Correspondence. Reply to Comment on "Recalculation, Evaluation, and Prediction of Surface Complexation Constants for Metal Adsorption on Iron and Manganese Oxides"

ABSTRACTAn important question concerning the transport of radionuclides from nuclear waste repositories is whether the adsorption of metals by rocks and soils can be predicted from the properties of the constituent minerals. Attempts by previous researchers to use sorption models based on linear adsorption or weighted "sorptive additivity" have met with limited success. In this study, a “competitive-additivity” model based on surface complexation theory was used to model the pH-dependent adsorption of lead by goethite/Ca-montmorillonite mixtures using complexation constants obtained from single sorbent systems. Measurements of lead adsorption by goethite, Ca-montmorillonite, and goethite-Ca-montmorillonite mixtures (and similar studies of copper and zinc adsorption) demonstrate that the two adsorbents compete for adsorption of metals over wide ranges of pH and concentrations of adsorbents and metals. The adsorption behaviors of the mixtures are determined by the relative concentrations of the adsorbents and their respective affinities for the adsorbate metal. Particle-particle interactions such as heterocoagulation of the oxide and clay do not appear to be significant for the majority of the adsorption sites in this system.

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Ultrasound-Assisted Citric Acid Extraction of Zinc in Plateau Red Soil and Tessier Speciation Study

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.726-731.4464 ◽

2013 ◽

Vol 726-731 ◽

pp. 4464-4467

Author(s):

Wei Wei ◽

Xue Jin Zhou ◽

Yun Tao Gao

Keyword(s):

Heavy Metal ◽

Citric Acid ◽

Manganese Oxides ◽

Red Soil ◽

Extraction Rate ◽

Acid Extraction ◽

Speciation Study ◽

Ultrasonic Assisted ◽

Ultrasound Assisted ◽

Iron And Manganese

Taking plateau red soil as research object, using the ultrasonic-assisted organic acid extraction the heavy metal zinc in it, and analyze the form of zinc. Results showed that the extraction rate can reach 68%, with the increase of time, the extraction effect of zinc is obviously enhanced in this method. Ultrasonic-assisted citric acid extraction soil can increase the extraction rate of exchangeable, bound to carbonates and bound to iron and manganese oxides relatively.

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Strategies for EELS Data Analysis. Introducing UMAP and HDBSCAN for Dimensionality Reduction and Clustering

Microscopy and Microanalysis ◽

10.1017/s1431927621013696 ◽

2021 ◽

pp. 1-14

Author(s):

Javier Blanco-Portals ◽

Francesca Peiró ◽

Sònia Estradé

Keyword(s):

Dimensionality Reduction ◽

Clustering Analysis ◽

Manganese Oxides ◽

Spatial Clustering ◽

State Of The Art ◽

Core Loss ◽

Nonnegative Matrix ◽

Case Scenario ◽

Electron Energy Loss ◽

Iron And Manganese

Hierarchical density-based spatial clustering of applications with noise (HDBSCAN) and uniform manifold approximation and projection (UMAP), two new state-of-the-art algorithms for clustering analysis, and dimensionality reduction, respectively, are proposed for the segmentation of core-loss electron energy loss spectroscopy (EELS) spectrum images. The performances of UMAP and HDBSCAN are systematically compared to the other clustering analysis approaches used in EELS in the literature using a known synthetic dataset. Better results are found for these new approaches. Furthermore, UMAP and HDBSCAN are showcased in a real experimental dataset from a core–shell nanoparticle of iron and manganese oxides, as well as the triple combination nonnegative matrix factorization–UMAP–HDBSCAN. The results obtained indicate how the complementary use of different combinations may be beneficial in a real-case scenario to attain a complete picture, as different algorithms highlight different aspects of the dataset studied.

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