• cromo esavalente
• contaminazione da cromo
• trattamento tramite zeoliti modificate
• zeolite
• Cr-treatment
• Cr-contaminated waters
• iron-modified zeolite
• hexavalent chromium

Zeolites are aluminosilicate minerals with a porous three-dimensional structure, characterized by a remarkable ion-exchange capacity and reversible dehydration. In their natural state, zeolites are adapted at sorbing cations from liquid matrices. Nevertheless, chemical modifications can activate zeolites for anion sorption, specifically targeting chromate (CrO4--) and dichromate (Cr2O7--), the two primary forms of hexavalent chromium [Cr (VI)] in water, known for their toxicity and potential harm to both human health and the environment.
Two different methods were employed to chemically modify a natural zeolite with iron, aiming to enhance its capacity to remove Cr(VI) from a synthetic solution. The first approach involves the introduction of bivalent iron ions into the zeolite structure as reducing agents to convert Cr(VI) to Cr(III). The second method imply the precipitation of trivalent iron oxides/hydroxides on the zeolite's surface, capable of complexing with chromium.
This study aims to comprehensively assess the efficacy of both methods in treating Cr (VI)-contaminated water, by using Cr-bearing synthetic solutions. Natural zeolite and both types of iron-modified zeolites were characterized to evaluate their structural and morphological properties before and after chromium sorption. Batch and column tests have been conducted using both natural and modified zeolites to assess the removal of Cr (VI) from solutions.