Effect of Introducing Ozone Prior to Elemental Chlorine Free Bleaching of Wheat Straw Pulp on Pulp, Paper and Effluent Properties

Abstract

Ozone has been considered for the development of greener processes for hardwood and softwood pulps. This paper summarizes the results obtained using ozone bleaching on wheat straw pulp, followed by elemental chlorine free bleaching. This work evaluated the effect of introducing ozone bleaching on the optical properties of wheat straw pulp, along with the content of metal ions and hexenuronic acid in the pulp, pulp strength and morphological properties, as well as effluent properties. Introducing an ozone stage into the ECF bleaching sequence of wheat straw pulp improved pulp brightness by 2.5 units, pulp whiteness -by 4.0 units, while reducing the hexenuronic acid content by 21.6% and brightness reversion -by 34.8%, and allowed attaining physical strength and morphological properties comparable to those of the control. The introduction of the ozone treatment reduced the Fe, Cu and Mn content in the pulp by 6%, 11% and 31%, respectively. It also significantly reduced the COD in the bleaching filtrate by 41.2%, BOD -by 39.6%, colour level -by 57.9% and AOX -by 47.3%, compared to the control. The introduction of ozone prior to elemental chlorine free bleaching of wheat straw pulp was demonstrated to improve effluent quality, while yielding comparable pulp and paper properties.

Suitability of Corn Stalk Pulp for Improving Physical Strength Properties of Agro-Residue Pulp

“…12 Ash and silica content in the corn stalk was significantly lower, as compared to those of other agro-residues, except bagasse. [13][14][15] Earlier, the researchers reported contents of 27-28% hemicelluloses, 46.5% cellulose and 16.17% lignin in corn stalk, which were comparable with the values obtained in the present study. 16 Chesca et al 17 reported significantly lower cellulose content of 34.6-42.1%, pentosans of 17.6-20.7%, holocellulose of 62.5-67.7% and similar lignin content of 19.1-20.9%, ash content of 4.5-5.7% for Romanian corn stalk, as compared to the chemical composition of Indian corn stalk reported in this paper.…”

“…The fibre length and width of corn stalk pulp were comparatively higher than earlier reported values (0.818 mm fibre length and 17.5 µm fibre width) for wheat straw pulp. 13 Several other researchers have reported on the morphological properties of corn stalk pulp as being comparable to those of hardwood pulp. 16,20 The coarseness of the bleached corn stalk pulp, i.e.…”

“…94.1 µg/m, was also higher than an earlier reported coarseness of 71.8 µg/m for ECF bleached wheat straw pulp. 13 Higher coarseness of corn stalk pulp may result in higher physical strength properties of paper handsheets prepared from it, as compared to those of paper prepared from wheat straw pulp.…”

Proximate Chemical Analysis and Effect of Age and Height of Oxytenanthera abyssinica on Fiber Morphology and Chemical Compositions for Pulp and Paper Production Potential

“…High cellulose concentration yields high pulp yield, according to Biermann [77]. The hemicelluloses content of O. abyssinica is higher than that of D. brandisii [69], B. vulgaris [76], Phyllostachys edulis [39], and Daphniphyllum oldhami [76]. This also explains why the plant has a higher potential for pulp yield than the plant's mentioned above.…”

“…The chemical composition of other bamboo species in the current study was compared in Table 5. The table showed that the cellulose content (49.26 wt%) of 3year-old O. abyssinica was higher than that of other bamboo species such as Dendrocalamus brandisii (47.24 wt%) [69], Bambusa blumeana (40.3-45.1 wt%) [70], Bambusa tuldoides (35.2 wt%) [71,38], Gigantochloa levis (33.8 wt%) [71], Passiflora edulis (44.64 wt%) [39], and Daphniphyllum oldhami (47.1 wt%] [66]. This showed that O. abyssinica has a great potential for pulp yield and papermaking properties than the mentioned bamboo species.…”