Enhanced degradation of micropollutants by zero-valent aluminum activated persulfate: assessment of toxicity and genotoxic activity

Acid-washed zero-valent aluminum as a highly efficient persulfate activator for degradation of phenacetin

Phenacetin (PNT) is one of the most frequently detected nonsteroidal anti-inflammatory drugs in the water ecosystems, which poses a potential risk to environmental aquatic organisms. Acid-washed zero-valent aluminum (ZVAl) as a highly efficient activator for persulfate (PS) process was investigated to degrade PNT from the aqueous solution. The results indicated that acid-washed pretreatment for ZVAl could efficiently increase the degradation efficiency of PNT in the PS treatment. The degradation efficiency of PNT (50 μM) was up to 90% in 4 hours with the addition of 0.2 g/L acid-washed ZVAl and 8 mM PS at pH 6.8 and 25 °C. The PNT degradation followed pseudo-first order kinetics in the present system. High activator dosage, PS concentration, and reaction temperature could enhance the PNT degradation. The presence of inorganic anions (i.e., NO₃^-, HCO₃^-) and humic acid (HA) showed inhibitory effects on the PNT degradation. The reuse results illustrated the acid-washed ZVAl material would have continuous and efficient activation performance for PS to degrade the PNT. Radical scavenger experiments and electron paramagnetic resonance indicated that both SO₄^•- and •OH were major reactive species during the PNT degradation. The possible degradation pathways of PNT mainly included the break of C-N and C-O bonds and further oxidation.

Comprehensive review on iodinated X-ray contrast media: Complete fate, occurrence, and formation of disinfection byproducts

Iodinated contrast media (ICM) are drugs which are used in medical examinations for organ imaging purposes. Wastewater treatment plants (WWTPs) have shown incapability to remove ICM, and as a consequence, ICM and their transformation products (TPs) have been detected in environmental waters. ICM show limited biotransformation and low sorption potential. ICM can act as iodine source and can react with commonly used disinfectants such as chlorine in presence of organic matter to yield iodinated disinfection byproducts (IDBPs) which are more cytotoxic and genotoxic than conventionally known disinfection byproducts (DBPs). Even highly efficient advanced treatment systems have failed to completely mineralize ICM, and TPs that are more toxic than parent ICM are produced. This raises issues regarding the efficacy of existing treatment technologies and serious concern over disinfection of ICM containing waters. Realizing this, the current review aims to capture the attention of scientific community on areas of less focus. The review features in depth knowledge regarding complete environmental fate of ICM along with their existing treatment options.

Fe(II)-activated persulfate oxidation to degrade iopamidol in water: parameters optimization and degradation paths

Iodinated contrast media (ICM), which was widely used in medical imaging and was difficult to remove by conventional wastewater treatment methods, attained much attention due to its potential environmental impacts. Herein, iopamidol (IPM), one typical compound of ICM, was found to be rapidly degraded by ferrous activated persulfate oxidation (Fe(II)/PS) as compared with PS or Fe(II) alone. With a persulfate concentration of 1 mmol L⁻¹, n(Fe(II))/n(PS) of 1:10, and a pH of 3.0, 78% IPM was degraded within 60 min, with a degradation rate of 0.1266 min⁻¹. It was demonstrated that IPM degradation and deiodination were favored by a high temperature, while affected positively by acidic and neutral conditions. Radical quenching experiments and Electron Paramagnetic Resonace (EPR) spectra showed that the combined effects of SO₄⁻· and ·OH contributed dominantly to degrade IPM, while the ·OH played an essential role during the degradation reaction. Through the Discrete Fourier Transform quantum chemical calculation, the possible reaction pathways for the oxidation of IPM by ·OH are as follows: IPM-TP651-TP667-TP541-TP557, IPM-TP651-TP525-TP557, IPM-TP705-TP631-TP661, and IPM-TP705-TP735. The obtained results showed that IPM could be degraded effectively by Fe(II)/PS system, giving a promising technique for IPM removal from water.

Potential Health Risks Linked to Emerging Contaminants in Major Rivers and Treated Waters

The presence of endocrine-disrupting chemicals (EDCs) in our local waterways is becoming an increasing threat to the surrounding population. These compounds and their degradation products (found in pesticides, herbicides, and plastic waste) are known to interfere with a range of biological functions from reproduction to differentiation. To better understand these effects, we used an in silico ontological pathway analysis to identify the genes affected by the most commonly detected EDCs in large river water supplies, which we grouped together based on four common functions: Organismal injuries, cell death, cancer, and behavior. In addition to EDCs, we included the opioid buprenorphine in our study, as this similar ecological threat has become increasingly detected in river water supplies. Through the identification of the pleiotropic biological effects associated with both the acute and chronic exposure to EDCs and opioids in local water supplies, our results highlight a serious health threat worthy of additional investigations with a potential emphasis on the effects linked to increased DNA damage.