African Journal of
Pure and Applied Chemistry

  • Abbreviation: Afr. J. Pure Appl. Chem.
  • Language: English
  • ISSN: 1996-0840
  • DOI: 10.5897/AJPAC
  • Start Year: 2007
  • Published Articles: 357

Full Length Research Paper

Study of physical chemistry on biosorption of zinc by using Chlorella pyrenoidosa

Hassan Rezaei*, Satish D. Kulkarni and Praveen G. Saptarshi
Environmental Sciences Department, University of Pune – Pune, India.  
Email: [email protected]

  •  Accepted: 11 October 2011
  •  Published: 30 November 2011

Abstract

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 zinc has been used in many industrials and removal of Zn ions from waste waters is significant. Biosorption is one of the economic methods that is 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 Zn ions in aqueous solutions. Batch adsorption experiments were performed on these leaves and it was found that the amount of metal ions adsorbed increased with the increase in the initial metal ion concentration. In this study effect of agitation time, initial metal ion concentration, temperature, pH and biomass dosage were studied. Maximum metal uptake was observed at pH = 5. Maximum metal uptake (qmax) was 101.11 mg/g. The biosorption followed both Langmuir and Freundlich isotherm model. The adsorption equilibrium was reached in about 1 h. The kinetic of biosorption followed the second – order rate. The biomass could be regenerated using 0.1 M HNO3. A positive 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.Fourier transform infrared (FTIR) spectrums of C. 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.

 

Key words: Biosorption, Chlorella pyronoidosa, Zn, isotherm models, kinetic.