EQUILIBRIUM MODELLING AND SPECTROSCOPIC STUDIES FOR THE BIOSORPTlON OF ZW' IONS FROM AQUEOUS SOLUTION USING IMMOBILIZED SPlRULINA PLATENSIS

Biosorption equilibrium of zinc ions to spirulina plutensis both in free and immobilized forms were studied inbatch system with respect to ph, metal ion concentration. algal dosages and time. the maximum adsorption wasobserved at ph~8, optimummetal ion concentration and algal dose were 100mg/l and 1gil ooml, respectively.biosorption equilibrium was established in 90 minutes. the maximum attainable biosorption was found to be97.1% for spirulina platensis. the equilibrium adsorption capacities of adsorbents used for zinc ions weremeasured and extrapolated using langmuir and freundlich isotherms models. langmuir model was found to bein better correlation with experimental data. the maximum langmuir constantsq, (mg/g) and b were 92.93 and0.0012, respectively for spiralina platensis embedded in calcium alginate matrix. the immobilized spirulinaplatensis in calcium of alginate matrix was the best biosorbent, 0.1 m edta was used as an eluant, which allowedthe reuse of biomass in three biosorption-desorption cycles without considerable loss in biosorption capacity. 8995~/o zinc ions 'a'cfc desorbed with edta. the functional groups involved in zinc biosorption were identifiedby using fourier transform infra red spectroscopy. spectroscopic analysis of algae revealed the presence ofcarboxyl. hydroxyl, amino, amide and imine groups, which were responsible for biosorption of zinc ions.