Abstract
The highly prescribed antidepressant, citalopram, as one of newly emerging pollutants, has been frequently detected in the aquatic environment. Citalopram oxidation was examined during sodium hypochlorite (NaOCl) and chlorine dioxide (ClO2) chlorination processes since conventional wastewater treatment plants cannot remove citalopram effectively. Citalopram has been demonstrated to form N-nitrosodimethylamine (NDMA) during chlorination in our previous study. Further investigation on NDMA formation kinetics was conducted in the present study. Influences of operational variables (disinfectant dose, pH value) and water matrix on citalopram degradation, as well as NDMA generation, were evaluated. The results indicated high reactivity of citalopram with NaOCl and ClO2. NDMA formation included two stages during CIT oxidation, which were linear related with reaction time. NaOCl was more beneficial to remove CIT, but it caused more NDMA formation. Increasing disinfectant dosage promoted citalopram removal and NDMA formation. However, no consistent correlation was found between citalopram removal and pH. Contrary to the situation of citalopram removal, NDMA generation was enhanced when citalopram was present in actual water matrices, especially in secondary effluent. DMA, as an intermediate of citalopram chlorination, contributed to NDMA formation, but not the only way.
Highlights
A higher prevalence of psychiatric disorders and increasing awareness of mental health issues caused the number of prescriptions for psychiatric pharmaceuticals, antidepressants, promptly increasing [1]
Contrary to the situation of citalopram removal, NDMA generation was enhanced when citalopram was present in actual water matrices, especially in secondary effluent
We investigated the characterizations of CIT oxidation during NaOCl and ClO2
Summary
A higher prevalence of psychiatric disorders and increasing awareness of mental health issues caused the number of prescriptions for psychiatric pharmaceuticals, antidepressants, promptly increasing [1]. Selective serotonin reuptake inhibitors (SSRIs) antidepressants, which are used to treat psychiatric disorders, panic disorder, and social phobia, have been widely marketed since the mid-1980s [3]. As a new class of emerging pollutants, antidepressants have caused worldwide concern due to their persistence and acute toxicity to aquatic life [4]. Between 12% and 23% of CIT is excreted unaltered in the urine due to the incomplete disintegration in human body [9]. Human excretion and disposal of unused or expired drugs in toilets may be the major input of CIT in the wastewater [10]. Wastewater treatment plants (WWTPs) cannot remove personal care products (PPCPs) residues and metabolites effectively since conventional
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