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United States Department of Agriculture

Agricultural Research Service

Research Project: Influence of Structure and Moisture on Cotton Fiber Properties

Location: Cotton Structure and Quality Research

Title: Modeling of total water content in cotton before and after cleaning with the shirley analyzer

Authors
item Montalvo, Joseph
item von Hoven, Terri

Submitted to: Journal of Cotton Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: February 21, 2012
Publication Date: October 8, 2012
Citation: Montalvo Jr, J.G., Von Hoven, T.M. 2012. Modeling of total water content in cotton before and after cleaning with the shirley analyzer. Journal of Cotton Science. 16(3):200-209.

Interpretive Summary: Moisture content in cotton and botanical cotton trash are important in ginning and storage of bales before use. The standard test methods are based on oven drying at 105oC; all of the loss in weight is attributable to moisture. A more accurate reference method was developed based on oven drying in combination with Karl Fischer Titration of the water vapor from the dried cotton or trash. Our approach in these studies was twofold. First, analyze the water in cotton before and after cleaning with a mechanical cleaner, and the isolated trash. In the second phase of the work, build a model to help explain the difference in water content in cotton before and after mechanical cleaning. The directly measured difference in water content before and after cleaning was small, and agreed with the model predictions. Water content in the cotton trash was about twice that in the cleaned cotton. Water content of cotton during ginning and in storage is critical to maintain fiber quality. For the first time, it is possible to measure more accurately the water content in cotton before and after cleaning, and in botanical cotton trash.

Technical Abstract: The Shirley analyzer is used worldwide to measure nonlint content in cotton. The aim of this study was to build and test a model of the difference in total water content in cotton before cleaning (i.e., raw cotton) and after cleaning with the Shirley analyzer. First, the total water content in cotton before cleaning was expressed as a function of the mass fraction of the aggregate impurities removed in cleaning, and the water content in the impurities and in the cleaned cotton. Then this expression was rearranged to give the desired model to predict the difference in total water content before and after cleaning. To test the model, two cultivars were cleaned in the Shirley analyzer and all materials analyzed for total water content by Karl Fischer Titration. The grand means in water content across both cultivars were (%): before cleaning, 7.83; after cleaning, 7.73, and impurities, 14.81. Thus, the directly measured grand means difference across both cultivars in water content before and after cleaning was only 0.10%. This compared well with the averaged predicted difference using a mass fraction of impurities of 0.0135 (after corrected for entrained lint) from published work on six cottons. This study has demonstrated that the model can help to explain and predict the total water content in cotton before and after cleaning with a specific kind of mechanical cleaner.

Last Modified: 4/17/2014
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