Humic materials oxides

Under drinking water plant treatment conditions, humic materials and/ or resorcinol do not produce trihalomethanes with chlorine dioxide even when a slight excess of chlorine (1 percent to 2 percent) is present. Also, saturated aliphatic compounds are not reactive with chlorine dioxide. Alcohols are oxidized to the corresponding acids. 

The microbial degradation of contaminants under anaerobic conditions using humic acids as electron acceptors has been demonstrated. These included the oxidations (a) chloroethene and 1,2-dichloroethene to CO2 that was confirmed using C-labeled substrates (Bradley et al. 1998) and (b) toluene to CO2 with AQDS or humic acid as electron acceptors (Cervantes et al. 2001). The transformation of l,3,5-trinitro-l,3,5-triazine was accomplished using Geobacter metallireducens and humic material with AQDS as electron shuttle (Kwon and Finneran 2006). 

M. Schnitzer and D. A. Hindle, Effect of peracetic acid oxidation on N-containing components of humic materials. Can. J. Soil Sci. 60 541 (1980). 

A fraction of organic C oxidizable with 333 mM KMn04 is another measure of labile organic matter (Blair et al. 1995). This fraction encompasses all those organic components that can be readily oxidized by KMnCL including labile humic material and polysaccharides (Conteh et al. 1999). It commonly accounts for 15-20% of total soil organic C (Blair et al. 1998 Conteh et al. 1998). 

A recent modification of the hydrolysis-oxidation technique19 has produced strong support for the acid hydrolysis results already mentioned. In this instance samples of purified cotton linters were treated for varying times with boiling 2.5 N hydrochloric acid or with 2.5 N hydrochloric acid- 0.6 M ferric chloride. The latter was necessary where the hydrolysis extended over periods longer than 12 minutes and acted to hinder the formation of humic materials. By filtration and washing, a series of hydrocelluloses was obtained which corresponded to times of hydrolysis varying from 0 to 7 hours. 

Fig. 10.9 Electrophoretic mobility of synthetic Fe oxides (0.01 g L" ) in the presence of humic material from a eutrophic lake. Curve a goethite in an Na -Cl"-HCOi medium, total ionic strength 2-10" M, no humic material. Curve b ...

Step 3. Elute XAD-8 resin in reverse direction with 0.1 N NaOH acidify immediately to avoid oxidation of humic material. 

However, bearing in mind these caveats, we can make certain generalizations about the behavior of the actinide elements in natural waters. Americium and curium remain in the +3 oxidation state over the natural range of environmental conditions. For plutonium, Pu(III) is unstable to oxidation at environmental acidities, and so the other three states are observed with the dominant oxidation state in natural waters being Pu(V). [Humic materials cause a slow reduction of... 

It was previously noted that no evidence for direct photolysis for PFOS or PFOA has been observed experimentally. In aqueous solutions alone and in the presence of hydrogen peroxide (H2O2), iron oxide (Fe203) or humic material, PFOS has been observed to undergo some indirect photolysis [28] whereas PFOA did not undergo indirect photolysis [29]. Using an iron oxide photo-initiator matrix model, the indirect photolytic half-life for PFOS was estimated to be > 3.7 years at 25 °C. The half-life of PFOA was estimated to be > 349 d. 

Reductive dissolution of transition metal oxide/hydroxide minerals can be enhanced by both organic and inorganic reductants (Stone, 1986). There are numerous examples of natural and xenobiotic organic compounds that are efficient reducers of oxides and hydroxides. Organic reductants associated with carboxyl, carbonyl, phenolic, and alcoholic functional groups of soil humic materials are one example. However, large... 

Aluminum occurs widely in nature in silicates such as micas and feldspars, complexed with sodium and fluorine as cryolite, and in bauxite rock, which is composed of hydrous aluminum oxides, aluminum hydroxides, and impurities such as free silica (Cotton and Wilkinson 1988). Because of its reactivity, aluminum is not found as a free metal in nature (Bodek et al. 1988). Aluminum exhibits only one oxidation state (+3) in its compounds and its behavior in the environment is strongly influenced by its coordination chemistry. Aluminum partitions between solid and liquid phases by reacting and complexing with water molecules and anions such as chloride, fluoride, sulfate, nitrate, phosphate, and negatively charged functional groups on humic materials and clay. 

Direct methods for determining the combinational form of an element or its oxidation state include infrared absorption spectrometry, X-ray diffraction and, more recently, electron paramagnetic resonance - nuclear magnetic resonance -and Mossbauer spectrometry. With such techniques the combinational forms of major elements in soil components such as clay minerals, iron, manganese and aluminium oxyhydroxides and humic materials and the chemical structures of these soil components have been elucidated over the past 50 years. These direct, mainly non-destructive, methods for speciation are dealt with in some detail in Chapter 3 and are not further discussed here. 

Also, research on the use of UV/H202 system to treat NOM has been carried out [192-194], Backlund [192] carried out the oxidation of an aquatic humic material with a 254-nm UV lamp in the presence and absence of hydrogen peroxide. He reported significant increases in the humic removal rate with the combined system. He noticed the destruction of macromolecules to yield smaller fragments and identified some compounds such as oxalic acid, acetic acid, malonic acid, etc., which accounted for 20% and 80% of the NOM in UV and UV/H202 systems. Also, he observed that these processes do not lead to any mutagenic activity in the treated water. 

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