The influence of pulping and washing conditions on the properties of Eucalyptus grandis unbleached kraft pulps treated with chelants

The addition of a phosphonated chelant (DTPMPA) at different points of a TCF bleaching sequence and its effect on pulp properties were studied in this work. An industrial Eucalyptus grandis kraft pulp was submitted to a counter-ion exchange (Ca2+ or Na+ form) and was then bleached using DTPMPA in the washing or in the bleaching stages of two distinct sequences: OOpP and OQOpP (20 pulps). The counter-ion exchange affected fibre length, as well as the handsheets bulk and air permeability (higher for Na+-based pulps) and handsheet tensile strength, brightness, skeletal density, and total porosity based on Hg porosimetry (higher for Ca2+-based pulps). The hydrogen peroxide consumption in Op and P stages achieved the lowest values when the chelant was distributed rather than applied in a separate Q stage. The addition of chelant in the P stage provides pulps with higher ISO brightness (>85%). The chelant effects were always more noticeable in Ca2+-based pulps.

Section: Introductionmentioning

confidence: 88%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Characterization of Eucalyptus grandis kraft pulps treated with phosphonates in different stages of TCF bleaching

Área

Felissia

Carvalho

et al. 2011

“…In the study performed by Khristova et al (2006), in which alkaline cellulosic pulps (kraft, kraft-AQ, soda-AQ, ASA and ASAM) of 4 varieties from Sudan (Eucalyptus camaldulensis, E. citriodora, E. microtheca, and E. tereticornis) were analysed, the following results were obtained: Tensile index at a refining degree of 30ºSR was between 61.7 N m/g and 85 N m/g; burst index was between 3.1 kPa m 2 /g and 5.6 kPa m 2 /g; and tear index was between 6.9 mN m 2 /g and 10.4 mN m 2 /g. In the work of Area et al (2010) concerning kraft pulps treated with chelants agents of Eucalyptus grandis, the strength properties at 30 ºSR (aproximately), were between 85.2 N m/g and 103 N m/g for tensile index; 5.3 kPa m 2 /g and 7.1 kPa m 2 /g for burst index; and 7.8 mN m 2 /g and 9.9 mN m 2 /g for tear index. In the work of Colodette et al (2002) conerning kraft pulp of Eucalyptus grandis (beating at 40 W h, 3000 PFI aproximately and Kappa numbers 16 to 17) using high and low residual alkali (14-18 g/L and 3-4 g/L) and high and low temperatures (170ºC and 160ºC), values for tensile index, burst index, and tear index falling between 95.6 N m /g and 112.1 N m/g; 6.1 kPa m 2 /g and 7.9 kPa m 2 / g; 9.2 mN m 2 /g and 11.2 mN m 2 /g respectively, were achieved.…”

Section: Table 3 Characterization Of Kraft Pulp From Leucaena Diversi...mentioning

confidence: 98%

Process optimization in kraft pulping, bleaching, and beating of Leucaena diversifolia

Feria

García

Pérez

et al. 2011

A variety of the Leucaena genus, Leucaena diversifolia, was used for pulp and paper making by kraft and refining processes and a OD(EP)DP bleaching sequence. The same species has been suggested as an energy crop and, in fact, this species used shows a high gross heating value; besides, this variety of Leucaena has appropriate characteristics for pulp and paper making. The holocellulose content was higher than Eucalyptus globulus, and ash and lignin contents were comparable to other varieties of Leucaena. Pulps with a kappa number between 17 and 18, and 21.4 cP viscosity were obtained using an active alkali concentration of 31%. Also, paper sheets showed good strength properties, comparable or even greater than those obtained with Eucalyptus or others varieties of Leucaena at comparable refining degrees, between 30 and 40 ºSR. The pulp was successfully bleached in all cases with a kappa number below 1.5 in the EP stage and a value of brightness higher than 90%.

“…Ramírez et al (2009) reported a tensile index of 90.0 Nm/g, a tear index of 7.8 mNm 2 /g, a burst index of 5.6 kPa m 2 /g, and a specific bulk of 1.4 cm 3 /g for E. globulus kraft pulp refined to 30 ºSR. Area et al (2010) reported the following strength properties for E. grandis kraft pulps at 30 ºSR: tensile index between 85.2 Nm/g and 103 Nm/g, burst index between 5.3 kPa m 2 /g and 7.1 kPa m 2 /g, and tear index between 7.8 mNm 2 /g and 9.9 mNm 2 /g. Mutje et al (2005) reported for a commercial eucalypt kraft pulp at 26.5 ºSR a tensile index of 76.7 Nm/g and a burst index of 7.8 kPa m 2 /g.…”

Section: Pulp Propertiesmentioning

confidence: 99%

Incorporation of bark and tops in Eucalyptus globulus wood pulping

Miranda¹,

Gominho²,

Pereira³

2012

Bark and the tops of E. globulus trees were considered for kraft pulping under industrial conditions. Pulping experiments included wood, bark, tops, and composite samples. Top wood had an average chemical composition most similar to that of wood but with somewhat lower cellulose content (52.8% vs. 56.9%) and higher lignin content (18.8% vs. 17.8%). There was also a small difference between tops and wood for non-polar extractives, which were higher for tops (2.0% vs. 1.4%). Bark had a less favorable chemical composition with more extractives, especially polar extractives (5.3% vs. 1.6%) and 1% NaOH solubility (19.9% vs. 12.2%), pentosans (23.7% vs. 21.3%), and ash (2.9% vs. 1.0%), although the fiber length was higher (1.12 mm vs. 0.98 mm). The kraft pulps obtained using bark showed significantly lower yield, delignification degree, and strength properties but had a quicker response to refining. The incorporation of tops and bark in the wood pulping in levels below or similar to a corresponding whole-stem, however, had a limited effect on pulp yield, kappa number, refining, and pulp strength properties. These additional raw-materials, which were estimated to be 26% of the commercial stem wood (14% bark and 12% tops), may therefore be considered in enlarging the eucalypt fiber feedstock in kraft pulping.