Chromium Removal from Aqueous Solutions by Different Plant Species

Abstract

The aim of this study was to evaluate the potential efficiency of three plant species to remove chromium from wastewaters. Wheat (Triticum aestivum), rape (Brassica napus var. Oleracea) and buckwheat (Fagopyrum esculentum) were grown hydroponically under controlled conditions. The uptake of Cr (III) and Cr(VI), and its effect on plant growth were measured in culture solution. Cr(VI) was more toxic than Cr(III). In all species, Cr(III) affected growth only at the highest concentration, while Cr(VI) was toxic at lower concentrations. Plant Cr-concentration was far higher in the root than in the shoot of the three plant species grown with both Cr(III) or Cr(VI). Plants grown in Cr(III) showed higher tissue concentration and chromium removal efficiency than those grown in Cr(VI). In Cr(III), Cr-oxide and hydroxide precipitation on root surface was observed. It can be suggested that plant roots act as a powerful agent of Cr(III) removal and that a greater amount of plant roots would be necessary to remove Cr(VI) rather than Cr(III). Buckwheat was the most efficient species at removing and plants were able to retain their capacity for Cr-removal even though they may have shown strong toxicity symptoms.

Keywords:

• Chromium removal
• Cr(III)
• Cr(VI)
• wastewater
• terrestrial plants