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Study of physical chemistry on biosorption of copper by using chlorella pyrenoidosa

Hassan Rezaei, Satish D.Kulkarni, Praveen G.Saptarshi

Discharge of heavy metals from metal processing industries is known to have adverse effects on the environment. Biosorption of heavy metals by metabolically inactive biomass of microbial organisms is an innovative and alternative technology for removal of these pollutants from aqueous solution. Presence of heavy metals in the aquatic system is posing serious problems and copper has been used in many industrials and removal of Cu ions fromwastewaters is significant. Biosorption is one of the economicmethods that used for removal of heavy metals. In the present study, the biomass generated from the dried Chlorella pyronoidsa was used for evaluating the biosorption characteristics of Cu ions in aqueous solutions. Batch adsorption experiments were performed on these leaves and it was found that the amount ofmetal ions adsorbed increasedwith the increase in the initialmetal ion concentration. In this study effect of agitation time, initialmetal ion concentration, temperature, pH&biomass dosagewere studied.Maximummetal uptakewas observed at pH= 5.Maximummetal uptake (qmax)was 142.86mg/ g. The biosorption followed both Langmuir and Freundlich isothermmodel but Freundlich isothermmodelwas better thanLangmuirwithR2= 0.985. The adsorption equilibriumwas reached in about 1 h. The kinetic of biosorption followed the second – order rate. The biomass could be regenerated using 0.1MHNO3.Apositive value of H° indicated the endothermic nature of the process. A negative value of the free energy (G°) indicated the spontaneous nature of the adsorption process. A positive value of S° showed increased randomness at solid–liquid interface during the adsorption of heavy metals, it also suggests some structural changes in the adsorbate and the adsorbent. FTIR Spectrums of Chlorella pyrenoidosa revealed the presence of hydroxyl, amino, carboxylic and carbonyl groups. The scanning electron micrograph (SEM) clearly revealed the surface texture and morphology of the biosorbent.