Modulating electron density enable efficient cascade conversion from peroxymonosulfate to superoxide radical driven by electron-rich/poor dual sites.

The superoxide radical (•O2-)-mediated peroxymonosulfate (PMS)-based photo-Fenton-like reaction enables highly selective water decontamination. Nevertheless, the targeted construction of •O2--mediated photo-Fenton-like system has been challenging. Herein, we developed an electron-rich/-poor dual sites driven •O2--mediated cascade photo-Fenton-like system by modulating electron density. Experimental and theoretical results demonstrated that PMS was preferentially adsorbed on electron-poor Co site. This adsorption promoted O-O bond cleavage of PMS to generate hydrogen peroxide (H2O2), which then migrated to electron-rich O site to extract eg electrons for O-H bond cleavage, rather than competing with PMS for Co site. The developed versatile cascade reaction system could selectively eliminate contaminants with low n-octanol/water partition constants (KOW) and dissociation constants (pKa) and remarkably resist inorganics (Cl-, H2PO4- and NO3-), humic acid (HA) and even real water matrices (tap water and secondary effluent). This finding provided a novel and plausible strategy to accurately and efficiently generate •O2- for the selective water decontamination.

Bimetallic capture sites on porous La/Bi hydroxyl double salts for efficient phosphate adsorption: Multiple active centers and excellent selective properties.

The rapid development of modern agriculture aggravated water eutrophication. Therein, efficient and selective removal of phosphorus in water is the key to alleviating eutrophication. It is well known that lanthanum (La)-based material is a kind of outstanding phosphorus-locking agent. Therefore, improving the property of La-based adsorbents is a hot topic in this field. Herein, novel porous hydroxyl double salts (La/Bi-HDS) with bimetallic capture sites were prepared. The experimental result shows that La/Bi-HDS could maintain the high removal rate in the solution with a higher concentration of competing ions and the maximum P adsorption quantity of La/Bi-HDS attains 168.12 mg/g. Mechanistic studies supported by density functional theory (DFT) calculation demonstrate that introducing Bi3+ optimizes the electronic structure of La, reducing adsorption energy. In addition, the surface analysis shows that the introduction of Bi, which increases the pore size and volume of the material, improves the utilization efficiency of the active site. In a word, the introduction of Bi element as a strategy of killing two birds with one stone successfully improved the performance of La-based adsorbent. It provided a new direction for developing an efficient phosphorus-locking agent.

Spin state-dependent in-situ photo-Fenton-like transformation from oxygen molecule towards singlet oxygen for selective water decontamination.

The development of 1O2-dominanted selective decontamination for water purification was hampered by extra H2O2 consumption and poor 1O2 generation. Herein, we proposed the reconstruction of Fe spin state using near-range N atom and long-range N vacancies to enable efficient generation of H2O2 and sequential activation of H2O2 into 1O2 after visible-light irradiation. Theoretical and experimental results revealed that medium-spin Fe(III) strengthened O2 adsorption, penetrated eg electrons to antibonding p-orbital of oxygen, and lowered the free energy of O2 activation, enabling the oxygen protonation for H2O2 generation. Thereafter, the electrons of H2O2 could be extracted by low-spin Fe(III) and rapidly converted into 1O2 in a nonradical path. The developed 1O2-dominated in-situ photo-Fenton-like system had an excellent pH universality and anti-interference to inorganic ions, dissolved organic matter, and even real water matrixes (e.g., tap water and secondary effluent). This work provided a novel insight for sustainable and efficient 1O2 generation, which motivated the development of new-generation selective water treatment technology.

Enhanced photo-Fenton degradation of tetracycline hydrochloride by 2, 5-dioxido-1, 4-benzenedicarboxylate-functionalized MIL-100(Fe).

Heterogeneous photo-Fenton technology has drawn tremendous attention for removal of recalcitrant pollutants. Fe-based metal-organic frameworks (Fe-MOFs) are regarded to be superior candidates in wastewater treatment technology. However, the central metal sites of the MOFs are coordinated with the linkers, which reduces active site exposure and decelerates H2O2 activation. In this study, a series of 2, 5-dioxido-1, 4-benzenedicarboxylate (H2DOBDC)-functionalized MIL-100(Fe) with enhanced degradation performance was successfully constructed via solvothermal strategy. The modified MIL-100(Fe) displayed an improvement in photo-Fenton behaviors. The photocatalytic rate constant of optimized MIL-100(Fe)-1/2/3 are 2.3, 3.6 and 4.4 times higher compared with the original MIL-100(Fe). The introduced H2DOBDC accelerates the separation and transfer in photo-induced charges and promotes Fe(II)/Fe(III) cycle, thus improving the performance. •OH and •O2- are main reactive radicals in tetracycline (TCH) degradation. Dealkylation, hydroxylation, dehydration and dealdehyding are the main pathways for TCH degradation.

High-efficiency leaching of valuable metals from waste Li-ion batteries using deep eutectic solvents.

With the penetration of lithium-ion batteries (LIBs) into electric vehicles, the recycling of waste LIBs is inevitable from the perspective of health, economy and environmental protection. Herein is reported a novel green method for extracting valuable metals from the cathode of LIBs, in which the Deep Eutectic Solvent (DES) is used as leachate to dissolve electrode material waste. Mixing choline chloride (ChCl) and malonic acid is helpful to effectively improve the reduction ability of DES, resulting in superior leaching efficiency. At the lower temperature (100 °C), the leaching efficiency of cobalt and lithium reached up to 98.61% and 98.78%, respectively. X-ray absorption near edge structure (XANES) spectroscopy demonstrated that DESs could act as both leachate and reducing agent, which could destroy the covalent bonds of metal oxides to form a cobalt (II)-chlorine complex. This method is straightforward to operate and does not involve the additional reducing agents, which is held promise to bring economic and sustainable development prospects in the field of lithium battery development.

Cl-based functional group modification MIL-53(Fe) as efficient photocatalysts for degradation of tetracycline hydrochloride.

MIL-53(Fe) catalyst has been widely used to treat the pollutants in water. However, the limited number of electrons in MIL-53(Fe) catalyst has always affected the rate at which Fe3+ can be reduced to Fe2+. We modulated iron-based metal-organic frameworks (MOFs) using organic ligands modified with chlorine functional groups. The characterization results indicate that the 2Cl-MIL-53(Fe) catalyst exhibited the optimal photoelectric properties while maintaining the original structural characteristics. The experimental analyses and the first-principles study suggest that the introduction of a chlorine functional group not only reduced the band gap width and enhanced the visible-light absorption capacity, but also significantly enhanced the electron cloud density of Fe-O clusters. This could further accelerate the redox cycle of Fe(III)/Fe(II), beneficial for H2O2 activation. The constructed Cl-MIL-53(Fe) catalyst exhibited a 3.8 times higher reaction rate constant than pure MIL-53(Fe) catalyst. The specific TCH degradation pathway and mechanism of 2Cl-MIL-53(Fe) treatment are proposed. This study provides a new strategy for iron-based MOFs as a heterogeneous photo-Fenton catalyst to degrade pollutants in water.

In situ preparation of BiOCl0.75I0.25/g-C3N4-Cl in reduced graphene hydrogel photoanode for simultaneous removal of tetracycline hydrochloride and hexavalent chromium with efficient electricity generation.

A novel three-dimensional porous photoanode of BiOCl0.75I0.25/g-C3N4-Cl/reduced graphene hydrogel (BOCI/CNCl/rGH) was successfully fabricated by a combined in-situ growth and re-dispersion strategy. It was verified that BOCI/CNCl composite exhibited photocatalytic efficiency, and the introduced rGH not only provided superior conductivity which was favorable for charge transfer, but also increased the specific surface area and reactive sites than the fluorine-doped tin oxide (FTO) coated glass. On the basis of these advantages, the short-circuit current and maximum power density were increased by 5.1 and 1.2 times, and the respective removal efficiency of tetracycline hydrochloride (TCH) and hexavalent chromium (Cr(VI)) was increased by 29% and 32% in BOCI/CNCl/rGH, comparing with BOCI/CNCl/FTO. Notably, the removal efficiencies could reach 87% and 85% in TCH and Cr(VI) coexistence system, which were higher than those in TCH or Cr(VI) alone system. This study provides a novel strategy for designing highly efficient photoanode for multiple pollutants removal and electricity generation.

Nitrogen Vacancy-Modulated Peroxymonosulfate Nonradical Activation for Organic Contaminant Removal via High-Valent Cobalt-Oxo Species.

Rapid generation of high-valent cobalt-oxo species (Co(IV)═O) for the removal of organic contaminants has been challenging because of the low conversion efficiency of Co(III)/Co(II) and the high activation energy barrier of the Co(II)-oxidant complex. Herein, we introduced nitrogen (N) vacancies into graphite carbon nitride imbedded with cobalt carbonate (CCH/CN-Vn) in a peroxymonosulfate (PMS)/visible light system to break the limitations of a conventional two-electron transfer path. These N vacancies enhanced the electron distribution of the Co 3d orbital and lowered the energy barrier to cleave the O-O bond of PMS in the Co(II)-PMS complex, achieving the modulation of major active species from 1O2 to Co(IV)═O. The developed synergistic system that exhibited adsorption and oxidation showed remarkable selectivity and contaminant removal performance in inorganic (Cl-, NO3-, HCO3-, and HPO4-) organic (HA) and even practical aqueous matrices (tap water and secondary effluent). This study provides a novel mechanistic perspective to modulate the nonradical path for refractory contaminant treatment via defect engineering.

Optimization of the photocatalyst coating and operating conditions in an intimately coupled photocatalysis and biodegradation reactor: Towards stable and efficient performance.

Intimately coupled photocatalysis and biodegradation (ICPB) is an attractive novel technology for the mineralization and detoxification of persistent organics. Good photocatalytic performance is essential for an advanced ICPB operation, and the photocatalyst coating and illumination conditions are strong determining factors. In this work, response surface methodology (RSM) involving the central composite design (CCD) was employed to discover optimal operating conditions, by using tetracycline hydrochloride (TCH) as the model pollutant. Polyvinyl butyral (PVB) was employed to form an adhesion layer, enhancing P25 TiO2 activity and stability. We achieved the optimal coating conditions with a mixing time of 20 h, TiO2 dosage of 8 g/L, and PVB concentration of 0.5 wt.%. The optimum running conditions for an ICPB-reactor were found to be at a carrier volume ratio of 40% and light intensity of 6000 µw/cm2. These conditions were essential for the production of desired intermediates and functional microbial survival. At the optimized parameters ranges, ∼98% TCH removal and ∼40% mineralization was achieved, and the inhibition on Q67 illuminance was only 30.32%. This is the first work on optimizing the fabrication and operation of ICPB, which is meaningful for the application of ICPB in practical engineering.

Comparing dark- and photo-Fenton-like degradation of emerging pollutant over photo-switchable Bi2WO6/CuFe2O4: Investigation on dominant reactive oxidation species.

The extensive use of tetracycline hydrochloride (TCH) poses a threat to human health and the aquatic environment. Here, magnetic p-n Bi2WO6/CuFe2O4 catalyst was fabricated to efficiently remove TCH. The obtained Bi2WO6/CuFe2O4 exhibited 92.1% TCH degradation efficiency and 50.7% and 35.1% mineralization performance for TCH and raw secondary effluent from a wastewater treatment plant in a photo-Fenton-like system, respectively. The remarkable performance was attributed to the fact that photogenerated electrons accelerated the Fe(III)/Fe(II) and Cu(II)/Cu(I) conversion for the Fenton-like reaction between Fe(II)/Cu(I) and H2O2, thereby generating abundant •OH for pollutant oxidation. Various environmental factors including H2O2 concentration, initial pH, catalyst dosage, TCH concentration and inorganic ions were explored. The reactive oxidation species (ROS) quenching results and electron spin resonance (ESR) spectra confirmed that •O2- and •OH were responsible for the dark and photo-Fenton-like systems, respectively. The degradation mechanisms and pathways of TCH were proposed, and the toxicity of products was evaluated. This work contributes a highly efficient and environmentally friendly catalyst and provides a clear mechanistic explanation for the removal of antibiotic pollutants in environmental remediation.

Could co-substrate sodium acetate simultaneously promote Chlorella to degrade amoxicillin and produce bioresources?

Integrating microalgae culture and wastewater purification is a promising technology for sustainable bioresource production. However, the challenge is that toxins in wastewater usually limit risk elimination and cause poor bioresource production. Easy-to-biodegrade substrates could alleviate the resistant stress on a bacterial community but we know little about how they function with microalgae. In this study, we tested if Easy-to-biodegrade substrates could simultaneously promote Chlorella to degrade antibiotic amoxicillin (AMO) and produce bioresources. Sodium acetate (NaAC) was used as the representative co-substrate. The results showed NaAC could enhance AMO removal by 76%. The ß-lactam structure was destroyed and detoxified to small molecules, due to the up-regulation of hydrolase, oxidoreductase, reductase, and transferase. Chlorella biomass production increased by 36%. The genes encoding the glutathione metabolism and peroxisome pathways were significantly up-regulated to alleviate the antibiotic stress, and the DNA replication pathway was activated. As a result, the production of lipid, carbohydrate, and protein was enhanced by 61%, 122%, and 34%, respectively. This study provides new insights for using microalgae to recover bioresources from toxic wastewater and reveals the critical underlying mechanisms.

Tetracycline hydrochloride degradation over manganese cobaltate (MnCo2O4) modified ultrathin graphitic carbon nitride (g-C3N4) nanosheet through the highly efficient activation of peroxymonosulfate under visible light irradiation.

Peroxymonosulfate (PMS) activation by heterogeneous transition metal oxides is an effective approach for treating emerging pollutants in water. However, the low PMS activation efficiency associated with the valency conversion rate of transition metals has been a major challenge to sulfate radical-based oxidation. In this work, manganese cobaltate (MnCo2O4) nanoparticles anchored on graphitic carbon nitride (g-C3N4) flakes (MnCo2O4/g-C3N4) were successfully prepared and showed high PMS activation efficiency under visible (Vis) light. The obtained catalysts degraded 96.1% of the tetracycline hydrochloride (TCH) through the synergistic effect of PMS and photocatalysis. The reaction rate constant (0.2505 min-1) was 5.3 and 1.8 times higher in the MnCo2O4/g-C3N4/PMS/Vis system than in the pristine g-C3N4 (0.0471 min-1) and MnCo2O4 (0.1435 min-1) systems, respectively. The characterization results verified that g-C3N4, which functions as the electron donor in the photocatalytic heterojunction system, could transmit numerous photogenerated electrons to MnCo2O4, thereby increasing the cyclability of divalent-trivalent metal ions. The composites also showed good stability, cycling capability, and cation/anion tolerance. Tentative degradation mechanism and reaction pathways were proposed based on the reactive species and degradation products.

Simultaneous elimination of amoxicillin and antibiotic resistance genes in activated sludge process: Contributions of easy-to-biodegrade food.

Antibiotics are continuously released into aquatic environments and ecosystems where they accumulate, which increases risks from the transmission of antibiotic resistance genes (ARGs). However, it is difficult to completely remove antibiotics by conventional biological methods, and during such treatment, ARGs may spread via the activated sludge process. Easy-to-biodegrade food have been reported to improve the removal of toxic pollutants, and therefore, this study investigated whether such co-substrates may also decrease the abundance of ARGs and their transferal. This study investigated amoxicillin (AMO) degradation using 0-100 mg/L acetate sodium as co-substrate in a sequencing biological reactor. Proteobacteria, Bacteroidetes, and Actinobacteria were identified as dominant phyla for AMO removal and mineralization. Furthermore, acetate addition increased the abundances of adeF and mdsC as efflux resistance genes, which improved microbial resistance, the coping ability of AMO toxicity, and the repair of the damage from AMO. As a result, acetate addition contributed to almost 100% AMO removal and stabilized the chemical oxygen demand (~20 mg/L) in effluents when the influent AMO fluctuated from 20 to 100 mg/L. Moreover, the total abundance of ARGs decreased by approximately ~30%, and the proportion of the most dominant antibiotic resistance bacteria Proteobacteria decreased by ~9%. The total abundance of plasmids that encode ARGs decreased by as much as ~30%, implying that the ARG spreading risks were alleviated. In summary, easy-to-biodegrade food contributed to the simultaneous elimination of antibiotics and ARGs in an activated sludge process.

Efficient photoactivation of peroxymonosulfate by Z-scheme nitrogen-defect-rich NiCo2O4/g-C3N4 for rapid emerging pollutants degradation.

Limited peroxymonosulfate (PMS, HSO4-) activation efficiency resulted from slow metal reduction has been a challenge in visible-light (vis) assisted sulfate radical-based oxidation. Herein, a Z-scheme photocatalyst composed of nitrogen-defect-rich graphitic carbon nitride nanosheets embedded with nickel cobaltate nanoparticles (NiCo2O4/g-C3N4-Nvac) was elaborately designed to accelerate Ni(III)/Ni(II) and Co(III)/Co(II) cycles for PMS activation in PMS/vis system. The NiCo2O4/g-C3N4-Nvac exhibited remarkable enhancement with a tetracycline hydrochloride (TCH) degradation rate constant (0.1168 min-1), higher than those of NiCo2O4/g-C3N4 (0.0724 min-1) and g-C3N4 (0.0233 min-1), respectively. Also, the removal efficiencies of 95.5%, 94.2%, 98.0% and 91.4% for carbamazepine, 4-chlorophenol, atrazine and p-nitrophenol were achieved within 30 min, respectively. Theoretical and experimental results suggested that nitrogen (N) vacancies modulated electric structure to build Z-scheme-charge-transfer platform for rapid reduction of Ni(III) and Co(III), thereby accelerating PMS activation for remarkable removal of emerging pollutants. NiCo2O4/g-C3N4-Nvac exhibited excellent stability and corresponding electrical energy per order (EE/O) in different water matrix was evaluated. Additionally, TCH degradation behavior, pathways and toxicity of products were analyzed, respectively. This work provided an novel paradigm to design the efficient photo-activator of PMS for environmental remediation.

Co-substrate addition accelerated amoxicillin degradation and detoxification by up-regulating degradation related enzymes and promoting cell resistance.

ß-Lactam antibiotics are the most commonly used antibiotics, and are difficult to remove by conventional biological treatments because of their persistent and toxic nature. The addition of co-substrates has been successfully employed to improve the removal of refractory pollutants. So, we hypothesized that the co-substrate strategy would increase antibiotic degradation and benefit microbial survival. In this work, we reported that co-substrate (acetate) addition up-regulated key degrading enzymes and resistance related genes in a model bacteria strain (L. aquatilis) when being treated with 0.055 mM amoxicillin (AMO). ß-Lactamase, amidases, transaminase, and amide C-N hydrolase showed increased activation. As a result, AMO removal reached ∼95 %, a ∼60 % increase over the control. Furthermore, the addition of acetate drove the down-stream TCA cycle, which accelerated the detoxification of the intermediates and reduced the microbial inhibition by the antibiotic products to as low as ∼15 %. Besides, the expression levels of genes encoding the efflux pump, penicillin binding proteins, and ß-Lactamase were up-regulated, and the inhibition of peptidoglycan biosynthesis was down-regulated. The cell density was enhanced by ∼170 % and showed improved DNA replication. In conclusion, the addition of the co-substrate accelerated AMO degradation and detoxification by up-regulating degrading enzymes and promoting cell resistance.

Promoting Chlorella photosynthesis and bioresource production using directionally prepared carbon dots with tunable emission.

Green microalgae are promising and sustainable bioenergy and biomass feedstocks, that specifically utilize blue and red light for photosynthesis. Using carbon dots (CDs) to optimize photoluminescence is an attractive strategy for enhancing microalgal bioresource production; however, CD synthesis traditionally requires harsh conditions and laborious procedures. Little research has focused on developing CDs with tunable emission that precisely satisfy photosynthetic requirements. In this work, we directionally prepared non-toxic CDs using a simple method, which could adsorb light at spectra 500-600 nm and emit red light at 580-700 nm. CDs significantly promoted microalgae (Chlorella) growth by ~15%. Meanwhile, potential intracellular bioresources, pigments, carbohydrates, proteins, and lipids were generally enhanced. CDs, combined with an extracellular polymeric substance of microalgal cells, served as numerous micro-bulbs for Chlorella irradiation to sustainably provide optimized light. In this context, photosystems I and II were both stimulated. As such, we prepared CDs with tunable emission, which could significantly enhance microalgae and bioresource production.

Towards a simultaneous combination of ozonation and biodegradation for enhancing tetracycline decomposition and toxicity elimination.

In this study, a new intimately coupling technology of advanced oxidation and biodegradation was proposed, called simultaneous combination of ozonation and biodegradation (SCOB), which uses ozonation in place of traditional photocatalysis. SCOB was evaluated for its ability to degrade and detoxify tetracycline hydrochloride (TCH). Biodegradation alone only resulted in negligible TCH removal, while ozone alone caused less effective performance, with TCH degradation rate constants of 29-171% lower than those of SCOB. The optimal ozone dose was 2.0 mg-O3/(L·h), and it contributed to remove 97% of the TCH within 2 h under SCOB operation. The SCOB effluent was not toxic to S. aureus after 8 h of exposure. During six SCOB operation cycles, the biomass in the biofilm remained stable, and cell structure was relatively intact. SCOB significantly improved TCH degradation and reduced toxicity of the effluent.

Enhanced photocatalytic performance of metal silver and carbon dots co-doped BiOI photocatalysts and mechanism investigation.

The photocatalytic technology provides a promising and effective strategy for the transformation and degradation of contaminants. Herein, we accurately fabricated a novel ternary photocatalyst, namely, metal silver (Ag) and carbon dots (CDots) co-doped BiOI nanocomposite (Ag/CDots/BiOI) via the reduction method with ionic liquids 1-butyl-3-methylimidazolium iodine ([Bmim]I) at room temperature. The morphologies and microstructures showed the Ag and CDots were uniformly loaded on the surface of BiOI, forming a ternary system. The characterization results implied that an intense interaction was formed between Ag and CDots on the BiOI, which could achieve the broad spectrum utilization of visible light and boosted the photocatalytic performances. The 0.9-Ag/2-CDots/BiOI (0.9 wt% of Ag, 2 wt% of CDots) presented the highest photocatalytic activity with ~ 100% in 4-Chlorophenol, 68.8% in mineralization, and 87.4% in dechlorination in 6 h under visible light illumination. The enhanced photocatalytic activity could be ascribed to the surface plasmon resonance effect of Ag, the up-converted photoluminescence (PL) properties of CDots, and the electron transfer properties of both Ag and CDots. Moreover, a possible photocatalytic reaction mechanism was discussed in detail by band structure analysis and radical scavenger quenching experiments. This study provides a promising approach for promoting the utilization efficiency for solar energy and sustainable environmental remediation.

Eliminating partial-transformation products and mitigating residual toxicity of amoxicillin through intimately coupled photocatalysis and biodegradation.

Intimately coupled photocatalysis and biodegradation (ICPB) is a promising technology for treating wastewater containing antibiotics. While past work has documented the benefits of ICPB for removing and mineralizing antibiotics, its impacts on mitigating biotoxicity from products has not been studied. We fabricated an ICPB carrier by coating Ag-doped TiO2 on the outer skeleton of sponge carriers and allowing biofilm to grow in the internal macro-pores. We used amoxicillin (C16H19N3O5S) as the model antibiotic. The amoxicillin-removal rate contents with ICPB was greater by 40% vs. photocatalysis and 65% vs. biodegradation, based on the first-order kinetic simulation. While mineralization of amoxicillin was minimal for photocatalysis or biodegradation alone, it was ∼35% with ICPB. Photocatalysis alone led to accumulation of C14H21N3O2S; biodegradation alone resulted in accumulation of C14H21N3O3, C16H18N2O4S, and C15H21N3O3; but they were negligible after ICPB. As a result, ICPB reduced toxicity impacts measured by Staphylococcus aureas growth, Daphnia magna mobility, and teratogenicity to Zebrafish embryos. In contrast, photocatalysis alone increased each of the toxicity effects. In sum, ICPB gave greater removal and mineralization of amoxicillin, and it mitigated biotoxicity from treatment products.

Visible-light-driven photo-Fenton reaction with α-Fe2O3/BiOI at near neutral pH: Boosted photogenerated charge separation, optimum operating parameters and mechanism insight.

The performance of the Photo-Fenton process is still limited by the low conversion rate of Fe3+/Fe2+ under near neutral conditions. We report a α-Fe2O3/BiOI catalyst that enhanced the efficiency of Fe2+ generation. The structure, morphology, chemical composition and chemical states of the catalyst were characterized. The α-Fe2O3/BiOI catalyst exhibited remarkable degradation performance for methyl orange (MO), phenol and tetracycline hydrochloride (TCH). The degradation efficiency of α-Fe2O3/BiOI with an optimum α-Fe2O3 loading was 3 and 10 times higher than those of pristine BiOI and α-Fe2O3, respectively. The excellent degradation performance arose from the synergistic effect of the efficient separation and transfer of photogenerated charge at the α-Fe2O3/BiOI solid-solid interface and the optimized Fenton reaction at the solid-liquid interface. The effects of operating parameters including the H2O2 concentration, solution pH, catalyst concentration and MO concentration on the degradation efficiency were investigated. Electron spin resonance results and reactive oxidation species scavenger experiments indicated that superoxide radicals could be transferred into hydroxide radicals via the activation of H2O2. A possible degradation pathway of TCH is proposed. This strategy provides a new perspective for improving the cyclic ability of Fe3+/Fe2+ over heterogeneous catalysts.