DOI: https://doi.org/10.55373/mjchem.v27i6.64

Keywords: Seaweed; drying method; Sargassum sp.; Kappaphycus sp.; and Padina sp.; heavy metals; biosorbents; isotherm; kinetic study

Abstract

This study investigated the potential of three seaweed species - Sargassum sp., Kappaphycus sp., and Padina sp. - as biosorbents for removing chromium (Cr⁶⁺) and cadmium (Cd²⁺) from aqueous solutions. Dried seaweed samples were introduced into metal-containing solutions, and to evaluate their heavy metal adsorption efficacy. Analytical techniques including Fourier Transform Infrared Spectroscopy (FTIR), Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES), and Field Emission Scanning Electron Microscopy (FE-SEM) were employed to evaluate the biosorbents. Among the seaweed species studied, Sargassum sp. demonstrated the highest efficiency as a heavy metal absorbent. Optimal conditions that enhanced adsorption effectiveness, especially in freeze-dried samples, were identified at pH 6. Freeze-dried samples of Sargassum sp. achieved an adsorption efficiency of 75.2 %, highlighting pH 6 as the optimal condition for adsorption across all seaweed species. Functional groups such as -OH, C=C, and S=O were found to play pivotal roles in the biosorption process. Equilibrium uptake studies were conducted using isotherm models, with the Langmuir isotherm demonstrating the best fit, indicating monolayer adsorption. Moreover, adsorption kinetics for Sargassum sp. followed a pseudo-second order model, suggesting chemisorption mechanisms involving chemical interactions between sorbates and surface functional groups. Overall, these findings underscore the potential of Sargassum sp. as an effective biosorbent for heavy metal removal, and offer insights into optimizing biosorption processes for environmental remediation applications.