Evaluation of the lead removal capacity by the adsorption process of Corbula trigona shell powder: modeling and optimization through reponse surface methodology

Abstract

This study is based on the evaluation of the adsorption process using Corbula trigona shell powder to remove lead from aqueous solution in a batch mode. Different analytical techniques, including X-ray diffraction, Fourier transform infrared spectroscopy, and EDS-coupled scanning electron microscopy, were used to characterize the shell powder before and after lead treatment. Regarding the pollutant removal, a Plackett–Burman design (PBD) was first used to determine the influencing factors from the following experimental domain: solution pH (3–9), adsorbent mass (0.1–0.5 g), contact time (40 –240 min), initial pollutant concentration (10 –60 mg L⁻¹), and adsorbent size (100 –200 μm). The respective contributions of the various factors listed above are 31.7%, 30.51%, 25.17%, 12.44%, and 0.18%. As a result, solution pH, adsorbent mass, contact time, and initial pollutant concentration were selected to optimize the lead removal process using the composite central plan. The optimal lead removal conditions were 99.028% by setting the solution pH to 4.5, initial lead concentration to 47 mg L⁻¹, contact time to 125 min, and adsorbent mass to 0.2 g. In addition, it was found that the composite central plan could be a reliable statistical tool to model and determine the optimal conditions.