Eco-Friendly Synthesis of Carboxymethyl Cellulose-DTPA-Incorporated Lettuce Leaves for Lead Decontamination: Modeling, Economic Evaluation, and Practical Wastewater Treatment.

Abstract

The development of environmentally friendly materials for the efficient elimination of heavy metals is both ecologically and economically important. In this study, lettuce leaves (LC), a low-cost agricultural byproduct, were modified using carboxymethyl cellulose (CMC) and diethylenetriaminepentaacetic acid (DTPA) to create a biomaterial aimed at removing Pb²⁺ ions. The synthesized LC/CMC-DTPA was ascertained through Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), zeta potential, and X-ray diffraction (XRD). Under optimized conditions, the LC/CMC-DTPA biosorbent reached a Pb²⁺ elimination efficiency of 93.33% and a biosorption capacity of 93.33 mg/g. The biosorption process was governed by a Langmuir isothermal sorption and fitted second-order sorption, with a maximum uptake capacity of 358.23 mg/g. The biosorbent displayed a drastically stronger affinity for Pb²⁺ over Ni²⁺, with elimination performances of 91.23 and 51.16%, respectively. Furthermore, LC/CMC-DTPA showed moderate regeneration stability, with only a 14.69% decline in the Pb²⁺ adsorption efficiency after four reuse cycles under harsh conditions. In a practical application, the biosorbent successfully removed 75.68% of Pb²⁺ from lead battery recycling wastewater. Overall, these findings highlight LC/CMC-DTPA as a highly effective, sustainable, and eco-friendly material to eliminate Pb²⁺ from contaminated water.