Influence of Pyrolysis Temperature on the Adsorption Efficiency of Date Palm’s Petiole Biochar for N and P in Aqueous Solutions

The significant presence of nitrogen (N) and phosphorus (P) in wastewater poses considerable environmental challenges, including eutrophication and soil and water contamination. This research examines the adsorption efficacy of biochar produced from date palm petiole subjected to pyrolysis at temperatures of 300°C, 500°C and 700°C for the removal of nitrate (NO₃⁻), ammonium (NH₄⁺), and phosphorus (P) from aqueous environments. Characterization of the biochar revealed that increasing the pyrolysis temperature resulted in enhanced porosity, surface area, and carbon content, along with a decrease in oxygen-containing functional groups. The adsorption kinetics were most accurately represented by the pseudo-first-order model for both NO₃⁻ and P, whereas NH₄⁺ followed a pseudo-second-order model, indicative of chemisorption processes. The biochar obtained at 700°C (BC-700) exhibited the highest adsorption capacities for NH₄⁺ and P, attributable to its highly developed microporous structure and improved cation exchange capacity. Conversely, the removal of NO₃⁻ was limited across all biochar samples. The Freundlich isotherm model offered the most suitable representation of the adsorption data, indicating the presence of heterogeneous sorption sites. These results underscore the potential of pyrolyzed biochar as an environmentally sustainable adsorbent for nutrient removal from wastewater, with optimized pyrolysis conditions enhancing adsorption efficiency. However, additional investigations are warranted to augment the removal efficiency of nitrate through biochar modifications or the implementation of integrative treatment strategies.