FINAL CHLORINE DIOXIDE STAGE AT NEAR-NEUTRAL pH FOR BLEACHING EUCALYPTUS PULP

Ribeiro, Robisnéa A.; Gomes, Fernando José Borges; Floriani, José N.; Damásio, Renato Augusto Pereira; Demuner, Iara Fontes; Colodette, Jorge Luiz

doi:10.5935/0100-4042.20140251

Cited by 3 publications

(2 citation statements)

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“…The tensile index of the control sequence was 23% higher than that with 10 kg/odt of carryover in the unrefi ned pulp. Increasing the chlorine dioxide consumption during bleaching in the sequence with carryover may cause greater fi ber degradation (Feria et al, 2013;Ribeiro et al, 2014). This was not recorded in this research, because the pulp tear index was 16% higher and viscosity was similar in the sequence with 10 kg .…”

Section: Alkaline Fi Ltrate Recirculation and Cellulosic Pulp Qualitymentioning

confidence: 69%

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The Effects of Alkaline Filtrate Recirculation Towards the Properties of Long Fiber Pulps With Od(epo)ded Bleaching Sequence

Souza

Zanuncio

Colodette

2018

CERNE

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The effects of alkaline fi ltrate recirculation towards the properties of long fi ber pulps with od(epo)ded bleaching sequence. CERNE, v. 24, n. 3, p. 233-239, 2018. HIGHLIGHTS The alkaline fi ltrate recirculation increased the reagents load during bleaching. The alkaline fi ltrate recirculation did not alter the quality of the refi ned pulp. The alkaline fi ltrate recirculation increased calcium, chloride, sodium and sulfate levels in the D stage and sodium and sulfate levels after the (EPO) stage ABSTRACT Circuit closure can reduce water consumption, but negative effects on pulp quality and equipment wear may make it unfeasible. This study aimed to evaluate how the alkaline fi ltrate of the recirculation stage (EP) affects bleaching, pulp quality and characteristics of the fi ltrates produced. Pre-delignifi ed cellulose pulp from a mixture of three coniferous woods was used. Bleaching followed the D(EPO)DED sequence, with the addition of 5, 10 and 15 kg. odt-1 of the alkaline fi ltrate (EP) to the pre-O 2 pulp. The physical and mechanical cellulosic pulp properties were evaluated in the control and with 10 kg. odt-1 of the alkaline fi ltrate. The inorganic compound accumulation in the system was evaluated in the control pulp and with 15 kg. odt-1 of the alkaline fi ltrate. The fi ltrate use increased the ClO 2 consumption for bleaching and sulfuric acid and NaOH to adjust the pH of the stages. The pulp tensile index was higher and the tear index lower with the fi ltrate use in pulp without refi nement, however the properties of refi ned pulp were similar between treatments. The fi ltrate increased the calcium, chloride, sodium and sulfate levels in the D stage and that of sodium and sulfate after the (EPO) stage. Filtrate recirculation can reduce water use, but it increases bleaching costs and metal accumulation in the system. v.24 n.3 2018 THE EFFECTS OF ALKALINE FILTRATE RECIRCULATION TOWARDS THE PROPERTIES OF LONG FIBER PULPS WITH OD(EPO)DED BLEACHING SEQUENCE 234 CERNE SOUZA et al.

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Section: Alkaline Fi Ltrate Recirculation and Cellulosic Pulp Qualitymentioning

confidence: 69%

“…odt -1 of carryover increased consumption by 18 and 19%, respectively. The ClO 2 consumption generates organic acids, consuming the NaOH and, therefore, the load of the latter must be increased in the subsequent stages (Biermann, 1996;Ribeiro et al, 2014;Wilke et al, 2015).…”

Section: Carryover Recirculation and Consumption Of Chemical Reagentsmentioning

confidence: 99%

The Effects of Alkaline Filtrate Recirculation Towards the Properties of Long Fiber Pulps With Od(epo)ded Bleaching Sequence

Souza

Zanuncio

Colodette

2018

CERNE

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Reduction of adsorbable organically bound halogens (AOX) formation at near-neutral pH chlorine dioxide bleaching of softwood kraft pulp

et al. 2020

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AbstractRecently, a new type of bleaching sequence, Elemental Chlorine Free (ECF) light with one D stage, has been developed. It combines the efficiency and high selectivity of chlorine dioxide (ClO2) bleaching with more environmental friendly oxygen based bleaching chemicals. This work examines the effect of pH on the formation of adsorbable organically bound halogens (AOX) in an intermediate D stage – a single ClO2 stage at the middle of an ECF light bleaching sequence. Carbon dioxide (CO2) is used to generate a bicarbonate buffer in situ, stabilizing the pH during the bleaching. Near-neutral pH is hypothesized to decrease the formation of strongly chlorinating species, so that the AOX formation is reduced. The results indicate that a near-neutral pH D stage can reduce the AOX content in the effluents with up to 30%. The ISO brightness was unchanged to a lower ClO2 consumption. The pulp viscosity was slightly higher after near-neutral pH D stage, but to its disadvantage a lesser delignification and removal of HexA was obtained. The degradation of HexA correlated well with the AOX, affirming earlier theories that HexA has a major impact on the AOX formation. The higher amounts of residual HexA and lignin resulted in more thermal yellowing of the pulps bleached with a near-neutral pH D stage.

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Bleaching of bagasse-pulp using short TCF and ECF sequence

Dhiman

Sharma

Lal

et al. 2021

Nordic Pulp &Amp; Paper Research Journal

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More than 70 % bleached chemical pulp is produced in India through elemental chlorine-free bleaching in which chlorine-based compounds like chlorine dioxide is a dominant chemical which generates chlorinated organic toxins harmful to the environment. Present studies demonstrate short sequence of bleaching combined with acid treatment, followed by pressurized oxygen delignification. It was found that efficiency of oxygen improved by adding hydrogen peroxide as an additive in oxygen delignification with subsequent treatment with ozone or chlorine dioxide as bleaching agents. It was observed that by using additive in ODL process, pulp can achieve 70±1 (%ISO) brightness. Reduction attains in kappa number 65–70 % as compared to 45–50 % in control oxygen delignification stage. Through AOpZ and AOpD bleaching sequences, full brightness achieved 84–85 (%ISO) without considerable loss in mechanical strength properties compared to DEpD sequence. A potential reduction in COD, color, and AOX was 28, 53.3, and 88 % respectively were observed in AOpZ short bleaching sequence compared to DEpD bleaching.

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FINAL CHLORINE DIOXIDE STAGE AT NEAR-NEUTRAL pH FOR BLEACHING EUCALYPTUS PULP

Cited by 3 publications

References 0 publications

The Effects of Alkaline Filtrate Recirculation Towards the Properties of Long Fiber Pulps With Od(epo)ded Bleaching Sequence

The Effects of Alkaline Filtrate Recirculation Towards the Properties of Long Fiber Pulps With Od(epo)ded Bleaching Sequence

Reduction of adsorbable organically bound halogens (AOX) formation at near-neutral pH chlorine dioxide bleaching of softwood kraft pulp

Bleaching of bagasse-pulp using short TCF and ECF sequence

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