Effective Residual Ink Concentration Research Articles

Surface characterization of pulp fiber from mixed waste newspaper and magazine deinked-pulp with combined cellulase and laccase-violuric acid system (LVS)

The current study assesses the use of combined cellulase and laccase-violuric acid system (LVS) for deinking secondary fibers containing mixed 70% old newsprint (ONP) and 30% old magazine (OMG). Optical and strength properties, surface chemical composition, fiber crystallinity, fiber morphology changes during the deinking process, and pulp water retention value (WRV) were assessed by electron spectroscopy for chemical analysis (ESCA), Fourier transform infrared spectrometry (FTIR), field emission scanning electron microscopy (FESEM), and the centrifuge method. Results revealed the synergistic delignification and deinking effects of cellulase and LVS making enzymatic treatment a promising alternative for chemical deinking. Pulp deinked with cellulase-LVS indicated a lower ERIC (effective residual ink concentration), better optical and strength properties, fiber surface with higher O/C ratio, and lower lignin coverage, higher fiber crystallinity index, and improved pulp WRV. Furthermore, FESEM photographs demonstrated that more fibrils appeared on the fiber surface due to synergistic effects between enzymes.

A pollution reducing enzymatic deinking approach for recycling of mixed office waste paper.

The efficiency of xylano-pectinolytic enzymes, co-produced by a single microbial strain Bacillus pumilus, was analysed for the recycling of mixed office waste paper through deinking and compared with the alkaline chemical deinking method. Enzymes showed maximum deinking at pH 8.5, pulp consistency of 10%, xylanase-pectinase dose of 12 and 4 IU per gram pulp, respectively, after 120 min of deinking period, and temperature at 50 °C. A chemi-enzymatic approach was employed with xylano-pectinolytic enzymes and various concentrations of deinking chemicals, which showed that enzyme-treated mixed office waste pulp requires only 40% chemicals for deinking, in order to get the almost same level of various handsheets properties, as obtained by the chemical method with 100% chemicals. Similarly, the effluent load of BOD and COD contents was also decreased by 17.90 and 19.75%. This combinational approach of deinking significantly improved the various properties of the handsheets and resulted in gain of 7.5, 9.38, 6.33 and 11.65% in tear factor, burst factor, breaking length and viscosity of the handsheets, while the effective residual ink concentration analysis of deinked handsheets of mixed office waste paper showed deinking efficiency of 22.45%, which revealed the removal of ink particles during enzymatic deinking steps.

Macroscopic and microscopic properties of fibers after enzymatic deinking of mixed office waste paper

The deinking of mixed office waste paper by cellulase, M/Las (modification of laccase aspartic acid system), and C-M/Las (cellulase synergistic modification of laccase aspartic acid system) was investigated. The fiber morphology parameters, hydrogen bond patterns, cellulose crystallinity, and fiber microstructure were observed via fiber quality analyzer (FQA), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and scanning electron microscopy (SEM). The results showed that the effective residual ink concentration of enzyme deinked pulp decreased compared with blank pulp (pulp without enzymatic treatment). The deinking efficiencies of C-M/Las, cellulase, and M/Las were 18.17%, 14.01%, and 12.31%, respectively. FQA analysis indicated that the fiber length and curl index decreased, while the fiber width slightly increased. FTIR analysis revealed that after cellulase, M/Las, and C-M/Las treatment, the content of intermolecular hydrogen bonds increased by 14.65%, 13.37%, and 19.80%, respectively. This indicates that there is a synergistic effect between cellulase and M/Las. XRD showed that the cellulose crystallinity decreased after enzymatic deinking. SEM micrographs of fibers treated with enzymes revealed that the fiber surface became rough and more fibrils appeared. The water retention value was increased after enzymatic deinking.

Bio-deinking of mixed office waste paper by Penicillium citrinum NCIM-1398 and its comparative study with conventional chemical deinking

Penicillium citrinum NCIM-1398 is a co-producer of endo β-1,4-glucanase, xylanase, and amylase enzymes. The synergistic effect of the enzymes present in the cocktail was found to be advantageous in deinking white mixed office waste (MOW) paper. Enzymatic deinking of MOW reduced the dependence on chemicals by up to 50% during chemical deinking and improved optical properties compared with the chemical deinking process. The chemi-enzymatic approach improved pulp brightness by 12.6% compared with MOW pulp. The ERIC (Effective residual ink concentration) value was reduced by up to 39.2%, whereas the strength properties of tear index, tensile index, and burst index achieved gains of 3.2%, 9.9%, and 6.2%, respectively, compared with the control. Whereas chemi-enzymatic treatment showed a reduction of 67.1% in COD and 61.8% in BOD, and there was an increase of 15.4% in total solid of effluents respectively, compared with the respective controls. Scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, and X-ray diffraction (XRD) studies revealed that the pulp was modified by enzymatic and chemi-enzymatic treatments, which facilitate ink removal during deinking of pulp.

Wheat bran as substrate for enzyme production and its application in the bio-deinking of mixed office waste (MOW) paper

Judicial utilization of various low-cost agro-industrial wastes and optimization of various process parameters can reduce production costs of enzymes. Wheat bran was found to be the best carbon source among various agro-industrial wastes explored for Penicillium citrinum NCIM-1398. Additionally, ammonium sulphate was found as the optimum nitrogen source at moisture content 70%, pH 5.5, and temperature 30 °C for enzyme production. The maximal enzyme activities of endo β-1,4-glucanase, xylanase, FPase, and amylase were 21.0 IU/gds, 3140 IU/gds, 3.59 FPU/gds, and 73.4 IU/gds, respectively. Bio-deinking of mixed office waste paper improved the pulp brightness by 9.5%, and the effective residual ink concentration were decreased by 26.3% in comparison to MOW after pulping. Similarly, dirt counts were reduced from 4880 to1360 ppm at an enzyme dose of 6.0 IU/g compared to deinking without enzyme. The strength properties of enzymatically deinked pulp such as tear index, tensile index, and burst index increased by 6.92%, 11.31%, and 7.61%, respectively, compared with the control.

Effects of enzyme treatment on surface properties of Mg(OH)2-based peroxide bleached deinked pulp

Enzyme (laccase/mediator or lipase) treatment, X-ray photoelectron spectroscopy (XPS), and scanning electron microscopy (SEM) surface analysis techniques were combined to explore the surface properties of Mg(OH)2-based peroxide bleached DIP (deinked pulp). The XPS survey spectra and SEM images showed that some trace elements, such as calcium, silicon, and aluminum, were present on the sample surface, in addition to the main elements, carbon and oxygen. The surface of enzyme-treated pulp was covered by the precipitated lignin or extractives. However, when the enzyme-treated pulps were bleached, the amount of precipitated lignin or extractives was considerably reduced. Lipase-treated, bleached pulp had better physical properties and lower effective residual ink concentration (ERIC) values than laccase/mediator-treated bleached pulp, which further indicated that lipase not only removed surface lignin and extractives, but it also was able to remove more residual ink contaminants.

Electric treatment for hydrophilic ink deinking.

Hydrophilic inks have been widely used due to higher printing speed, competitive cost and being healthy non-organic solvents. However, they cause problems in both product quality and process runnability due to their hydrophilic surface wettability, strong negative surface charge and sub-micron size. Electric treatment was shown to be able to increase the ink sizes from 60 nm to 700 nm through electrocoagulation and electrophoresis. In addition, electric treatment assisted flotation could reduce effective residual ink concentration (ERIC) by 90 ppm, compared with only 20 ppm by traditional flotation. Furthermore, the effect of electric treatment alone on ink separation was investigated by two anode materials, graphite and stainless steel. Both of them could remove hydrophilic inks with less than 1% yield loss via electroflotation and electrophoresis. But graphite is a better material as the anode because graphite reduced ERIC by an additional 100 ppm. The yield loss of flotation following electric treatment was also lower by 17% if graphite was the anode material. The difference between the two electrode materials resulted from electrocoagulation and ink redeposition during electric treatment. An electric pretreatment-flotation-hyperwashing process was conducted to understand the deinking performance in conditions similar to a paper mill, and the ERIC was reduced from 950 ppm to less than 400 ppm.

Preparation of Xylanase Loaded Biomass-based Deinking Agents and their Application in Secondary Fiber Recycling

Recently, biomass-based deinking agents have attracted considerable interest in the pulp and paper industry due to their clean, renewable, and good deinking properties. In this study, the xylanase loaded biomass-based deinking agent (XBD) was prepared with coconut oleic acid, palmitic acid, rosin, and xylanase. The preparation technology of XBD was optimized by an orthogonal test and range analysis. The effects of the moisture content, free alkali, and chelating agent on the enzyme activity of XBD were determined via a single factor experiments. Based on the analysis of the optical and physical properties, the optimum xylanase addition into the biomass-based deinking agent was 15 wt.%, the brightness of the secondary fiber after flotation was 60.2% ISO, and the effective residual ink concentration was 223 ppm.

Deinking process water flotation: An innovative solution to improve deinking and papermaking processes efficiency

High and uncontrolled surface active substances (SAS) concentrations in deinking line process waters strongly disturb flotation deinking. Indeed, their adsorption at air/water and ink/water interfaces stabilizes air bubbles and ink particles, reducing ink collection during flotation. In addition, foam stabilization promoted by SAS reduces froth drainage and consequently enhances suspended solids losses. All in all, selectivity of flotation is negatively affected by excessive SAS concentrations. Floating process water with adapted technology, a patented solution, is an efficient way to decrease SAS concentration and thereby recover flotation deinking selectivity. This concept was tested at industrial scale with success. First loop clear filtrates of a deinked pulp line (for newsprint production) were floated. At steady state, this treatment allows a 20% reduction of the SAS concentration in first loop process water. Evaluation of ink removal selectivity at pre-flotation and post-flotation showed a significant improvement in comparison with reference values. During the trial, the mill could either produce pulp with lower ink content and consequently higher brightness (50 ppm effective residual ink concentration [ERIC] less, corresponding to a 1 brightness point increase) for similar losses, or similar pulp quality with 1% to 2% yield improvement, representing a huge cost reduction. In addition, beneficial side effects were reported, such as reduced deinking chemicals consumption (soda, silicate, and bleaching agents) and better paper machine runnability, especially in terms of stickies breaks.

Statistical experimental design of a novel deinking reactor based on centrifugal force under electric field concept

The aim of this research was to study a new invention concept of ink removal processes by a combined effect of centrifugal force and electrical force. After deinking treatment with different voltage conditions, the effective residual ink concentration (ERIC) index from the test samples were lower than the operation without voltage input, indicating the applied electric force promotes deinking. With a certain operating time and ink coverage, the percentage weight loss of the pulp yield after deinking treatment has been lower by applying electrostatic force. From an analysis of variance (ANOVA), the optimum point of the process was obtained with low ink coverage of used paper, medium operating time and high voltage supply. This novel electrostatic separation is proved to be an effective method for paper recycling process since it has no chemical usage; thus, no requirement for further chemical separation.

Biochemical evaluation of xylanases from various filamentous fungi and their application for the deinking of ozone treated newspaper pulp

Filamentous fungi, Aspergillus oryzae MDU-4 was biochemically selected among different species of Aspergillus and Trichoderma, for xylanase production. The enzyme activity and specific activity of partially purified xylanase from A. oryzae MDU-4 was 7452IU/ml and 13,549IU/g, respectively. Temperature and pH optima for xylanase were found to be 60°C and 6.0, respectively. The reaction kinetics of xylanase was found to be Km (3.33mg/ml) and Vmax (18,182μmol/mg). The implementation of ozone treatment in the deinking of newspaper pulp resulted in high crystallinity index (72.1%) and more fibrillar surface. Furthermore, the xylanase treated pulp showed significant improvement in optical properties such as brightness (57.9% ISO) and effective residual ink concentration (211ppm). Scanning electron microscopy analysis suggests perforations in xylanase treated pulp samples. Here we report biochemical evaluation of xylanases and a combination of ozone treatment followed by catalytically efficient fungal xylanase selected for the cost competitive deinking of newspaper pulp.

Ecological Sustainability and Waste Paper Recycling

In accordance with environmental sustainability and in order to optimize the recycling process of prints from indirect electrophotography with liquid toner the results of investigating the effects of changes in printing conditions on the characteristics of recycled fibres is presented. Changing of printing machine conditions, respecting of voltage variations, comprises of the reverse rollers and intermediate cylinder.Based on the results it can be concluded that the change in the voltage of the reverse rollers more affect the recycling efficiency with respect to the voltage change of the intermediate cylinder. Brightness gain is higher when the print for recycling is made on uncoated paper compared to coated, and dependent on the voltage changes. Effective residual ink concentration decreases far more on handsheets obtained from recycled samples on uncoated paper in relation to both sides coated paper. Increasing the positive voltage of intermediate cylinder and increasing the negative charge of reverse rollers increases the 3 D gamut CIE L*a*b* color cubic units. Guidelines for the size of the voltage in order to obtain optimal print reproduction are provided.The further research will include the development in area of clean technologies, advanced materials, closed loop systems; therefore the significant terms in the area of environmental sustainability.

Effect of wavelength selection on determination of ink content and ink elimination at 700 or 950 nm

Effective residual ink concentration (ERIC) and ink elimination (IE) are often used to evaluate the removal of printing ink in deinking. For these measurements, the light reflectance is recorded at 950 nm or 700 nm even though only the use of the former for effective residual ink concentration is instructed in the ISO and TAPPI standards. In this study, these two wavelengths were compared using a set of recycled pulp samples having variable fiber fines, fillers, and ink contents. It was seen that both wavelengths are well suited for the determination of effective residual ink concentration, especially when the recovered papers are not green or blue. Effective residual ink concentration values measured at 700 nm are higher than those obtained with 950 nm because, in addition to black printing ink, the presence of cyan-colored inks contributes to the former. Ink elimination values are similar for both wavelengths because ink elimination is a percentage ratio of ink removal in flotation. The fine materials and printing ink also affect light scattering at 950 nm, although the range appears narrower for 950 nm than for 700 nm.

Improving Recycled Fiber by Applying <i>In-Situ</i> Aragonite Calcium Carbonate Formation Process

Needle-shaped aragonite, a thermodynamically metastable polymorph of CaCO3, was synthesized in a deinked old newspaper pulp (ONP) slurry, otherwise known as the in-situ aragonite formation process, in order to improve the optical properties such as the brightness and ERIC value (effective residual ink concentration) as well as to preserve the strength properties such as the breaking length of the resultant handsheet. The brightness and ERIC value of the handsheet obtained from pulp that was subjected to the in-situ aragonite formation process was improved by 20.4% (from 56.8 to 68.4%) and 55.4% (from 292.1 to 130.4ppm), respectively, relative to a raw ONP sample. The effects of the in-situ aragonite formation process on the resultant handsheet were compared with the results obtained from a similar process in which rhombohedraltype calcite was synthesized instead of the needle-shaped aragonite. From the comparison, it can be concluded that the in-situ aragonite formation process provides better optical and strength properties to the resultant handsheet than that of calcite, and this is attributed to the needleshaped morphology of aragonite. [doi:10.2320/matertrans.M2013369]

Prints Recycling in Function of the Press Conditions and Substrate Characteristics

The directions of the ecological sustainability in printing reproduction are in the area of the application of the renewable and recycled raw materials, in the decrease of the energy consumption, the usage of the energy from the renewable sources and in the production without waste. This article presents the research results of voltage changes of the intermediate cylinder in indirect electrophotography with liquid toner on dirt count and area on handsheet made from fibers after prints pulping and flotation, brightness and effective residual ink concentration. Since on the indirect transfer of ElectroInk except the voltage of the intermediate cylinder also impacts temperature, its influence on the dirt count and area is showed. Uncoated and both side coated substrates were used for printing. The results show that changes in voltage of the intermediate cylinder in the printing affects the characteristics of pulped and floated fibers and dirt count and area on handsheets. Dominant factor of studied process is surface treatment of the printing substrate. Maximum efficiency of deinking flotation (87.7%) was observed on non coated paper print, at the voltage of the intermediate cylinder of 700V. The efficiency of deinking flotation on both sides coated paper prints in dependence on the voltage of the intermediate cylinder in most cases is below 10%. The results show that an increase in temperature of the intermediate cylinder increases dirt count and area on handsheetst after pulping prints under experimental conditions. Increased efficiency of flotation was found for print obtained at a lower temperature of the intermediate cylinder.

Combined Enzymatic and Physical Deinking Methodology for Efficient Eco-Friendly Recycling of Old Newsprint

BackgroundThe development in the deinking process has made recycled fiber a major part of the raw material for pulp and paper industry. Enzymes have revolutionized the deinking process obtaining brightness levels surpassing conventional deinking processes. This study explores the deinking efficiencies of bacterial alkalophilic laccase (L) and xylanase (X) enzymes along with physical deinking methods of microwaving (MW) and sonication (S) for recycling of old newsprint (ONP).Methods and ResultsThe operational parameters viz. enzyme dose, pH and treatment time for X and L deinking were optimized statistically using Response Surface Methodology. Laccase did not require any mediator supplementation for deinking. Deinking of ONP pulp with a combination of xylanase and laccase enzymes was investigated, and fiber surface composition and morphological changes were studied using X-ray diffraction, fourier transform infrared spectroscopy and scanning electron microscopy. Compared to the pulp deinked with xylanase (47.9%) or laccase (62.2%) individually, the percentage reduction of effective residual ink concentration (ERIC) was higher for the combined xylanase/laccase-deinked pulp (65.8%). An increase in brightness (21.6%), breaking length (16.5%), burst factor (4.2%) tear factor (6.9%), viscosity (13%) and cellulose crystallinity (10.3%) along with decrease in kappa number (22%) and chemical consumption (50%) were also observed. Surface appeared more fibrillar along with changes in surface functional groups. A combination of physical and enzymatic processes (S-MW-XL) for deinking further improved brightness (28.8%) and decreased ERIC (73.9%) substantially.ConclusionThis is the first report on deinking of ONP with laccase without any mediator supplementation. XL pretreatment resulted in marked improvement in paper quality and a new sequence being reported for deinking (S-MW-XL) will contribute further in decreasing chemical consumption and making the process commercially feasible.

폐신문지(廢新聞紙)(ONP)로부터 부유선별(浮遊選別)을 이용한 잉크분리(分離)시 초음파처리(超音波處理) 효과(效果)

재생률이 높은 폐신문지(old newspaper, ONP)를 부유선별법을 이용하여 탈묵을 진행하였을 시, 해리시간, 초음파처리에 따른 백색도, 잔류잉크농도(effective residual ink concentration, ERIC), 수율의 효과를 규명하였다. 또한 부유선별시 pH, 포수제에 따른 백색도, ERIC과 수율의 효과도 규명하였다. 해리시간이 증가할수록 백색도와 ERIC이 증가함을 보였으나 수율의 차이는 없었다. 해리시간이 30분일 때 백색도 58% ERIC 182.9 ppm이였고, 해리를 더 진행하더라도 백색도의 증가를 볼 수 없었다. 단 해리 된 ONP를 초음파발생장치를 이용하여 초음파처리를 했을 경우 단 2분의 해리시간으로도 58%이상의 백색도를 얻을 수 있었다. 초음파처리를 20분간하고, pH 11에서 포수제로 등유을 사용했을 때 백색도가 59.32%로 가장 높았다. In this study, the sonication method was applied to remove ink from old newspaper(ONP) using flotation. Results indicated increased whiteness and effective residual ink concentration (ERIC) with longer disintegration. Therefore 58% of whiteness and 182.9 ppm ERIC were obtained for 30 minutes of disintegration time without the change in yield. Longer disintegration than 30 minutes had no effects on whiteness without the application of ultra-sonication. On the other hand, higher than 58% of whiteness was achieved in 2 minutes of disintegration when the ultra-sonication was applied. The highest whiteness (59.32 %) was obtained by applying sonication for 20 minutes and froth flotation with kerosene as a collector under the alkaline condition (pH 11).

Study of Flotation Deinking of Old Magazine and Mixed Office Waste Paper

The effect of flotation parameters such as flotation consistency, temperature, flotation time, air to pulp ratio, and velocity of pulp flow (turbulence level) on OMG/MOW deinking efficiency was studied by using a high-consistency laboratory pulper and a laboratory deinking cell. The optimized flotation conditions were: flotation consistency 1.1%, 40°C, 8min, air to pulp ratio 40%, velocity of pulp flow 3.5m/s and pH 9.0. By using the optimized flotation conditions, the deinked pulp brightness could reach 70.56%ISO, 11.78%ISO higher than that of the control, the effective residual ink concentration was 108.46 mg/kg, which less than 378.14mg/kg of the control, theoretic deinking efficiency was up to 88.41%.

Improvement of ink and heavy metal removal from old corrugated container stock by alkali kneading

One of the possible ways to strengthen competitiveness of Kraft paper industry is to replace the expensive virgin unbleached kraft pulp (UKP) with old corrugated container (OCC), a cheaper and lower grade raw material. When OCC is utilized to produce kraft paper, the main problems are the impaired appearance of the products, and heavy metals and hazardous materials in the products caused by the printed ink and other contaminants. In order to improve the removal efficiency of ink and heavy metals from old corrugated container stock, the effect of adding alkali during kneading of OCC stock was investigated. It was found that adding NaOH and sodium silicate during kneading could improve detachment of ink from fiber surface and removal of it from stock and hence improve heavy metal removal from OCC stock. Since alkali addition improves ink detachment, effective residual ink concentration (ERIC) of pulp was decreased and brightness was increased. Tensile strength and tensile energy absorption (TEA) were increased with addition of alkali.

Study of Flotation Deinking Efficiency of Old Newspaper and Old Magazine

The effect of flotation parameters such as flotation consistency, temperature, flotation time, air to pulp ratio, velocity of pulp flow (turbulence level), and pH on old newspaper/old magazine deinking efficiency was studied by using a laboratory deinking cell developed by ourselves. The optimized flotation conditions were: flotation consistency 1.2%, 50°C, 6min, air to pulp ratio 50%, velocity of pulp flow 3.5m/s and pH 8.5. By using the optimized flotation conditions, the deinked pulp brightness could reach 59.15%ISO, 10.18%ISO higher than that of the control, the effective residual ink concentration was 234.65 mg/kg, which less heavily than 875.56 mg/kg of the control, theoretical deinking efficiency was up to 84.42%.