Reuse of polymeric resin for production of activated hydrochar applied in removal of bisphenol A and diclofenac synthetic aqueous solution

Abstract

Spent ion exchange resins were subjected to hydrothermal carbonization (HTC) and physical activation to produce adsorbents, which were tested for the adsorption of bisphenol A (BPA) and sodium diclofenac (DCF) in water. PAHF0.35.WV and PAHF0.50.WV were the materials that presented the largest specific surface area, around 200 m2/g. The best performance was in the adsorption of BPA, with an adsorption capacity of 24.45 and 23.34 mg/g. The kinetic and adsorption isotherm models that presented the best adjustments of the curves to the experimental data were the pseudo-secondorder model and the Freundlich model. The maximum adsorption capacity of DCF was 17.82 mg/g for PAHF0.35.WV and 15 mg/g for PAHF0.50.WV. The best fit of the adsorption kinetic curves to the experimental data was for the pseudo-second-order model. In the adsorption isotherms, the Langmuir and Freundlich models presented the best fit. The toxicity study with the microalgae Raphidocelis subcapitata did not demonstrate any toxic effects of the adsorbents. Material regeneration tests indicated a recovery of the adsorption capacity of around 50% in the first cycle, and from the second cycle onwards, the recovery was not satisfactory. However, the results indicate that the anionic resin residue has potential for use in the production of activated hydrocarbons.