Abstract

Cryptomelane (α-MnO₂) nanoparticles synthesis was achieved via a Sol-Gel route in mild conditions. XRD analysis showed that the α-MnO₂ phase was of high purity and crystallized in the monoclinic space group I2/m, with 12 nm average crystallite size (D). After interaction with an organic pollutant (Phthalic acid, PA), excepting the pronounced decrease in β angle, α-MnO₂ cell parameters slightly changed, probably resulting from leaching of K⁺ cations. Adsorption isotherm of PA on α-MnO₂ nanoparticles was fitted in L2 type Langmuir model. Accordingly, an outer-sphere PA-Mn surface complex was suggested. Further, the mineral oxide exerted a low activity in the decarboxylation of PA. Raman analysis illustrated the major bands, of α-MnO₂, and their evolution after adsorption indicated the effect of PA on the phase structure, as revealed by the XRD Rietveld refinement. AFM analysis showed stick shaped nanoparticles with D = 15 nm, but the interaction with PA induced aggregation.

摘要

钾锰矿（α-MnO的₂）纳米颗粒的合成经由在温和的条件溶胶-凝胶途径来实现的。XRD分析表明，α-MnO的₂相是高纯度的，并在斜空间群结晶I2 /米，具有12纳米的平均微晶尺寸（d）。与有机污染物（邻苯二甲酸，PA），除了在β角的显着降低相互作用后，α-MnO的₂小区参数稍微改变可能是由钾浸出所得⁺阳离子。在PA的吸附等温线α-MnO的₂将纳米颗粒装配在L2型Langmuir模型中。因此，提出了外球PA-Mn表面复合物。此外，无机氧化物在PA的脱羧中发挥低的活性。拉曼分析示出的主要条带，α-的MnO ₂，以及吸附后其演变指示PA的作用，对相结构，由XRD Rietveld精修所揭示。原子力显微镜分析显示棒状纳米颗粒的D = 15 nm，但与PA的相互作用引起聚集。