Adsorptive removal of COD from produced water using tea waste biochar

This study was conducted to explore the effectiveness of tea waste (TW) biochar (BC) as an adsorbent for the oxidizable organic contaminants measured as chemical oxygen demand (COD) in produced water (PW). BCs were prepared by modifying the TW with single (pre-pyrolysis) and combined (pre and post pyrolysis) treatments using phosphoric acid and hydrogen peroxide solutions. Based on FTIR, XPS, XRD and BET characterizations, the combined modified BC had higher oxygen-containing functional groups (-OH and -COOH), surface area (82 ± 0.50 m2/g) and pore volume (0.08 ± 0.001 cm 3/g) compared to single modified BC (60 ± 0.50 m2/g, 0.02 ± 0.002 cm 3/g). The Langmuir monolayer adsorption model best fitted both BCs with separation factor R L