Microplastic-Assisted Removal of Phosphorus and Ammonium Using Date Palm Waste Derived Biochar

Microplastics (MPs) are emerging environmental pollutants worldwide, posing potential health risks. Moreover, MPs may act as vectors for other contaminants and affect their fate, transport, and deposition in the environment. Therefore, efficient and economical techniques are needed for the removal of contemporary MPs and contaminants from the environment. The present research study investigated the sorption of phosphorus (P) and ammonium (NH₄⁺) onto date palm waste-derived biochar (BC) from an aqueous solution in the presence of polyamide (PA) and polyethylene (PE) MPs. The BC was prepared at 600 °C, characterized for physio-chemical properties, and applied for P and NH₄⁺ removal via isotherm and kinetic sorption trials. The results of the sorption trials demonstrated the highest removal of NH₄⁺ and P was obtained at neutral pH 7. The highest P sorption (93.23 mg g^-1) by BC was recorded in the presence of PA, while the highest NH₄⁺ sorption (103.76 mg g^-1) was found with co-occurring PE in an aqueous solution. Sorption isotherm and kinetics models revealed that P and NH₄⁺ removal by MP-amended BC followed chemisorption, electrostatic interaction, precipitation, diffusion, and ion exchange mechanisms. Overall, co-existing PA enhanced the removal of P and NH₄⁺ by 66% and 7.7%, respectively, while co-existing PE increased the removal of P and NH₄⁺ by 55% and 30%, respectively, through the tested BC. Our findings suggested that converting date palm waste into BC could be used as a competent and economical approach to removing P and NH₄⁺ from contaminated water. Furthermore, microplastics such as PE and PA could assist in the removal of P and NH₄⁺ from contaminated water using BC.