Evaluation of the Adsorbent Potential of Biochar Obtained by Pyrolysis to Remove Emerging Contaminants

Emerging contaminants (EC) can be harmful to human health and the environment, as many of these compounds are persistent, bioaccumulative, toxic and are not regulated. Drugs are part of this group, including hormones (estrone, β-estradiol) and sunscreens (oxybenzone and octocrylene) used in this study. The adsorption capacity of biochar generated from the pyrolysis of rice husks from the region of Pelotas-RS-Brazil was evaluated in this study. The objective was to characterize the biochar and evaluate its adsorbent potential in the removal of hormones and sunscreens. The characterization of biochar was carried out through surface area (BET), Zero charge point (ZPC), X-ray diffraction (XFR), fixed carbon, volatile, and ash. The effectiveness in removing ECs was evaluated by stirring rice husk pyrolysis biochar (RHPB) (0.2 g and 0.5 g) in synthetic aqueous solutions fortified with 10.0 µg L-1 of the analytes at 25 °C for 1 hour at 150 rpm. The RHPB was filtered off and the analytes were desorbed with acetone and dichloromethane (DCM) under ultrasound for 30 min. The extract was concentrated, derivatized by silylation, and analyzed by gas chromatography coupled to mass spectrometry (GC-MS). Biochar showed promising removal results, reaching values of 60.1% removal for β-estradiol, 59.4% for estrone, 44.6% for octocrylene and 37.4% for oxybenzone.