Analysis of the competitive adsorption of pharmaceuticals on waste derived materials

• Waste derived adsorbents remove marked quantity of pharmaceuticals from water.
• Adsorption of pharmaceuticals from multi-component solution is highly competitive.
• Various components of adsorbents contribute to the pharmaceutical removal.
• CBZ is mainly removed by an organic phase.
• Adsorption of SMX and TMP is governed by an inorganic phase.

To simulate complex pollutant conditions encountered in wastewater treatment plant influents, a solution containing three common pharmaceuticals was prepared. The adsorbents were exposed to various dilutions (1–100 mg/L) of a solution containing equal amounts carbamazepine (CBZ), sulfamethoxazole (SMX), and trimethoprim (TMP). The adsorbents were composed of varying proportions of sewage sludge and fish waste, such that the former represented 100%, 90%, 75% and 25% of the composition, while the remainder consisted of fish waste. Adsorption isotherms were used to determine adsorption capacity for each pharmaceutical. To understand the surface changes during adsorption, analysis by TA-MS and potentiometric titration were carried out. The results were compared to those obtained for single-component pharmaceutical solutions. CBZ was consistently adsorbed from the multi-component solution in greater quantities than was either SMX or TMP on all adsorbents. The adsorption of SMX was most negatively impacted by the presence of multiple pharmaceuticals. The best adsorbent performance varied depending on the pharmaceutical, as the mechanism of adsorption varied between pharmaceuticals, with CBZ interacting more with the carbon phase of the material, whereas SMX and TMP were more apt to react with the inorganic content.

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