Berhane Tedros M, Levy Jonathan, Krekeler Mark P S, Danielson Neil D
Department of Geology and Environmental Earth Science, Miami University, 250 S Patterson Avenue, Shideler Hall, Oxford, OH 45056, USA.
Department of Geology and Environmental Earth Science, Miami University, 250 S Patterson Avenue, Shideler Hall, Oxford, OH 45056, USA.
Chemosphere. 2017 Jun;176:231-242. doi: 10.1016/j.chemosphere.2017.02.068. Epub 2017 Feb 17.
Kinetic sorption of bisphenol A (BPA), carbamazepine (CMZ) and ciprofloxacin (CIP) by three palygorskite-montmorillonite (Pal-Mt) granule sizes was studied. For BPA, CMZ and CIP, apparent sorption equilibrium was reached within about 3, 5 and 16 h, respectively. The highest and the lowest sorption capacities were by the small and the large granule sizes, respectively. Experimental results were compared to various sorption kinetics models to gain insights regarding the sorption processes and achieve a predictive capacity. The pseudo-second order (PSO) and the Elovich models performed the best while the pseudo-first order (PFO) model was only adequate for CMZ. The intraparticle-diffusion (IPD) model showed a two-step linear plot of BPA, CMZ and CIP sorption versus square root of time that was indicative of surface-sorption followed by IPD as a rate-limiting process before equilibrium was reached. Using the pseudo-first order (PFO) and the pseudo-second order (PSO) rate constants combined with previously-established Langmuir equilibrium sorption models, the kinetic sorption (k) and desorption (k) Langmuir kinetic rate constants were theoretically calculated for BPA and CIP. Kinetic sorption was then simulated using these theoretically calculated k and k values, and the simulations were compared to the observed behavior. The simulations fit the observed sorbed concentrations better during the early part of the experiments; the observed sorption during later times occurred more slowly than expected, supporting the hypothesis that IPD becomes a rate-limiting process during the course of the experiment.
研究了三种不同粒度的坡缕石-蒙脱石（Pal-Mt）颗粒对双酚A（BPA）、卡马西平（CMZ）和环丙沙星（CIP）的动力学吸附。对于BPA、CMZ和CIP，分别在约3、5和16小时内达到表观吸附平衡。吸附容量最高和最低的分别是小颗粒和大颗粒。将实验结果与各种吸附动力学模型进行比较，以深入了解吸附过程并获得预测能力。伪二级（PSO）模型和Elovich模型表现最佳，而伪一级（PFO）模型仅适用于CMZ。颗粒内扩散（IPD）模型显示BPA、CMZ和CIP吸附与时间平方根的两步线性图，这表明在达到平衡之前，表面吸附之后是IPD作为限速过程。使用伪一级（PFO）和伪二级（PSO）速率常数结合先前建立的Langmuir平衡吸附模型，理论计算了BPA和CIP的动力学吸附（k）和解吸（k）Langmuir动力学速率常数。然后使用这些理论计算的k和k值模拟动力学吸附，并将模拟结果与观察到的行为进行比较。在实验早期，模拟结果与观察到的吸附浓度拟合得更好；后期观察到的数据比预期的吸附慢，这支持了IPD在实验过程中成为限速过程的假设。
