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This paper evaluates the deinkability of thermochromic offset inks. For this purpose, three thermochromic inks were printed on white uncoated paper, in laboratory conditions. These prints were mixed in equal shares and recycled by means of chemical deinking flotation under defined conditions in the laboratory according to INGEDE method 11p. Deinkability is evaluated by calculating the flotation yield, pulp’s brightness and whiteness increase and the colour properties, determination of residual ink area, as well as ash content elimination. The obtained results indicate that thermochromic prints are poorly deinkable. The image analysis shows that flotation deinking managed to eliminate only 12.8% of the total dirt area of thermochromic ink. Only a small increase in deinked handsheets brightness and whiteness (approx. 5% and 2%) is noticed. The results of surface properties determination showed that the adhesion of inks on the paper is high. Thermochromic inks can affect wastewater too, by affecting its colouration due to their interactions with deinking solution and/or as a result of their mechanical damage during defibration.

This study was undertaken to investigate the suitability of applying the conventional method of chemical deinking flotation of digital offset prints and ecological implications of the disposal of digital offset prints, with special emphasis on the content of heavy metal cations. The EDXRF method was used to determine the concentrations of Pb, Zr, Sr, As, Co, Zn, Cu, Ni, Fe, Mn, Cr, V, Ti, Ca, and K cations in handsheet ashes after flotation as well as in ashes of foams separated from cellulose suspension in the flotation phase. The same method was applied to determine the concentrations of Pb, Cr, Mn, Fe, Ni, Cu, Zn, and Co in process water filtrates obtained from the cellulose suspension after flotation and in foam filtrates. Centrifuging and coagulation previously treated flotation process water, while foam filtrates were centrifuged. Concentrations of Pb, As, Sr, Zr, K, Ca, Ti, V, Cr, Mn, Fe, Cu, and Zn were determined in the sediments obtained by centrifuging process water. The trials were done with unprinted substrates without deinking chemicals, with unprinted substrates in the presence of deinking chemicals and with printed substrates in the presence of deinking chemicals. Cation analysis revealed that deinking chemicals facilitate release of cations from the substrate and their transition into process water. Concentrations of most cations in the flotation process water, in foam water as well as in the sediment of the process water of printed substrate flotation deinking were lower than those obtained by flotation of unprinted substrate suspension. Polymer particles of ElectroInk incompletely separated from cellulose fibers prevent release of cations from cellulose fibers into process water. Deinking chemicals do not affect release of cations from ElectroInk particles, so the substrate is the main source of increased concentration of cations in the water of digital offset print deinking. The major part of cations in process water is bound to the colloid particles of the filler (CaCO3) released by substrate disintegration and to particles of fine fibers.

Traditional chemical deinking process is widely used in paper recycling industry and it is considered to be effective for the removal of ink particles. Considering that the process uses large quantities of water and chemicals the effluents can contain inorganic and organic pollution. In this study effluent characteristics from laboratory deinking process of LEP technology prints were examined. The prints were obtained by varying the voltage of the developing drum in indirect electrophotography printing with liquid toner on two different paper substrates. The effluents obtained after all chemical flotation deinking processes were analysed in terms of pH, electrical conductivity, total organic compound and chemical oxygen demand.

International audience; To improve paper recycling, the potential of an innovative deinking process using a reactive ozone/oxygen gas mixture instead of air was studied on two recovered paper furnishes (offset print and newsprint/magazine mixture). Using suitable O3 concentrations, ink removal, following first-order kinetics, increased and losses dropped leading to better selectivity than using air alone. The ozone benefits in term of selectivity depended on temperature and paper furnishes and reached 100% for newsprint/magazine furnish at ambient temperature. Finally deinking effluent COD was significantly reduced and the ozone-based flotation allowed the reduction of the alkaline chemistry used before flotation.

La presente tesis tuvo como propósito observar el comportamiento de las tintas frente al destintado por flotación, en fuentes de papel periódico de México (Nacional), Estados Unidos (USA y NY T) y Alemania (Alemán) a diferentes dosificaciones con un tensoactivo ácido graso etoxilado. El destintado por flotación consiste en separar las partículas de tinta de la superficie de las fibras, es un proceso donde se combina la tinta, los agentes químicos y las burbujas de aire, este proceso es muy eficiente en la remoción de partículas de tintas mayores a 10 μm. Se utilizó el método para destintado por flotación en medio alcalino. Con respecto, a los resultados en la dosificación de 0,4% con el tensoactivo, ésta fue la que mostró la mejor eficiencia en Blancura ISO para todas las fuentes de papel periódico. Donde, el Nacional mostró un aumento en blancura del 32% comparado con la muestra testigo, el Alemán mostró un aumento del 17%, el USA del 23% y el NY T del 65%. En cuanto al, porcentaje de remoción de tintas y demás sustancias ajenas al papel, provenientes de la ceniza del rechazo del destintado, el Alemán resultó con un (49%), el NY T obtuvo (31%), el USA y Nacional (22 y 14) % respectivamente. Estos resultados muestran que en el destintado por flotación en medio alcalino, con un tensoactivo ácido graso etoxilado, el NY T resultó ser el mejor en cuanto a Blancura ISO y segundo en remoción de partículas de tinta. Por lo tanto, se concluye que fue un proceso eficiente para esta fuente de papel periódico (NY T), debido a que con una dosificación de 0,2% es suficiente para lograr una Blancura ISO cercana al 100%. This thesis was aimed to observe the behavior of inks versus flotation deinking in newsprint sources Mexico (National), U.S. (USA and NY T) and Germany (German) at different doses with a surfactant ethoxylated fatty acid. The inking by flotation is to separate ink particles from the surface of the fibers, a process which combines ink, chemicals and air bubbles, this process is very efficient in removing ink particles between 10 -100 μm. Method was used for inking by flotation in alkaline medium. With respect to results in the dosage of 0.4% surfactant, it was the one that showed the best efficiency in ISO Whiteness for all sources of newsprint. Where, the National showed an increase in whiteness of 32% compared with the control sample, the German showed an increase of 17%, the USA of 23% and 65% NY T. As to, percentage removal of inks and other foreign substances to the paper, from the ashes of the refusal of deinking, the German was a (49%), the NY T obtained (31%), the USA and National (22 and 14)% respectively. These results show that the deinking by flotation in an alkaline medium with a surfactant ethoxylated fatty acid, the NY T was the best in terms of ISO Whiteness and second in removal of ink particles. Therefore, it was concluded that an efficient process for this source of newsprint (NY T), because with a dosage of 0.2% is sufficient to achieve an ISO whiteness of nearly 100%. 112 semestral

Mineral oils present in recycled paper are complex mixture of mineral oil saturated hydrocarbons (MOSH) and mineral oil aromatic hydrocarbons (MOAH), some of which can have carcinogenic and mutagenic properties. Mineral oils can be brought into the paper recycling loop through the use of the old newspapers and advertising brochures which contain mineral oil based printing inks. The mineral oil mixtures have the ability to migrate via the vapour phase into food contained in recycled packaging. In this study, three groups of recovered papers, chosen with respect to paper type and printing technique, were treated in laboratory conditions by means of two different deinking methods. Recovered papers consisting of old newspapers (ONP) printed with coldset inks, supercalendered (SC) papers printed by means of rotogravure and lightweight coated (LWC) papers printed with heatset inks were subjected to separate flotation deinking and adsorption deinking treatments. After each conducted deinking treatment, filter pads were prepared from corresponding deinked pulps and subsequently analyzed on the content of saturated and aromatic mineral oil hydrocarbons (MOSH, MOAH) by GC/FID measurements. Adsorption deinking is a novel method of ink removal from recovered paper slurries, developed at the Professorship for Paper Technology at the Dresden University of Technology. The principle of adsorption deinking is based on the ability of certain polymers to extract ink and other hydrophobic components from the pulp. In this deinking method the polymeric beads serve as a “dirt catcher” instead of air bubbles used in the flotation deinking. The aim of the study was to compare the effectiveness of two different deinking methods (adsorption deinking and flotation deinking) in the reduction of mineral oil hydrocarbons from defined recovered paper grades. For most tested samples adsorption deinking was found to be more successful in the reduction of mineral oils than the conventional flotation deinking method. Over 60% up to 80% of mineral oils were removed from recovered papers by means of adsorption deinking. It was also established that adsorption deinking was quite effective in the reduction of amounts of mineral oils even in cases when it was not efficient enough in removing printing ink particles from a recovered paper pulp.

This paper describes the improved removal of impurities (coating, ink/toner) from offset prints produced by digital printing of two-side coated paper. The substrates were printed by conventional and digital offset processes. Based on image analysis results it was established that deinking flotation is an inefficient method for ink particle removal from digital offset printed paper, but it is efficient for ink removal from conventional offset printed paper. On the other hand, pre-treatment with hydrogen peroxide solution gives better results for ink particle removal from digital offset prints than from conventional offset prints. Optimal parameters for hydrogen peroxide pre-treatment for both offset prints were chosen based on unprinted substrate mass loss results in the preliminary investigation. These results showed that hydrogen peroxide pre-treatment is more successful at removal of impurities in comparison with flotation deinking without pre-treatment.

This paper presents the results of trials to evaluate the color-stripping behaviour of offset printing colors and the effect of coating on deinking performance. Oil-based four-color inks were separately printed as base printing on coated and uncoated white poster paper, and then extensive pulping and deinking processes were carried out. Standard offset printings were conducted on paper samples using cyan, magenta, yellow, and black colors (CMYK), and the effects of deinking efficiency on the removal of each color were analysed. The pulps were made at Micro-Maelstrom Laboratory Pulper at specified conditions with and without bleaching agents. Formamidin sulfinic acid and hydrogen peroxide formulation were used as reductive and oxidative bleaching agents, respectively. Flotation deinking and thickening of pulp were practiced using Degussa flotation and thickening cell. The changes in the optical properties, such as brightness, whiteness, and color value (CIE L, a b) of deinked pulp were determined. It was found that optical properties of color-stripped pulps from coated papers were better than that of uncoated office papers. However, yield was quite low in coated papers since fillers were lost during flotation process. Cyan color was found to be the most difficult one in four main color printing inks stripping out in the deinking process.

In this study, recovered paper samples consisting of three print and substrate combinations, were prepared and treated in laboratory conditions by means of two different deinking methods. Recovered papers consisting of old newspapers (ONP) printed with coldset inks, rotogravure printed supercalendered (SC) papers and light weight coated (LWC) papers printed with heatset inks were submitted to a separate flotation deinking and adsorption deinking treatments. After each conducted deinking treatment, the filter pads were prepared from corresponding deinked pulps and were subsequently analyzed on the content of saturated and aromatic mineral oil hydrocarbons (MOSH, MOAH) by GC/FID measurements. Aim of the investigation was to compare the effectiveness of two different deinking methods (adsorption deinking and flotation deinking) in reduction of mineral oil hydrocarbons from the defined recovered paper grades. For most of the tested samples adsorption deinking was found to be more successful in reduction of mineral oils than the conventional flotation deinking method. Through adsorption deinking over 60% up to 80% of mineral oils were removed from recovered papers. It was also found that adsorption deinking was quite effective in reduction of amounts of mineral oils even in cases when it was not efficient enough in removing printing ink particles from recovered paper pulp.

In this study, recovered paper samples consisting of three print and substrate combinations, were prepared and treated in laboratory conditions by means of two different deinking methods. Recovered papers consisting of old newspapers (ONP) printed with coldset inks, rotogravure printed supercalendered (SC) papers and light weight coated (LWC) papers printed with heatset inks were submitted to a separate flotation deinking and adsorption deinking treatments. After each conducted deinking treatment, the filter pads were prepared from corresponding deinked pulps and were subsequently analyzed on the content of saturated and aromatic mineral oil hydrocarbons (MOSH, MOAH) by GC/FID measurements. Aim of the investigation was to compare the effectiveness of two different deinking methods (adsorption deinking and flotation deinking) in reduction of mineral oil hydrocarbons from the defined recovered paper grades. For most of the tested samples adsorption deinking was found to be more successful in reduction of mineral oils than the conventional flotation deinking method. Through adsorption deinking over 60% up to 80% of mineral oils were removed from recovered papers. It was also found that adsorption deinking was quite effective in reduction of amounts of mineral oils even in cases when it was not efficient enough in removing printing ink particles from recovered paper pulp.

La tesi realitza un estudi detallat dels principals processos que tenen lloc durant l'eliminació de tinta tòner per flotació.L'estudi del procés d'adhesió de tinta a la superfície de bombolles d'aire s'ha realitzat mitjançant visió artificial. Els resultats obtinguts han mostrat que un excés de tensioactiu provoca una disminució de la quantitat de tinta unida a la bombolla d'aire i per tant una disminució de l'eficàcia del procés de flotació. La caracterització de les bombolles d'aire presents en una cel·la de flotació ha posat de manifest que tant el cabal d'aire com la velocitat de l'agitador configuren la distribució de diàmetres final. L'estudi del procés d'eliminació de tinta per flotació en absència de fibres cel·lulòsiques ha mostrat que les variables físico-químiques estudiades són les que tenen una major influència en el procés d'eliminació de tinta tòner per flotació.Finalment s'han addicionat fibres cel·lulòsiques a la suspensió. S'ha pogut comprovar que s'aconsegueix una bona eliminació de tinta sempre i quan les condicions hidrodinàmiques siguin les adequades., First of all the adhesion of ink particles to air bubbles surface was studied by means of artificial vision. Results obtained showed that an excess of surfactant decreases ink adsorption decreasing flotation efficiency. Air bubbles created in a lab-scale flotation cell were characterized by means of artificial vision. Results showed that air flow and agitation rate configure the final air bubble distribution.Ink removal from a flotation cell was studied without the presence of cellulose fibers. Results obtained showed that the physico-chemical variables studied had a major influence on ink removal than hydrodynamic variables studied.Finally, cellulose fibers were added to the suspension. Results obtained showed that it was possible to obtain good flotation results provided that the hydrodynamic conditions were carefully adjusted.

The recycling process of the paper waste consist of four main process: (1) preparation of the cellulose suspension of the waste paper in which the ink/toner particles and other impurities are dispersed, (2) deinking cellulose suspension by separating and removing the dispersed particles of ink/toner from the cellulose suspension, (3) bleaching the cellulose suspension after deinking and (4) treatment of the processed water with the aim to reuse it in the recycling process [1]. In the paper industry two basic deinking processes are used: (flotation deinking, selective process in which by the air blowing through the cellulose suspension in the flotation cell the particles of ink/toner collected in the form of froth, are removed and (2) wash deinking where the particles of toner are removed from the cellulose suspension by washing them in great quantities of water. The success of flotation deinking depends on the type and concentration of the chemical agents which influence the swelling of cellulose fibers, removal of ink/toner on the cellulose fibers, coagulation, sedimentation, flocculation etc. [2, 3, 4]. The efficiency of the chemical deinking flotation of Indigo prints is weak. The reason for that is firstly the way of sample production. By the activity of heat liquid toner warms up. Hot polymerized toner is transferred to the cold printing substrate. By print disintegration the polymer film becomes soft and it fragments into particles of the broad range of sizes and irregular shapes [5, 6, 7].

The aim of the study was to compare the efficiency of two deinking methods in the reduction of mineral oil hydrocarbons from recovered paper grades, which are going to be used in production of food packaging paper. Old newspapers (ONP) printed with coldset inks, supercalendered (SC) papers printed by rotogravure, and lightweight coated (LWC) papers printed with heatset inks were deinked by flotation and adsorption treatments. After each treatment, filter pads obtained from deinked pulps were analysed on the content of saturated and aromatic mineral oil hydrocarbons (MOSH, MOAH) by GC/FID measurements, as well as on the brightness and ash content. The results have shown that adsorption deinking is almost as efficient as flotation in ink removal in the case of ONP deinking, but less effective in the case of heatset and rotogravure inks (SC and LWC printed papers). However, for most tested samples adsorption deinking was found to be more successful in the reduction of mineral oils than the conventional flotation deinking method. Main conclusion was that over 60% up to 80% of mineral oils can be removed from recovered papers by means of adsorption deinking.