Orange II Degradation Research Articles

Optimizing orange II wastewater treatment: Unveiling the catalytic potential of nitrate and iodide ions in ultraviolet photolysis

The rapid ultraviolet photolysis of Orange II (OII) was investigated in a simulated wastewater containing nitrate and iodide ions (UV/NO3−-I− system). The study examined the various factors influencing OII degradation. Direct photolysis was found to have a negligible impact, and OII degradation primarily relied on indirect photolysis. In the UV/NO3−-I− system, OII was completely removed, and the kinetic constants for this system were 5.3 and 3.3 times higher than those for the UV/I− and UV/NO3− systems, respectively. Active substance quenching experiments and electron paramagnetic resonance spectroscopy revealed that hydroxyl radicals played a crucial role in OII degradation. The degradation pathway of OII was proposed using density functional theory calculations and liquid chromatography-mass spectrometry. The figure-of-merit electrical energy per order for the UV/NO3−-I− system was significantly lower than the UV/I− and UV/NO3− systems. Toxicity analysis also showed that UV/NO3−-I− system reduced ecotoxicity of OII. Therefore, the UV/NO3−-I− system holds promise for practical applications in the degradation of organic pollutants.

Survey of catalytic performance of TiO2 via coupling with ZSM-5 Zeolite under UV light for activation of peroxymonosulfate Applied towards Orange II (OII) degradation

Background: The widespread presence of organic dyes in the various industries’ effluent such as paper, textile, and clothing has led to significant environmental pollution. Titanium oxide (TiO2 ) nanoparticles immobilized on zeolite (ZSM-5) were investigated under UV light for activation of peroxymonosulfate (PMS) for photocatalytic degradation of Orange II (OII) dye in aqueous solutions. Methods: In this study, the photocatalyst used was prepared by immobilizing different amounts of TiO2 nanoparticles on ZSM-5. Characterization analyses including X-ray diffractometer (XRD), Fourier transform infrared (FTIR), BET, scanning electron microscope (SEM), and energy dispersive X-ray spectroscopy (EDS) were performed on the synthesized samples. Then, the effect of various parameters, such as TiO2 nanoparticles loading onto the ZSM-5, pH, contact time, dye concentration, and TiO2 / ZSM-5 dosage, is investigated for the removal of OII as a model molecule under the UV irradiation with 15 W power. Results: The highest removal percentage of OII dye (97.44%) was obtained in the optimal operating conditions of pH=3, the initial dye concentration=5 ppm, amount of TiO2 /ZSM-5=10 mg/L, amount of PMS=50 mg/L, and reaction time=120 minutes. The Langmuir–Hinshelwood kinetics model fitted with the experimental data. Conclusion: The obtained results of this research showed that PMS can be used as a suitable oxidant activated with ZSM-5/TiO2 nanocomposite in OII degradation in different water environments, by optimizing the effective operating factors.

Efficient degradation of the refractory organic pollutant by underwater bubbling pulsed discharge plasma: performance, degradation pathway, and toxicity prediction.

It is essential to develop an efficient technology for the elimination of refractory contaminants due to their high toxicity. In this study, a novel underwater bubbling pulsed discharge plasma (UBPDP) system was proposed for the degradation of Orange II (OII). The degradation performance experiments showed that by enhancing the peak voltage and pulse frequency, the degradation efficiency of OII increased gradually. The removal efficiencies under different air flow rates were close. Reducing OII concentration and solution conductivity could promote the elimination of OII. Compared with neutral and alkaline conditions, acidic condition was more beneficial to OII degradation. The active species including ·OH, ·O2-, 1O2, and hydrated electrons were all involved in OII degradation. The concentrations of O3 and H2O2 in OII solution were lower than those in deionized water. During discharge, the solution pH increased while conductivity decreased. The variation of UV-vis spectra with treatment time indicated the effective decomposition of OII. Possible degradation pathways were speculated based on LC-MS. The toxicity of intermediate products was predicted by the Toxicity Estimation Software Tool. Coexisting constituents including Cl-, SO42-, HCO3-, and humic acid had a negative effect on OII removal. Finally, the comparison with other technology depicted the advantage of the UBPDP system.

In situ formation of MnO2/Ni(OH)2@nickel foam with porous architecture for triggering persulfate-based advanced oxidation process

MnO2/Ni(OH)2 was grown in situ on three-dimensional nickel foam (NF), which was then used to activate potassium persulfate (PS) for orange II (OII) degradation. The structure and morphology of the prepared materials were characterized by X-ray diffraction, field emission scanning electron microscopy and transmission electron microscopy. The removal efficiency of OII was 98.68% with MnO2/Ni(OH)2@NF/PS system in 40 min. The three-dimensional hierarchical structure of mesoporous material promoted the efficient and fast electron transfer during catalytic activity. Based on classical quenching experiments and the electron spin resonance experiments, ·OH and SO4·− were identified as the active species in MnO2/Ni(OH)2/NF/PS system for OII degradation and a degradation mechanism was proposed for this system. Compared with traditional micro-nano particle catalysts, 3D MnO2/Ni(OH)2@NF has the advantages of convenient recovery and good stability. MnO2/Ni(OH)2@NF catalyst could be recycled for at least three times, and the degradation rate was 89.06% after three cycles. This MnO2/Ni(OH)2@NF is expected to be used as a green heterogeneous catalyst.

Activating peroxymonosulfate using carbon from cyanobacteria as support for zero-valent iron

In the present study, the cyanobacterial char (ACC) prepared from Chaohu cyanobacteria was used as a nanoscale carrier for zero-valent iron (NZVI) to synthesize a highly efficient activation material designated as cyanobacterial char-supported nanoscale zero-valent iron (NZVI@ACC), which was subsequently used for activating peroxymonosulfate (PMS) to degrade the orange II (OII) dye. The XRD and XPS results revealed that NZVI was anchored onto the ACC through coordination bonding, forming a stable structure. The SEM and TEM observations revealed that the NZVI was embedded in the sheet structure of the ACC. The NZVI@ACC had a larger specific surface area (42.249 m2/g) and also magnetism, due to which its components could be separated through an externally applied magnetic field. Using this NZVI@ACC/PMS system, the rate of degradation of OII (100mg/L) reached 98.32% within 14min. The OII degradation reaction using the NZVI@ACC/PMS system followed first-order kinetics. The activation energy of this degradation reaction was 17.34kJ/(mol·K). Quenching and EPR experiments revealed that various free radicals (SO4·-, ·OH) were produced, with SO4·- playing the major role in the reaction. The theoretical calculations revealed that SO4·- attacked the 12 (N) of OII, thereby destroying and degrading both azo and hydrogenated azo structures of OII. The presence of halogen ions in the actual dye-containing wastewater samples inhibited the OII degradation by the NZVI@ACC system to different degrees, and the inhibition effect followed the order I- > Br- > Cl-.

Dual roles of MoS2 nanosheets in advanced oxidation Processes: Activating permonosulfate and quenching radicals

Peroxymonosulfate (PMS) based advanced oxidation processes (AOPs) have received increasing attention in wastewater treatment attributed to the high efficiency for organic pollutants removal. Our study reported that single layer MoS2 exhibited greatly efficient PMS activation through one electron transfer and thus showed excellent orange II (OII) degradation performance. Sulfate radical (SO4∙−) and hydroxyl radical (∙OH) were detected as the primary reactive oxygen species (ROS) in the activation reaction system by radical quenching experiments and EPR spectroscopy. More importantly, we note that excessive dosage of 1T-dominated MoS2 had a quenching effect on SO4∙− and ∙OH, which caused the decline of OII degradation efficiency. Compared to 1T-dominated MoS2, 2H-MoS2 nanomaterial was a weaker radical quencher and exhibited better organic dye pollutant degradation performance owing to its better chemical stability and adsorptive property. In addition, aligned stacks of MoS2 nanosheets were prepared to preserve oxidation surface/edges, which weakened the ROS quenching effect and thus improved OII removal capacity. The dual roles of MoS2 nanosheets, i.e. activating PMS and quenching free radicals, were systematically studied for the first time. Meanwhile, the protection of oxidation active sites proved to be a feasible way of suppressing ROS quenching effect to improve the degradation performance in PMS-AOPs, and thus providing a new sight for the activator design.

A natural manganese ore as a heterogeneous catalyst to effectively activate peroxymonosulfate to oxidize organic pollutants

Heterogeneous transition metal catalysts are indispensable in improving environmental pollution. However, their fabrication is often costly and cumbersome, and they can easily pollute the environment. This study proposed using a natural Gabonese ore (GBO) containing MnxOy and FexOy as catalysts to degrade orange II (OII) via peroxymonosulfate (PMS) activation. The GBO + PMS system exhibited extraordinarily high stability and catalytic activity towards OII elimination (92.2%, 0.0453 min−1). The reactive oxygen species (ROS) generated in the system were identified using radical scavenging tests and electron spin-resonance (ESR) analysis. Singlet oxygen (1O2) represented the dominant reactive species for OII degradation, while the system presented a lower reaction energy barrier and was effective in a broad pH range (2–10). This work also proposed the activation mechanism for the GBO + PMS system and OII degradation pathways. This study revealed a new approach for exploring inexpensive, eco-friendly, efficient, and stable heterogeneous transition metal catalysts.

Heterogeneous activation of persulfate by Bi2MoO6–CuS composite for efficient degradation of orange II under visible light

Here in, a special catalytic system of potassium persulfate (K2S2O8, PS) activated by Bi2MoO6–CuS composite was established for the orange II (OII) degradation under visible light. The Bi2MoO6–CuS composite was synthesized by a two-step hydrothermal and solvothermal methods. The structure, morphology, light absorption and photocatalytic properties of the composite were respectively characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), UV–visible diffuse reflectance spectroscopy (UV–vis DRS). The removal efficiency of OII degradation in the Bi2MoO6–CuS/PS/vis system reached to 98% within 80 min, which was much higher than that of either Bi2MoO6 or CuS alone. A feasible mechanism analysis of OII degradation was proposed and validated by simple classical quenching experiments and electron spin resonance (ESR) spectroscopy. The high removal efficiency by the nanocomposite could be attributed to highly active species of O2·-, ·OH and SO4•− radicals in the Bi2MoO6–CuS photocatalytic oxidation system. Moreover, the composite material retained its activation performance even after 5 degradation cycles, which suggested its high stability.

Photocatalytic wet peroxide assisted degradation of Orange II dye by reduced graphene oxide and zeolites

AbstractBackgroundPhotocatalytic degradation of Orange II (OII) dye has been carried out with commercially available materials, namely sodium Y zeolite (NaY), ammonium Y zeolite (NH4Y), and reduced graphene oxide (RGO). The catalysts were characterized by N2 adsorption at −196 °C, pH at the point of zero charge (pHpzc), and ultraviolet/visible (UV/Vis) diffuse reflectance absorbance. The initial screening of processes like adsorption, oxidation with hydrogen peroxide alone, direct photolysis, combination of H2O2 with the catalyst, and/or with UV/Vis radiation has been done. For the process with better performance (radiation combined with the oxidant and using the materials as photocatalysts), a parametric study was carried out to evaluate the effect of pH, H2O2 concentration, catalyst dose, radiation intensity, and radiation type (UV/Vis or visible radiation) in OII degradation and mineralization.ResultsThe screening demonstrated that radiation plays an important role in the hydroxyl radical formation and, inherently, in the oxidation of OII and in the mineralization of the organic compounds formed. Still, for all catalysts tested, the existence of optima in terms of pH (2.0), catalyst dose (100 mg L−1), and H2O2 concentration (6 mM) was found, while the maximum radiation intensity (500 W m−2) and UV/Vis radiation incidence benefits the oxidation process. However, the best process performance was achieved when using the catalyst that absorbs more radiation (RGO), yielding OII and TOC removals of 97.7% and 87.9%, respectively, after 90 min of reaction time.ConclusionTaking into account the great performance reached, a possible application of such catalysts in the treatment of textile dyeing effluents is anticipated. © 2020 Society of Chemical Industry (SCI)

Improved dark ambient degradation of organic pollutants by cerium strontium cobalt perovskite

This work investigates the effect of cerium substation into strontium cobalt perovskites (CeSrCoO) for the oxidative degradation of Orange II (OII) in dark ambient conditions without the aid of any external stimulants such as light, heating or chemical additives. The OII degradation rate by CeSrCoO reached 65% in the first hour, whilst for the blank sample without cerium (SrCoO) took over 2 hr to reach the same level of OII degradation. Hence, the cerium substitution improved the catalytic activity of the perovskite material, mainly associated with the Ce0.1Sr0.9CoO3 perovskite phase. Upon contacting CeSrCoO, the –NN- azo bonds of the OII molecules broke down resulting in electron donation and the formation of by-products. The electrons are injected into the CeSrCoO and resulted in a redox pair of Co3+/Co2+, establishing a bridge for the electron transfer between OII and the catalysts. Concomitantly, the electrons also formed reactive species (·OH) responsible for OII degradation as evidenced by radical trapping experiment. Reactive species were formed via the reaction between O2 and donated electrons from OII with the aid of cobalt redox pair. As the prepared materials dispensed with the need for light irradiation and additional oxidants, it opens a window of environmental applications for treating contaminated wastewaters.

Influence of chloride ions on organic contaminants decolorization through the Fe0-activated persulfate oxidation process: efficiency and intermediates.

This study was conducted to evaluate the influence of chloride ions (Cl-) on organic contaminants decolorization by the Fe0-activated persulfate process (PS/Fe0), as well as the generation of transformation products. Orange II (OII) was chosen as the target pollution. The results indicated that Cl- influenced the OII decolorization by PS/Fe0 system, resulting in the generation of chlorine-containing by-products. OII containing Cl- solution can be efficiently decolorized by PS/Fe0 process, and the decolorization efficiencies changed depending on Cl- concentration due to the reaction between Cl- and sulfate radicals (SO4 -•). The operating cost for 94% color and 64% chemical oxygen demand (COD) removal of the OII dye was estimated at 0.73 USD/m3. The chlorine-containing by-products, such as chlorobenzene, 3,5-dichloro-benzene-1,2-diol, and 2,3-dichloro-2,3-dihydro-1,4-naphthoquinone, were generated during the reaction. The results further indicated that increasing both PS concentration and temperature enhanced OII decolorization and reduced the generation of chlorine-containing intermediates. The addition of ultrasound can further decrease the generation of chlorine-containing intermediates under high-temperature conditions. The proposed pathways of decolorization of OII containing Cl- also indicated that SO4 -• dominated the OII degradation, while the presence of Cl- led to the generation of chlorine-containing intermediates.

Effective degradation of azo dyes in the dark by Cu2+ active sites in CaSrNiCu oxides

Metal oxides containing calcium strontium nickel and copper (CSNC) were investigated for the degradation of an azo dye Orange II (OII) pollutant under dark conditions and without any external stimulant. The most active catalyst contained equimolar concentration of Ni and Cu. The reaction proceeded rapidly reaching 50% OII degradation within the first 5 min and 95% by 2 h with 54% of the organic carbon mineralized. The pristine CSNC catalyst containing Ni2+/Cu1+ underwent partial oxidization to Ni3+/Cu2+. Despite this oxidation change, the CSNC catalyst remained stable for over 15 cycles, and Cu2+ proved to be an active reaction site as the Ni3+ phase is not catalytically active. The degradation mechanism under dark conditions occurs by OII contacting the catalytic surface of CSNC where NN azo bonds were broken and electrons were donated. Concomitantly, more electrons were donated by the oxidation of Ni2+/Cu1+. Electrons led to the formation of reactive species (O2•-, HO2• and OH⋅) and hydrogen peroxide, as confirmed by the partial mineralisation of OII and radical trapping experiment.

Heterogeneous Fenton oxidation of Orange II using iron nanoparticles supported on natural and functionalized fique fiber

A detailed study of a catalyst, synthesized by impregnation of iron species on the surface of functionalized fique fiber was performed. Wet impregnation ranging from 1 to 5 days was evaluated in order to assess the amount of iron deposited as a function of time. Quantification of adsorbed iron species was done by atomic absorption spectroscopy (AAS), getting values of 10.9, 14.9, 13.2, 15.9 and 14.9 wt% from 1 to 5 days respectively. X-ray spectroscopy (XRF), X-ray diffraction (XRD) and Fourier Transformed Infrared spectroscopy (FTIR) were used to determine the identity and quantity of species present in the sample, providing evidence of Fe2O3 (hematite) species and showing that under the impregnating conditions there is not complete evolution of iron crystalline structures. SEM images of the iron-impregnated functionalized-fiber revealed areas with substantial nanoparticles aggregation and areas where they are finely dispersed. This nanostructured biomaterial was tested as catalyst in the degradation and mineralization of Orange II (OII) under reaction conditions that promotes a Fenton heterogeneous type reaction. The best experimental conditions obtained under a Box-Behnken experimental design yield up to 93.23% OII degradation.

Surface and catalytic properties of stable Me(Ba, Ca and Mg)SrCoO for the degradation of orange II dye under dark conditions

This work investigates the surface and catalytic properties of Co containing metal oxides MeSrCoO by partially substitution of Sr with another alkaline metal Me (Ba, Ca and Mg). The catalysts were used for the degradation of a textile dye orange II (OII) under dark conditions and without the addition of any chemical additive, light irradiation or energy input. Although all catalysts were prepared under the same conditions, BaSrCoO formed a pure perovskite phase, while MgSrCoO and CaSrCoO resulted in a mixture of perovskite and metal oxide phases. All these catalysts were characterised by a non-porous materials with low surface areas (<∼1 m2 g−1). A total value of ∼80% OII degradation percentage was reached in 4 h and ∼90% in 8 h, though their surface properties resulted in different reaction kinetics. For instance, BaSrCoO and MgSrCoO reaction kinetics were faster and fitted a second order reaction whilst CaSrCoO was slower and fitted a first order reaction. OII degradation was mainly attributed to the catalytic surface properties of these metal oxides, as sorption was not significant except for CaSrCoO which explains the lower reaction kinetics. All catalysts demonstrated good stability over 7 cycle testing (56 h), which was also confirmed by XRD and XPS analysis of pristine and spent samples. Interestingly, non-substituted SrCoO resulted in a similar OII degradation rate, but decayed cycling stability. Hence, the partial substitution of Sr with alkaline metals (Ba, Ca and Mg) conferred increased surface stability. Due to the catalytic surface property of MeSrCoO, the primary reaction mechanism was the contact of OII with the catalyst, leading to the generation of electrons. Subsequently, the electrons reacted with dissolved O2 in the solution, and in a series of reactions, formed hydroxyl radicals and singlet oxygen, leading to OII further degradation.

Ceramic metal oxides with Ni2+ active phase for the fast degradation of Orange II dye under dark ambiance

Ceramic metal oxides based on calcium strontium nickel (CSN) were synthesized via a combined EDTA-citric acid complexation method and evaluated using Orange II (OII) as the model pollutant under dark conditions, without adding any external stimulants. The CSN catalyst was characterized by a very fast reaction reaching 97% OII degradation within 5min. The surface of CSN metal oxides proved to be very active toward the breakdown of the -N˭N- azo bond of OII. A second electron generating pathway was found as Ni2+ phase in the CSN catalyst oxidized to Ni3+ for the spent catalyst. Both electron generating pathways resulted in the formation of hydroxyl radicals (OH·) as determined using radical quenchers. Hydroxyl radicals were responsible for the formation of several intermediate products. The Ni2+ phase was very active contrary to the Ni3+ phase which could not degrade OII. The fast degradation kinetics of OII using CSN in dark at room temperature was attributed to the double electron generation pathways.

Degradation of azo dye Orange II under dark ambient conditions by calcium strontium copper perovskite

This work investigates the effect of calcium strontium copper (CSC) based catalysts for the degradation of an azo dye orange II (OII) under dark conditions without the addition of peroxides or ozone. CSC were synthesized via a combined EDTA-citric acid complexation method. The resultant catalyst was composed of perovskite and metal oxide phases, however, the perovskite phase was the most active for degradation of OII. The content of Ca and Sr in the A-site of the perovskite structure was varied whilst the B-site was Cu rich. CSC compounds with higher Ca content in the A-site were slightly more effective at degrading OII. The degradation kinetics under dark conditions was fast with up to 80% of OII being degraded within 10min. TOC results showed that the degradation was only partial as more than 60% of the organic carbon remained in the solution, supported by the formation of by-products determined by HPLC. The remainder of the carbon were found to be adsorbed on the surface of the spent CSC catalyst, as by-products of the reaction and OII molecules. The CSC catalyst proved to be effective for breaking NN bonds from solutions containing low (10ppm) to high (100ppm) OII concentrations. This reaction produced electrons which generated radical species, including hydroxyl radicals as confirmed by 2-propanol, which further degraded OII and its by-products.

Aligned α-FeOOH nanorods anchored on a graphene oxide-carbon nanotubes aerogel can serve as an effective Fenton-like oxidation catalyst

The self-assembled synthesis of a hierarchical graphene oxide (GO)-carbon nanotubes (CNTs)-α-FeOOH decorated composite aerogel (α-FeOOH@GCA) through a facile in-situ hydrolysis route is reported for the first time and the materials was tested for its performance as Fenton-like catalyst. The introduction of GO-CNTs clearly mediated the morphology to aligned α-FeOOH nanorods (ca. 100nm) within aerogel matrix comparing with pristine urchin-like α-FeOOH three-dimensional microstructures (ca. 1μm). This three dimensional porous aerogel network provided efficient charge/mass-transfer leading to great enhancement of the catalytic activity of α-FeOOH. The outstanding catalytic performance of this composite in degradation of organics with different charge and structure, i.e. Orange II (OII), rhodamine B (RhB), methylene blue (MB), phenol and endocrine disruptor bisphenol A (BPA) was demonstrated. For example, the discoloration of OII with pseudo first-order rate constant of 0.10min−1 significantly exceeded that of pristine α-FeOOH. At relatively low concentration of α-FeOOH@GCA catalyst (125mgL−1) and H2O2 (0.55mM) showed excellent catalytic activity for efficient (∼99%) discoloration of OII (40mgL−1) under a 60min UV365 irradiation in the pH range 3–10. The different charge of five target contaminats greatly determined the surface-catalyzed degradation kinetics at natural solution pH in the order of cationic>neutral>anionic organics due to the negatively charged carbon-based aerogel matrix. The new identified desulfonation intermediates elucidated through UPLC–MS analysis indicated two reaction pathways: 1) hydroxylation and 2) desulfonation by-products followed by cleavage of the azo bond as the predominant degradation pathway of OII. The elimination of the acute toxicity of the parent contaminant to luminescent bacterium Q67 was consistent with the formation of less toxic degradation by-products identified. Free radical quenching studies accessed the role of hydroxyl radical (OH), superoxide anion radical (O2−) and singlet oxygen (1O2) as the dominating reactive oxygen species (ROS). The quantitative studies to measure radical concentrations using relative molecular probes showed the effective activation of H2O2 led to high rate production of ROS accounted for OII degradation. The greatly enhanced photocatalytic property of this hybrid was correlated with the efficient conversion between Fe2+/Fe3+ and synergistic coupling between α-FeOOH and carbon-based aerogel matrix evidenced through the formation of FeOC chemical bonds was verified by X-ray photoelectron (XPS) analysis. Based on its simple and scalable preparation route as well as its excellent UV365 or visible light-responsive catalytic performance, this hybrid exhibits a high potential to be used as an efficient and environmental-friendly catalyst for water remediation.

Rapid Visible Light Induced Photocatalytic Degradation of Orange-II Using H2O2 Sensitized Cu2O

Rapid Visible Light Induced Photocatalytic Degradation of Orange-II Using H2O2 Sensitized Cu2O

Degradation of Orange II by Fenton reaction using ilmenite as catalyst.

This work deals with the degradation of the azo-dye Orange II (OII) by a heterogeneous process with dark Fenton. Natural and purified ilmenites from Colombian soil were used as catalysts. The catalysts have different physicochemical properties and are basically composed of TiO2 and Fe2O3. Ilmenites (FeTiO3), raw materials highly available at low cost, were studied by means of conventional metallography (polished grain mounts), as well as BET, XRD, and XRF in order to determine their possible source area and the factors that influence their use as a catalyst for OII degradation. The pH, the ilmenite amount, the initial CH2O2, and the temperature of the reaction system were studied. Complete degradation of dye was observed within 7h, while 90% of OII was removed in 7h using Cumaribo Ilmenite. Graphical Abstract ᅟ.

Photodegradation of Orange II using waste paper sludge-derived heterogeneous catalyst in the presence of oxalate under ultraviolet light emitting diode irradiation

A waste paper sludge-derived heterogeneous catalyst (WPS-Fe-350) was synthesized via a facile method and successfully applied for the degradation of Orange II in the presence of oxalic acid under the illumination of ultraviolet light emitting diode (UV-LED) Powder X-ray diffraction, Fourier-transform infrared spectroscopy, scanning electronic microscopy and N2 sorption isotherm analysis indicated the formation of α-Fe2O3 in the mesoporous nanocomposite. The degradation test showed that WPS-Fe-350 exhibited rapid Orange II (OII) degradation and mineralization in the presence of oxalic acid under the illumination of UV-LED. The effects of pH, oxalic acid concentration and dosage of the catalyst on the degradation of OII were evaluated, respectively. Under the optimal conditions (1g/L catalyst dosage, 2mmol/L oxalic acid and pH3.0), the degradation percentage for a solution containing 30mg/L OII reached 83.4% under illumination by UV-LED for 80min. Moreover, five cyclic tests for OII degradation suggested that WPS-Fe-350 exhibited excellent stability of catalytic activity. Hence, this study provides an alternative environmentally friendly way to reuse waste paper sludge and an effective and economically viable method for degradation of azo dyes and other refractory organic pollutants in water.