Waste mussel shells as an adsorbent for Phosphate removal in solution: kinetic and isotherm model

Abstract

Eutrophication occurs when there is excess nutrient, such as phosphates, in water bodies. It causes algae bloom, which in turn disrupts aquatic life. In this study, low-cost waste mussel shell was applied as adsorbent to remove phosphate from aqueous solution (KH2PO4) by using different adsorbent types and particle sizes. Even though the application of waste mussel shell has been studied before, this study focused on comparing raw and calcined mussel shells with different particle sizes. Waste mussel shells contain high calcium carbonate (CaCO3) and are readily available to be used as an adsorbent to remove phosphates. The study applied pseudo-first-order and pseudo-second-order models for the kinetic model and used Langmuir and Freudlich models for the isotherm model to verify adsorption data with differential equation models. The results show that calcined waste mussel shell adsorbent with a size of 1.18 mm showed the highest phosphate removal (97%). Meanwhile, the best R2 value obtained was 0.999 from the pseudo-second-order model for the 0.075 mm calcined waste mussel shells. The application of waste mussel shells for phosphate removal from solutions can be a significant contribution as an alternative adsorbent in water treatment technologies