Degradation aspects of endocrine disrupting chemicals : A review on photocatalytic processes and photocatalysts

Endocrine disrupting chemicals (EDCs) can interfere human and animal endocrine glands and organs, and thus hazardous effects of the EDCs result in a great environmental challenge for health. Considering their chemical structures with characteristic functional groups and their pharmacological effects in applications, the EDCs as target substrates for degradation can be generally classified into 5 groups, including hormones and steroids containing phenolic hydroxyl/carbonyl groups, pesticides and herbicides with aromatic rings and heterocyclic rings as well as chlorine substituents, additives of personal care products (parabens and phenones), plasticizers (bisphenols and phthalates), and other organic pollutants (PFCs, PCBs, PBDEs, carbamazepine, metformin, phenols, dioxins and PAHs). In this article, the hazards of EDCs and recent advances of photocatalytic degradation (PCD) for the EDCs are summarized and reviewed. Photocatalytic process appears to be a very promising technology in the treatment of EDCs, but the efficiencies are highly relying on performance of the photocatalysts. To evaluate the rates of EDCs photodegradation catalyzed by various as-synthesized and commercial photocatalysts, the catalytic activities of photocatalysts are summarized in terms of unified TOFs (turn over frequencies), and the fundamental photocatalytic mechanisms are discussed. The existence and roles of possible intermediate products during the EDCs degradation are also considered and discussed. There is still a challenge to achieve a maximum mineralization without endocrine disrupting intermediate products and perform high-efficient degradation of EDCs using low-cost solar energy, especially under visible and near-infrared light.