Rapid Removal of Azophloxine via Catalytic Degradation by a Novel Heterogeneous Catalyst under Visible Light

Abstract

Azo dyes are the most widely used synthetic dyes in the printing and dyeing process. However, the discharge of untreated azo dyes poses a potential threat to aqueous ecosystems and human health. Herein, we fabricated a novel heterogeneous catalyst: activated-carbon-fiber-supported ferric alginate (FeAlg-ACF). Together with peroxymonosulfate (PMS) and visible light, this photocatalytic oxidation system was used to remove an azo dye—azophloxine. The results indicated that the proposed catalytic oxidation system can remove 100% of azophloxine within 24 min, while under the same system, the removal rates were only 92% and 84% when ferric alginate was replaced with ferric citrate and ferric oxalate, respectively, which showed the superiority of FeAlg-ACF. The degradation of azophloxine is achieved by the active radicals (SO4•− and •OH) released from PMS and persistent free radicals from activated carbon fiber. Moreover, due to ferric alginate’s highly intrinsic photosensitivity, visible radiation can further enhance the ligand-to-metal charge transfer (LMCT) processes. After 24 min of treatment, the total organic carbon of the azophloxine solution (50 μmol/L) decreased from 1.82 mg/L to 79.3 μg/L and the concentration of nitrate ions increased from 0.3 mg/L to 8.6 mg/L. That is, up to 93.5% of azophloxine molecules were completely degraded into inorganic compounds. Consequently, potential secondary contamination by intermediate organic products during catalytic degradation was prohibited. The azophloxine removal ratio was kept almost constant after seven cycles, indicating the recyclability and longevity of this system. Furthermore, the azophloxine removal was still promising at high concentrations of Cl−, HCO3−, and CO32−. Therefore, our proposed system is potentially effective at removing dye pollutants from seawater. It provides a feasible method for the development of efficient and environmentally friendly PMS activation technology combined with FeAlg-ACF, which has significant academic and application value.

Critical assessment of advanced oxidation processes and bio-electrochemical integrated systems for removing emerging contaminants from wastewater

“…Likewise, an investigation demonstrated that persulfate (PS)based AOPs are also efficient in degrading emerging pollutants from wastewater. 113 The same research indicated that the PS-based Fenton system achieved 96% degradation efficiency for 50 mg L −1 sulfamerazine within a time period of 30 min. 113,114 Meanwhile, when compared with the hybrid system, an investigation by Yang and co-workers revealed that BEF systems have shown the degradation of metoprolol, a betablocker, to be nearly 95% within an HRT of 6 h from the initial pollutant concentration of 10 mg L −1 .…”

“…113 The same research indicated that the PS-based Fenton system achieved 96% degradation efficiency for 50 mg L −1 sulfamerazine within a time period of 30 min. 113,114 Meanwhile, when compared with the hybrid system, an investigation by Yang and co-workers revealed that BEF systems have shown the degradation of metoprolol, a betablocker, to be nearly 95% within an HRT of 6 h from the initial pollutant concentration of 10 mg L −1 . 115 Furthermore, in comparison to the standalone CW system (76.3% removal of SMX with a hydraulic retention time (HRT) of 10 days), the CW-MFC exhibited a signicant improvement in SMX removal, which was mainly due to the integration of both the technologies.…”

Natural and Synthetic Fiber‐Based Adsorbents for Water Remediation

“…The incorporation of intrinsic photosensitive materials such as ferric alginate into adsorbents facilitates the removal of azophloxine because it introduces the relevance of the absorption of light in the overall process. [113] The development of lanthanum oxide ceramic nanowires decorated with nickel nanoparticles exhibited superior performance for the removal of rhodamine B due to the decoration with metal particles and available sites on the fiber surface for the adsorption of contaminants. [114] Similarly, electrospun fibers were prepared by deacetylated cellulose acetate and polydopamine for the adsorption of methylene blue.…”

“…The incorporation of intrinsic photosensitive materials such as ferric alginate into adsorbents facilitates the removal of azophloxine because it introduces the relevance of the absorption of light in the overall process. [ 113 ]…”

Peroxymonosulfate Activation by Photoelectroactive Nanohybrid Filter towards Effective Micropollutant Decontamination

“…Various heterogeneous catalysts have been widely used for PMS activation to produce highly reactive species. Among these, ironbased catalysts are of particular interest due to their exceptional high performance and cost effectiveness [7,8]. Yet, their application is significantly hindered by the challenges associated with the post-separation of powder-like catalysts from the reaction solution, potential Fe ion leaching and poor mass transport in conventional batch reactors.…”