Sun coral powder as adsorbent: Evaluation of phosphorus removal in synthetic and real wastewater

• Release of P in water bodies is a severe environmental problem in many countries.
• Exotic sun coral spread over 2000 km of the Brazilian coast displace native species.
• Low cost adsorbent made from sun coral exoskeleton removes P from wastewater.
• Adsorption follows the Langmuir model, being exothermic and spontaneous.
• Sun coral adsorbent proved to be more effective for P removal than other materials.

Two exotic species introduced during the 90 s known as sun coral currently spread along 2000 km of the Brazilian coast pose a severe threat to the marine biodiversity. Since they have exoskeletons with high concentration of calcium carbonate, the present investigation focused on the removal of phosphorus from wastewater, using exoskeleton’s powder in three forms: raw (RSC); physically modified (SCA) and chemically modified (SCC). A Central Composite Design with Response Surface Methodology was applied to the assays along to studies of kinetics, thermodynamics and equilibrium and sorbent’s characterisation by FTIR, XRD and SEM-EDX techniques. The maximum P removal capacities of RSC, SCA and SCC were 6826, 7062 and 9597 mg P kg−1, respectively. In all cases, the adsorption followed the Langmuir’s pseudo-second-order kinetic model being the process thermodynamically appropriate. The sun coral-based adsorbent is an attractive option for wastewater treatment and may contribute to the control of the sun coral population.

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