pH和盐对活性炭纤维吸附2,4-二硝基酚的影响

Effect of pH and Salt on Adsorption of 2,4-Dinitrophenol with Activated Carbon Fiber

采用静态吸附的方法,研究了pH和盐对活性炭纤维ST-8和ST-13吸附水中2,4-二硝基酚的影响。结果表明,在pH0～14范围内,吸附量先随着pH的增大而增大,然后吸附量随着pH的增大而减小;在pH11时,吸附量最小但不为零;在pH11～14范围内,吸附量随着pH增大而增大;ST-8和ST-13吸附2,4-二硝基酚的最佳pH分别为2和3。pH对吸附的影响主要是改变2,4-二硝基酚的存在形态、活性炭纤维表面的电荷和溶液的物理化学性质。盐的存在对吸附2,4-二硝基酚有利;低pH时,氯化钠的作用是盐析效应;在pH较大时,氯化钠的作用是屏蔽效应。在pH为11的条件下,氯化钠浓度为5.0mol/L时,ST-13可以完全消除静电斥力,而ST-8只能克服大部分的静电斥力。

Effects of pH and salt on the adsorption of 2, 4-dinitrophenol onto activated carbon fiber （ACF） ST-8 and ST- 13 were studied. Results showed that at pH 0-14, the adsorption amount firstly increased with increasing pH, then decreased with increasing pH, it was minimum but not zero at pH 11. At pH 11-14, the adsorption amount increased with increasing pH. The optimal pH for ST-8 and ST-13 adsorption of 2, 4-dinitrophenol were 2 and 3 respectively. Presence of sodium chloride presented positive effect on the adsorption. The effect of NaCl on the adsorption was attributed to salting-out effect at lower pH values while the effect of NaCl was screening effect at the higher pH values.