Selective adsorption of drug micropollutants from synthetic wastewater using hydrochar derived from carbonisation of unused leaves

One-step hydrothermal carbonisation method was used to synthesise hydrochar, SRL HC (Saccarum ravannae hydrochar), and SOL HC (Saccarum oficinarum hydrochar), which were employed to remove highly toxic and emerging contaminants drugs, diclofenac, ibuprofen, and naproxen from the synthetic aquatic environment. The presence of hydroxyl and carboxylic acid groups makes these hydrochars an efficient adsorbent. The adsorption experiments were conducted to optimise various parameters such as pH, adsorbent dose, contact time, and temperature. Then maximum adsorption capacity of diclofenac, ibuprofen, and naproxen on SRL HC was found to be 230.04, 201.92, 191.43 mg/g, while the maximum adsorption capacity of SOL HC were 103.40, 77.72, 62.02 mg/g at 303 K. The adsorption of drugs fits well with the pseudo-second-order kinetics model and the Langmuir adsorption isotherm model with a high correlation coefficient (R² ˃ 0.99). Thermodynamic studies indicated that adsorption was chemisorptive and endothermic. Adsorption in real water samples along with reusability was also performed with these hydrochars.