Efficient removal of triclosan from water through activated carbon adsorption and photodegradation processes

This study investigated the application of adsorption with activated carbons (ACs) and photodegradation to reduce the concentration of triclosan (TCS) in aqueous solutions. Concerning adsorption, ACs (Darco, Norit, and F400) were characterised and batch experiments were performed to elucidate the effect of pH on equilibrium. The results showed that at pH = 7, the maximum adsorption capacity of TCS onto the ACs was 18.5 mg g-1 for Darco, 16.0 mg g-1 for Norit, and 15.5 mg g-1 for F400. The diffusional kinetic model allowed an adequate interpretation of the experimental data. The effective diffusivity varied and increased with the amount of TCS adsorbed, from 1.06 to 1.68 × 10-8 cm2 s-1. In the case of photodegradation, it was possible to ensure that the triclosan molecule was sensitive to UV light of 254 nm because the removal was over 80 % using UV light. The removal of TCS increased in the presence of sulfate radicals. It was possible to identify 2,4-dichlorophenol as one of the photolytic degradation products of triclosan, which does not represent an environmental hazard at low concentrations of triclosan in water. These results confirm that the use of AC Darco, Norit, and F400 and that photodegradation processes with UV light and persulfate radicals are effective in removing TCS from water, reaching concentration levels that do not constitute a risk to human health or environmental hazard. Both methods effectively eliminate pollutants with relatively easy techniques to implement.

Pollutants of emerging concern in tourist beaches of Guerrero, Mexico: A first approach to sources

The presence of Emerging Pollutants (EPs) on the beaches of Acapulco, Mexico, is evaluated for the first time. Samples were taken from the discharge of the wastewater treatment plant at Olvidada beach, and at three beaches that receive contributions from different streams that cross through the city in Santa Lucia Bay (SLB). Using solid phase extraction and gas chromatography/mass spectrometry, 77 EPs were identified. A semiquantitative evaluation of their concentrations were made using the relative areas of the chromatographic peaks, showing that the contamination of the beaches of SLB is mainly due to the pollutants going into the streams of the micro-basins. A statistical factor analysis of all the EPs allowed differentiation of the sampling points, reducing the number of variables, which benefits future analytical determinations in the study area. Due to the toxicological characteristics of the compounds found, their presence on public-use beaches represents a risk to human health.