Effects of lignin on biochar from pyrolysis: emphasis on removing naproxen as pharmaceutical pollutants in wastewater

The increasing demand for effective and eco-friendly drug purification methods has led to a growing interest in exploring the potential of using biomass-derived activated carbon. This research investigated the adsorption process of the nonsteroidal anti-inflammatory drug naproxen from wastewater using biochar made from palm date and orange peels with a weight ratio of 4:1 in a batch system. Biocarbon by single-stage chemical activation, using zinc chloride as an activating agent with a 1–1.4 mm particle size and nitrogen flow rate of 0.5 L/min, was produced at 600 °C for 60 min. The experiment resulted in an optimum pH of 3, an equilibrium contact time of 210 min, and 0.11 g/L adsorbent. The kinetic study showed the pseudo-first-order model’s efficiency in the adsorption kinetics analysis. The naproxen adsorption isotherms obtained from experiments have been investigated, and it has been shown that the Temkin and Freundlich isotherms fit the data better than the Langmuir isotherms. The effect of adsorption parameters, including contact time, solution pH, adsorbent amount, initial pharmaceutical solution concentration, and temperature, was investigated. The maximum adsorption capacity for palm date and orange peel was 91.40 mg/g and 120.68 mg/g, respectively. The biochar obtained from orange peel performed much better than the palm date on naproxen uptake, and the difference in lignocellulosic composition was the rationale for this difference in adsorption. The findings of this study provide valuable insights into the field and pave the way for further research in the future.