强力霉素在凹凸棒土上的吸附行为

通过等温吸附平衡法研究了强力霉素在凹凸棒土上的吸附行为,考察了pH、反应时间、离子强度和离子类型等因素对吸附的影响,探讨了吸附机理.结果表明,pH=8.5时,饱和吸附容量最大,为293.35μmol.g-1;强力霉素在凹凸棒土上的吸附可用Langmuir型等温方程和准二级动力学方程很好地拟合;离子强度对强力霉素的吸附影响不是很明显;0.05 mol.L-1NaOH能显著地将强力霉素从凹凸棒土上解吸下来.红外表征结果说明凹凸棒土对强力霉素的吸附可能是化学吸附,酸性条件下,强力霉素主要通过阳离子交换、静电作用、氢键作用等吸附在凹凸棒土上,部分H+可能通过强力霉素质子化吸附到凹凸棒土上.弱碱性条件下主要通过水桥接,与凹凸棒土层间阳离子配位以及结合于凹凸棒土边缘吸附位点达到吸附.

Adsorption of doxycycline on attapulgite

The adsorption of doxycycline on attapulgite was investigated by isothermal adsorption method.The parameters affecting adsorption capacity such as adsorbent addition,pH,reaction time,ionic strength and iron type as well as adsorption mechanism were examined in detail.The experimental results showed that the adsorption capacity reached 292.35 μmol · g-1 at pH 8.5.The adsorption reaction of doxycycline was best described with Langmuir isotherm equation and pseudo-second-order kinetic model.Ionic strength had no obvious effect on the adsorption.Doxycycline desorbed remarkably in 0.05 mol · L-1 sodium hydroxide.FTIR spectra demonstrated that the major interaction force between doxycycline and attapulgite was chemical adsorption.At acidic condition,most of H+ adsorbed through the protonation of doxycycline.And cation exchange,electrostatic interaction and hygrogen bonding may be the dominate adsorption mechanisms.At weak alkali condition,doxycycline could interact with attapulgite through water bridge,coordinating with the interlayer cation of attapulgite and bonding with adsorption sites on the edge of attapulgite.