Impact of variability of cotton gin trash on the properties of powders prepared from distinct mechanical approaches

Abstract

Cotton gin trash (CGT), a large quantity by-product of cotton ginning process can differ in its contents among different seasons, cotton harvesting methods and ginning processes, due to its complex mixture. Finding a sustainable and constant powder fabrication method across different variety of CGT is important for practical application of CGT powder. However, the impact of variability of CGT and the powder preparation methods on the properties of CGT powder have not been addressed in the literature so far. In this study, achieving micro-sized powder from CGT was targeted and difference in the particle size and properties of the prepared powders were investigated in relation to their fractional content across different batches and drying techniques. This will facilitate choosing the right method to reach desired particle size and properties of CGT for a targeted application. Three different batches of CGT were collected from New South Wales, Australia, across three different years (2017, 2018, and 2022). The micro-sized CGT powders were then fabricated through mechanical milling and using two different methods: spray drying and ring grinding. A wide range of micro-sized particles (4.9–92.6 μm) was achievable from CGT by varying the milling time and drying method. Though the cotton fibre content affected particle size of the milled slurry, its impact was found minor when the milled slurry was converted into dried CGT powder. The powder morphology and chemical structure of CGT powder from different batches were not significantly different though the crystallinity index was found higher for the samples with higher amount of cotton fibres. The thermal stability of powders was mainly affected by milling time, drying technique, and fibre content though the impact was minimal. The moisture absorption of the CGT powder was found higher for ring ground powders, which was further improved by lower cotton content. Overall, this study provides an applicable and sustainable powder production method which could be used to optimise milling times, and drying techniques across different CGT sources to obtain required particle size for utilisation of CGT, such as composite reinforcement. • Reporting a sustainable and constant cotton gin trash (CGT) powder fabrication method. • A wide range of micro-sized CGT particles (4.9–92.6 μm) was produced. • Drying method was found more impactful on CGT powder size rather than CGT variability.