The suitability of Eucalyptus grandis bark and root for the pulp and paper industry was investigated. The bark of E. grandis was cooked using sodium borohydride (NaBH4) in the kraft process, while the root of E. grandis was cooked using the soda-anthraquinone (AQ) process. Four different charges (0.0, 0.3, 0.5, 0.7%) of NaBH4 and AQ used as catalysts were added to the cooking liquor used in the processes. The chemical, mechanical and optical properties of the produced pulps were investigated and characterized. The yields, viscosity values, kappa numbers, as well as the brightness, tensile, burst and tear indices of the pulps were determined. The yield (RP: 39.1%, BP: 36.8%), viscosity value (RP: 897 cm3/g, BP: 650 cm3/g) and the kappa numbers (RP: 90, BP: 50) of the pulps produced from the root (RP) were higher than those of the pulps produced from bark (BP). The catalysts generally affected all the pulp properties, improving the properties of BP and RP. It was concluded that E. grandis bark and root can be suitable for the pulp and paper industry.
Chemical treatment with sodium hydroxide, formamide and ethyl acetate is shown to affect certain properties of paper made from recovered fibres. Sodium hydroxide treatment improves the brightness of sheets by approx. 0.12–17.2% under similar recycling conditions. All chemical treatments usually improve the tensile and burst strengths of sheets to some degree. The highest tensile and burst strength values of 42.09 Nm/g and 2.60 kPa m2/g were obtained at the first recycling stage with 10% ethyl acetate treatment (O10Et1), and these represent approximately 142.2% and 100% improvement of tensile and burst strength respectively. In contrast, although the results revealed that certain chemical treatments markedly improved both tensile and burst strengths, there is some variation observed for tear strengths. The largest improvement in tear strength (72.9%) was found at the third recycling stage with 5.0% formamide treatment (O5Fa3), followed by O10Et3 (33.9%) and O10Na3 (29.2%). It is important to note that the highest tear strength value of 9.09 Nm2/g was found at the second recycling stage of the control samples. The results clearly show that the tensile and burst strengths of sheets can be improved by certain chemical treatments, but there is no correlation with tear strengths.
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