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Chemistry of Chlorine Dioxide Pulp Bleaching

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Chemistry of Chlorine Dioxide Pulp Bleaching [email protected] Bleaching History • Bleach - blecan (Anglo Saxon) – to fade • First dates back to ancient Gauls: sunlight on vegetable fibers moistened with alkaline solution from wood or vegetable ash • Process: alkali treatment, exposure on grassy meadows to sun, washing, repeat, final treatment with lactic acid from sour milk – Became known as “grass bleaching” – Perfected around Haarlem, Holland – Material generally of linen fibers [email protected] Bleaching History • 1756 – Francis Home (Scotland) – Discovered that by substituting dilute sulfuric acid for lactic acid in last step, operating time is reduced. – Still is a grass bleaching operation and not used yet for paper – “White” paper made from sorted white rags • 1774 – Karl Wilhelm Scheele (Swedish Chemist) – discovered chlorine and pioneered use as a bleaching chemical on vegetable fibers • Berthollet – French chemist – discovered chlorine could be absorbed in solution of caustic potash and resulting solution had efficient bleaching action with less degrading effect on the finished goods (product) [email protected] Bleaching History • Thomas Henry – English – extended use of bleaching solution to paper (rag) • 1798 – Charles Tennant – Scotland – formulated calcium hypochlorite by reaction of chlorine gas with milk of lime • 1799 – Charles Tennant – patent on production of bleaching powder by action of chlorine on slaked lime – became world’s most dominant bleaching agent [email protected] Bleaching History • 1920’s: Continuous operating bleaching introduced by Thorne in multi-stage bleaching – for purification of pulp from demand for large tonnages of nitrocellulose during WWI – 2 stage hypochlorite then added alkaline extraction in between hypochlorite stages • Use of Chlorine dioxide investigated from 1920 – 1940, put into production 1940’s [email protected] Chlorine Dioxide History • 1946 – 1980’s used as a later bleaching stage, not for delignification – CEHDED, CEDED • Late 1980’s realized that ClO2 and Cl2 used together had a higher delignification efficiency than Cl2 alone • Environmental regulations dictated the switch from elemental chlorine (Cl2 & HOCl) to ClO2 and other TCF methods [email protected] Chlorine Dioxide • Molecular Weight: 67.45 • Boiling Point: 11°C • Yellow green to orange gas, with a sharp pungent odor • Water soluble, 10 g/L • Oxidant • Density: 2.4 x’s water • Decomposes to Cl2 and O2 with noise, heat, flame, and minor pressure wave [email protected] Formation of Chlorine Dioxide • Reduction of chlorate in acidic medium: - + - –ClO3 + 2 H + e Æ ClO2 + H2O • Oxidation of chlorite ion: - - –ClO2 Æ ClO2 + e [email protected] Reductive Chemistry • Reducing agents are used to make the e- 2- + - –SO2 + 2 H2O Æ SO4 + 4 H + 2 e + - –CH3OH + H2O Æ HCOOH + 4 H + 4 e - - –Cl Æ ½Cl2 + e + - –H2O2 Æ O2 + 2 H + 2 e [email protected] Making Chlorine Dioxide - 2- •2 ClO3 + SO2 Æ 2 ClO2 + SO4 - + •4 ClO3 + CH3OH + 4 H Æ 4 ClO2 + HCOOH + 3 H2O - - + •ClO3 + Cl + 2 H Æ ClO2 + Cl2 + H2O - + •2 ClO3 + H2O2 + 2 H Æ 2 ClO2 + O2 + 2 H2O - + - - •ClO3 + 6 H + 6e Æ Cl + 3 H2O [email protected] Chlorine Dioxide Chemical properties: One of several known oxides of chlorine. Chlorine dioxide is a powerful oxidizing agent - an electron receiver. This means that the chlorine dioxide molecule is in constant search for an additional electron. → Disinfection The destruction of pathogenic and other kinds of microorganisms by physical or chemical means When a bacterial cell comes into contact with chlorine dioxide it donates an electron from its cell wall, thereby creating a breach in the cell wall through which cell contents pass in an attempt to bring the concentrations on either side of the cell membrane to equilibrium. The cell dies through lysis. [email protected] Chlorine Dioxide How long has chlorine dioxide been used? Chlorine dioxide has found widespread use since the early 1950s in the treatment of drinking water and swimming pools. Today, chlorine dioxide is used by many large cities in Europe, such as (1956) Brussels, Zurich, Düsseldorf, Toulouse and Vienna, to sanitize the drinking water supply. [email protected] Chlorine Dioxide Chlorine dioxide has many applications: • Food industry Fruit and vegetable washing Meat and poultry disinfection Sanitizing food process equipment • Medical “Tristel” sterilizing solutions for medical instruments Air disinfection and building decontamination. (2001 anthrax attacks, US) • Personal hygiene Mouthwashes (~0.003%) Toothpastes Contact lens cleaners • Other industry Cooling systems and towers in the control of Legionella.(Gram negative bacterium) [email protected] Bleaching Pulp with Chlorine Dioxide Advantages ¾High brightness and brightness stability ¾Excellent for shive and dirt removal - the best ¾Highly selective - little degradation of pulp - ¾Less organic chlorine than Cl2 and ClO ¾Radical scavenger [email protected] Bleaching Pulp with Chlorine Dioxide Disadvantages ¾ Highly explosive – hence generate on-site ¾ Highly corrosive - need titanium equipment - high capital cost ¾ Expensive ¾ Toxic - handle with care ¾ AOX ¾ Chlorate formation ¾ 26-40% loss in oxidation power [email protected] ClO2 Delignification Process Conditions • Total Chemical Charge: 0.15 – 0.25 kappa factor • Chlorine dioxide charge: 25 – 100% of the total • Temperature: 30 -60° C • Total Time: 20 – 60 minutes • End pH: 1.5 – 3 • Consistency: 3 – 4% [email protected] Chlorine Dioxide Puffs • Puff – deompostion of chlorine dioxide –2 ClO2 Æ Cl2 + 2 O2 + heat – Low speed wave of reaction (< 1m/s) • Explosion: > 300 m/s – Generators designed for up to 200 mm Hg [email protected] AOX vs. ClO2 Substitution 8 7 Kappa 6 5 Unbl 30 EO 23.5 4 EOP 20.5 3 O 16.6 2 AOX, kg/admt AOX, 1 0 0 20406080100 ClO2 Substitution, % [email protected] Liebergott Substitution of Chlorine Dioxide • AOX Generation – AOX (kg/t) = 0.1 (Cl2, kg/t active chemical) – AOX (kg/t) = 0.1(1/2.63)(.526)(ClO2, kg/t active chemical) 0.02(ClO2, kg/t act chemical) • On an equal weight basis ClO2 is 2.63 times as as reactive as Cl2 - - Cl2 + 2e = 2Cl ⇒ 71/2 = 35.5 - - ClO2 + 5e = Cl ⇒ 67.5/5 = 13.5 35.5 / 13.5 = 2.63 [email protected] Chloroform – CHCl3 0.35 % ClO2 sub 0.3 100% 0.25 71% 0.2 46% 0.15 28% 0.1 0% 0.05 Chloroform, kg/odmt 0 0 0.1 0.2 0.3 0.4 Chlorine Factor [email protected] Effect of Chlorine Multiple on Dioxin Formation [email protected] Substitution of Chlorine Dioxide for Chlorine Old Bleaching Sequences: (CD)E1D1E2D2 O (CD)E1D1E2D2 ECF Sequences: D0E1D1E2D2 O D0E1D1E2D2 ECF = Elemental Chlorine-Free [email protected] Chlorine Dioxide O Cl O O Cl O O Cl O [email protected] Chlorine Dioxide • Chemistry - - ClO2 + e ⇒ ClO2 - + - ClO2 + 3H + 2e ⇒ HClO + H2O + - - HClO + H + 2e ⇒ Cl + H2O + - - ClO2 + 4H + 5e ⇒ Cl + 2H2O Equivalent Weight: ClO2 = 67.5/5 = 13.5 Cl2 = 71/2 = 35.5 [email protected] Basic Cation Radical Mechanism of Chlorine Dioxide R OCH3 O R1 ClO2 R = Alkyl or R2 R R1 = H, Alkyl or Aryl ClO 2 CT - Complex OCH3 π-Complex O R1 + H+ - HClO2 R R1 = Alkyl R R R R = H R 1 or aryl OCH3 OCH3 OCH3 OCH3 OCH3 + O + OH O O+ O R1 R1 R1 Phenolic structures Non-phenolic structures Brage, Ericksson and Gierer, Holzforschung, 45(1):23 (1991) [email protected] Basic Phenolic Compound Reactions CH3 OCH3 O CH3 CH3 - CH3 OClO CH3 ClO2 ClO2 H OCH OCH OCH -OClO OCH3 3 3 3 O O O O + H2O - HClO2 - HOCl - HOCl CH3 CH3 H3C COOCH3 CH2 O CH3 Bicreosol OCH3 CH3O CH O 3 O OH O OCH3 O OCH3 O OCH3 ClO2 + HClO2 O + H2O OH - CH3 H2C OClO CH2OH CH3 - HClO 2 OClO- + H2O OCH OCH3 O OCH3 3 - CH3OH O OH O OH Dimers + H2O - HOCl and polymers - HOCl H3C CH3 COOCH3 CHO O CO2CH3 O CO2H OCH3 OH Brage, Ericksson and Gierer, Holzforschung, 45(1):23 (1991) [email protected] Basic Non-Phenolic Compound Reactions CH3 CH3 ClO2 ClO2 CH3 + ClO2 ClO2 + OCH3 + OCH3 OCH3 OCH3 + OCH3 OCH3 CH3 CH CH CH3 H 3 3 H + + OCH3 OCH 3 OCH3 OCH3 + OCH3 CH3O + OCH3 OCH3 ClO2 ClO2 ClO2 ClO2 CH - 3 OClO CH3 CH CH3 H 3 - H OClO + - OCH OCH3 + OClO 3 OCH OCH3 OCH 3 CH3O - + OCH3 + 3 OClO OCH3 + H O 2 + H2O + H2O + H2O - HOCl - HClO2 - CH3OH - CH3OH + - CH3OH - H - HOCl - HOCl + - H - H+ CH3 O CH 3 CH 3 CH3 O O HO H CO CH OCH3 2 3 CO2CH3 OCH3 O CO CH OCH3 2 3 [email protected] Brage, Ericksson and Gierer, Holzforschung, 45(1):23 (1991) ClO2 Oxidation of Methylveratrylalcohol Effect of pH on Rate of Reaction 100 80 pH 2 60 pH 4 pH6 40 pH 8 20 Percent Compound I 0 050100150 Reaction Time (min.) [email protected] Effect of pH on the Reaction of ClO2 with Methylveratrylalcohol (MVA) HO CH3 MVA OCH3 OCH3 O H3C O O OCH3 H3C OCH3 OCH3 O O OCH 3 O 3 5 6 HO CH3 HO CH3 CH CH Cl Cl Cl OCH3 OCH3 OCH3 Gunnarsson and Ljunggren, Acta Chem. Scand., 50: 442 (1996) OCH3 OCH3 OCH3 8 9 10 [email protected] Effect of End pH in a D1 Stage on Brightness and Chlorite and Chlorate Formation Rapson, H., and C.B Anderson, Tappi, 61 (10):97 (1978) ClO2- 86 ClO3- 1.8 84 ClO3- + ClO2- 1.6 82 Brightness 80 1.4 78 1.2 76 1.0 Chlorate and/or chlorite, % of 74 0.8 available chlorine Brightness, % Brightness, 0.6 72 on pulp 70 0.4 0.2 68 66 2357810 End pH in the D1 stage [email protected] - - Effect of pH on ClO3 and ClO2 formation in ClO2 prebleaching of oxygen delignified kraft pulp 5.0 4.0 3.0 Chlorite Chlorate 2.0 1.0 Concentration (mM) 0.0 0 2 4 6 8 10 12 End pH Kappa no.
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  • Durian Rind Soda-Anthraquinone Pulp and Paper: Effects of Elemental Chlorine-Free Bleaching and Beating

    Durian Rind Soda-Anthraquinone Pulp and Paper: Effects of Elemental Chlorine-Free Bleaching and Beating

    Journal of Tropical Forest Science 30(1): 106–116 (2018) Masrol SR et al. https://doi.org/10.26525/jtfs2018.30.1.106116 DURIAN RIND SODA-ANTHRAQUINONE PULP AND PAPER: EFFECTS OF ELEMENTAL CHLORINE-FREE BLEACHING AND BEATING Masrol SR1, 2, 3, *, Ibrahim MHI3, 4, Adnan S5, Abdul Raub R4, Sa’adon AM4, Sukarno KI4 & Yusoff MFH 4 1Faculty of Engineering Technology, Universiti Tun Hussein Onn Malaysia, Pagoh Education Hub, 84600 Pagoh, Muar, Johor, Malaysia 2Innovative Manufacturing Technology Research Group, Advanced Technology Centre, Pagoh Education Hub, 84600 Pagoh, Muar, Johor, Malaysia 3Advanced Manufacturing and Materials Center, Universiti Tun Hussein Onn Malaysia, 86400 Parit Raja, Batu Pahat, Johor, Malaysia 4Faculty of Mechanical and Manufacturing Universiti Tun Hussein Onn Malaysia, 86400 Parit Raja, Batu Pahat, Johor, Malaysia 5Forest Research Institute Malaysia, 52109, Kepong, Selangor, Malaysia *[email protected] Submitted April 2017; accepted August 2017 A study was conducted to investigate the preliminary characteristics of soda-anthraquinone (soda-AQ) durian rind waste pulp and paper with the effects of elemental chlorine-free (ECF) bleaching and beating revolutions. Pulping was carried out using rotary digester with 0.1% antraquinone, 20% active alkali (NaOH), cooking time of 120 min and temperature of 170 °C. ECF bleaching with chlorine dioxide – alkali extraction – chlorine dioxide – alkali extraction – peroxide sequence and beating in the range of 0 to 1000 revolutions were applied to the unbeaten and unbleached pulp. ECF bleached pulp produced soda-AQ durian rind paper with greater tensile index, burst index, tear index, number of folds, brightness and scattering coefficients, but with slightly lower opacity compared with paper made from unbleached pulp.