Phenolic Wastewater Research Articles

Enhanced Photocatalytic Decomposition of Phenol in Wastewater by Using La-Tio2 Nanocomposite

Enhanced Photocatalytic Decomposition of Phenol in Wastewater by Using La-Tio2 Nanocomposite

Low-cost Y-type zeolite/carbon porous composite from coal gasification fine slag and its application in the phenol removal from wastewater: fabrication, characterization, equilibrium, and kinetic studies.

As an industrial solid waste, coal gasification fine slag (CGFS), which consists of many elements, such as silicon, aluminum, and carbon, could be used as an important resource. Therefore, this solid waste was used as a raw material to prepare high-value-added adsorption material for the treatment of industrial wastewater in this study. A hydrothermal synthesis method was applied to convert CGFS into a Y-type zeolite/carbon porous composite. The effects of time and temperature on the synthesis were studied. XRD, SEM, and other techniques were used to analyze the material and its physicochemical properties. Additionally, the adsorption performance of the material for phenol was studied. The results showed that the composite has better adsorption capacity for phenol than CGFS. The Freundlich model and pseudo-second-order kinetics well fitted the adsorption behavior of the composite, which demonstrated that the adsorption of phenol was dominated by chemical adsorption.

Photocatalytic Degradation of Phenol in Wastewater: A Mini Review

A major public health concern in many developing countries, including Nigeria, is the quality of their water supply. Everything a live entity does depends on water, a fundamental component of the biosphere. To ensure that water is safe for industrial and home use, it must be treated before consumption. However, phenolic compounds are found in our water bodies due to the polluted wastewater from industrial, agricultural, and home activities. Nature also has a role in their occurrence. These substances are poisonous and can cause long-term harm to both humans and animals. This paper reviewed research on the photodegradation of phenol utilizing nanoparticles in water treatment. This provides additional information and facts on cost-effective methods of treating wastewater and mineralizing phenol into valuable chemicals.

Efficient degradation of phenolic wastewaters by a novel Ti/PbO2-Cr-PEDOT electrode with enhanced electrocatalytic activity and chemical stability

• A novel Ti/PbO 2 -Cr-PEDOT electrode was fabricated via electrodeposition method. • The phenol degradation efficiency and TOC removal efficiency were 100% and 95.02%. • The Ti/PbO 2 -Cr-PEDOT electrode had good electrochemical stability. • The possible mechanism of electrocatalytic degradation of phenol was proposed. Novel Ti/PbO 2 -Cr-PEDOT electrodes were prepared by electrodeposition for electrochemical degradation of phenolic wastewater. The electrodes were characterized by XRD, SEM-EDS, XPS, and FT-IR to study the crystalline, surface morphology, elements distribution, and microstructure of the electrodes. A flat and compact interface was obtained with Cr and PEDOT doping into β-PbO 2 plate by electrodeposition method. The linear sweep voltammetry (LSV) and electrochemical impedance spectroscopy (EIS) were conducted to explore the electrochemical performance of the prepared electrodes. The Ti/PbO 2 -Cr-PEDOT electrode exhibited a higher oxygen evolution potential (OEP, 2.53 V vs SCE) and a lower charge transfer resistance compared with Ti/PbO 2 . Phenol degradation efficiency of 100% and TOC removal rate of 95.02% were achieved in the electrochemical degradation of phenol within 120 min. The optimal process parameters (phenol concentration = 1000 mg·L -1 , electrolyte concentration = 4.0 g·L -1 , current density = 15 mA·cm −2 and electrode distance = 3 cm) in the process of electrochemical oxidation of phenol wastewater were explored. Active species trapping experiments proved that ·OH radicals played an important role in the electrochemical system. Furthermore, the electrode also showed high activity for the degradation of other phenolic wastewaters such as phloroglucinol (η DEP = 100%), bisphenol A (η DEP = 97.17%) and p-chlorophenol (η DEP = 89.77%) within 60 min. A possible degradation pathway was proposed based on the intermediate products determined by HPCL. The Ti/PbO 2 -Cr-PEDOT electrode showed excellent stability with only 3% loss of degradation efficiency (η DEP = 96.95%) after recycling tests for 5 times. These results suggest that Ti/PbO 2 -Cr-PEDOT is a promising electrode for electrochemical degradation of phenolic wastewaters.

Persulfate oxidation enhanced extraction to improve the removal of high concentration phenol wastewater

An efficient and low-cost method for utilization of waste sludge and treatment of high salt and high phenol wastewater.

Yacon (Smallanthus sonchifolius) peel as a promising peroxidase source for the treatment of phenolic wastewater

Peroxidases are versatile enzymes that catalyse the oxidation of many inorganic and organic substrates. There are numerous vegetable sources of peroxidases, including the yacon (Smallanthus sonchifolius), an easy-to-grow plant. This study aimed to extract, purify and characterise the peroxidases obtained from yacon roots. We partially purified the enzyme from yacon pell using an aqueous two-phase system (ATPS) and obtained 4.66 purification-fold and 33.87% activity recovery. The enzyme showed an optimal temperature of catalysis 60 °C and optimal pH 11 using pyrogallol as substrate. Considering the oxidation of 2,4-dichlorophenol, these conditions were 37.5 °C and pH 7. Furthermore, the enzyme presented substrate inhibition at high hydrogen peroxide concentrations. The presence of 5 mM Cu2+ inhibited, while and 5 mM Co2+ activated the enzyme. The enzyme remained stable at 50 °C for 60 min and showed improved thermostability compared to horseradish peroxidase. The kinetic mechanism of yacon peroxidase was investigated, and our studies suggested the enzyme follows a Ping-Pong Bi–Bi mechanism. Finally, 2,4-dichlorophenol was selected as a target pollutant, and we obtained as many as 86.26% of bioconversion using yacon peroxidase. The results presented in this article suggest that yacon is a promising source of peroxidase and can be an alternative for bioprocesses applications.

Design of solvent mixtures for removal of phenol from wastewater using a non-linear programming model with a multi-start method

The optimization-based design of solvent mixtures used for phenolic wastewater treatment was investigated in this work. A nonlinear programming （NLP） model was formulated based on the concepts of computer-aid molecule design (Computer-Aided Molecular Design, CAMD) to select solvent mixtures with the best extraction performance considering the constraints of extraction process and the environmental impact. Due to the complexity of the NLP model, multi-start method was adopted to solve this problem in order to get near global optimal solution. The results of the calculations suggested that the optimal mixture consisted of 70.1% n-octanol and 29.9% 2-octanone (molar fraction).The 119 sets of experimental results showed that the extraction ability of the optimal solvent mixture identified by CAMD technique was among the top 6 sets compared to the experiment results. The results suggested that the developed NLP model could be able to screen the optimal solvent mixture in phenolic wastewater treatment.

Investigation and evaluation of membrane fouling in a microbial fuel cell-membrane bioreactor systems (MFC-MBR)

Two membrane bioreactors with and without adding an electric circuit (named as MFC-MBR and C-MBR, respectively) were established to investigate the effects of micro-electric field on membrane fouling. With the aeration rate of 1.5 L/min, the synergistic effect of aeration and micro-electric field was the best in reducing membrane fouling and COD in treatment of a simulated phenol wastewater. Compared with C-MBR, the running time of MFC-MBR was extended for 16 days. Scanning electron microscope (SEM) and energy-dispersive X-ray detector (SEM-EDX) demonstrated that less foulants were attached to the membrane and the attachment was loosend in MFC-MBR. The decreased absolute value of zeta potential indicated repulsion among the negatively-charged sludge particles was reduced and flocculation of the sludge was improved, which alleviated the membrane fouling. The soluble microbial products (SMP) and loosely-bound extracellular polymeric substances (LB-EPS) were also decreased in MFC-MBR. It was found that migration and neutralization of the negatively-charged particles, and degradation of microorganisms contributed to the alleviation of membrane fouling. Moreover, the decreases of carbohydrates in LB-EPS led to higher protein/carbohydrates (PN/PS) ratio, which was a key parameter for alleviating membrane fouling. Meanwhile, the increase of tightly bound extracellular polymeric substances (TB-EPS) could also slow down membrane fouling. Because TB-EPS can be used as a binder to strengthen the flocculation of sludge particles.

Preparation and characterization of a novel Ni-doped TiO2 nanotube-modified inactive electrocatalytic electrode for the electrocatalytic degradation of phenol wastewater

A Ni-TiO2-NTs substrate and SnO2-Sb catalytic layer are formed on a Ni-Ti surface by the anodic oxidation method and sol-gel method, respectively, and a Ni-Ti/Ni-TiO2-NTs/SnO2-Sb electrode is successfully prepared for use as an electrocatalytic oxidation anode for wastewater treatment. Scanning electron microscopy (SEM) analysis shows that the Ni-TiO2-NTs base layer has a highly ordered and vertically formed nanotube array morphology, and the SnO2-Sb catalyst layer has a uniform and dense nanoparticle morphology. X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) analyses show that the base layer is made of Ni-TiO2 and the catalyst layer consists of SnO2-Sb. Electrochemical analysis shows that the oxygen evolution potential (OEP) of the electrode is increased to 2.3 V, and the working life is extended to 653 h. Using phenol as the treatment target, the phenol degradation rate reaches 87% in 3 h, and the COD removal rate reaches 54.2%. Compared with the traditional Ti/SnO2-Sb electrode, the current efficiency increases by 1.57 times, and the energy consumption decreased by 59.92%. Therefore, the Ni-Ti/Ni-TiO2-NTs/SnO2-Sb electrode is a promising electrochemical anode material for the treatment of phenol wastewater.

Enhancing electronic metal support interaction (EMSI) over Pt/TiO2 for efficient catalytic wet air oxidation of phenol in wastewater

Phenol is one of the major hazardous organic compounds in industrial wastewater. In this work, a highly active Pt/TiO2 catalyst for catalytic wet air oxidation (CWAO) of phenol was obtained by supporting pre-synthesized Pt on TiO2. During the followed hydrogen reduction, strong hydrogen spillover occurred without the migration of TiO2 onto Pt. The reduced support then enhanced the electron transfer from TiO2 to Pt, increasing the percentage of partially negative Pt (Ptδ-), which has been confirmed by XPS. The strong EMSI made the obtained catalyst far more active than Pt/TiO2 prepared by impregnation method. The electron-enriched Pt/TiO2 achieved total organic carbon (TOC) conversion of 88.8% and TOF 149 h−1 at 100 °C and 2 MPa O2, while conventional Pt/TiO2 gave TOC conversion of 39.5% and TOF 41 h−1 for CWAO of phenol. Our work indicates that the enhancement of EMSI between metal and support can be an effective approach to develop highly active catalysts for phenol treatment.

Mushroom tyrosinase immobilized in metal–organic frameworks as an excellent catalyst for both catecholic product synthesis and phenolic wastewater treatment

AbstractBACKGROUNDMetal–organic frameworks (MOFs) have gained increasing attention with ever‐expanding applications. Developing new MOF‐based immobilized enzymes with new applications is required, not only for demonstrating the generality and applicability of using MOFs for enzyme immobilization, but also to provide potential biocatalysts for industrial applications. To the best of the authors’ knowledge, this is the first report of immobilizing mushroom tyrosinase on zeolitic imidazolate frameworks (ZIFs), with two new applications being developed.RESULTSUpon immobilization through a one‐pot in situ encapsulation approach, the resultant tyrosinase@ZIF‐8 was characterized in structural features and catalytic properties. It was much more stable against pH and temperature relative to the free enzyme. The new biocatalyst was highly efficient in catalyzing the synthesis of catecholic products with pharmacological benefits (l‐DOPA, piceatannol and 3′‐hydroxypterostilbene) and in eliminating phenolic pollutants (phenol, p‐cresol, p‐chlorophenol). Excellent productivities were obtained for the synthesis of the three catecholic products (0.14, 1.38 and 1.46 g L−1 h−1, respectively). A complete removal of the three phenolic pollutants was achieved within 2.5 h, superior to other processes mediated by the same enzyme, or others, immobilized on different supports. The reusability of the new biocatalyst can be remarkably improved by entrapment into polyvinyl alcohol‐alginate gel.CONCLUSIONSTyrosinase can be immobilized on a new type of MOF with advantages such as easy preparation and excellent catalytic performance. This novel immobilization strategy for tyrosinase offers an excellent biocatalyst potent for both catecholic product synthesis and phenolic wastewater treatment. © 2021 Society of Chemical Industry (SCI).

Persulfate enhanced electrochemical oxidation of phenol with CuFe2O4/ACF (activated carbon fibers) cathode

Phenol wastewater is threatened to human living environment and should been treated carefully before discharging into the environment. For my research, electrochemical (EC) oxidation of phenol using CuFe2O4/ACF cathode and mixed metal oxide (RuO2/Ti) anodes was investigated. In order to increase the EC oxidation efficiency of phenol, persulfate (PS) was added into the EC system. Various systems including EC-1 oxidation (RuO2/Ti cathode and RuO2/Ti anode), EC-2 oxidation (ACF cathode and RuO2/Ti anode), EC-3 oxidation (ACF cathode and RuO2/Ti anode, adding CuFe2O4 particle), PS oxidation (only adding PS) and EC/PS oxidation (CuFe2O4/ACF cathode and RuO2/Ti anode, adding PS) for phenol removal were compared, and the removal efficiency of phenol was determined to be 19%, 25%, 46%, 43 and 85%, respectively. Effects of K2S2O8 concentration, current density and initial pH on the removal efficiency of phenol were analyzed. The optimal phenol removal efficiency (97%) was achieved after 60 min reaction under conditions: PS concentration of 1.00 mM, current density of 50 A/m2, and initial pH of 7.0. The generation of reactive oxidant species in solution was confirmed by the electron spin resonance technique, which was in accord with the radical quenching experiments results, indicating that oxidation of phenol was assigned to radical oxidation and non-radical oxidation processes.

Performance deterioration of Sb-SnO2/C membrane anode treating phenolic wastewater and anode regeneration: Adsorption and physicochemical change of catalysts

• The removal performance of Sb-SnO 2 /C for phenol deteriorated with time. • The adsorption of benzoquinone had a significant impact on phenol degradation. • Sn(OH) 4 and decreased crystallinity of SnO 2 also led to performance deterioration. • The degradation performance was fully restored after cleaning and recalcination. Stability of anodes is the core of electrochemical oxidation (EO), but there still lacks systematic investigation on the stability of anodes under the conditions of long-term wastewater treatment. Sb-SnO 2 anode was selected for investigation in this study due to its outstanding electrocatalytic activity. The sol–gel method was utilized to coat the Sb-SnO 2 onto a carbon membrane to form the Sb-SnO 2 /C membrane anode, and its stability during long-term treatment of phenol was studied in an electrocatalytic membrane reactor. The results showed that the COD removal efficiency of Sb-SnO 2 /C dropped from 80.6% to 41.3% after 6 days. Carbonaceous intermediates were found to be adsorbed onto Sb-SnO 2 /C, mainly including aromatic intermediates and fatty acids. The adsorption of benzoquinone had a significant adverse impact on the phenol degradation of Sb-SnO 2 /C, leading to a decreased COD removal efficiency. The formation of Sn(OH) 4 , decreased crystallinity of Sb-SnO 2 , and the reduced Sb/Sn of the used Sb-SnO 2 /C were also proposed to lead to the performance deterioration. NaOH cleaning (pH = 11.9) was able to remove the adsorbed carbonaceous intermediates and improved the COD removal from 41.3% to 64.3%. Recalcination after chemical cleaning could further improve the COD removal efficiency to 89.7%, close to the initial value.

Novel core-shell Fe-UiO-66/silicalite-1 catalysts for efficient degradation of phenolic wastewater

Novel Fe supported core-shell catalysts, composite materials of metal-organic frameworks (UiO-66) and zeolite (Silicalite-1), were designed for efficient catalytic wet peroxide oxidation of phenolic wastewater. The core-shell materials using UiO-66 and Silicalite-1 as the core layer or shell layer were prepared by secondary synthesis method and characterized by SEM, TEM, EDS mapping, XRD and FT-IR. The Fe species (5 wt%) supported core-shell catalysts were prepared by incipient wetness impregnation method. Characterization results certificated the successful preparation of core-shell catalysts, namely, Fe-UiO-66/Silicalite-1 (UiO-66 as the core material) and Fe-Silicalite-1/UiO-66 (Silicalite-1 as the core material). Meanwhile, the Fe supported core-shell catalysts exhibited good catalytic activity with complete phenol degradation and TOC conversions of 66% and 69% over the Fe-UiO-66(25)/Silicalite-1 and Fe-Silicalite-1(25)/UiO-66, respectively, without poisonous by-products detected in the treated wastewater, which further proved the green characteristic of the catalysts. The Fe leaching concentration in the treated solution over the Fe-UiO-66/Silicalite-1 and Fe-Silicalite-1/UiO-66 catalyst is 0.235 ppm and 0.352 ppm which certificated the enhanced stability of the MOFs Fenton catalysts by preparing the supported core-shell catalysts.

Synthesis of Pd/CeOx/Nano-graphite composite cathode for electro-catalytic degradation of phenol

To improve the cathode electro-catalytic degradation performance of electrochemical advanced oxidation processes (EAOP), Pd metal and CeOx co-modified Nano-graphite (Pd/CeOx/Nano-G) composite was synthesized by chemical precipitation and reduction methods, and Pd/CeOx/Nano-G cathode was prepared by a hot-pressing method. The as-prepared composite and electrode were characterized by X-ray photoelectron spectroscopy, X-ray diffraction and scanning electrons microscopy. Results revealed that the mix-crystal structural CeOx (Ce2O3 and CeO2) and Pd0 metal were formed. The cathode was applied for the electro-catalytic degradation of phenol wastewater. The degradation efficiency of phenol by Pd1.0/CeOx5.0/Nano-G cathode reached 99.6% within 120 min degradation, which were higher than that of CeOx5.0/Nano-G and Nano-G cathodes. Both of the Pd metal and CeOx could improve the O2 reduction to H2O2 and promote the H2O2 dissociation to •OH for phenol oxidation. Additionally, the effects of electro-catalytic reaction parameters on the phenol degradation were investigated. The results indicated that Pd/CeOx/Nano-G cathode would have promise for further practical application in organic wastewater treatment.

Experimental study of manganese dioxide doped with metal for the treatment of phenolic wastewater

The wastewater containing phenol is harmful, and the process is complicated, photocatalytic oxidation technology is believed to be the greenest and promising strategy for contaminants removal because of the solar energy utilization and no additional oxidants. Herein, manganese dioxide(MnO2) doped with metal was fabricated by a low-temperature hydrothermal method, the specific surface area of MnO2 photocatalyst was significantly enhanced by doping metal ion. This making the photocatalytic performance improved obviously, and further applying for phenol degradation under visible light irradiation at room temperature.

Effect of Culture Condition and Growth Kinetics on Phenol Biodegradation by an Indigenous Rhodococcus pyridinivorans Strain PDB9T NS-1

The US Environmental Protection Agency listed phenolic compounds as priority pollutants, and their occurrence in water systems poses serious health risks to humans and other living species. The culture conditions are extremely crucial for microbial growth, enzymatic and cellular metabolic activities. Thus, the effects of different culture parameters like pH, temperature (°C), and agitation speed (RPM) on the indigenous Rhodococcus pyridinivorans strain PDB9T NS-1 were modeled using response surface methodology (RSM) and central composite design (CCD). The results showed that the main effect of pH and interaction between pH and agitation speed had a significant to a moderately significant effect on phenol degradation by the indigenous R. pyridinivorans strain PDB9T NS-1. Almost complete phenol degradation was obtained at an optimal setting of pH 7.5, 187 rpm, and 34 °C in 18 h. Growth and phenol degradation kinetics of the actinomycetes was examined in a batch shake flask under the optimized conditions. The growth of Rhodococcus species at varying initial levels of the phenol followed a Pamukoglu and Kargi substrate inhibition model with half-saturation constant (Ks ) of 54.21 mg/l, maximum specific growth rate (µ max) of 0.169 (1/h), substrate inhibition constant (Ksi ) of 243.26 mg/l. The results obtained from the optimization of culture conditions and growth kinetics by the indigenous R. Pyridinivorans strain PDB9T NS-1 suggest the potential of the system in the treatment of phenolic wastewater.

Cu(II) doped FeOCl as an efficient photo-Fenton catalyst for phenol degradation at mild pH

In this work, the Cu(II) doped iron oxychloride composites (Cu-FeOCl) were successfully synthesized and applied to the photo-Fenton degradation of phenol for the first time. Effect of various objective parameters on catalytic performance have been systematically evaluated, such as the doping amount of Cu(II), catalyst dose, pH value and H2O2 dose. The Cu(II) doping in FeOCl accelerated significantly the decomposition of H2O2 to generate hydroxyl radicals (•OH). Furthermore, the introduction of Cu(II) would produce lattice defects on the surface of FeOCl, which was benefit for the separation efficiency of the photogenerated electron-hole pairs. The 0.5Cu-FeOCl composite exhibited excellent degradation performance over a wide pH range of 3–8. The 0.5Cu-FeOCl/H2O2/Vis system degraded 95.2% of phenol (20 mg/L) within 14 min and removed 79.9% TOC within 120 min with low dosage of H2O2 (3 mM). The main intermediates of phenol degradation were identified by LC-MS, and a possible photo-Fenton catalytic mechanism for phenol degradation by 0.5Cu-FeOCl catalyst was proposed. This study would provide some new insights into developing photo-Fenton catalysts and treatment of phenolic organic wastewater.

Fe-Mn doped powdered activated carbon pellet as ozone catalyst for cost-effective phenolic wastewater treatment: Mechanism studies and phenol by-products elimination

A novel bimetallic doped PAC (Fe-Mn/PAC) pellet was prepared with a facile sol-gel method and used as an ozone catalyst for phenolic wastewater (PWW) treatment. Adoption of Fe-Mn/PAC pellet in microbubble ozonation enhanced the 1-h chemical oxygen demand (COD) and phenol removal in PWW to 79% and 95%, respectively. With ozone dosage of 10 mg/L, 1 g/L Fe-Mn/PAC pellet exhibited ozone conversion of 92%. In comparison to microbubble ozonation process, Fe-Mn/PAC induced microbubble-catalytic ozonation process promoted ozone decomposition rate by 1.9 times. In terms of •OH production, Fe-Mn/PAC pellet enhanced •OH exposure by 10 times, with a Rct value of 2.92 × 10 -8. Rct kinetic model also suggested that Fe-Mn/PAC pellet obtained higher kinetic rate constants for initiating and promoting •OH generation. Usage of Fe-Mn/PAC pellet in microbubble ozonation for phenolic wastewater treatment also reduced the total ozone consumption by 70%. In Fe-Mn/PAC induced microbubble-catalytic ozonation process, the ratio between ozone consumption and COD removal (ΔO3/ΔCOD) was 0.91. Fe-Mn/PAC pellet characterization with X-ray photoelectron spectroscopy (XPS), Fourier-transform infrared (FT-IR) and X-ray powder diffraction (XRD) analysis revealed successful doping of Fe-Mn on PAC substrate and larger numbers of carbon-oxygen/hydroxyl surface groups, which played key roles in ozone decomposition and •OH production.

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.