Ink Removal Efficiency Research Articles

Development and Optimization of Chemical Deinking of Laser-Printed Paper

For the recycling paper process, the main problem is a high residual ink left on the paper, affecting the recycled paper's quality. Especially for laser-printed paper, ink strongly interacts with the paper fiber. A conventional chemical deinking has been used to remove laser ink with a high deinking efficiency but a low yield of recycled paper pulp. Recently, enzymatic deinking has gained attention due to its friendly environment. However, a complex procedure is required, and ink removal efficiency is lower than the conventional method. This research aims to simplify a chemical deinking process by decreasing reaction time, optimizing chemical components, and reducing experimental steps. Without pulping step, the laser-printed paper sheet was immersed in the chemical solution for a specific time, and the ink was removed by water spray. Results revealed that the chemical solution containing 1.5% sodium hydroxide, 2% sodium silicate, 1% hydrogen peroxide, and 0.3% tween-80 with a reaction time of 5 min at 60°C gave the highest paper yield of 97.3% and the lowest dirt count of 89.0 mm2/m2. The final product was still in the form of a paper sheet.

Investigation of deinking efficiencies of trigromi laserjet printed papers depending on the number of recycling

PurposeThis study aims to determine the ink removal efficiency of papers with different recycling numbers and to examine some electrophotographic printing properties.Design/methodology/approachThe base papers prepared according to the INGEDE 11p standard are subjected to six recycling stages (RS) under equal conditions. The physical-optical properties of the papers obtained at the end of each RS are measured and CMYK (cyan, magenta, yellow, key) color measurement scales are printed on each paper with electrophotographic printing. Color measurements of the printed papers are measured using the X-Rite eXact spectrophotometer, adhering to the ISO 13655:2017 standard. According to the measurement results of the optical properties, the ink removal efficiency of each recycling step is determined as a percentage (%) using some formulas.FindingsAs general, according to DEMLab and IERIC data, it is determined that the ink removal efficiency increased as the recycling repetition increased. In DEMf factor values, the highest deinking efficiency is obtained after the fourth RS. There is no significant difference between the printing properties of the samples.Originality/valueIt has been a matter of curiosity that papers lose their properties after how many RS. Many studies have been carried out on this subject and it has been presented by experimental methods that the printability properties of papers increase or decrease after which RS. This study can be a pioneer for future studies.

Deinking of Black Toner Ink from Laser Printed Paper by Using Anionic Surfactant

The objective of this research was to synthesize natural anionic surfactant from renewable material and use of this surfactant for ink removal from printed paper via flotation deinking in paper recycling process. The work included the preparation of the castor seed raw material, extraction of castor oil, preparation of anionic surfactant and deinking flotation of waste printed paper. Foamability and foam stability, critical micelle concentration and hydrophilic lipophilic balance of the surfactant was characterized and used to evaluate its fundamental deinking ability properties for the purpose of deinking flotation. The hydrophilic-lipophilic balance (HLB) of the fatty acid soap of 19.48, average Foamability height of 49cm and critical micelle concentration (CMC) of 0.0065M was obtained. Lab scale flotation deinking process was done and the basic flotation parameters like flotation time, fatty acid soap dosage and pH were optimized for evaluating deinking efficiency. The flotation deinking efficiency was probed by measuring the residual ink concentration of the hand sheet via Perkin Elmer spectroscopy before and after deinking flotation. The individual and interaction effects between the basic parameters were studied by using design Expert Software 6.0.8. For the deinking flotation, the maximum ink removal efficiency was determined to be 78.02% at the flotation time of 90min, fatty acid soap dosage of 1.5% and pH of 9. Increasing flotation time from 30min up to 90 min and decreasing fatty acid dosage from 3% to 1.5% and increasing of pH from 3 up to 9 were found to have increased the ink removal efficiency.

Engineering a Chimeric Lipase-cutinase (Lip-Cut) for Efficient Enzymatic Deinking of Waste Paper

Lipase and cutinase belong to the esterase family and have biological applications in many fields. To develop more efficient biocatalysts that can be used for waste paper deinking, a chimeric lipase-cutinase (Lip-Cut) was constructed and successfully overexpressed in Pichia pastoris. The chimeric Lip-Cut exhibited lipase and cutinase activities that were 127% and 210% higher than their parent enzymes, respectively. Cut was superior to Lip in ink removal and improvement of paper brightness than Lip. The Lip-Cut displayed a better ink removal efficiency and paper brightness than that of the Lip, Cut, and Lip/Cut mixture. When the chimeric Lip-Cut was used, the ink removal efficiencies were 25.8% and 16.2% higher than that of the control-treated laser-printed paper and newspaper, which had sheet brightness values of 88% ISO and 59% ISO, respectively. The results demonstrated that the proper construction of bi-functional Lip-Cut could enhance the catalytic properties through the synergistic action of the two moieties because of the complementary advantages in the substrate specificities and catalysis patterns of both enzymes. This may provide an effective way to engineer more efficient bi-functional lipases and cutinases for deinking waste paper.

Characterization of a cutinase from Myceliophthora thermophila and its application in polyester hydrolysis and deinking process

Abstract A gene encoding cutinase (MtCUT) from Myceliophthora thermophila was expressed in Pichia pastoris. The optimal temperature and pH for MtCUT were 30 °C and 8.5, respectively. MtCUT showed high activities toward a broad range of p-nitrophenyl esters, and the highest specific activity was recorded for p-nitrophenyl butyrate. MtCUT hydrolyzed and broke down apple cutin into C16 and C18 family fatty acids. MtCUT could efficiently degrade polycaprolactone (PCL), the weight loss of which was 78.5% in 36 h. In addition, MtCUT could degrade PVAc, a kind of adhesive that is frequently used in papermaking and in synthetic toner or ink. Its performance in the deinking of waste papers was investigated and compared with that of commercial lipase in this study. The results showed that an ink removal efficiency of 78.4% on laser-printed paper and 81.3% on newspaper was obtained using MtCUT at 30 °C, which was better than that of lipase from Candida rugosa (CrLIP) (77.0% and 76.0%, respectively). The properties of the MtCUT-treated samples were similar to that of the control samples. This revealed that the cutinase MtCUT from M. thermophila has a great potential in PCL hydrolysis and the deinking process.

Comparison of Froth-flotation Efficiency between Fatty Acid and Non-ionic Surfactant Added to Recovered Paper with Increased Mixing Ratio of OMG

The main sources of recovered paper for newsprint are old newsprint (ONP) and old magazine (OMG). Recently, a lot of advertisement flyers are flowing into bales of ONP and portion of OMG is increasing in recovered paper because the consumption level of coated paper increases. In this study, nonionic surfactant and fatty acid were used as the de-inking agent for froth-flotation process of mixed recovered paper to investigate the effect of increased mixing ratio of OMG. De-inking efficiency of nonionic surfactant decreased as the mixing ratio of OMG increased; ink removal efficiency of froth-flotation is poor, however, the reject ratio increases due to ash from OMG. In comparison with nonionic surfactant, the ash from OMG had a little effect on reject ratio and optical properties of fatty acid applied flotation accept. If nonionic surfactant and fatty acid are added to pulper and flotation cell sequentially, excessive ash from OMG may not give an adverse effect on de-inking efficiency of mixed recovered paper.

Added soap contact time with recycled pulp improves flotation deinking efficiency and reduces cost

Optimization of the fatty acid soap addition points increased soap contact time with recycled pulp before flotation. This, in turn, resulted in improved ink removal efficiencies for three of four types of commercial flotation cells. Mill A saved 25% in fatty acid flotation collector dosage while maintaining the same brightness gain and ink removal efficiency. In mill B, increasing the soap contact time improved the aeration of one line of flotation cells, which in turn led to a 1-point brightness improvement of deinked pulp and savings in bleaching chemicals. Both mills showed 30%–54% lower carryover of saturated fatty acids from the flotation collector to newsprint made from deinked pulp and thermomechanical pulp. Flotation cells with longer residence times and aeration injectors in good order did not show any improvement in aeration or flotation efficiency. Soap contact times with pulp, whether before or during flotation, should be on the order of 9–20 min to assure maximal flotation efficiency. Increasing soap contact time before flotation to 45-60 min did not further improve flotation efficiency.

The Effects of Sodium Percarbonate and Perborate Usage on Pulping and Flotation Deinking Instead of Hydrogen Peroxide

The main objective of this study was to evaluate the potential of sodium percarbonate and sodium perborate utilization during repulping of old news and magazine paper mixture. A series of experiments were performed to determine the effects of bleaching agents on ISO brightness and ink removal efficiency of pulp after flotation deinking. Conventionally, with other parameters are constant, the ISO brightness of pulp was increased from 45.24% to 54.10% and ink elimination ratio at 950 nm of pulp was increased to 69.12% with 1% sodium hydroxide and 1% (as active oxygen content) hydrogen peroxide usage. However, when sodium percarbonate was utilized instead of hydrogen peroxide (as 1% active oxygen content) without alkaline addition, the ISO brightness of the pulp was increased to 55.00%. Also, unlike the other bleaching agents, a favorable effect of sodium percarbonate on ink detachment was observed. The ink elimination ratio of floated pulp was increased to 74.31% with 1% (active oxygen) sodium percarbonate addition without alkaline usage. There were no additive effects of sodium perborate usage on brightness, and ERIC value of pulp could be determined. In this respect, sodium percarbonate utilization without sodium hydroxide addition was proposed for effective repulping, deinking, and prebleaching of waste papers, in a similar manner to the use of hydrogen peroxide.

OMG Neutral Deinking Technical Conditions and Mechanism

Single factor experiment was used to investigate neutral deinking technology of old magazine paper (OMG) by self-compounded NTM-2 deinking agent. Olympus inverted biological microscope were used to research distribution state of ink particles in the secondary pulp before and after deinking treatment. Scanning electron microscopy (SEM) was used to analyze fiber surface changing during neutral deinking and ink particles dispersing behaviors in the paper. The results showed that NTM-2 deinking agent had a good deinking effect to OMG, optimum operation conditions of neutral deinking was NTM-2 0.5%, deinking temperature 50°C, deinking time 40min, repulper time 25s, pulp consistence 1.0%, and floatation time 6 min. Under these conditions, brightness of the deinked pulp increased 8.4%SBD, and the ink removal efficiency reached by 90%. Olympus inverted biological microscope images showed that there were a large number of ink particles in the un-treated pulp, and these ink particles integrated with fibers tightly. After treated by neutral deinking, most of ink particles were separated from the fiber, dispersed and suspended in the pulp evenly. SEM images indicated that there were little ink particles in the secondary paper, the fiber surface turned more smoother, and the clean degree would nearly corresponding to the effect of alkaline deinking.

Study on the Colloid Chemistry Behavior in Domestic Old Book Paper (DOBP) Deinking System

In this paper, the domestic old book paper(DOBP) was subjected to deinking process. Surface and colloid characterisitics of DOBP deinking pulp(DIP) system was investigated. The relation between surface and colloid characterisitic changes and efficiency of deinking (brightness and residual ink particles content) was studied. Technical conditions that affect the deinking pulp’s colloid chemical behavior were also analyzed here.The results showed that colloid-chemical behavior of DOBP deinking system could be changed during the deinking process. The colloid-chemical behavior, such as Zeta potential and surface tention, had a certain corresponding relation with deinking efficiency of DOBP deinking system. When Zeta potential of the deinking system was more great, and surface tension was more low in a certain range(Zeta potential was -17.0~ -16.0mV and surface tension was 59.0~61.0mN/m), brightness and ink removal efficiency of DOBP will be improved.

Optimization of chemical and enzymatic deinking of photocopier waste paper

The utilization of post-consumer papers in the production of new paper products is increasing all over the world in recent years. Recycling of photocopier paper is a major problem due to difficulty in removal of non-impact ink. Enzymes offer potential advantages in ecofriendly deinking of recovered paper. In this study the deinking of photocopier paper was examined using chemicals and a commercial cellulase enzyme. Parameters of deinking experiments were optimized for hydrapulping. The ink was removed by flotation and washing processes. Then these parameters were compared in terms of ink removal ability of the process, as well as optical and strength properties of the deinked paper. The application of enzymatic deinking improved ink removal efficiency by 24.6% and freeness by 21.6% with a reduction in drainage time of 11.5% in comparison to those obtained with chemical deinking. The physical properties, namely burst index and tensile index, were observed to improve by 15.3% and 2.7%, respectively and brightness and tear index decreased by 2.1% and 21.9%, respectively. Results of deinking efficiency of photocopier paper showed that the enzyme used in the present work performed better than the conventional chemicals used for deinking.

Understanding the Role of Surface Active Substances in Flotation Deinking Mills by Coupling Surfactant and Ink Balance With Process Simulation

Surfactants are largely present in papermaking/recycling processes. They are added intentionally or come with raw materials or process/functional additives. Once they have reached the process, they build-up in the circuits and, depending on their surface activity and concentration, they can have adverse effects on deinking and on the whole papermaking process, such as excessive frothing, depression of ink floatability, and paper sizing/retention difficulties. In this paper, the removal of apparent surface active chemicals (ASAASAASAC) is first evaluated in different flotation deinking mills through mass balances using surface tension measurements and a specific methodology. Mill data show that, in two-stage deinking lines, ASAASAASAC are slightly concentrated in the second stage, contributing to an increase in pulp frothing behavior, in flotation loss, and in some cases to a low ink removal efficiency. Trends observed in deinking mills are then interpreted using experimental data obtained at the laboratory scale in the presence of a model surfactant, and by process simulation. The effect of ASAASAASAC concentration on the efficiency of the flotation deinking process is explained in terms of their effect on particle and water transport sub processes, namely, flotation, entrainment, frothing, and drainage.

Optimization and Management of Flotation Deinking Banks by Process Simulation

In this work, the contribution of flotation deinking banks design on ink removal efficiency, selectivity, and specific energy consumption was simulated using a semiempirical approach. Single-stage with mixed tank/ column cells, two-stage, and three-stage configurations were evaluated, and the total number of flotation units in each stage and their interconnection were used as main variables. Explicit correlations between ink removal efficiency, selectivity, energy consumption, and line design were developed for each configuration. When considering a conventional two-stage configuration as reference, a decrease in the specific energy consumption for constant ink removal efficiency and selectivity was obtained with the single-stage bank with a stack of flotation columns at the front of the line, whereas an increase in ink removal selectivity for constant ink removal efficiency and specific energy consumption was obtained with the three-stage bank. The present results show that the performance of conventional flotation deinking banks can be improved by optimizing process design and implementing mixed tank/column technologies in the same deinking line.

Modelling transport phenomena in a flotation de-inking column: Focus on gas flow, pulp and froth retention time

A laboratory flotation column using Venturi aerators and a vacuum system to remove froth was used to investigate the contribution of gas flow, pulp flow, cell volume and froth retention time on the ink removal efficiency and on cellulose fibres and mineral fillers loss. The increase in the gas flow from 4 to 8 L/min gave a general rise of particle transport from the pulp slurry to the froth with an ensuing strong increase in ink removal, from 75% to 85%, and water and total loss, from 10% to 40% and 15% to 30%, respectively. Whereas, the increase of the cell volume from 14 to 24 L improved ink removal from 72% to 80% without considerably affecting flotation loss. The rise of the froth retention time in the flotation cell from 5 to 20 s before removal gave a general decrease in the flotation loss from 20% to 11% without a corresponding decrease in ink removal. This trend was interpreted as reflecting poor ink drainage through the froth. The increase of both pulp and froth retention time in the flotation cell appeared as the most favourable way to improve ink flotation selectivity. A mathematical model, describing particle removal during flotation in terms of true flotation, entrainment and drainage, was proposed and used to fit experimental data.

フローテーション法脱墨剤の開発 脱墨機構に関する考察

Following the recent worldwide demand for high-quality recycled pulp, the technology for deinking equipment and deinking agents has made remarkable progress.Particularly, there is a great demand for new, efficient deinking agents designed for state of the art equipment coming into use by various paper manufacturers.In response to this demand, a laboratory evaluation method was developed to measure deinking agent efficiency. By introducing the concepts of ink removal energy in the pulping process, agitation Reynolds number and gas-liquid ratio in the flotation process, a method capable of providing experimental conditions suitable to represent actual mill systems was achieved. Using this evaluation method, new deinking agents were developed having excellent ink removal and ink collection efficiency and rapid foam collapse after flotation. By utilizing the developed evaluation method and controlling the addition of alkyleneoxide to a high alcohol, the above-mentioned properties can be fitted to individual mill systems. Newly developed high-alcohol-type EOPO copolymers (single-chain type) are compared to fatty acid and oil & fat type EOPO copolymers (double-chain type) using the described laboratory method.

Manufacturing of The Deinked Pulp with High Brightness

High brightness as well as as low dirt level are required for the deinked pulp for printing paper. The good bleachability and ink-removal efficiency from fibers are essential for manufacturing the deinked pulp with high brightness.This paper deals with two important processes, i.e., the detachment of ink from fibers and the removal of ink particles suspending in the pulp slurry. The emphasis is on the mechanism and the technique of the detachment of ink from fibers.