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| Synchronous rapid desorption of Cr(Ⅵ) and Cr(Ⅲ) on modified stalk adsorbent |
| Received:February 08, 2017 |
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| KeyWord:corn stalk;chromium;adsorption;desorption;speciation transformation;quantitative analysis |
| Author Name | Affiliation | E-mail | | WANG Zhen-qian | College of Civil Engineering, Huaqiao University, Xiamen 361012, China | | | CAO Wei | College of Civil Engineering, Huaqiao University, Xiamen 361012, China | weicao@hqu.edu.cn | | LIU Shu-po | College of Civil Engineering, Huaqiao University, Xiamen 361012, China | |
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| Abstract: |
| The removal mechanism of Cr(Ⅵ) by a novel low-cost adsorbent(modified corn stalk) is a complicated process that includes adsorption and reduction. In this study, a method for desorption of Cr on corn stalk was developed. The method can quantitatively describe the adsorption and speciation transformation during the absorption of Cr(Ⅵ) by transferring Cr(Ⅵ) and Cr(Ⅲ) from the solid-phase to the liquid-phase. The experimental factors, such as different desorption solutions(HCl, H3PO4, NaCl), concentrations, contact time,and temperature were investigated and the optimal desorption condition was determined. The results showed that Cr(Ⅵ) and Cr(Ⅲ) could be desorbed sufficiently and 95% of Cr was recovered by adding 20 mL 2 mol·L-1 H3PO4 solution at 25 ℃ for a 10-min contact time. Based on the desorption method, the distribution of Cr(Ⅵ) and Cr(Ⅲ) in solid and liquid phases was quantitatively analyzed to explore the mechanisms of adsorption and speciation transformation of Cr(Ⅵ). The adsorption process on stalk followed Langmuir isotherm adsorption model and the adsorption capacity of Cr(Ⅵ) was 35.9 mg·g-1. The amount of Cr(Ⅲ) increased with the growth of absorbed Cr(Ⅵ) and there was a positive correlation between them(R2=0.986). The amount of Cr(Ⅲ) tended to stabilize after the adsorption reached equilibrium at 3.7 mg·g-1. |
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