Surface Chemical Properties of Clay Minerals and Soils from Theoretical and Experimental Developments in Electroosmosis

2009 ◽  
pp. 44-44-9 ◽  
Author(s):  
Hans F. Winterkorn
Keyword(s):  
Clay Minerals ◽  
Chemical Properties ◽  
Surface Chemical

Effect of High-Temperature Defibration on the Chemical Structure of Hardwood

Holzforschung ◽  
2002 ◽  
Vol 56 (1) ◽  
pp. 51-59 ◽  
Author(s):  
P. Widsten ◽  
J.E. Laine ◽  
P. Qvintus-Leino ◽  
S. Tuominen
Keyword(s):  
High Temperature ◽  
Lignin Content ◽  
Bulk Composition ◽  
Chemical Properties ◽  
Water Extract ◽  
Fiber Surface ◽  
Phenolic Hydroxyl ◽  
Hydroxyl Groups ◽  
Surface Chemical ◽  
Alkyl Aryl

Summary The present paper aims at elucidating the effect of high-temperature defibration at different temperatures on the bulk and surface chemical properties of defibrated birch, aspen and eucalypt. The results indicate that defibration of these hardwoods results in partial depolymerization of fiber lignin via (homolytic) cleavage of interunit alkyl-aryl (β-O-4) ether bonds. This increases the phenolic hydroxyl content and produces relatively stable (phenoxy) radicals. Syringyl-type lignin is more extensively depolymerized than guaiacyl-type lignin. Defibration generates water-extractable material, which is enriched in hemicellulose-derived carbohydrates and has a substantial content of aromatic compounds rich in phenolic hydroxyl groups. The amount of water-extract and the extent of lignin interunit ether bond cleavage increase with an increase in defibration temperature. The differences between various hardwood species in this respect are small. The surface chemical composition of the fibers differs considerably from their bulk composition, but is not significantly influenced by variations in defibration temperature. Lipophilic extractives cover a large portion of the fiber surface, while the lignin content of lipophilic extractives-free fiber surfaces is 2–3 times as high as the bulk lignin content of the fibers.

scholarly journals COMPOSITION, MICROSTRUCTURE AND PROPERTIES OF QUATERNARY CLAYS OF THE PRIKHANKAYSKAYA DEPRESSION (PRIMORYE)

2019 ◽  
Vol 14 (1) ◽  
pp. 20-34
Author(s):  
T. G. RYASHCHENKO ◽  
N. N. UKHOVA ◽  
S. I. SHTELMAKH ◽  
N. I. BELYANINA ◽  
P. S. BELYANIN
Keyword(s):  
Clay Minerals ◽  
Laboratory Data ◽  
Chemical Properties ◽  
Exchange Capacity ◽  
Climatic Conditions ◽  
Water Soluble ◽  
Laboratory Studies ◽  
Microstructural Parameters ◽  
Physical Chemical ◽  
Study Results

The article considers the study results of composition, microstructure and physical-chemical properties of the quaternary clays of the Prikhankayskaya depression in district of the lake Khanka (Primorye) on the example of air-dry samples of geological borehole 45-b in the range of 18–62 m. The objective of research was to obtain new information about the properties of widespread clay sediments in this area using geologic-lithological materials and laboratory data. The schematic geologic-lithological column was composed with the selection of various zones in the quaternary clay sediments section and the border with sediments of the Neogene System. The methodological scheme of laboratory studies of clays was proposed. This scheme includes the determination of chemical and microelement composition, clay minerals, contents of carbonates, water-soluble salts, mobile forms of aluminum oxide, humus, as well as microstructural parameters (method «Microstructure») and some physical-chemical properties. Geochemical coefficients (Kz, CIA, CIW, ICV) determined the degree of chemical maturity of clays and confirmed the results of palynological studies reflecting the fluctuations of the climatic conditions of their formation. For the group of toxic microelements for the first time the special indicator (Zc) was calculated. Which was the criterion for a degree of pollution of the clay sediments section. Clay minerals of the quaternary clays are represented by smectite and hydromica. The clear change in the mineral association was found when passing to the Neogene sediments (kaolinite prevails). The method «Microstructure» revealed the aggregated type of clays microstructure, the domination of the particles of coarse dust fraction among the primary (free) particles and the almost complete absence of the particles of fine-grained sand fraction, the participation of various fractions in the composition of aggregates. The variants of the formation of certain types of aggregates (on sizes) in the fluviolacustrine «khankayskiy» clays are presented. Solid part density, water resistance (soaking time), sedimentation volume, plasticity, relative swelling (samples-pastes) were determined using standard methods for clays. By special methods, the cation exchange capacity was measured and the calculated values of the plasticity index were obtained from forecasting formulas using the yield limit. The proposed methodological scheme of complex laboratory studies of clay sediments can be recommended for problematic geologic-lithological and engineering-geological sections.

scholarly journals The hidden ecological resource of andic soils in mountain ecosystems: evidences from Italy

2017 ◽  
Author(s):  
Fabio Terribile ◽  
Michela Iamarino ◽  
Giuliano Langella ◽  
Piero Manna ◽  
Florindo Antonio Mileti ◽  
...  
Keyword(s):  
Clay Minerals ◽  
Chemical Properties ◽  
Organic C ◽  
Mountain Ecosystems ◽  
C Storage ◽  
Mountain Landscapes ◽  
Ecological Importance ◽  
Mineral Soils ◽  
Physical And Chemical ◽  
And Chemical Properties

Abstract. Andic soils have unique morphological, physical and chemical properties that induce both considerable soil fertility and great vulnerability to land degradation. Moreover they are the most striking mineral soils in terms of large organic C storage and long C residence time; this is especially related to the presence of poorly crystalline clay minerals and metal-humus complexes. Recognition of these soils is then very important. Here we attempt to show, through the combined analysis of 35 sampling points chosen, throughout the Italian non volcanic mountain landscapes, in accordance to specific physical and vegetation rules, that soils rich in poorly crystalline clay minerals have an utmost ecological importance. More specifically, in various non-volcanic mountain ecosystems (> 700 m) and in low slope gradient locations (

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