Degradation of geosmin and 2-methylisoborneol in UV-based AOPs for photoreactors with reflective inner surfaces: Kinetics and transformation products

Spirulina-based carbon materials as adsorbents for drinking water taste and odor control: Removal efficiency and assessment of cyto-genotoxic effects

The sensory quality of drinking water, and particularly its taste and odor (T&O) is a key determinant of consumer acceptability, as consumers evaluate water by their senses. Some of the conventional treatment processes to control compounds which impart unpleasant T&O have limitations because of their low efficiency and/or high costs. Therefore, there is a great need to develop an effective process for removing T&O compounds without secondary concerns. The primary objective of this study was to assess for the first time the effectiveness of spirulina-based carbon materials in removing geosmin (GSM) and 2-methylisoborneol (2-MIB) from water, two commonly occurring natural T&O compounds. The efficiency of the materials to remove environmentally relevant concentrations of GSM and 2-MIB (ng L-1) from ultrapure and raw water was investigated using a sensitive headspace solid-phase microextraction coupled with gas chromatography mass spectrometry (HS-SPME-GC/MS) method. Moreover, the genotoxic and cytotoxic effects of the spirulina-based materials were assessed for the first time to evaluate their safety and their potential in the treatment of water for human consumption. Based on the results, spirulina-based materials were found to be promising for drinking water treatment applications, as they did not exert geno-cytotoxic effects on human cells, while presenting high efficiency in removing GSM and 2-MIB from water.

Insights into the carbon nanotubes-mediated activation of permanganate for decontamination under high salinity

Radical-based advanced oxidation process (AOPs) has attracted great interests in wastewater treatment field. However, by the traditional radical-based method, the degradation of organic pollution is greatly suppressed when radicals react with the co-existing anions in the solution. Herein, an efficient method for degrading of contaminant under high salinity conditions is discussed through a non-radical pathway. Carbon nanotubes (CNTs) was employed as an electron transfer medium to facilitate the electron conversion from contaminants to potassium permanganate (PM). Based the results of quenching experiments, probe experiments, and galvanic oxidation process experiments, the degradation mechanism of CNTs/PM process was demonstrated to be electron transfer, rather than reactive intermediate Mn species. As a result, typical influencing factors including salt concentration, cations, and humic acid have less of an impact on degradation during CNTs/PM processes. In addition, the CNTs/PM system exhibits superior reusability and universality of pollutants, which has the potential to be applied as a non-radical pathway for the purification of contaminant in the large-scale high salinity wastewater treatment.

Catalytic oxidation activation of peroxymonosulfate over Fe-Co bimetallic oxides for flurbiprofen degradation

In this research, FeCo₂O₄ nanomaterial was successfully synthesized by a typical sol-gel method and conducted as an effective agent for peroxymonosulfate (PMS) activation to eliminate antibiotics flurbiprofen (FLU), a strong nonsteroidal drug. FeCo₂O₄ nanomaterial was characterized by XRD, TEM, SEM, and XPS. Various characterization results proved that FeCo₂O₄ held stable spinel structure. The interfering factors including initial pH, PMS concentration, catalyst dosage, inorganic anions, and humic acid on FLU removal were also discussed. The conclusion was that the removal efficiency of FLU reached 98.2% within 120 min after adding FeCo₂O₄ (0.4 g L^-1) and PMS (3 mM). The optimal pH for FLU degradation was the initial pH of 6.5; too acidic or alkaline was not conductive to the degradation. The existence of HA and Cl^- restrained the degradation of FLU, and HCO₃^- promoted the removal, while the influence of NO₃^- and SO₄^2- could not be considered. The radical scavenging experiment confirmed that ^•OH, O₂^•-, and SO₄^•- participated in FLU removal and SO₄^•- functioned a leading role. FeCo₂O₄ showed high efficiency for PMS activation in pH range of 3.0 to 10.0. After the fourth cycle operation, the FLU removal rate exceeded 76.9%, and the Co leaching rate was low during the catalytic reaction. This study shows that FeCo₂O₄ nanomaterial is an efficient and environment-friendly catalyst, which can be applied for PMS activation to remove organic pollutants in water.