Removal of Hexavalent Chromium Ions from Industrial Effluents Using Natural and Modified Diatomite, Taurite, Lewatit M500, and Activated Carbon

Hexavalent chromium Cr (VI) compounds present in ilmenite concentrate not only pose significant environmental hazards due to their toxicity but also complicate further processing, interfering with technological operations in industrial production. The high chromium content in ilmenite concentrates hinders their conversion into titanium-containing slag, necessitating the removal of chromium ions to permissible residual levels to produce titanium dioxide. In this study, various sorbents were investigated for the removal of chromate ions from the industrial effluents generated during ilmenite concentrate processing. The sorbents examined included natural and modified diatomite, activated carbon, taurite (shungite), and the ion-exchange resin Lewatit M500. The structures of both natural and modified diatomite were analyzed using scanning electron microscopy (SEM). It was determined that natural diatomite samples consist of diatom frustules of various shapes and their fragments, with structural element sizes ranging from submicron dimensions to 50 µm. A mathematical analysis of the sorption data for hexavalent chromium ion removal from solutions was performed. The results demonstrated high sorption efficiencies for Lewatit M500 (98.34%) and diatomite modified with iron compounds (98.95%). The findings suggest that diatomite is a promising sorbent for chromate ion removal from wastewater due to its availability and potential for chemical modification.