Kinetic Model of Lead Adsorption by Raw and Carbonized Ceratophyllum demersum: Mechanisms and Rate Analysis

Abstract

This work sought to examine the adsorption kinetics of lead (Pb²⁺) ions on several types of Ceratophyllum demersum raw (CD), carbonized (CDCA), acid-activated (CDAC), and base-activated (CDBC). Graphs depicting lead adsorption over time indicate that the process occurs in two phases: an initial quick adsorption phase within the first few minutes (attributable to the availability of active sites), succeeded by a slow adsorption phase until equilibrium is attained. The adsorption process was examined by pseudo-first-order (PFO) and pseudo-second-order (PSO) kinetic models to clarify the processes and rate-limiting phases. Batch tests were performed at temperatures between 20 and 35 °C, with W⁺ concentrations quantified by Atomic Absorption Spectroscopy (AAS). The results indicated that the PSO model exhibited a superior fit (R² = 0.994-0.999) relative to the PFO model (R² = 0.981-0.988), suggesting that chemisorption is the predominant process. Base-activated carbon (CDBC) demonstrated superior adsorption efficiency due to increased surface functional groups. The results correspond with international research on biomass-derived adsorbents, validating the efficacy of C. demersum for sustainable wastewater treatment.