Polymeric hydrochars produced from ion exchange resin residue applied in the removal of emerging contaminants in water

The presence of emerging contaminants of concern in surface waters is a problem because water treatment systems are not always designed to remove these contaminants. The objective of this study was to apply hydrothermal carbonization and physical activation to produce adsorbents from ion exchange resin residue, a residue not yet explored by these adsorbent production methodologies. The adsorbents were applied to remove bisphenol-A (BPA) and diclofenac (DCF) from water and were characterized by FT-IR, SEM, BET, metal, Boehm and PZC analyzes and ecotoxicity in water using the microalgae Raphidocelis subcapitata. Regeneration of adsorbents by ozonation for hydrochar adsorbent was studied. For the adsorption tests, the occurrence of DCF precipitation was observed. For BPA, the best results were in the pH range between 2.0 and 6.0. The ideal adsorbent dosage was 3.0 g/L for both adsorbents with BPA adsorption capacity close to 10 mg/g. The kinetic studies indicated a better fit of the data to the pseudo-second order model, with R² equal to 0.930 and 0.979 for the two adsorbents tested and the adsorption isotherms showed a better fit to the Langmuir model with R² of 0.996 and 0.994 and q_max of 12.87 mg/g and 8.21 mg/g. The ecotoxicity test of the adsorbents produced indicated that the materials were not toxic to the microalgae Raphidocelis subcapitata. The hydrocarbonized adsorbent regeneration tests through ozonization indicated an optimal ozonization time of 5 min with 70% regeneration.