Stabilization of iron-catalysed hydrogen peroxide decomposition by magnesium

Abbot, J.; Brown, D. G.

doi:10.1139/v90-237

Cited by 32 publications

(21 citation statements)

References 16 publications

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“…Agnemo and Gellerstedt (1979) found an energy of activation of 68 kJ/mol at pH 10.5. Even with the small variation in pH, values from Abbot and Brown (1990) and Hobbs and Abbot (1994) were fairly close to the regression line; the value from Agnemo and Gellerstedt (1979) was not as close. The generally good agreement of the data from different sources, however, lead us to conclude that the procedures used were adequate for the relative comparisons being made in this work.…”

Section: Discussionmentioning

confidence: 75%

The Effect of Magnesium Ions and Chelants on Peroxide Bleaching

Lapierre¹,

Berry²,

Bouchard³

2003

Holzforschung

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IntroductionAlkaline hydrogen peroxide has been used for many years as a bleaching agent for high yield pulps and has more recently been used routinely for the bleaching of chemical pulps (Pryke et al. 2000). Maximum peroxide bleaching performance is achieved when the peroxide stage is preceded by a metal management stage using acids or chelants (Basta et al. 1991;Bouchard et al. 1995;Lapierre et al. 1995), and when optimum amounts of hydrogen peroxide (H 2 O 2 ), sodium hydroxide (NaOH), magnesium sulphate (MgSO 4 ) and diethylenetriaminepentaacetate (DTPA) are added (Basta et al. 1991;Lierop et al. 1994;Bouchard et al. 1995;Lapierre et al. 1995). While much has been written on the optimum physical operating conditions (time, temperature, consistency, mixing) and on the optimum charges of these P-stage chemicals, little attention has been given to the importance of the order of addition when the chemicals are applied to chemical pulps.In a previous report (Lapierre et al. 2000), we assessed the effects of chemicals, individually and combined, and the effect of the order of addition of these chemicals on peroxide bleaching performance when using an acid-treated or a chelated oxygen-delignified softwood kraft pulp. The findings were: 1) magnesium was substantially more effective when in a complex form with either pulp or a chelant; 2) peroxide bleaching of an acid-treated pulp was significantly less affected by the order of addition of the P-stage chemicals than when using a chelated pulp; 3) adding Mg and NaOH (or vice versa) sequentially into a bleaching solution before adding the solution into pulp caused inefficient peroxide bleaching, particularly with a chelated pulp; 4) the optimum concentration of Mg for use in peroxide bleaching could be determined by following the peroxide residual; and 5) the addition of magnesium to an acid-treated pulp was essential for good peroxide bleaching while the addition of magnesium to a chelated pulp provided only a marginal improvement in most modes of addition. We also speculated that different magnesium forms (e.g., Mg(pulp) -x , Mg(DTPA) -4 and Mg(OH) 2 ) affected the catalytic activity of transition metals towards peroxide decomposition to differing degrees.As oxygen delignified pulps still containing lignin were used, it was impossible to separate the catalytic peroxide decomposition by transition metals from the peroxide reaction with lignin, and thus to determine where in the pulp-liquor system magnesium or chelants or both were deactivating transition metals. In this work, we have studied the peroxide decomposition kinetics with different modes of addition of the P-stage chemicals in the presence of fully ECF-bleached (D 0 E P D n D) softwood kraft pulps which are virtually lignin free, in peroxide-stage filtrate, in alkaline filtrates and in water. L. Lapierre et al.: Peroxide Decomposition in Chemical Pulps 627 Holzforschung / Vol. 57 / 2003 / No. 6 SummaryWe recently reported that during peroxide bleaching, magnesium is substantially more effective when in a comp...

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Section: Discussionmentioning

confidence: 75%

The Effect of Magnesium Ions and Chelants on Peroxide Bleaching

Lapierre¹,

Berry²,

Bouchard³

2003

Holzforschung

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“…Nevertheless, since Mn is the most critical metal ion for hydrogen peroxide decomposition (Lapierre , priority must be given to its removal. Simulation also evidences that MGDA complexes a high amount of Mg, which might be another disadvantage, because the presence of Mg in the pulp might be beneficial in the peroxide stage (Colodette et al 1989;Abbot and Brown 1990). A pH between 6.5 and 7 was defined to proceed to the experimental tests.…”

Section: Computer Chemical Simulationsmentioning

confidence: 99%

“…These metals are in the process as impurities of chemicals used in the bleaching, washing waters and wood itself and the control of its presence is very important to minimize hydrogen peroxide degradation and maximize bleaching efficiency (Wuorimaa et al 2006). On the other hand, the presence of magnesium (Mg) in the bleaching step is important to stabilize the metal ions that increase peroxide degradation (Colodette et al 1989;Abbot and Brown 1990).…”

Section: Introductionmentioning

confidence: 99%

Pre-treatment of the paper pulp in the bleaching process using biodegradable chelating agents

Pinto¹,

Ascenso

Barros

et al. 2013

Int. J. Environ. Sci. Technol.

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The aim of this work was to study the application of two biodegradable chelating agents, pyridine-2,6-dicarboxylic acid (PDA) and methylglycinediacetic acid (MGDA), in the treatment of the pulp, prior to hydrogen peroxide bleaching. Such compounds must remove transition metals (Mn, Fe and Cu) from pulp, that catalyze the degradation of hydrogen peroxide, and Ca, which is also problematic due to the formation of precipitates that accumulate in the equipment. Computer simulations were first performed to study the best conditions for metal complexation, and optimum pH was defined as 5-5.5 for PDA and 6.5-7 for MGDA. Metals removal from the pulp, as well as the subsequent bleaching process (Q-P1-Paa-P2), were tested experimentally, and performances were compared to ethylenediaminetetracetic acid (EDTA). PDA removed both Mn and Ca efficiently, leaving most Mg in the pulp after first chelation stage, while MGDA had a lower Ca removal, even using a higher pH and concentration. Residual hydrogen peroxide and kappa number after peroxide stages showed a similar bleaching efficiency between the studied compounds and EDTA.

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“…In all cases, except run 9, the composition of the monosaccharides was, within error, identical with the one from the standard reaction, run 1. Only the chromic acid oxidized cellulose yielded an excess of 0.8 mole% mannose, which must result from keto group formation at C-2 of an anhydroglucose unit of the cellulose chain: (Samuelson 1983;Burton and Campbell 1985;Abbot and Brown 1990). In preliminary experiments it was found that ferrous sulfate alone also speeds up the hydrolysis of cellulose.…”

Section: Kinetics Of Oxidation By Iodometrymentioning

confidence: 99%

Degradation and Oxidation Reactions of Cellulose Dissolved in Phosphoric Acid

Garves¹

1993

HFSG

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Stabilization of iron-catalysed hydrogen peroxide decomposition by magnesium

Cited by 32 publications

References 16 publications

The Effect of Magnesium Ions and Chelants on Peroxide Bleaching

The Effect of Magnesium Ions and Chelants on Peroxide Bleaching

Pre-treatment of the paper pulp in the bleaching process using biodegradable chelating agents

Degradation and Oxidation Reactions of Cellulose Dissolved in Phosphoric Acid

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