The role of copper ions in hydrogen peroxide bleaching: Their origin, removal, and effect on pulp quality

TAPPI Journal ◽  
2012 ◽  
Vol 11 (7) ◽  
pp. 37-46 ◽  
Author(s):  
PEDRO E.G. LOUREIRO ◽  
SANDRINE DUARTE ◽  
DMITRY V. EVTUGUIN ◽  
M. GRAÇA V.S. CARVALHO
Keyword(s):  
Hydrogen Peroxide ◽  
Copper Ions ◽  
Peroxide Bleaching ◽  
Metals Removal ◽  
Peroxide Decomposition ◽  
Equipment Corrosion ◽  
And Performance ◽  
And Control ◽  
Main Effects

This study puts particular emphasis on the role of copper ions in the performance of hydrogen peroxide bleaching (P-stage). Owing to their variable levels across the bleaching line due to washing filtrates, bleaching reagents, and equipment corrosion, these ions can play a major role in hydrogen peroxide decomposition and be detrimental to polysaccharide integrity. In this study, a Cu-contaminated D0(EOP)D1 prebleached pulp was subjected to an acidic washing (A-stage) or chelation (Q-stage) before the alkaline P-stage. The objective was to understand the isolated and combined role of copper ions in peroxide bleaching performance. By applying an experimental design, it was possible to identify the main effects of the pretreatment variables on the extent of metals removal and performance of the P-stage. The acid treatment was unsuccessful in terms of complete copper removal, magnesium preservation, and control of hydrogen peroxide consumption in the following P-stage. Increasing reaction temperature and time of the acidic A-stage improved the brightness stability of the D0(EOP)D1AP bleached pulp. The optimum conditions for chelation pretreatment to maximize the brightness gains obtained in the subsequent P-stage with the lowest peroxide consumption were 0.4% diethylenetriaminepentaacetic acid (DTPA), 80ºC, and 4.5 pH.

scholarly journals Looking for the “Dream Catalyst” for Hydrogen Peroxide Production from Hydrogen and Oxygen

Catalysts ◽  
2019 ◽  
Vol 9 (3) ◽  
pp. 251 ◽  
Author(s):  
Federica Menegazzo ◽  
Michela Signoretto ◽  
Elena Ghedini ◽  
Giorgio Strukul
Keyword(s):  
Hydrogen Peroxide ◽  
Heterogeneous Catalysts ◽  
Direct Synthesis ◽  
Particle Morphology ◽  
Synthetic Methods ◽  
Side Reactions ◽  
Catalyst Morphology ◽  
And Performance ◽  
The Ideal

The reaction between hydrogen and oxygen is in principle the simplest method to form hydrogen peroxide, but it is still a “dream process”, thus needing a “dream catalyst”. The aim of this review is to analyze critically the different heterogeneous catalysts used for the direct synthesis of H2O2 trying to determine the features that the ideal or “dream catalyst” should possess. This analysis will refer specifically to the following points: (i) the choice of the metal; (ii) the metal promoters used to improve the activity and/or the selectivity; (iii) the role of different supports and their acidic properties; (iv) the addition of halide promoters to inhibit undesired side reactions; (v) the addition of other promoters; (vi) the effects of particle morphology; and (vii) the effects of different synthetic methods on catalyst morphology and performance.

scholarly journals THE ROLE OF TRUST IN RELATIONSHIP DEVELOPMENT AND PERFORMANCE IMPROVEMENT

2015 ◽  
Vol 21 (7) ◽  
pp. 845-853 ◽  
Author(s):  
Xianhai Meng
Keyword(s):  
Questionnaire Survey ◽  
Significant Contribution ◽  
Major Influence ◽  
Monitoring And Control ◽  
Collaborative Relationships ◽  
New Approach ◽  
And Performance ◽  
Qualitative Methodologies ◽  
And Control

The importance of inter-organizational trust to project success has been increasingly highlighted in the construction industry. This study aims to explore the role of trust between project parties. It adopts a combination of quantitative and qualitative methodologies. Based on the analysis of the responses of a questionnaire survey, trust is demonstrated to have a significant contribution to the development of cooperative or collaborative relationships; fostering trust proves to have a major influence on the improvement of project performance; and some relationship and performance indicators are found to have closer associations with trust than others so that trust is more important to the development of relationship and the improvement of performance in these aspects. The analysis of questionnaire responses also provides significant evidence for the reduction in monitoring and control following the increase of mutual trust. The questionnaire survey is followed by a series of expert interviews, both of which contribute to the establishment of a model that links trust with relationship and performance and distinguishes the new approach that is based on trust from the traditional mechanism that relies on monitoring and control.

Role of Surface Reactivity in Processing and Performance of Magnesium Alloys

2015 ◽  
Vol 828-829 ◽  
pp. 401-406 ◽  
Author(s):  
Frank Czerwinski
Keyword(s):  
Magnesium Alloys ◽  
Surface Reactivity ◽  
Surface Oxide ◽  
Diffusion Characteristics ◽  
Component Manufacturing ◽  
And Performance ◽  
General Aspects ◽  
Liquid States ◽  
And Control

The surface reactivity of magnesium alloys at high temperatures required for their processing in solid, semisolid and liquid states is reviewed emphasizing presently existing barriers of its understanding and control. In addition to general aspects of magnesium oxidation, other forms of reactivity such as ignition and flammability are discussed. Since surface oxide, composed of pure MgO, does not offer a sufficient protection, operations of raw alloy melting and component manufacturing require protective atmospheres what has detrimental implications on process economy and product performance. Efforts to develop ignition resistant magnesium alloys through modification of their chemistry are described with a particular role of rare earths and other elements with high affinity to oxygen. It is concluded that all forms of magnesium reactivity in solid and liquid state could be explained through diffusion characteristics of surface oxide formed during processing and service.

scholarly journals Innovative Method of Utilising Hydrogen Peroxide for Source Water Management of Cyanobacteria

2021 ◽  
Author(s):  
Jianyin huang ◽  
Maximus Ghaly ◽  
Peter Hobson ◽  
Christopher W.K. Chow
Keyword(s):  
Water Quality ◽  
Hydrogen Peroxide ◽  
Water Samples ◽  
Uv Light ◽  
Cyanobacterial Blooms ◽  
Suitable Model ◽  
Hydrogen Peroxide Decomposition ◽  
Peroxide Decomposition ◽  
And Control ◽  
The Impact

Abstract The treatment and control of cyanobacterial blooms using copper-based algaecides in water reservoirs has historically been used, however, due to the adverse impact of copper on the environment, water authorities have been researching and studying new and innovative ways to control cyanobacterial blooms. Hydrogen peroxide has been investigated as an environmentally friendly alternative and this research aims to determine the impact of water quality on its effectiveness based on the decay characteristics in different water samples. Natural water samples from South Australian reservoirs were used to evaluate hydrogen peroxide decomposition and provide a better strategy for water operators in using it as an algaecide. Our experiments show the dependency of hydrogen peroxide decomposition not only on water quality but also on the initial hydrogen peroxide dose. A higher initial hydrogen peroxide dose can trigger the increase of pH, leading to increased consumption of hydrogen peroxide. In addition, the hydrogen peroxide decomposition is significantly accelerated with the rise of copper concentration in water samples. Moreover, it is found that UV light can also affect the decomposition rate of hydrogen peroxide. The hydrogen peroxide decay is more significant under UV light for the samples with lower hydrogen peroxide concentrations. Our study also shows the impact of DOC on hydrogen peroxide decomposition is not substantial. The study also presents a modelling method to optimise hydrogen peroxide application based on water quality characteristics. Our findings can provide knowledge for the water industry to produce a suitable model which can be used to optimise the application of hydrogen peroxide for the control of cyanobacteria.

On the role of iron and copper ions in hydrogen peroxide-induced cellular DNA damage

2002 ◽  
Vol 32 (2) ◽  
pp. 198-199 ◽  
Author(s):  
Dimitrios Galaris ◽  
Ben-Zhan Zhu ◽  
Balz Frei
Keyword(s):  
Hydrogen Peroxide ◽  
Dna Damage ◽  
Copper Ions ◽  
Cellular Dna

New evidence for the role of the borohydride pretreatment on the hydrogen peroxide bleaching of kraft pulp

RSC Advances ◽  
2015 ◽  
Vol 5 (119) ◽  
pp. 98067-98074 ◽  
Author(s):  
Jing Li ◽  
Huichao Hu ◽  
Yanting Song ◽  
Xin-Sheng Chai
Keyword(s):  
Hydrogen Peroxide ◽  
Kraft Pulp ◽  
Carbonyl Groups ◽  
Bleaching Process ◽  
Peroxide Bleaching ◽  
Chemical Pulps ◽  
New Evidence ◽  
Lignin Structure

New evidences for the role of borohydride pretreatment in hydrogen peroxide bleaching process of eucalyptus chemical pulps were provided, i.e., suppressing the catalysis effect of Fe(iii), decreasing carbonyl groups, and constituent lignin structure.

Coercive Family Processes and the Development of Child Social Behavior and Self-Regulation

2015 ◽  
Author(s):  
James Snyder
Keyword(s):  
Social Interaction ◽  
Cognitive Processing ◽  
Molecular Genetic ◽  
Self Regulation ◽  
Family Processes ◽  
Social Actions ◽  
And Control ◽  
Main Effects

This chapter (1) examines the multiple ways in which coercive processes may be manifested during family interaction in addition to their more blatant, aversive forms, including emotion dismissing, invalidating, intrusive/controlling social actions; (2) assesses the role of higher cognitive processing and control in coercive social interaction in the context of previous assumptions that coercive processes are primarily overlearned and automatic; (3) examines the utility of extensions of environmental main effects models of coercive processes by explicitly focusing on synergistic models that involve child temperamental self-regulatory capacities (reflecting underlying molecular genetic and neurobiological mechanisms); and (4) assesses the role of coercive family processes in relation to borderline features and trauma/PTSD.

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