Soils composition tests

Cinders and acid peaty soils are obviously among the soils most corrosive toward copper. There is, however, no direct relationship between the rate of corrosion and any single feature of the soil composition or constitution". For instance, in the American tests corrosion in several soils with either low pH or high conductivity was not particularly severe, while the British tests show that high chloride or sulphate contents are not necessarily harmful. 

The liquid in which the SAH swelling takes place in real soil (the soil solution) always contains a more-or-less wide set of dissolved salts. Their nature and amount depend on the soil composition, the degree of its salinity, the nature of water entering the soil (rainfall, irrigation, river, or groundwater), the fertilizers used. As a rule, alkali cations, Ca2 +, Mg2+, Fe3+, Al3+, and anions CP, CO, SO4, etc. are the main components of the soil solution there exist various models of soil solution and nutrient mixtures employed in research, including SAH testing. 

An accurate evaluation of kxa is complicated by the heterogeneous nature and poor definition of contaminant/soil systems. Some success has been achieved in modeling mass transfer from a separate contaminant phase. During degradation these nonaqueous phase liquids (NAPLs) often dissolve under conditions where phase equilibrium is not achieved and dissolution is proportional to k a. Experimental determinations and correlations for k-p depend on interfacial area of the NAPL and liquid velocity at the interface (Geller Hunt, 1993). For adsorbed contaminants, kxa varies with soil composition and structure, concentration and age of contamination, and therefore with time. For example, slurry reactor tests indicate that the rate of naphthalene mass transfer decreases with time, with media size, and with aging of the tar prior to testing (Luthy et al., 1994). 

Pamukcu and Wittle [133] investigated the feasibility of electrokinetic treatment at 30 V of different clay mixtures containing a number of heavy metals including Cd, Co, Ni, and Sr. The metal removal success ranged between 85-95% and appeared to depend on the soil matrix, the metal, and the pore fluid composition. At low initial metal concentrations, electroosmosis appeared to be the dominant mechanism for metal removal. At higher concentrations, electrolytic migration of the ionic species played a more dominant role. Of the three soil types tested, kaolinite had the highest electroosmotic efficiency. 

Soil Extract and Soil Fortification Experiments. We tested for possible interfering soil coextracted materials by adding hydroxyatrazine to the methanol/water extract of five soils of known composition. Hydroxyatrazine was measured by ELISA using MAb 4009-85-3 before and after the addition of hydroxyatrazine to the soil extract. As shown in Figure 2, all soil types tested gave acceptable recoveries (97% mean recovery), suggesting that in these samples, no interfering substances were coextracted. 

Silica concentration was plotted vs. the square root of time to test for possible diffusion control (17, 18) in the release of silica. An allowance was made for filtering time. Soil composite A displayed a release pattern which suggested diffusion control at one rate for the first 8 hours (Figure 15), and then the slope changed to a rate similar to that seen in soil composite B. A break in slope in the line for soil B apparently occurred at the third aliquot collected. 

An example of the first approach was given in Ref. [2]. The AWPA (the American Wood-Preservers Association) Soil Block test method has been employed. Samples were polyethylene-wood composite materials with wood content ranging from 50 to 70% (w/w). Weight losses as a result of microbial degradation were up to 18% when treated for 16 weeks with white-rot organism, Trametes versicolor, and up to 7% when treated for 12 weeks with brown-rot organism, Gloeophyllum trabeum. 

Stndying microbial degradation of 50% WPCs by brown-rot and white-rot fungi (G. trabeum and T. versicolor, respectively), it was found that the decay was more prononnced as the wood particle size increased [9]. The authors found that decay in the pine-based composites was more sensitive to particle size than that in the maple-based composites. It is noticeable from the above examples that for the same soil block test, ASTM 1413 or similar to it, the weight loss figures are quite different, and vary from fractions of a percent to qnite high numbers. Indeed, as it was shown, extended composite material samples are mnch more sensitive to soil block test compared to compression-molded and injection-molded sample. After 12 weeks,... 

Regarding an efficiency of zinc borate in the soil block test, it was shown that with brown-rot fungi, G. trabeum, acting on extruded HOPE composites containing 50% pine wood floor, zinc borate effectively suppressed weight loss as follows 47% suppression with 0.2% zinc borate, 53% suppression with 0.5% zinc borate, and 72% suppression with 1% of zinc borate [10],... 

J.A. Silva Guzman, J.J. Morrell, and B.L. Gartner. Comparison of agar (MEA and DPA) and soil block tests for assessing decay of wood plastic composites. In Eighth International Conference on Woodflber Composites, Madison, WI, May 23-25, 2005. 

SEM micrographs of biodegradable polymer green composite, tested by the soil burial test. 

The loss of TS observed by Shubhra et al. is shown in Figure 9.8. It was found that TS values of the composites decreased slowly. For silk fibre/PP composites the TS value was 54.7 MPa whereas after 24 weeks of soil burial test it was 49.1 MPa. So, after 24 weeks of soil burial, silk fibre reinforced PP composite lost 10.2% TS, whereas silk-reinforced PP and NR blend (50 50) composite lost 24.3% TS. For silk-reinforced PP and NR blend (50 50) composites the TS value was 39.9 MPa whereas after 24 weeks of soil burial test it was 30.2 MPa. The author mentioned that this 14.1% higher loss of TS is due to incorporation of NR in the PP matrix. The author found that if NR is low (25% instead of 50%), the composite loses less TS value after 24 weeks of degradation test (from 42.4 MPa to 34.3 MPa, which is 19.1%). 

The loss of BS observed by Shubhra et al. is shown in Figure 9.9. It was found that BS values of the composites decreased more rapidly than TS values. For silk fibre/PP composites the BS value was 58.3 MPa whereas after 24 weeks of soil burial test it was 50.7 MPa. So, after 24 weeks of soil burial, silk fibre reinforced PP composite lost 13% BS whereas silk-reinforced PP and NR blend... 

Figure 9.8 Loss of tensile strength of rubber composites during soil burial test.

Figure 11.1 SEM images of the samples before and after the soil burial test, (a) TPU/ NR blend, (b) TPU/NR chitin reinforced composite.

Routray M, Rout SN, Mohanty GC, Nayak PL (2013) Preparation and characterization of soy protein isolate films processed by compression and casting. J Chem Pharm Res 5(11) 752-761 Sareena C, Sreejith MP, Ramesan MT, Puiushothaman E (2014) Biodegradation behaviour of natural rubber composites reinfOTced with natural resource fillers—monitoring by soil burial test J Reinf Plast Compos 33(5) 412—429... 

Although all these complicating factors cannot be reproduced in small-scale tests, it will be of value to summarise the main knowledge that has been gained from long-period burial trials conducted in the United States and in Great Britain . The subject will be considered under two heads effect of metal composition and effect of the soil. 

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