“ Laboratory study to evaluate methods for deinking water-based flexographic printed ONP ” Akpojotor Shemi Pulp and Paper Engineering
Furnish type Flexographic ink newsprint Oil based ink newsprint
Ink Properties Composition Flexographic ink Oil based ink Pigment Carbon black Carbon black Acrylic resins * Binders Hydrocarbon resins Solvent Water Oil Properties Surface Chemistry Hydrophilic Hydrophobic Size (diameter) 1 microns 50 microns *Acrylic resins
Conventional flotation assisted with electric field α ) is the float cell β ) channel for rejects η overflow φ - χ ) outlet for circulation of + pulp slurry γ δ ) pump φ ε ) air injector φ ) pipe in which electric field ε treatment takes place ι α γ ) air from air compressor β η ) power source supplies χ electrical voltage ι ) inlet for circulation of pulp δ slurry. The float cell is equipped with heat exchange for temperature control
Why flexographic inks are problematic � Poly acrylic acids as binders � Binds ink to the paper � Dispersant � Keeps the carbon black particles dispersed and stable � All carbon black have chemisorbed oxygen complexes (i.e., carboxylic, quinonic, lactonic, phenolic groups Ionization � Fully ionize at alkaline conditions. Negatively charge
Behavior of ink particle dispersion. The double layer model is used to visualize the ionic environment in the vicinity of a charged colloid and explains how electrical repulsive forces occur. Total potential energy as function of distance of separation between two particle To the right of the energy barrier, the suspension is stable To the left of the energy barrier, the suspension is unstable
Summary of deinking technology � Two pH stage treatment � Modified ink size � High cost of pH change � Organically modified clay � Adsorption unto clay � White water dead load � Electric field technology
Electric volts, bubble size Current (Ampere) volts No of bubbles Volume of bubbles Volume of bubbles (ml) % delta E (millions) (ml) dispersed air 25 μ m Electrolysis of water 0 0 - 67.5 267 1000 78 94 7079 68.0 400 1500 238 141 7079 70.8 506 1700 302 178 7079 68.3 •Deinking efficiency improves with increasing current and voltage. •The number of bubbles increases with increasing current and voltage.
Pulping time, Temperature and Electric field Electric field Temperature Pulping time % Change in ERIC Estimated effects x1 ( o C) (min) X2 x3 no e.f. 30 5 41.0 41.4 e.f. 30 5 42.3 2.2 X1 no e.f. 43 5 44.5 3.1 X2 e.f. 43 5 45.7 -0.5 X1x2 no e.f. 30 20 35.4 -4.7 X3 e.f. 30 20 39.7 1.0 X1x3 no e.f. 43 20 39.3 -0.3 X2x3 e.f. 43 20 41.4 -0.5 X1x2x3 •Both Electric field and Temperature improves deinking efficiency. •But pulping time has an negative effect on deinking
Z-weighted factor. T e mpe ra ture E le c tric fie ld Surfa c ta nt E RIC E RIC Solid Z- we ig hte d ( o C) (Kvolts) (mic r o-lite rs) (fe e d) (Ac c e pt) loss fa c tor E KA RF 4031 25 0 0 3964 2797 5.7 5.9 25 1.25 0 3911 2282 8.6 7.9 48 0 10 3767 1712 12.5 7.8 48 1.25 10 3770 1621 11.8 10.3 25 0 30 3663 2347 12.9 3.6 25 1.25 30 3830 2284 15.6 4.0 • Typically in deinking operation there is a direct correlation between ERIC reduction and yield loss
Electric field, pH, consistency, surfactant & soap dosage Electric field NaOH Consistency Surfactant Soap Experiment no. (volts) x1 (ml) (%) (µL) (µL) x2 x3 x4 0 0 0.5 0 0 1 1000 0 0.5 0 0 2 0 5 0.5 0 0 3 1000 5 0.5 0 0 4 0 0 1 0 0 5 1000 0 1 0 0 6 0 5 1 0 0 7 1000 5 1 0 0 8 0 0 0.5 10 30 9 1000 0 0.5 10 30 10 0 5 0.5 10 30 11 1000 5 0.5 10 30 12 0 0 1 10 30 13 1000 0 1 10 30 14 0 5 1 10 30 15 1000 5 1 10 30 16
Electric field, pH, consistency, surfactant & soap dosage 400 400 300 300 200 200 100 100 0 0 x4 x1x4 x1x2x4 x2x4 x3x4 x1x3x4 x2x3x4 x1x2x3x4 GRAND x1 x2 x1x2 x3 x1x3 x2x3 x1x2x3 -100 -100 -200 -200 X1, X2, X3, X4 all had positive effect on deinking efficiency X2 has the most positive effect on deinking efficiency
Electric field, pH, consistency, surfactant & soap dosage 3000 2500 2000 ERIC Feed 1500 Accept Feed-Accept 1000 500 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
Electric field, organoclay, alkaline charge Electric NaOH / alkaline Organoclay 0.5% delta ERIC estimated field (pH)(mL) (250ulCT/0.5%(0.25)clay effect 4ml sodium silicate, 4ml sodium hydroxide X1 X2 x3 0 - - 931.2 1197.55 1.36 X1 1250 - - 807.5 516.83 X2 0 + - 1366.6 1250 + - 1491.6 61.58 X1x2 0 - + 721.55 -189.08 X3 1250 - + 724.8 0.71 X1x3 0 + + 1196.7 -42.91 X2x3 1250 + + 1197.6 -62.76 X1x2x3
Surfactant FEED and ACCEPT ERIC and percent reduction in ERIC 2000 50 1. Cetyltrimethyl % reduction in ERIC ammonium bromide 45 1500 (CTAB) Feed 40 2. Quaternary ERIC 1000 accept ammonium 35 compounds, dicoco % ERIC reduction alkyldimethyl, 500 30 chlorides 3. Alkyldiphenyloxide 0 25 Disulfonate Nonionic anionic cationic,quat, Amphoteric Ctab 4. Amphoteric • Cationic surfactant has better yield 5. Non ionic Surfactant • Amphoteric surfactant was not effective • Nonionic and anionic reduce ERIC with lower yield
Organoclay and electric field Experiment No Electric field volts Organoclay 1%(500ul arquad C-75) 0.5%(0.25)clay 1 0 - 2 1000 - 3 0 + 4 1000 + 2500 •Yield was 86% 2000 •BRIJ 700 Nonionic surfactant was ERIC used in all experiments 1500 Feed Accept Feed-Accept 1000 500 0 1 2 3 4
What contributes to deinking and ERIC reduction with electric field? Fine bubbles � Hydrogen peroxide generation � Electric field detachment of ink particle that are easily attached to � bubbles Generation of metal ions � Possible agglomeration of ink particles � Poly acrylic acid �
Summary � Factorial design of experiment was used to evaluating deinking variables � Deinking efficiency is improved with the introduction of electric field � Z factor shows that deinking efficiency is improved with justifiable yield
Thank you � Dr. Hsieh � International Paper � Danny Haynes
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