Effective biosorptive removal of Pb2+ ions from wastewater using modified lettuce leaves: A novel sustainable and eco-friendly biosorbent

• Lettuce leaves (LC) served as a biosorbent for the uptake of Pb 2+ ions. • The decoration of alginate and DTPA led to a remarkable improve in uptake capacity. • The LC/ALG-DTPA biosorbent has a high adsorption capacity of 168.35 mg/g. • Adsorption mechanism is primarily driven by the formation of a Pb 2+ -DTPA complex. • The biosorbent can remove up to 73.42 % of Pb 2+ ions from urban wastewater. The design and synthesis of green material for the efficient treatment of heavy metal is of great environmental and economic significance. In the current report, lettuce leaves (LC) an inexpensive agricultural waste were modified employing alginate (ALG) and diethylenetriaminepentaacetic acid (DTPA) to generate a novel biosorbent for the sequestration of Pb 2+ ions. The biosorbents were characterized utilizing scanning electron microscopy (SEM), X-ray diffraction (XRD), fourier transform infrared spectroscopy (FT-IR), and energy dispersive X-ray spectroscopy (EDX). Under optimal conditions, the Pb 2+ biosorption efficiency and adsorption capacity onto LC/ALG-DTPA were 89.02 % and 71.22 mg.g -1 , respectively. The chemical adsorption was controlled by second-order kinetics and Langmuir's isothermal, revealing the highest biosorption capacity of 168.35 mg.g -1 . The biosorption system demonstrated a significantly higher affinity for Pb 2+ compared to Ni 2+ , with removal efficiencies of 86.54 and 30.13 %, respectively. Our findings indicated that the LC/ALG-DTPA exhibited moderate stability during regeneration, revealing a 15.43 % decrease in Pb 2+ biosorption efficiency after five cycles of immersion in harsh conditions. Notably, LC/ALG-DTPA removed up to 73.42 % of Pb 2+ species in urban wastewater and the cost of biomaterial preparation was calculated in detail. These results highlight LC/ALG-DTPA as a high-efficiency, eco-friendly biosorbent for eliminating Pb²⁺ from water, supporting its potential in wastewater treatment.