Biosorption of cadmium and nickel ions using marine macrophyte, Cymodocea nodosa

Seagrass (Cymodocea nodosa) ability to remove cadmium and nickel ions from single metal solutions was investigated in the present study. Metal ions were measured in the solution using an atomic absorption spectrophotometer. Various operational parameters (initial pH, biomass dose, metal ion concentration, and contact time) were tested and found to affect the uptake capacity of Cd (II) and Ni (II). More than 70% of biosorption capacity occurred in the first few minutes for both metal ions. The pseudo-second-order kinetic model and the Langmuir model were found to best fit the experimental data of Cd (II) and Ni (II) biosorption. The maximum uptake capacity (q(max)) was 11.6 and 16.7 mg.g(-1) for Cd (II) and Ni (II), respectively. The biosorbent was characterised using Fourier transform infrared spectrometry (FTIR), scanning electron microscope (SEM), and energy-dispersive X-ray spectroscopy (EDX). The infrared spectrum demonstrated that hydroxyl, carboxyl, and phenolic functional groups are the major binding sites for Cd (II) and Ni (II) metals. The ion exchange mechanism plays an important role during biosorption process as shown in EDX analysis. Our results conclude that marine macrophyte C. nodosa can be used as a low-cost biosorbent for the removal of Cd (II) and Ni (II) in wastewater.