Pulping and Bleaching of Hydro Distillation Waste of Citronella Grass (Cymbopogon winterianus Jowitt) for Papermaking

Purpose This investigation is aimed to explore the pulp and papermaking potential of solid residue left after isolation of essential oil from Cymbopogon winterianus Jowitt using hydro distillation, as well as to evaluate the physical strength properties of pulp and paper produced from it. Methods Soda, soda-AQ (soda-anthraquinone) and kraft pulping of oil isolated C. winterianus were optimized and the corresponding optimum unbleached pulp in each process was subjected to environment friendly ECF (elemental chlorine free) bleaching using D(1)EpD(2) (D = chlorine dioxide in acidic medium; Ep = alkaline extraction with addition of hydrogen peroxide; 1 and 2 = first and second time) sequence. Fibre morphological investigation and fibre classification of bleached pulp from every optimized pulping process were also carried out. Hand sheets of bleached pulps were prepared to evaluate the physical strength properties. All the methods were followed as per standard procedures. Results The proximate chemical composition of oil isolated C. winterianus revealed 62.70% holocellulose, 37.62% alpha-cellulose, 21.10% pentosans and 24.10% lignin. Kraft pulping at 12% NaOH dose and 20% sulphidity produced unbleached pulp with kappa 18.72, yield 43.68%, brightness 21.36% and viscosity 32.6 cp; while bleached pulp with brightness 83.67% and viscosity 16.7 cp. However, hand sheets prepared from soda-AQ pulping exhibited tensile index 31.5 N m/g, tear index 5.02 m Nm(2)/g and burst index 2.20 kPam(2)/g which were superior to kraft pulping. Soda pulp demonstrated inferiority in quality to kraft and soda-AQ pulps. No significant differences were observed in fibre morphology of pulps from different processes while fibre classification revealed maximum useful bleached fibres 55.9% from kraft pulping. Conclusions This research proved that C. winterianus solid residue left after isolation of essential oil could be a substantial source for pulp and papermaking using conventional pulping processes and ECF bleaching sequence at process conditions described in this work.