Abstract:
The main aim of this study was the determination of temperature influence on adsorption mechanisms of anionic poly(acrylic acid) (PAA) and cationic polyethylenimine (PEI) on the surface of activated carbons (AC) obtained via chemical activation of nettle (NE) and sage (SA) herbs. All measurements were performed at pH 3 at three temperature values, i.e., 15, 25 and 35 °C. The adsorption/desorption of these polymers from single and mixed solution of adsorbates was also investigated. The viscosity studies were additionally performed to obtain hydrodynamic radius values characterizing polymeric macromolecules conformation in the solution. These data are very important for the explanation of changes of linear dimensions of polymer chains with the rise of temperature caused by the modification of polymer-solvent interactions. Moreover, the XPS studies for the systems showing the highest adsorbed amounts in the specific temperature conditions were carried out. These were the systems containing PEI, PAA and NE-AC activated carbon at 25 °C. In such a case, the maximum adsorption capacity towards PAA macromolecules from a single solution of adsorbate reaches the value of 198.12 mg/g. Additionally, the thermodynamic parameters including the free energies of adsorption, as well as changes in free enthalpy and entropy were calculated.
摘要:
本研究的主要目的是确定温度对阴离子聚(丙烯酸)(PAA)和阳离子聚乙烯亚胺(PEI)在通过荨麻(NE)和鼠尾草(SA)草药的化学活化获得的活性炭(AC)表面的吸附机理的影响。所有测量均在三个温度值的pH3下进行,即,15、25和35℃。还研究了这些聚合物从吸附物的单一和混合溶液中的吸附/解吸。另外进行粘度研究以获得表征溶液中聚合物大分子构象的流体动力学半径值。这些数据对于解释由聚合物-溶剂相互作用的改性引起的聚合物链线性尺寸随温度升高的变化非常重要。此外,对特定温度条件下吸附量最高的系统进行了XPS研究。这些是含有PEI的系统,25℃的PAA和NE-AC活性炭在这种情况下,单一吸附液对PAA大分子的最大吸附量达到198.12mg/g。此外,热力学参数,包括吸附自由能,以及自由焓和熵的变化进行了计算。