Statistical Design and Green Extraction of Protein-Based Bio-Coagulant from Morinda citrifolia Seed for Sustainable Phosphate Removal
Dian Arrisujaya

Doctoral Study Program in Chemistry, Department of Chemistry, Universitas Indonesia, Depok 16424, Indonesia

Abstract

The transition toward sustainable chemical processes has stimulated increasing interest in biomass-derived functional materials for environmental remediation. This study presents a green chemistry approach for developing a protein-based bio-coagulant from Morinda citrifolia seed via salt-assisted extraction aimed at enhancing chemically active biomolecules involved in pollutant binding. The material was applied for phosphate removal as a representative case of nutrient contamination in aquatic systems. Functional group analysis using Fourier Transform Infrared spectroscopy indicated enrichment of amide and hydroxyl groups associated with proteinaceous compounds that promote adsorption and coagulation interactions. To achieve systematic process understanding, Response Surface Methodology employing a Box-Behnken Design was implemented to evaluate the combined effects of pH, coagulant dosage, and initial phosphate concentration on removal efficiency and adsorption capacity. Statistical modelling demonstrated strong agreement between predicted and experimental responses, identifying coagulant dosage as the most influential parameter controlling phosphate removal performance. Optimised conditions enabled removal efficiencies above 90% under near-neutral pH, indicating chemical stability and practical applicability without extensive pH adjustment. The removal behaviour is attributed to synergistic adsorption-coagulation mechanisms driven by electrostatic interaction between anionic phosphate species and positively charged biomolecular sites. This work highlights the integration of green extraction, statistical optimisation, and natural material chemistry as an effective framework for sustainable water treatment and chemistry education innovation.

Keywords: green chemistry, response surface methodology, bio-coagulant, sustainable materials, phosphate remediation

Topic: Environmental Chemistry