Preparation of peanut shell biochars and their adsorption properties for heavy metal ions

This study utilized peanut shells as the adsorbent material, producing peanut shell biochar (PSB) via pyrolysis to examine its adsorption properties.The production yield, pH, elemental composition, and specific surface area were examined at different pyrolysis temperatures of PSB. Adsorption mechanism of PSB was elucidated using a scanning electron microscope (SEM) and Fourier transform infrared spectroscopy (FTIR).The carbonization process of PSB is typically divided into five stages: primary matter, excessive carbon, amorphous carbon, composite carbon, and turbostratic carbon.This study examined the effects of pyrolysis temperature, adsorption time, initial solution concentration, and adsorbent mass on the adsorption capacity.The adsorption kinetics of PSB were investigated and modeled using appropriate correlation models.Batch adsorption experiments utilizing PSB were conducted, and adsorption isotherms were evaluated.The findings reveal that PSB exhibits the highest adsorption capacity for lead(II) ions, followed by copper(II) and cadmium(II).Pyrolysis enhances the durability and adsorption characteristics of peanut shells.PSB serves as an effective adsorbent for treating water contaminated with heavy metals. • Pyrolysis temperature critically modulates the physicochemical properties of peanut shell biochar (PSB). • FTIR spectroscopy reveals functional group evolution, clarifying structural differences between low- and high-temperature biochars. • Selective adsorption capability for various heavy metal ions is demonstrated. • Dual objectives of agricultural waste valorization and heavy metal pollution control are achieved.