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The development of heterogeneous Fenton catalysts with good performance and stability is a challenge in the field of wastewater treatment. In this work, MgAlFe hydrotalcite-like compounds (MgAlFe-HTLcs) were prepared by solid phase reaction at room temperature and modified via a hydrothermal process. The experimental results showed that MgAlFe-HTLcs had a good layered structure with the same proportion of iron and aluminium, 18 h of crystallisation time and 110°C of crystallisation temperature and the lamellar structure was more uniform by solid grinding. Furthermore, the addition of iron can activate H2O2 more effectively to generate active oxygen which is •OH. The degradation experiments demonstrated that nearly 99.0% degradation efficiency was achieved for 10 mg/L Malachite Green (MG) solution within 60 min at the conditions of 0.10 g·L−1 MgAlFe-HTLcs, 0.10 mol·L-1 H2O2 and a natural pH of 6.3. Total organic carbon (TOC) removal reached 72.2% in a 70 min reaction. BET and XRD were measured to further discuss the stability and durability. Finally, a possible mechanism for the degradation of MG was presumed. [ABSTRACT FROM AUTHOR]

In this work, micro-spherical β-NiOOH/FeMoO 4 with multiple active sites was prepared by one-step solvothermal method and its performance in the photo-Fenton system was investigated. The results indicate that highest degradation efficiency of methylene blue (MB) was obtained when the molar ratio of nickel to iron was 1:2.5. In addition, composites were assessed for its degradation performance for MB by adjusting the concentration of H 2 O 2 , pH and catalyst dosage. The pseudo-first-order kinetic rate constant of MB degradation in β-NiOOH/FeMoO 4 catalyzed photo-Fenton system was 0.234 min−1 about 5 folds that of pristine FeMoO 4 micro-sphere. The degradation mechanism of MB was deduced by active species quenching experiments and technology of coumarin fluorescent probe. And its degradation pathway was proposed by LC-MS identifying reaction intermediates produced during photo-Fenton catalysis. Recycling tests have confirmed excellent stability of β-NiOOH/FeMoO 4 composite. In conclusion, this study demonstrates the β-NiOOH/FeMoO 4 composite is a promising heterogeneous photo-Fenton catalyst. [Display omitted] • Microspheres with special particle accumulation surface structure were prepared. • The doped of Fe enables NiOOH to crystallize stable into β phase. • The degradation efficiency of MB can reach 99.5% in 18 min. • The generation potential of ·OH was indirectly determined by the coumarin fluorescence probing technique. [ABSTRACT FROM AUTHOR]

[Display omitted] • The right amount of cobalt ions could induce the formation of Fe 1-x S. • 100 mL orange II solution (30 mg/L) was degraded to 99.9% within 15 min. • OH and h+ played an important role in the photo-Fenton-like process. • FeS 2 -Fe 1-x S exhibited excellent stability and high catalytic degradation activity for other dyes. It is a challenge to develop heterogeneous Fenton-like catalysts with excellent performance and stability in the field of wastewater treatment. In this work, the FeS 2 -Fe 1-x S heterostructure catalyst was prepared by solvothermal method through adding cobalt element to change the particle nucleation process and inhibit the transformation process of pyrrhotite (Fe 1-x S) phase to pyrite (FeS 2) phase. Then, a series of experiments were devised to clarify the catalytic activity of FeS 2 -Fe 1-x S heterostructure. The degradation experiments exhibited that 99.9% degradation efficiency was achieved for 30 mg/L orange II solution within 15 min at the conditions of 0.2 g/L FeS 2 -Fe 1-x S, 2 mM H 2 O 2 and pH = 3.0. In addition, the reusability of the FeS 2 -Fe 1-x S catalyst was also investigated and the result displayed that degradation efficiency of orange II can reach 95.2% after eight cycles. The degradation of orange II was enhanced by Fenton reaction between FeS 2 -Fe 1-x S and dissolved oxygen, which could smoothly release Fe2+ and Fe3+ for the activation of H 2 O 2 to produce more hydroxyl radicals. Finally, the degradation pathway of orange II was proposed by detecting intermediates produced in FeS 2 -Fe 1-x S/H 2 O 2 photo-Fenton-like system by liquid chromatography-mass spectrometry (LC-MS). In short, FeS 2 -Fe 1-x S is a promising catalyst for removing the organic pollutants from solutions. [ABSTRACT FROM AUTHOR]

• The Orange II degradation efficiency attained to 98.9% within 15 min. • OH played an important role in the Cu 2 O(SO 4)-Fe9/H 2 O 2 Fenton-like process. • The degradation rate constant of Cu 2 O(SO 4)-Fe9 is 9.33 and 4.07 times of Cu 2 O(SO 4) and α-Fe 2 O 3 , respectively. • Orange II degradation is conducted through destruction of conjugated structures and mineralization. Hematite (α-Fe 2 O 3), as one of Fenton reagents, is widely investigated for the treatment of wastewater in the field of advanced oxidation processes (AOPs). Considering the fast charge carrier recombination of hematite (α-Fe 2 O 3), we have successfully synthesized a novel and high active heterogeneous Fenton catalyst α-Fe 2 O 3 /Cu 2 O(SO 4) for the degradation of organic pollutants. The results show that the as-obtained Cu 2 O(SO 4)-Fe9 composite exhibits excellent degradation properties of Orange II. 98.9% degradation rate was achieved for 100 mL of 50 mg/L Orange II solution in the condition of 0.3 g/L Cu 2 O(SO 4)-Fe9 catalyst, 3 mM H 2 O 2 and pH = 3.5. The degradation rate constants of Cu 2 O(SO 4)-Fe9 in the photo-Fenton-like system are 9.33 and 4.07 times of Cu 2 O(SO 4) and α-Fe 2 O 3 , respectively. In addition, the mechanism and pathway for the degradation of Orange II were proposed. The scheme of combining copper-based oxysulfate Cu 2 O(SO 4) with hematite (α-Fe 2 O 3) could improve the efficiency of charge carrier separation, which will further enhance the catalytic activity and expand its application in water purification. [ABSTRACT FROM AUTHOR]

Elemental doping has been proven to be an effective strategy for increasing the catalytic activity and structural stability of Fenton catalysts. Therefore, this work reports that Mn-doped FeS 2 /Fe 2 O 3 (Mn 3 O 4 –FeS 2 /Fe 2 O 3) has excellent catalytic performance for the degradation of Orange II under simulated solar energy. Degradation experiment results showed that the sample with a manganese-iron molar ratio of 1:2 exhibited higher activity than others. The degradation rate of 20 mg/L OII reached 99.0% in 18 min under the conditions of 0.3 g/L Mn 3 O 4 –FeS 2 /Fe 2 O 3 , 5 mM H 2 O 2 and pH = 2.8. In addition to, the Mn 3 O 4 –FeS 2 /Fe 2 O 3 catalyst shows good reusability for Orange II and high activity for other dyes (MB, MG, Rh B and MO) under optimal conditions. Degradation mechanism study indicated that the heterogeneous Fenton reaction was promoted by retarding the recombination of photogenerated charge carriers and accelerating the cycle between Fe3+/Mn2+ and Fe2+/Mn3+, which improved photo-Fenton-like catalytic performance, resulting in the enhanced degradation of organic pollutant. Finally, a possible degradation pathway was proposed according to the results of liquid chromatography-mass spectrometry (LC-MS). In short, the catalyst has potential application value in wastewater treatment. • The degradation of Orange II by Mn 3 O 4 –FeS 2 /Fe 2 O 3 attained to 99.0% in 18 min. • Both.•OH and •O 2 − played important roles in the degradation process. • The photo-Fenton-like catalytic performance of the Mn 3 O 4 –FeS 2 /Fe 2 O 3 catalyst was enhanced. • The catalyst maintained excellent reusability for Orange II and high activity for other dyes. [ABSTRACT FROM AUTHOR]