TITLE:
Response Surface Optimization of a Cocoa Husk-Based Biosorbent for the Removal of Phosphate Ions
AUTHORS:
Christian Landry Yapi, Yapo Hermann Aristide Yapi, David Léonce Kouadio, Kouassi Serge Gbamélé, Issifou Ouattara Mama, Brou Dibi
KEYWORDS:
Biosorbent, Cocoa Husks, Phosphate, Central Composite Design, Response Surface
JOURNAL NAME:
Open Journal of Applied Sciences,
Vol.16 No.11,
November
10,
2026
ABSTRACT: Eutrophication of surface waters, driven by excessive phosphorus discharges, constitutes a major threat to aquatic ecosystems. The objective of this work was to identify the best conditions for preparing a cocoa husk biosorbent intended for phosphate removal, using a design-of-experiments approach. After the key factors had been selected with a Plackett-Burman screening matrix, a two-level factorial design was carried out. Although globally significant (p = 0.021), the resulting linear model proved inadequate (adjusted R2 = 63.88%), justifying recourse to a central composite design. The resulting quadratic model exhibited excellent statistical performance (R2 = 97.16%; adjusted R2 = 95.13%; coefficient of variation = 0.72%), confirming its predictive robustness. Optimization via the desirability function identified a NaOH concentration of 1 N and an activation time of 8 hours as the optimal conditions. During validation tests, a mean removal rate of 98.23% was obtained, in agreement with the predicted value of 99.67%. These results confirm the efficiency of the biosorbent and its competitiveness relative to commercial adsorbents.