As(V)/Cr(VI) pollution control in soils, hemp waste, and other by-products: competitive sorption trials

Abstract

We study As(V)/Cr(VI) competitive sorption on a forest soil, a vineyard soil, pyritic material, mussel shell, pine bark, oak ash, and hemp waste, adding variable As(V) and Cr(VI) concentrations or displacing each pollutant with the same concentration of the other. When using variable concentrations, As(V) showed more affinity than Cr(VI) for sorption sites on most materials (sorption up to >84 % on oak ash and pyritic material). The only exception was pine bark, with clearly higher Cr(VI) sorption (>90 %) for any Cr(VI)/As(V) concentration added. Regarding the displacement experiments, when As(V) was added and reached sorption equilibrium, the subsequent addition of equal Cr(VI) concentration did not cause relevant As displacement from oak ash and pyritic material, indicating strong As bindings, and/or low competitive effects. When Cr(VI) was added and reached sorption equilibrium, the subsequent addition of equal As(V) concentration caused Cr(VI) displacement from all materials except pine bark, indicating weak Cr bindings. In view of these results, oak ash and the pyritic material could be used to remove As(V) in concentrations as high as 6 mmol L(-1), even in the presence of a wide range of Cr(VI) concentrations, whereas pine bark could be used to remove Cr(VI) concentrations as high as 6 mmol L(-1). The other materials assayed (including hemp waste, studied for the first time as As(V) and Cr(VI) bio-sorbent) cannot be considered appropriate to remove As(V) and/or Cr(VI) from polluted media.

As(V) Sorption/Desorption on Different Waste Materials and Soil Samples

“…We studied the following materials: oak ash, hemp waste, pine bark, finely ground mussel shell, pyritic material, forest and vineyard soil samples. The forest and vineyard soil, as well as the mussel shell samples were previously described [ 13 ], as the oak ash and the hemp waste [ 18 ], the pyritic material [ 21 ], and the pine bark [ 22 ]. Furthermore, Rivas-Pérez et al [ 17 ] previously studied some of the materials here assayed.…”

“…We have previously studied As(V) retention on soils and wastes [ 11 , 12 , 13 , 14 , 15 , 16 , 17 ], using low As(V) concentrations (<1.5 mmol L −1 ). In recent works, we used different sorbent materials to study As(V) and Cr(VI) competitive sorption [ 18 , 19 ], but non-competitive As(V) sorption/release was not investigated.…”

Wheat Straw as a Bio-Sorbent for Arsenate, Chromate, Fluoride, and Nickel

“…In this way, the utilization of complementary bio-sorbents would be interesting. Specifically, pine bark could be used to retain Cr(VI) [26,27], whereas mussel shell could be used to facilitate As(V) retention [28]. Some studies have also dealt with the retention of pollutants on wheat straw, although under conditions different from those of the present work.…”

“…Ni 2+ showed notable sorption and an opposite trend to that of F − , with sorption percentage increasing when the highest Ni 2+ concentrations (3 and 6 mmol·L −1 ) were added. We have previously studied [10][11][12][13][25][26][27][28]] the effects of different concentrations, pH, incubation time, and other variables on As(V), Cr(VI), F − , and/or Ni 2+ retention on other sorbent materials, but it should be also performed for wheat straw in future works.…”

Adsorption of Cd (II), Pb (II) and Cr (III) on chemically modified Euterpe Oleracea biomass for the remediation of water pollution

“…The search for new adsorbents has been focused on biomaterials, because they are economically viable, biodegradable, and derived from renewable resources. In general, these materials are locally and easily available at large amounts; also, they are inexpensive and have little economic value (Cutillas-Barreiro et al, 2014;Quintáns-Fondo et al, 2016).…”