农业废弃物核桃壳粉对Cr(Ⅵ)的吸附特征研究  

The Characteristics of Cr(Ⅵ)Adsorbed by Walnuts Shell Powder

作　　者：李荣华[1] 张院民[1] 张增强[1] 孟昭福[1] 唐次来[1] 

机构地区：[1]西北农林科技大学理学院,陕西杨凌712100

出　　处：《农业环境科学学报》2009年第8期1693-1700,共8页Journal of Agro-Environment Science

基　　金：西北农林科技大学青年科研专项基金项目(08080271);陕西省自然科学基金(2005C105)

摘　　要：以核桃壳粉为吸附剂,通过批试验探讨了体系初始pH值、吸附剂用量、温度等因素对水溶液中Cr(Ⅵ)吸附的影响,并讨论了吸附过程中Cr的化学形态变化和吸附过程的热力学特征。结果表明,核桃壳粉对Cr(Ⅵ)的吸附最佳pH为1.0。向50mL50mg·L-1的Cr(Ⅵ)溶液中加入0.5g核桃壳粉,对溶液中Cr(Ⅵ)的去除可达95.39%,吸附过程伴随着氧化还原反应的发生;随着体系温度的升高,核桃壳粉对Cr(Ⅵ)的吸附量增加,吸附过程符合二级动力学过程,Langmuir模型能较好地反映吸附过程特征。对吸附热力学参数ΔG0、ΔHo和ΔSo的计算表明,吸附过程是吸热的自发过程,升高温度有利核桃壳粉对Cr(Ⅵ)的吸附,在301、308和318K条件下的最大吸附量分别为20.54、26.00和29.53g·kg-1。试验结合FTIR和SEM手段,对核桃壳粉进行了分析,发现核桃壳粉对Cr(Ⅵ)的吸附是一个包含氧化还原的极其复杂的反应过程,核桃壳粉是具有吸附污水中铬的能力和潜在利用价值的生物质吸附剂。In this paper, walnuts shell powder was investigated for its Cr（ Ⅵ） removal ability from aqueous solution. The effect of experiment parameters, such as pH, sorbent dosage, temperature were examined and the optimal experiment condition were studied.The species of chromium,adsorption thermodynamic and kinetics characterics were also discussed. The results showed that about 95.39% of Cr（ Ⅵ ） was removed by adding 0.5 g walnuts shell powder into 50 mL solution which contained 50 mg.L^-1 Cr（ Ⅵ ） under the optimal experiment such as pil1.0, 301 K and 6 h contact time, and the adsorption of Cr（ Ⅵ ） was coexist with redox process in the experiment. The adsorption capacity increased with the temperature increasing and the adsorption thermodynamic followed the Langmuir isotherm model while the adsorption kinetics followed the second-order model. The thermodynamic parameters such as ΔG^0,△H° and △S° for the process if Cr （ Ⅵ） adsorbed on walnuts shell powder were calculated and the results indicated that the overall adsorption process was endothermic and spontaneous. The adsorption capacity of the biosorbent were 20.54,26.00 and 29.53 g.kg^-1 when the temperature were 301,308 and 318 K respectively. Finally, the residues of the walnut shell were studied by using FTIR and SEM imagine. It indicated that the process of Cr（ Ⅵ ） adsorption on walnuts shell powder was coexist with redox process, and the walnuts shell powder was a potential biosorbent which could be used in chromium contaminated wastewater treatment process.

关 键 词：核桃壳粉 吸附 氧化还原 Cr(Ⅵ) 热力学 

分 类 号：X712[环境科学与工程—环境工程]