ABSTRACT In this study, Parthenium hysterophorus biomass was converted into biochar adsorbents (PTC300, PTC500, and PTC700) through pyrolysis at 300°C, 500°C, and 700°C, respectively. These biochars were subsequently evaluated for their efficacy in removing Cd(II) from industrial wastewater. The adsorption mechanisms were investigated using kinetic and isothermal models and post‐adsorption characterization of biochars with the help of Fourier‐transform infrared spectroscopy, scanning electron microscopy, and energy‐dispersive x‐ray spectroscopy. The PTC500 and PTC700 exhibited high aromaticity, hydrophobicity, porosity, and BET surface area (65.9 and 77.8 m 2 /g, respectively) because of high pyrolytic temperatures. Among the synthesized adsorbents, PTC500 exhibited the highest adsorption capacity (41.28 mg/g) as predicted by the Langmuir isotherm model in the batch adsorption study. From the real industrial wastewater, PTC500 resulted in 95% removal of Cd(II). The adsorption process followed the Langmuir isotherm, suggesting monolayer adsorption. Additionally, the pseudo‐first‐order kinetic model indicated that physical adsorption predominated on the surface of the biochars. The unique properties of the biochars, such as their porous structure, diverse surface functional groups, and high concentration of base cations, played a critical role in the effective adsorption of Cd(II). Key mechanisms involved in the adsorption process included surface complexation, Cd–π interactions, ion exchange, and precipitation.
Younas et al. (Mon,) studied this question.