Efficient removal of phosphate from aqueous solutions by red seaweed, Kappaphycus alverezii

In the present study, dead biomass of marine macro algae, Kappaphycus alverezii (K. alverezii) was used for the removal of phosphate from water. The effect of different parameters such as contact time, adsorbate concentration, biosorbent dose and temperature was investigated. The biosorption kinetics data were best described by the pseudo-second order rate equation, and equilibrium was achieved after 80 min. The phosphate biosorption was governed by film diffusion process. The maximum phosphate biosorption on K. alverezii was 59.77 mg/g at 25 °C and it followed the Redlich-Peterson model. The biosorption on K. alverezii increased with increasing temperature and was the highest at pH 6.0. The calculated thermodynamic parameters (ΔG°, ΔH° and ΔS°) showed that the biosorption of phosphate onto K. alverezii biomass was feasible, spontaneous and endothermic at 15-45 °C. Results suggest that the prepared biomass of K. alverezii has potential in remediation of phosphate contaminated waters.