Abstract
Activated carbon (AC) and activated biochar (ABC) are widely used as sorbents for micropollutant removal during water and wastewater treatment. Spent adsorbents can be treated in several ways, e.g., by incineration, disposal in landfills, or reactivation. Regeneration is an attractive and potentially more economically viable alternative to modern post-treatment practices. Current strategies for assessing the performance of regeneration techniques often involve only repeated adsorption and regeneration cycles, and rarely involve direct measurements of micropollutants remaining on the adsorbent after regeneration. However, the use of regenerated adsorbents containing such residual micropollutants could present an environmental risk. In this study, the extraction of eight active pharmaceutical ingredients (APIs) commonly found in treated effluents was evaluated using 10 solvents and sorption onto three different carbon materials. An optimized extraction method was developed involving ultrasonication in 1:1 methanol:dichloromethane with 5% formic acid. This method achieved recoveries of 60 to 99% per API for an API concentration of 2 μg/g char and 27 to 129% per API for an API concentration of 1 mg/g char. Experiments using a mixture of 82 common APIs revealed that the optimized protocol achieved extraction recoveries above 70% for 29 of these APIs. These results show that the new extraction method could be a useful tool for assessing the regenerative properties of different carbon sorbents.
Highlights
The per capita consumption of pharmaceuticals is increasing around the world (Bernhardt et al 2017; Klein et al 2018)
While extraction solvents are usually selected-based solely on the polarity of the target contaminants, an alternative approach is to mix miscible polar and nonpolar solvents to enable the desorption of a wider range of active pharmaceutical ingredients (APIs)
The extraction method for the 8 selected APIs was initially tested on Activated carbon (AC)
Summary
The per capita consumption of pharmaceuticals (including antibiotics, antidepressants, and painkillers) is increasing around the world (Bernhardt et al 2017; Klein et al 2018). Some active pharmaceutical ingredients (APIs) are partially metabolized, while others remain unchanged. These degradation products and the non-degraded APIs end up in wastewater treatment plants (WWTPs). To prevent these undesirable outcomes, many WWTPs have implemented tertiary treatment procedures designed to degrade (e.g., ozonation) or capture (using materials such as adsorbents) these contaminants before they enter the environment
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