Heavy metal biosorption using Tripneustes gratilla (striped sea urchin ) test: equilibrium isotherm and kinetic studies.

ABSTRACT: An untreated biosorbent prepared from Tripneustes gratilla test was utilized as an eco-friendly alternative for the aqueous removal of Mn(II), Co(II), Ni(II), and Cu(II). Characterization revealed a moisture content of 5.064 (=0.096)%, a pH of 8.279 (=0.033) at 20.9 (=0.5) C, a conductivity of 59.6 (=0.5)uS cm-1 at 24.6 (=0.3) 0C, and aqueous solubility of 6.1 (=0.3) %. ATR-FTIR analysis confirmed the presence of amorphous CaCO3 and supported physisorption. SEM-EDS revealed non-porous particulates, primarily composed of O (53%), Ca (34%), C (11%), and Mg (2%). Optimization determined an optimal pH of 6 for Mn and 5 for Co, Ni, and Cu, and an optimal biosorbent dosage of 125 g L-1 for Cu. Kinetic studies favoured PSO kinetics for all metals. Equilibrium isotherm studies showed that the Freundlich isotherm suited Mn biosorption best, whereas the Langmuir isotherm modelled Co, Ni, and Cu better. From the Dibinin-Radushkevich isotherm, physisirptive mean free energy values were determined for all metals. T. gratilla test shows promising biosorptive potential in the removal of the selected divalent metals at the given conditions.

Filipiniana

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