Biosorption of Cr (VI) by Typha angustifolia: Mechanism and responses to heavy metal stress

• T. angustata can survive in high concentrations of Cr (VI) solution up to 30 mg L−1.
• The removal efficiencies are range from 64% to 87% for 9−12 mg L−1 Cr (VI) solutions.
• It alleviates stress of Cr (VI) by secreting sugars and proteins.
• Synchrotron μXRF mapping showed the distribution of Cr (VI) in different parts.

In this study, Typha angustifolia was proven to have an excellent accumulation ability in high concentrations of wastewater solutions having Cr (VI) concentrations up to 30 mg L−1 for 20 days (74% of removal efficiency). Synchrotron microfocus micro X-ray fluorescence (μ-XRF) mapping showed that the uptaken Cr was mainly enriched in the outer layer of the roots and a small portion of it was uniformly distributed in the fronds. The total proteins, soluble sugars, and malondialdehyde in T. angustifolia increased when the concentration of Cr (VI) increased from 9 to 30 mg L−1. Transmission electron microscope (TEM) assay showed that no lignifications were observed when Cr was absorbed by T. angustifolia. It was concluded that T. angustifolia can uptake Cr by means of surface layer absorption and transportation, and alleviate stresses associated with the sorption of Cr (VI) by thickening of cell walls or secretion of chemical substances.

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