scholarly journals Kinetic study on iso-concentration hydrogen peroxide bleaching of poplar chemi-thermomechanical pulp by the process of continuous chemical supplement

BioResources ◽  
2018 ◽  
Vol 13 (3) ◽  
pp. 5408-5415
Author(s):  
Xianqi Sun ◽  
Qingxi Hou ◽  
Haizhen Shi ◽  
Lichun Zhou
Keyword(s):  
Kinetic Model ◽  
Initial Phase ◽  
Reaction Rate ◽  
Reaction Order ◽  
Slow Phase ◽  
Thermomechanical Pulp ◽  
Bleaching Process ◽  
Peroxide Bleaching ◽  
Bleached Pulp ◽  
Continuous Chemical

In the authors’ previous studies, a bleaching process based on continuous chemical supplementation (CCS) was proposed to improve the effectiveness of peroxide bleaching of chemi-thermomechanical pulp (CTMP). In this study, the kinetic model of the CCS process of peroxide bleaching was applied to poplar CTMP to explore how the bleaching rate was affected. The model was based on the rate of chromophore elimination characterized by the brightness gains of bleached pulp. The reaction rate of chromophore destruction proceeded via a rapid initial phase followed by a slow phase. The equation of reaction rate was confirmed. The value of reaction order was -3.62, and the activation energy was 288.8 kJ/mol. The developed kinetic model was a good fit for the experimental results.

A Survey of Hydrogen Peroxide Bleaching and FAS Bleaching of Liquid Package Recycled Pulp

2014 ◽  
Vol 1081 ◽  
pp. 48-52
Author(s):  
Zong Juan Xu ◽  
Yu Liu ◽  
Zhen Wang
Keyword(s):  
Adverse Effect ◽  
Hydrogen Peroxide ◽  
Process Conditions ◽  
Pulp Fiber ◽  
Bleaching Process ◽  
Peroxide Bleaching ◽  
Bleached Pulp ◽  
Recycled Pulp

This document demonstrates how to affect the brightness of liquid package recycled pulp by hydrogen peroxide bleaching and FAS beaching. The optimum H2O2 bleaching process conditions: 8% H2O2, 4% NaOH, bleaching temperature 80 °C, bleaching time 1.5h. The best FAS bleaching conditions was FAS dosage of 0.5%, NaOH dosage of 0.25%, bleaching temperature at 80 °C, time for 30min. And bleaching had no adverse effect on the performance of bleached pulp fiber.

scholarly journals Synthesis of KAlSiO4 by Hydrothermal Processing on Biotite Syenite and Dissolution Reaction Kinetics

Minerals ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 36
Author(s):  
Jiangyan Yuan ◽  
Hongwen Ma ◽  
Zheng Luo ◽  
Xi Ma ◽  
Qian Guo
Keyword(s):  
Reaction Rate ◽  
Reaction Order ◽  
Dissolution Behavior ◽  
Precipitation Process ◽  
Hydrothermal Processing ◽  
Hydrothermal Conditions ◽  
Effective Utilization ◽  
Comprehensive Utilization ◽  
Dissolution Reaction ◽  
Significant Process

To make potassium from K-bearing rocks accessible to agriculture, processing on biotite syenite powder under mild alkaline hydrothermal conditions was carried out, in which two types of KAlSiO4 were obtained successfully. The dissolution-precipitation process of silicate rocks is a significant process in lithospheric evolution. Its effective utilization will be of importance for realizing the comprehensiveness of aluminosilicate minerals in nature. Two kinds of KAlSiO4 were precipitated in sequence during the dissolution process of biotite syenite. The crystal structures of two kinds of KAlSiO4 were compared by Rietveld structure refinements. The kinetics model derived from geochemical research was adopted to describe the dissolution behavior. The reaction order and apparent activation energy at the temperature range of 240–300 °C were 2.992 and 97.41 kJ/mol, respectively. The higher dissolution reaction rate of K-feldspar mainly relies on the alkaline solution, which gives rise to higher reaction order. During the dissolution-precipitation process of K-feldspar, two types of KAlSiO4 with different crystal structure were precipitated. This study provides novel green chemical routes for the comprehensive utilization of potassium-rich silicates.

The Effect of Microwave Treatment on the Hydrogen Peroxide Bleaching of Soda-AQ Wheat Straw Pulp

2011 ◽  
Vol 236-238 ◽  
pp. 1307-1312
Author(s):  
Chao Jun Wu ◽  
Chuan Shan Zhao ◽  
Jun Li ◽  
Ke FU Chen
Keyword(s):  
Hydrogen Peroxide ◽  
Wheat Straw ◽  
Fiber Length ◽  
Weighted Average ◽  
Microwave Treatment ◽  
Arithmetic Average ◽  
Peroxide Bleaching ◽  
Bleached Pulp ◽  
Infra Red ◽  
Wheat Straw Pulp

In this paper, the effect of microwave treatment on the hydrogen peroxide bleaching of Soda-AQ wheat-straw pulp was investigated. The results showed that microwave treatment could increase the brightness of the hydrogen peroxide bleached pulp. The fiber coarseness of microwave enhancing peroxide bleached pulp was higher than that of the peroxide bleached pulp. However, the arithmetic average fiber length, the length weighted average fiber length and weight weighted average fiber length of the former was lower than that of the latter. Fourier transform infra-red spectroscopy (FTIR) and X-ray diffraction (XRD) spectra showed that CrI(%) crystallinity of microwave enhancing peroxide bleached pulp was similar as that of the peroxide bleached pulp but all higher than that of the Soda-AQ wheat-straw pulp. N·O′KI infra-red crystalline index of microwave enhancing peroxide bleached pulp were lower than that of the peroxide bleached pulp. The FTIR spectra of lignin showed that the microwave treatment had some influences on the methoxyl and phenolic group in lignin.

Hydrogen isotope exchange between D2 and H2O catalyzed by platinum plate

1989 ◽  
Vol 67 (5) ◽  
pp. 857-861 ◽  
Author(s):  
Shin-Ichi Miyamoto ◽  
Tetsuo Sakka ◽  
Matae Iwasaki
Keyword(s):  
Kinetic Model ◽  
Exchange Reaction ◽  
Hydrogen Isotope ◽  
Isotope Exchange ◽  
Reaction Rate ◽  
Hydrogen Adsorption ◽  
Platinum Catalyst ◽  
Isotope Exchange Reaction ◽  
Hydrogen Isotope Exchange ◽  
Supported Platinum

The reaction rate of hydrogen isotope exchange between D2 and H2O catalyzed by platinum plate is studied. The exchange reaction is described with the kinetic model which is the modification of that for the exchange reaction catalyzed by alumina-supported platinum catalyst. For the comparison of experimental results with this model relative amount of the number of sites for hydrogen adsorption was estimated from the initial rate of hydrogen isotope exchange between H2 and D2 on the same surface. The results show that the kinetic model is applicable for the plate catalyst if the number of the sites for hydrogen absorption, which is very sensitive to the surface state of the catalyst, was estimated not from the macroscopic surface area but from our scheme. Keywords: hydrogen isotope exchange reaction, platinum plate as catalyst.

Study on desorption of Mn, Fe, and Mg from TMP and evaluation of the complexing strength of different chelating agents using side reaction coefficients 10th EWLP, Stockholm, Sweden, August 25–28, 2008

Holzforschung ◽  
2009 ◽  
Vol 63 (6) ◽  
Author(s):  
Kim Granholm ◽  
Pingping Su ◽  
Leo Harju ◽  
Ari Ivaska
Keyword(s):  
Citric Acid ◽  
Metal Ions ◽  
Chelating Agents ◽  
Side Reaction ◽  
Sodium Dithionite ◽  
Thermomechanical Pulp ◽  
Peroxide Bleaching ◽  
Ph Values ◽  
Reducing Environment ◽  
Ph Range

Abstract Chelation of thermomechanical pulp (TMP) was studied in this work. The desorption of Mn, Fe, and Mg due to their impact on peroxide bleaching was investigated. The desorption experiments were performed with EDTA, citric acid, oxalic acid, and formic acid as chelating agents at different pH. Chelation experiments with EDTA were carried out at pH 3–11. Sodium dithionite was used as the reducing agent in studying chelation with EDTA in a reducing environment. Mn was very effectively desorbed with EDTA from TMP at pH <10 and the reducing environment further improved the removal of all the studied metal ions from TMP with EDTA. Citric acid also removed Mn effectively from TMP at pH 5. The thermodynamic stability constants of different metal chelates do not present the correct picture of how strongly the metal ions are bound by the chelating agents in different conditions. But by means of the side reaction coefficients (α M(L)-coefficients) it is also theoretically possible to evaluate and compare the real binding strengths between the metal ions and different chelating agents at varying pH values and other solution conditions. In this study, a theory is given for the calculation of side reaction coefficients. Values of the α M(L)-coefficients, for the pH range 0–14, are presented for EDTA, DTPA, and also for some other new potential environmentally friendly chelating agents.

scholarly journals PENGEMBANGAN BAHAN AJAR KIMIA RINTISAN SMA BERTARAF INTERNASIONAL KELAS XI MATERI LAJU REAKSI

2012 ◽  
Vol 13 (1) ◽  
pp. 1-12 ◽  
Author(s):  
Inova Putri Carera ◽  
I Wayan Dasna
Keyword(s):  
High School ◽  
High School Students ◽  
Reaction Mechanism ◽  
Reaction Rate ◽  
Reaction Order ◽  
Average Score ◽  
School Students ◽  
Factors Affecting ◽  
Rate Law

This study was aimed to develop teaching materials about chemical reaction rate which covered materials adapted to A-Level High School students of grade XI in Pioneer International Standard High School (RSMA-BI). The developmental research was adopting the instructional development model 4D which include four stages of development, namely define, design, develop, and disseminate. Instructional materials were written in English consist of seven topics titled: Reaction Rate Concept, The Exchange's Expressions, Rate Law and Reaction Order, Experimental Determination of a Rate Law, Reaction Mechanism, Theories of Reaction Rate, Factors Affecting Reaction Rate. Results of content validation from content experts obtained the average score of 3. 56 of 14 range of scores which means valid / good / decent. Test limited to high school students of RSBI obtained an average score of 3.35 (valid / good / decent). The results of the use of teaching materials obtained a score of 77.8 which is above the minimal passing grade (75). Therefore it can be concluded that the materials were feasible to be used in the classroom.Penelitian ini bertujuan untuk mengembangkan bahan ajar laju reaksi dengan cakupan materi yang disesuaikan dengan A-Level untuk siswa kelas XI Rintisan Sekolah Menengah Atas Bertaraf Internasional (RSMA-BI. Rancangan penelitian pengembangan mengadaptasi model pengembangan bahan ajar Model 4D yang meliputi empat tahap pengembangan, yaitu define, design, develop dan disseminate. Produk pengembangan adalah bahan ajar kimia RSMA-BI kelas XI materi laju reaksi yang ditulis dalam bahasa Inggris menggunakan pendekatan kontekstual. Bahan ajar terdiri atas empat bagian utama yaitu pendahuluan, materi, evaluasi dan penutup. Materi tersusun atas tujuh sub materi yaitu Reaction Rate Concept, The Rates Expressions, Rate Law and Reaction Order, Experimental Determination of a Rate Law, Reaction Mechanism, Theories of Reaction Rate, Factors Affecting Reaction Rate. Hasil validasi isi dari ahli materi diperoleh nilai rata-rata 3,56 dari rentang skor 1-4 dengan kriteria valid/baik/layak. Hasil uji terbatas pada siswa SMA RSBI diperoleh nilai rata-rata 3,35 dari rentang skor 1-4 dengan kriteria valid/baik/layak. Hasil uji penggunaan bahan ajar diperoleh skor sebesar 77,8. Skor ini diatas SKM (Skor Kelulusan Minimal) yaitu 75 sehingga dapat disimpulkan bahwa bahan ajar telah layak dan dapat digunakan dalam pembelajaran di kelas.

scholarly journals Further Understanding the Combined Bleaching Process of Peroxide and Optical Brightening Agent in a Spruce Thermomechanical Pulp

BioResources ◽  
2018 ◽  
Vol 13 (2) ◽  
Author(s):  
Hongjie Zhang ◽  
Ming Lei ◽  
Wenhui Zhang ◽  
Qun Li ◽  
Fengshan Zhang ◽  
...  
Keyword(s):  
Thermomechanical Pulp ◽  
Bleaching Process

scholarly journals Diagnosing surface versus bulk reactivity for molecular catalysis within metal–organic frameworks using a quantitative kinetic model

2020 ◽  
Vol 11 (28) ◽  
pp. 7468-7478
Author(s):  
Ben A. Johnson ◽  
Sascha Ott
Keyword(s):  
Kinetic Model ◽  
Charge Transport ◽  
Reaction Rate ◽  
Metal Organic Frameworks ◽  
Material Design ◽  
Surface Versus ◽  
Catalytic Material ◽  
Metal Organic ◽  
Intrinsic Reaction Rate ◽  
Molecular Catalysis

This report presents diagnostic criteria for determining the limiting processes of MOF-based catalysis: either mass/charge transport or the intrinsic reaction rate. This will facilitate future catalytic material design.

Sign in / Sign up

Export Citation Format

Share Document