Investigation of the formation of the [2(iohexol) + Mg]2+ complex and its fragmentation in electrospray ionization tandem mass spectrometry

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.

Occurrence and removal of pharmaceuticals, hormones, personal care products, and endocrine disrupters in a full-scale water reclamation plant

This study provided the first comprehensive data on the occurrence and removal of twenty-five target emerging contaminants (ECs) in a full-scale water reclamation plant (WRP) in the Southeast Asian region. Nineteen out of the twenty-five ECs were ubiquitously detected in raw influent samples. Concentrations of the detected ECs in raw influent samples ranged substantially from 44.3 to 124,966ng/L, depending upon the compound and sampling date. The elimination of ECs in full-scale conventional activated sludge (CAS) and membrane bioreactor (MBR) systems at a local WRP was evaluated and compared. Several ECs, such as acetaminophen, atenolol, fenoprofen, indomethacin, ibuprofen, and oxybenzone, exhibited excellent removal efficiencies (>90%) in biological wastewater treatment processes, while some of the investigated compounds (carbamazepine, crotamiton, diclofenac, and iopamidol) appeared to be persistent in the both CAS and MBR systems. Field-based monitoring results showed that MBR outperformed CAS in the elimination of most target ECs. The relationship between molecular characteristics of ECs (i.e. physicochemical properties and structural features) and their removal efficiencies during biological wastewater treatment was also elucidated. Excellent removal efficiencies (>90%) were often noted for ECs with the sole presence of electron donating groups (i.e. phenolic [OH], amine [NH₂], methoxy [OCH₃], phenoxy [OC₆H₅], or alkyl groups). Conversely, ECs with the absence of electron donating groups or the predominance of strong electron withdrawing groups (e.g. halogenated, carbonyl, carboxyl, and sulfonamide) tended to show poor removal efficiencies (<30%) in biological wastewater treatment processes.