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Combined Effect of Sunflower Stem Carbon–Calcium Alginate Beads for the Removal and Recovery of Chromium from Contaminated Water in Column Mode

Jain, Monika, Garg, V.K., Kadirvelu, Krishna, Sillanpää, Mika
Industrial & Engineering Chemistry Research 2015 v.54 no.5 pp. 1419-1425
Helianthus annuus, adsorbents, adsorption, alginates, chromium, desorption, economic sustainability, engineering, hydrochloric acid, models, pH, water pollution
Adsorptive removal of Cr(VI) was investigated in a downflow fixed bed column using sunflower stem carbon–calcium alginate beads (SSC-CAB) at various bed heights (28.0, 38.0, and 52.0 cm), initial Cr(VI) concentrations (10–20 mg/L), and flow rates (1.0–3.0 mL) at preoptimized pH = 2.0 for achieving the breakthrough curves. The adsorption capacity was calculated using the Bohart-Adams (BA) model which is widely used for column adsorption. The highest adsorption capacity of 4.09 mg/L was recorded at a bed height of 52.0 cm, flow rate of 1.0 mL/min, and an initial Cr(VI) concentration of 10.0 mg/L. The breakthrough time increased with a decrease in flow rate and Cr(VI) concentration and an increase in bed height. The adsorption capacity (N₀) at 50% breakthrough time was 20 mg/L. Cr(VI) loaded SSC-CAB adsorbent was washed with 0.5 M HCl solution at a flow rate of 2.0 mL/min, and the efficiency of the adsorbent regenerated by the desorbing agent was examined in three sorption/desorption cycles. Regeneration efficiency of SSC-CAB was 55% after the third cycle. The removal of Cr(VI) in the fixed bed column using sunflower stem carbon–calcium alginate beads is, thus, an effective, economically viable and environmentally feasible process.