Rose biomass as a potential biosorbent to remove chromium, mercury and zinc from contaminated waters

Abstract

Rose flowers are used for the extraction of essential oil or rose water. The vast majority of the leftover biomass is generally wasted. The aim of the present study was to analyse the rose flower biomass as a potential biosorbent for metals chromium(III), mercury(II) and zinc(II), to remove them from industrial effluents. A number of variables were analysed, including untreated, acid-treated and base-treated biomass, biomass dosage, metal ion concentration, contact time, and pH. Increase in biomass dosage and metal ion concentration increased biosorption. The pH proved to be a very important factor and all the metals showed high adsorption at slightly acidic to moderately basic pH 6–10. They showed very low uptake at low pH. Contact time had little effect on the adsorption capacity of zinc, but was very crucial in the case of mercury. Base treatment favoured adsorption of mercury and zinc. The adsorption of Cr³⁺, Hg²⁺ and Zn²⁺ on rose biomass can be explained by Langmuir and Freundlich isotherms equally well, and the adsorption process followed pseudo second order kinetics. The study suggests that the rose flower biomass can be used in the removal of these metals from contaminated waters employing optimum conditions indicated by the present work.

Keywords:

• Heavy metals
• wastewater
• rose biomass
• adsorption

Acknowledgments

The authors wish to thank the management of Forman Christian College, Lahore, for providing facilities for this research work; and also the leaned reviewer and the Editor for their help throughout the review process.