Identifying appropriate low-cost adsorbents from organic waste-derived modified biochars for the removal of pharmaceuticals, personal care products, and residual nutrients in engineered natural systems

This study assessed the effectiveness of acid-modified biochars derived from banana peel (BPB), corncob (CCB), and mango seed (MSB) as adsorbents, aiming to enhance engineered natural treatments for removing pharmaceutical and personal care products (PPCPs), including ibuprofen, methylparaben, and naproxen, along with nutrients. Batch experiments under various environmental conditions evaluated the performance of biochars prepared by pyrolysis and subjected to acid treatment to improve adsorption capacity. All three modified biochars exhibited promising potential, with maximum sorption capacities ranging from 5.39 to 33.72 mg/g for the targeted PPCPs. At a given concentration, CCB (3.81–12.51 mg/g) and BPB (3.32–13.97 mg/g) demonstrated comparable adsorption capacities for targeted nutrients, while MSB exhibited the lowest capacity (3.39–5.82 mg/g). This effectiveness in removing PPCPs and nutrients was ascribed to biochar properties such as diverse functional groups, pore volume, and size. The primary sorption mechanisms included pore filling, hydrogen bonding, n-π, and π-π interactions. Adsorption efficiency followed the order: CCB > BPB > MSB. Consequently, CCB-derived biochar was selected for fixed biochar column adsorption and bioreactor studies. The Thomas model precisely represented the breakthrough curve for targeted pollutant removal. These findings underscore the effectiveness of cost-effective, waste-derived biochars like CCB, with its high surface area (69.19 m²/g) and more adsorption capacity, for removing contaminants in engineered natural treatment systems, consequently aiding in waste management, carbon sequestration, and environmental sustainability.

Graphical abstract