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Problem of determining layer charge of shrink-swell soils of Peninsular India

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Title Problem of determining layer charge of shrink-swell soils of Peninsular India
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Creator Deshmukh, V.V., Ray, S.K., Chandran, P., Bhattacharyya, T., Sarkar, D. and Pal, D.K.
 
Subject Problem, layer charge, shrink-swell soils, Peninsular India,
 
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Determination of layer charge of soil clay smectites of the Peninsular India (PI) by alkylammonium method (Lagaly and Weiss, 1969) is generally encountered with some problems related to the inherent properties of smectites. The charges of these smectites are generally higher and the values are seldom closer to that of pure bentonite (Ray et al., 2003; Deshmukh, 2009). This is attributed to differential nature of smectites of Peninsular India. Detail study of the clay smectites indicate that hydroxy-interlayering (HI) is a common phenomenon (Pal and Deshpande, 1987, Bhattacharyya, et al., 1993, Deshmukh et al., 2009) in shrink-swell soils of PI. The presence of HI in smectites affects the determination of actual layer charge by alkylammonium method and the values obtained are found to be overestimated. The present study envisages to determine the layer charge of soil clay smectites before and after removal of HI. The EDTA method for the removal of HI from soil clay smectites has been used here for evaluation of the method. Two benchmark Vertisols from Maharashtra namely Seloo from Wardha and Saikhindi from Ahmednagar districts were chosen for the study. Fine clays were separated from the soils, characterized by XRD and were treated with alkylammonium hydrochlorides of various chain lengths before and after removal of HI.The fine clays contain dominant amount of smectite with small amounts of vermiculite and traces of chlorite, kaolin and feldspar. The smectites are partially chloritzed as evidenced by broadening towards the low angle side of 1.0 nm peak in K-saturated sample after subsequent heating to 550°C which is common in Vertisols. Greene-Kelly test showed the presence of both beidellitic/nontronitic and montmorillonite; where the former dominated over the latter. The weighted average layer charge by alkylammonium method for Seloo and Saikhindi fine clays are 0.450 and 0.432 mol(-)/(Si,Al)4O10(OH)2, respectively. The layer charge is highest at the surface and decreases down the depth for Seloo whereas for Saikhindi it showed irregular trend. After EDTA treatment and removal of HI, the semi-quantitative estimate showed a decrease in chlorite and increase in smectite values. This was also reflected in the values of weighted average layer charges (0.366 and 0.361 mol(-)/(Si,Al)4O10(OH)2 for Seloo and Saikhindi clays, respectively) which decreased from the original values without EDTA treatment. This also suggests that EDTA is an effective extractant to remove HI from soil clay smectites. The removal of HI by EDTA method resulted in the decrease in layer charge compared to the original fine clays. This can thus help to resolve the problem of determining the actual layer charge of hydroxy-interlayered smectites by alkylammonium method.
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Date 2020-06-27T01:30:46Z
2020-06-27T01:30:46Z
2011-02-18
 
Type Presentation
 
Identifier Deshmukh, V.V., Ray, S.K., Chandran, P., Bhattacharyya, T., Sarkar, D. and Pal, D.K. (2011). Problem of determining layer charge of shrink-swell soils of Peninsular India, National Symposium on Application of Clay Science: Agriculture, Enviroment and industry February 18-19, Nagpur, 2011, (Abstract), pp. 50
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http://krishi.icar.gov.in/jspui/handle/123456789/37491
 
Language English
 
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Publisher Not Available