Recovery of Phosphorus through Different Masses Calcined Chicken Eggshells Adsorbent in Water: Prediction, Kinetic and Isotherm Model

Abstract

Phosphorus (P) is a vital chemical element for the growth of living beings. However, the excess of phosphorus in wastewater due to discharge by the public causes’ nutrient pollution, leading to eutrophication through algae bloom. Eutrophication causes the death of aquatic life due to the absence of oxygen in the aquatic ecosystem and spreads diseases across the community through bioaccumulation when consumed. Recent studies have shown that eco-friendly adsorbents can remove excess phosphorus from wastewater. In recent research, a study was conducted to investigate the removal of phosphorus from water onto calcined waste chicken eggshells with different masses of adsorbents. Phosphorus was removed from the synthetic solution and domestic wastewater using waste chicken eggshell calcined at 900 °C with different adsorbent masses (2, 4, 6, 8 and 10 g). The result of the batch experiment was analysed using kinetic and isotherm models to reveal the adsorption mechanics. It was shown that the optimum contact time was 60 min and the optimum particle mass was 10 g of the adsorbent with 99.4% removal efficiency and 0.0328 mg/g for adsorption capacity. Between the two kinetic models, the Pseudo-First-Order model and the Pseudo-Second-Order model, Pseudo-Second-Order was more fitted for kinetic isotherm with a correlation coefficient, R², of 0.9992, which implies that the adsorption happens on low concentration solution and the adsorption rate is linearly proportional to the active sites on the adsorbent. The adsorption isotherm fits the Freundlich isotherm model with the correlation coefficient, R², of 0.6681, indicating that the adsorption process occurred in heterogenous sites and multilayer states. The study has shown that the calcined chicken eggshells were an excellent adsorbent to remove phosphorus from wastewater and suitable as an eco-friendly adsorbent to implement in the tertiary wastewater treatment for future environmental improvement.