Peroxymonosulfate activation by magnetic NiCo layered double hydroxides for naproxen degradation

The surface functional groups-driven fast and catalytic degradation of naproxen on sludge biochar enhanced by citric acid

In this work, a sludge biochar (CA-SBC-300) with efficient activation of peroxymonosulfate (PMS) was prepared by citric acid modification. CA-SBC-300 achieved efficient degradation of naproxen (NPX) (95.5%) within 10 min by activating PMS. This system was highly resilient to common disruptive factors such as inorganic anions, humic acid (HA) and solution pH. The results of XPS and Raman showed that the content of oxygenated functional groups (OFGs) and the degree of defects on the sludge biochar increased after citric acid modification, which may be an important reason for the enhanced catalytic performance of SBC. In the CA-SBC-300/PMS system, 1O2 and O2•- made the main contributions to the degradation of NPX. XPS analysis and DFT calculations demonstrated that C=O/C-O and pyridine N on CA-SBC-300 were the crucial active sites for PMS activation. According to the results of UPLC-MS analysis, three possible pathways for NPX degradation were inferred. This study provided a feasible strategy for sludge resource utilization combined with efficient catalytic degradation of toxic organic contaminants in wastewater.

Effective activation of peroxymonosulfate by CoCr-LDH for removing organic contaminants in water: from lab-scale to practical applications

In this study, CoCr layered double hydroxide material (CoCr-LDH) was prepared and used as an effective catalyst for peroxymonosulfate (PMS) activation to degrade organics in water. The prepared CoCr-LDH material had a crystalline structure and relatively porous structure, as determined by various surface analyses. In Rhodamine B (RhB) removal, the most outstanding PMS activation ability belongs to the material with a Co:Cr molar ratio of 2:1. The removal of RhB follows pseudo-first-order kinetics (R2 > 0.99) with an activation energy of 38.23 kJ/mol and efficiency of 98% after 7 min of treatment, and the total organic carbon of the solution reduced 47.2% after 10 min. The activation and oxidation mechanisms were proposed and the RhB degradation pathways were suggested with the key contribution of O2•- and 1O2. Notably, CoCr-LDH can activate PMS over a wide pH range of 4 - 9, and apply to a wide range of organic pollutants and aqueous environments. The material has high stability and good recovery, which can be reused for 5 cycles with a stable efficiency of above 88%, suggesting a high potential for practical recalcitrant water treatment via PMS activation by heterogeneous catalysts.

A review of the degradation of antibiotic contaminants using advanced oxidation processes: modification and application of layered double hydroxides based materials

In recent years, the treatment of organic pollutants has become a global concern due to the threat to human health posed by emerging contaminants, especially antibiotic contamination. Advanced oxidation processes (AOPs) can solve the organic pollution problem well, which have been identified as a promising solution for the treatment of hard-to-handle organic compounds including antibiotic contaminants. Layered double hydroxides (LDHs) are excellent catalysts because of their flexible tunability, favorable thermal stability, abundant active sites, and facile exchangeability of intercalated anions. This paper conducted a systematic review of LDHs-based materials used for common antibiotic removal by three significant AOP technologies, such as photocatalysis, the Fenton-like processes, and peroxymonosulfate catalysis. The degradation effects studied in various studies were reviewed, and the mechanisms were discussed in detail based on the type of AOPs. Finally, the challenges and the application trends of AOPs that may arise were prospected. The aim of this study is to suggest ways to provide practical guidance for the screening and improvement of LDH materials and the rational selection of AOPs to achieve efficient antibiotic degradation. This could lead to the development of more efficient and environmentally friendly materials and processes for degrading antibiotics, with significant implications for our ecological conservation by addressing water pollution.

Study on the dominant mechanism of direct hole oxidation for the photodegradation of tetracycline

Antibiotic contamination has a significant negative impact on China, one of the largest producers and consumers of antibiotics worldwide. In this study, a three-dimensional flower-like structure of CoFe-LDHs was used to efficiently degrade tetracycline (TC) in a system triggered by peroxymonosulfate (PMS) and exposed to visible light. After exploring the effects of different metal ratios, catalyst dosage, initial TC concentrations, and pH, the optimal reaction conditions were determined. In comparison to pure CoFe-LDHs, the TC elimination rate was dramatically increased by the addition of the PMS. The strong environmental resistance, excellent stability and reusability, and universal flexibility were shown. The quenching experiments and electron spin resonance detection showed that the creation of reactive oxygen species was facilitated by the synergistic transmission of electrons between the active bimetallic components. Further, photogenerated holes was the dominant oxidizing species, which contributed more to the degradation of TC. The potential degradation pathways and intermediate toxicity of TC were suggested. This work offers a new method dominated by photogenerated holes for efficiently removing TC effluent.