Remediation of Polluted with Chromium Waters and Soils Cultivated with Wheat (Triticum durum) Using Zeolites Modified with Iron Oxide

The present study examines the efficiency of soil amendments regarding the retention of chromate ions, from water and cultivated soil with wheat (Triticum durum). The minerals and iron oxides that have been used were zeolite, bentonite, goethite, and zeolite modified with goethite I and II. Each adsorbent was added to different Cr solutions, either Cr(NO3)3·9H2O or CrO3 in a proportion of 1/100 g adsorbent mL−1 solution. Moreover, greenhouse experiments were also conducted using the above materials as soil amendments. Two doses of chromate ions, i.e., 50 mg Cr(III) L−1 in the form of Cr(NO3)3·9H2O and 1 mg Cr(VI) L−1 in the form of CrO3, were added to plant pots cultivated with wheat. According to the results, the uptake of chromate ions from aqueous solutions onto different adsorbents has shown that modified zeolites (Z-G I and II) adsorb the highest amount of chromate ions, compared to all the other adsorbents. The statistical analysis of the greenhouse experimental data has shown that the increase of the dry weight in soils with amendments follows the order: Z-G II > G > Z-G I > B > Z for pots where Cr(NO3)3·9H2O solutions were added and Z-G II > G > Z > Z-G I > B for pots where CrO3 solutions were added, respectively. Moreover, all the used soil amendments reduced the total Cr concentration in plants, especially Z-G II. Consequently, such modified zeolites can be used for the remediation of polluted soils with chromium and the production of high-quality food products.