Alkaline Delignification of Cactus Fibres for Pulp and Papermaking Applications

Abstract

Stable aqueous suspensions with high cellulosic contents and low fractions of lignin have been prepared from Cactus fibres via chemical delignification of the Cactus biomass feedstock with a sodium hydroxide–anthraquinone (soda–AQ) mixture. In order to optimize the reaction parameters, various temperatures between 120 and 170 °C and reaction times between 60 and 180 min were examined. The optimal yield of the resulting alkaline pulps (corresponding to the complete reaction of the raw materials) was equal to 41.4%, while the morphological parameters of individual cellulose fibres (such as length, width, and fraction of fine elements) were determined using a MorFi analyser. The estimated degree of polymerization, water retention value, total charge, and drainability of the produced pulps confirmed their suitability for papermaking applications; as a result, paper sheets were manually prepared using a Rapid-Kothen sheet former apparatus. The morphological analysis of the produced paper was conducted using a scanning electron microscopy technique, and its structural and mechanical properties were evaluated with the standard laboratory testing equipment. The obtained results indicate that the paper fabricated from Cactus fibres via the soda–AQ delignification process exhibits homogenous morphology as well as satisfactory mechanical and structural properties.