Preparation of Acid-Treated Sunflower Straw Powder and Adsorption Behavior of Cr(VI) Ions onto it

摘要

The adsorption of Cr~(6+) ions by sulfuric acid -treated sunflower straw powder was investigated under batch mode. The influence of solution pH, adsorbent dosage, adsorbent particle size and temperature was studied. The results have shown that the absorbent was efficient, the removal ratio of Cr~(6+) up to 99.5% with an adsorbent dosage of 8 g·L~(-1), a pH of 6.0, at 25°C and particle size in 80-100 mesh. The negative changes in free energy (△G) indicate that the adsorption is a spontaneous process, the positive values of the adsorption entropy △S indicate the increased randomness of the Cr~(6+) on straw active carbon surface than in solution.