Neutralization of cotton seeds after chemical delinting

Abstract

Using sulfuric acid in the chemical delinting of cotton seeds is necessary to degrade the short fibers that adhere to the seed tegument after ginning. Neutralization with a basic solution is essential to stop the acid reaction after this process and ensure seed quality. Thus, the objective of this study was to evaluate the neutralization of cotton seeds and the waste generated during chemical delinting with concentrated sulfuric acid by using different basic compounds, defining the total amount of those necessary to neutralize the residue without damages to seed quality. For neutralization, three basic solutions were used at a concentration of 10% (w/V): sodium hydroxide (NaOH), sodium carbonate (Na2CO3), and calcium hydroxide [Ca(OH)2]. Analyses of the pH of the solutions during the delinting and of the process residual liquid were performed. The pH of the seed exudate was also analyzed. Lastly, the physiological quality of the seeds was evaluated by first and last germination count tests. We concluded that the use of calcium hydroxide solution [7.2% (w/V)] is efficient for neutralization following the chemical delinting of cotton seeds with concentrated sulfuric acid. Neutralization after delinting is essential to ensure the quality of cotton seeds. For the disposal or reuse of effluent generated during the delinting process, it is necessary to neutralize pH by using calcium hydroxide.