Organoarsenicals such as roxarsone (ROX) are extensively utilized in the poultry industry, and land application of poultry litter is an important route by which arsenics are introduced into the environment. In the present study, degradation of ROX and structurally related nitrophenols by a heat activated persulfate (PS) oxidation process, one in situ chemical oxidation process (ISCO), was systematically explored. The effects of temperature, PS dosage, pH and natural water constituents (i.e., fulvic acid, Cl−) on the degradation of ROX were investigated. Products analysis by solid phase extraction (SPE) and liquid chromatography-electrospray ionization-triple quadrupole mass spectrometry (LC-ESI-MS/MS) revealed that 2,4-dinitrophenol (2,4-DNP) and 2,4,6-trinitrophenol (2,4,6-TNP) were generated as major intermediate products, suggesting denitration–renitration process occurred during SO4˙−-based oxidation of ROX. Interestingly, the formation of polynitration by-products was further confirmed in heat activated persulfate oxidation of nitrophenols. Formation of inorganic arsenics during ROX degradation was measured by inductively coupled plasma-mass spectrometry (ICP-MS). It was evident that the arsenic substituent of ROX was converted to As(V). On the basis of the intermediate products identified, detailed mechanisms and transformation pathways for ROX oxidation were proposed. Results manifest that heat activated PS oxidation could be an efficient approach to treat ROX contamination. However, post-treatment is necessary for complete removal of As(V) to minimize ecotoxicological risks.
In this study, a novel Co 3 O 4 -La 2 O 2 CO 3 @C composite was fabricated via the calcination of Co-La bimetallic MOFs at 500 °C, and was employed to efficiently activate peroxymonosulfate (PMS) for simultaneous oxidation of roxarsone (ROX) and adsorption of concomitant inorganic arsenic. Approximately 100% of ROX (50 μmol L −1 ) was degraded by PMS (0.5 mmol L −1 ) activated with Co 3 O 4 -La 2 O 2 CO 3 @C (0.2 g L −1 ) at initial pH 6 within 10 min. Meanwhile, the produced inorganic arsenic was almost completely adsorbed within 90 min. The maximum adsorption capacity of As(V) by Co 3 O 4 -La 2 O 2 CO 3 @C was determined to be high up to 275.4 mg g −1 . Co 3 O 4 -La 2 O 2 CO 3 @C also exhibited superior stability. During 6 rounds, the degradation efficiency of ROX and the removal efficiency of the total As maintained almost 100% and more than 97%, respectively. SO 4 − and OH were confirmed to be the reactive oxygen species (ROS) in charge of the degradation of ROX and the conversion of As(III) to As(V). The investigation of the adsorption mechanism revealed that the As species were combined with La species via ligand and anion exchange, resulting in the formation of La-O-As bond. Furthermore, the practical application potential of Co 3 O 4 -La 2 O 2 CO 3 @C in the ROX degradation and the in-situ adsorption of the released arsenic were further evaluated in a continuous flow column reactor. The Co 3 O 4 -La 2 O 2 CO 3 @C composite as catalyst and adsorbent may offer a feasible strategy for the implementation of organoarsenic degradation and produced inorganic arsenic adsorption.
Despite potential of layered double hydroxides (LDHs) in photocatalytic wastewater treatment was demonstrated, their practical applications remain constrained by inherent limitations including sluggish charge separation kinetics and insufficient stability. To overcome these critical challenges, we engineered a boron-doped porous lignin carbon loaded with copper-iron layered double hydroxides (B-PLC/CuFe LDH) photocatalyst through hydrothermal synthesis. The dual-modification strategy overcomes inherent limitations of conventional LDH systems through boron-induced electronic coupling and interfacial engineering. Boron doping modulates the electronic structure of the porous lignin carbon (PLC), strengthening interfacial interactions with CuFe LDH layers, while the hierarchical carbon framework enhances LDH dispersion and charge transfer efficiency. Systematic characterization (UV-DRS, Mott-Schottky) revealed that boron doping synergistically widened the composite's bandgap from 1.54 eV (pristine PLC) to 1.83 eV (B-PLC-3/CuFe LDH), while maintaining strong visible-light harvesting. According to Electrochemical impedance spectroscopy (EIS), boron doping reduced electrochemical impedance, and increased photogenerated radical formation (·O 2 - and ·OH), collectively enabling efficient arsenic pollutant degradation. The optimized B-PLC-3/CuFe LDH achieved 84.7% roxarsone (ROX) degradation within 60 min under visible light, outperforming pristine PLC by 2.05 times. This work establishes a new paradigm for overcoming LDH's intrinsic limitations through defect-engineered carbon hybridization, opening avenues for sustainable heavy metal remediation.
危险品化学品经营许可证（带存储）