investigated by batch experiments. The catalysts were characterized by X-ray diffraction (XRD), Scanning electron microscopy (SEM), Brunauer–Emmett–Teller (BET), and X-ray photoelectron spectroscopy (XPS). Experimental results showed that the supported perovskite catalyst LaCoO3/CeO2 prepared using CeO2 as support, calcination temperature of 800 °C, and calcination time of 8 h had the best catalytic effect. The catalytic performance of the catalyst remained excellent after seven cycles. The best prepared catalyst was used in UV-CWPO of coal chemical wastewater membrane concentrate. The effects of H2O2 dosage, reaction temperature, reaction pressure, and catalyst dosage on UV-CWPO were determined. Under the conditions of H2O2 dosage of 40 mM, reaction temperature of 120 °C, reaction pressure of 0.5 MPa, catalyst dosage of 1 g/L, pH of 3, and reaction time of 60 min, the removal efficiencies of COD, TOC, and UV254 were 89.7%, 84.6%, and 98.1%, respectively. Under the optimal operating conditions, the oxidized effluent changed from high toxicity to non-toxicity, the BOD5/COD increased from 0.02 to 0.412, and the biodegradability of the oxidized effluent was greatly improved. The catalyst has a simple synthesis procedure, excellent catalytic performance, and great potential in the practical application of coal chemical wastewater treatment.

Magnetite-Based Catalyst in the Catalytic Wet Peroxide Oxidation for Different Aqueous Matrices Spiked with Naproxen–Diclofenac Mixture

Magnetite supported on multiwalled carbon nanotubes catalysts were synthesized by co-precipitation and hydrothermal treatment. The magnetic catalysts were characterized by X-ray diffraction, Fourier-transform infrared spectrometry, thermogravimetric analysis and N2 physisorption. The catalysts were then tested for their ability to remove diclofenac (DCF) and naproxen (NAP) from an aqueous solution at different conditions (pH, temperature, and hydrogen peroxide) to determine the optimum conditions for chemical oxidation. The optimization of the process parameters was conducted using response surface methodology (RSM) coupled with Box–Behnken design (BBD). By RSM–BBD methodology, the optimal parameters (1.75 mM H2O2 dosage, 70 °C and pH 6.5) were determined, and the removal percentages of NAP and DCF were 19 and 54%, respectively. The NAP–DCF degradation by catalytic wet peroxide oxidation (CWPO) was caused by •OH radicals. In CWPO of mixed drug solutions, DCF and NAP showed competitive oxidation. Hydrophobic interactions played an important role during the CWPO process. On the other hand, the magnetic catalyst reduced its activity after the second cycle of reuse. In addition, proof of concept and disinfection tests performed at the operating conditions showed results following the complexity of the water matrices. In this sense, the magnetic catalyst in CWPO has adequate potential to treat water contaminated with NAP–DCF mixtures.

Application of artificial intelligence for predicting reaction results in advanced oxidation processes

Response surface methodology (RSM) was used to predict total organic carbon (TOC) removal in advanced oxidation processes in wastewater-treatment fields. Because the disadvantage of RSM was poor generalization ability, we experimented with applying an Artificial neural network (ANN) to the processes. From RSM experimental data results, we found that ANN had better prediction ability than RSM. In catalytic wet air oxidation, the TOC-removal Mean square error (MSE) based on an ANN testing set was 6.10, which was smaller than that based on RSM (11.89), and the Isophorone-conversion MSE based on an ANN testing set was 0.31, which was also smaller than that based on RSM (3.13). In catalytic wet peroxide oxidation, the RSM-predicted TOC removal was 81.67%, which was not as close to the experimental TOC removal (91.4%) as the 88.40% attained by ANN. In wet electrocatalytic oxidation, the ANN-based prediction of TOC removal was 90.46%, which is closer to the experimental value (88.88%) than RSM-based 92.13%, whereas ANN-based prediction of chemical oxygen demand removal was 93.81%, which was closer to the experimental value (91.82%) than the RSM-based 94.33%. In conclusion, ANN had great potential for the future of chemistry and the chemical industry.

Developing Fe/zeolite catalysts for efficient catalytic wet peroxidation of three isomeric cresols.

Five Fe/zeolite (i.e., Fe/ZSM-5-1, Fe/ZSM-5-2, Fe/ZSM-5-3, Fe/MCM-22, and Fe/MOR) were prepared and tested as catalysts in the catalytic wet peroxide oxidation process (CWPO). Their adsorption and catalytic effects on the removal of three isomeric cresols were systematically explored. Sufficient characterizations were carried out to illuminate the iron species dispersed on the catalysts' surface porous channels. Other properties of the catalysts such as the Si/Al ratio, crystalline structures, and morphologies were systematically studied. After loaded with iron, the catalysts maintained zeolite's framework, which possessed specific porous structures and surface areas. Interestingly, the Si/Al ratio seemed to be an important issue influencing the adsorption and catalytic degradation of cresols due to n-π interaction and the acceleration of HO• generation, respectively. The amount of framework-Fe and Fe3+Al-Si in Fe/ZSM-5-3 was the most, which was crucial for its better catalytic ability than the other Fe/ZSM-5 catalysts (71.19% for m-cresol conversion). In conclusion, the catalytic activities of all the Fe/zeolites followed the sequence: Fe/ZSM-5-3> Fe/ZSM-5-2> Fe/ZSM-5-1> Fe/MCM-22>Fe/MOR. For three cresols, m-cresol was more susceptible to the attack of HO• than p- and o-cresol because more positions of m-cresol could be easy to be approached by the oxidizing agent. Considering the mild reaction condition in this study, such as 30 °C, pH=4.0, and catalyst dosage=1.0 g/L, the Fe/ZSM-5-3 was a promising zeolite catalyst for the degradation of refractory contaminants in practical wastewater.