Biosorption potential of Stoechospermum marginatum for removal of heavy metals from aqueous solution: Equilibrium, kinetic and thermodynamic study

Heavy metals are one of the core reasons for cancers and other disorders in humans and other organisms. Removal of heavy metal ions from contaminated resources is an expensive task. Replacement of deadly chemical adsorbents with biomaterials is an economic and eco-friendly approach for the treatment of contaminated water. The current study attempted to explore the biosorption potential of brown seaweed Stoechospermum marginatum to remove various heavy metal ions such as As, Zn, Cr and Pb. Structural analysis of the biomass before and after the biosorption was analyzed to check the structural characters and surface morphology of biomass. Functional groups responsible for the activity was studied by using the FTIR and it describes the presence of C-H bonds, carboxylic acid etc. which supports the biosorption. The surface morphology of biomass before and after biosorption was analyzed by SEM and XRD. SEM images show the vital change of biomass before and after biosorption. XRD result shows the crystalline phase of biomass. EDAX analysis on the metal bearing and raw biomass were conducted to check the localization of metals in the biomass. Influences of the parameters such as pH, time, initial metal concentrations, biomass concentration and temperature on the biosorption rate were also studied. The isotherm models such as Langmuir, Freundlich and Temkin was used to check the best fitting model. It was observed that, the present investigation fits with Langmuir model (32.154 mg/g) than the other models. Kinetic study indicates that the pseudo-second-order model suits for the reaction. The results showed that the biosorption was monolayer chemisorption. Moreover, the thermodynamic studies support the non-spontaneous reaction. The possibility of regeneration and reusability of heavy metal ions and biomass were also inspected.