Phytoextraction of Cr(VI) from soil using Portulaca oleracea

Abstract

Cr(VI) represents an environmental challenge in both soils and waters as it is soluble and bioavailable over a wide range of pH. In previous investigations, Portulaca oleracea (a plant local to the UAE) demonstrated particular ability for the phytoextraction of Cr(VI) from calcareous soils of the UAE. In this publication, the results of the evaluation of P. oleracea phytoextraction of Cr(VI) from UAE soil at higher concentrations are reported. P. oleracea was exposed to nine different concentrations of Cr(VI) in soil from 0 to 400 mg kg -1 . The uptake of Cr(VI) increased as its concentration in soil increased between 50 and 400 mg kg -1 , with the most efficient removal in the range from 150 to 200 mg kg -1 . The total chromium concentrations exceeded 4600 mg kg -1 in roots and 1400 mg kg -1 in stems, confirming the role of P. oleracea as an effective Cr(VI) accumulator. More than 95% of the accumulated Cr(VI) was reduced to the less toxic Cr(III) within the plant.

Uptake of Chromium by Portulaca Oleracea from Soil: Effects of Organic Content, pH, and Sulphate Concentration

“…Our previous studies on the uptake of chromium from UAE soil by P. oleracea showed that, at pH � 7.9 ± 0.1, the optimum concentration for the maximum uptake efficiency of the plant is at 200 mg/kg of chromium [7]. us, in the current study, the uptake of chromium by P. oleracea was monitored as the pH of the soil increased from 6.0 to 9.0 at a Cr(VI) loading of 200 mg/kg in the soil.…”

“…Okuhata et al [5] have investigated its ability to remove bisphenol derivatives from aquatic solution and it was able to remove 97% of 4,4′thiodiphenol from the culture within four days. Meanwhile, a significant number of studies focused on the ability of P. oleracea to extract heavy metals from contaminated soil or water [6][7][8][9][10][11][12][13][14]. ese studies show that the plant has a high tolerance for many metals, including Cd (II), Cu(II), Cr(III), Cr(VI), Fe(III), Mn(II), Ni (II), Pb(II), and Zn(II) ions, and has the ability to extract them to its roots from either soil or aqueous solutions with variant capacities.…”

“…It was, however, established that P. oleracea is a hyperaccumulator for Cr(VI); a hyperaccumulator plant can extract the metal at concentrations ten times (at least) higher than their concentrations in the soil or wastewater. We have previously reported that P. oleracea is tolerant to high concentrations of Cr(VI) in soil up to 400 mg/kg [6,7]. e plant was able to extract the metal (soil concentration of 200 mg/kg) into its roots with a total concentration exceeding 2000 mg/kg and a bioaccumulation factor (BAF) greater than 10.…”

“…TF is the ratio of the concentration of metal in dry shoots to its concentration in dry roots. erefore, P. oleracea has great potential for remediation of chromium-contaminated environmental media and detoxification of the metal [7].…”

Halophytes in India and Their Role in Phytoremediation

“…The study suggested that the good tolerance of this halophyte could be put to use in phytoextraction of moderately saline soils. A potential hyperaccumulator for the phytoextraction of chromium(VI) is Portulaca oleracea, as the total Cr concentrations in roots and stems exceeded 4600 mg kg À1 and 1400 mg kg À1 , respectively (Alyazouri et al 2013). Sesuvium portulacastrum efficiently accumulated Cr, Cd, Cu, Zn, Na, and Cl in its leaves and can be used for the phytoextraction of fields contaminated with multiple pollutants (Ayyappan et al 2016).…”