腐植酸对水体中五价钒的吸附

采用批次实验法,研究了腐植酸浓度、钒离子浓度、吸附时间、温度、溶液p H、离子强度、电解质等对腐植酸吸附水体中五价钒的影响。结果表明,钒溶液浓度为90.91 mg·L~(-1)条件下,腐植酸的浓度为1.09 g·L~(-1)时,腐植酸对钒的吸附量最大。随着钒溶液浓度的增加,吸附率逐渐降低并趋于0;而吸附量呈增加-缓慢增加-平衡的趋势;在腐植酸浓度为1.09 g·L~(-1)条件下,钒溶液浓度为1 818.18 mg·L~(-1)时,吸附量达到最大值,吸附等温线与Langmuir模型基本吻合。随着溶液pH、温度的增加,腐植酸对钒的吸附量逐渐减少,即在酸性、温度较低的条件下更有利于腐植酸对钒的吸附。随着溶液电解质浓度的增加,腐植酸对钒的吸附量逐渐降低。红外光谱和扫描电镜的结果显示,腐植酸对钒的吸附机制为钒在腐植酸的表面和内部形成稳定的络合物,这与腐植酸的O-H(或N-H)的氢键、C-O和C-H键的伸缩振动有关。因此,可以考虑用适量的腐植酸作吸附剂,去除水体中的钒,并调整环境条件增强吸附效果。

Adsorption of pentavalent vanadium by humic acid in water

Vanadium(V)is released naturally and anthropogenically to the environment and becomes an important pollutant. This study is conducted to examine adsorption characteristics of pentavalent VV(Ⅴ)] as NaVO3 in water by humic acid under a series of initial V con-centrations, humic acid concentrations, adsorption time, solution pH, temperature, ionic strength, and electrolyte type and concentrations. Results showed that:(1)at 90.91 mg·L-1 V(Ⅴ), the highest adsorption capacity of V was found at 1.09 g·L-1 of humic acid concentration;(2)with increases of V(Ⅴ)initial concentrations in solution, the adsorption rate gradually decreased, whereas the adsorption amount in-creased and reached the maximum at 1 818.18 mg·L-1 at 1.09 g·L-1 of humic acid concentration. Adsorption isotherm of V by humic acid could be well described by Langmuir model; (3)increasing solution pH and temperature gradually reduced the adsorption amount of V by humic acid, indicating that low temperature and low pH favored V adsorption by humic acid; (4)increasing electrolyte concentrations sup-pressed the adsorption of V by humic acid; (5)infrared spectrum and scanning electron microscopy showed that V complex was formed on the surface and the inside of humic acid and that the stretching vibration of O-H or N-H, C-O and C-H might also played role in V ad-sorption. Therefore, appropriate amount of humic acid could be used to remove V in water under certain environmental conditions.