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Flotation deinking is one of the most widely used techniques for the separation of ink particles from cellulose fibers during the process of paper recycling. It is a complex process influenced by a variety of factors, and is difficult to represent and usually results in models that are inconvenient to implement and/or interpret. In this paper, a comprehensive study of several machine learning methods for the prediction of flotation deinking performance is carried out, including support vector regression, regression tree ensembles (random forests and boosting) and Gaussian process regression. The prediction relies on the development of a limited dataset that assumes representative data samples obtained under a variety of laboratory conditions, including different reagents, pH values and flotation residence times. The results obtained in this paper confirm that the machine learning methods enable the accurate prediction of flotation deinking performance even when the dataset used for training the model is limited, thus enabling the determination of optimal conditions for the paper recycling process, with only minimal costs and effort. Considering the low complexity of the Gaussian process regression compared to the aforementioned ensemble models, it should be emphasized that the Gaussian process regression gave the best performance in estimating fiber recovery (R2 = 97.77%) and a reasonable performance in estimating the toner recovery (R2 = 86.31%). [ABSTRACT FROM AUTHOR]

Biofuels are the cheapest source of energy, and the continuous decline of traditional sources of energy with the increasing population leads to looking for alternatives to reduce the consumption of traditional sources of energy. Bioethanol production from lignocellulosic wastes and cellulosic wastes is not a new approach for fuel production but a cheap and accessible way for the production of fuel. Bacillus is one of the major species that can act as a source of diversified enzymes. In this study, it was emphasized on screening and isolation of a novel, characterization, and best catalytic action on both celluloses and proteins in the presence of different carbon and nitrogen sources. It was observed the effective catalytic breakdown of cellulose with the crude enzyme to glucose allowed fur for fermentation with Saccharomyces, ultimately leading to the generation of alcohol. The study aims to isolate the microbes that can produce cellulases and enzymes and could be used for biodegradation to produce ethanol in the reaction. The maximum enzyme activity was achieved at 3.112 UI with optimized pH and temperature, and the maximum conversion of sugars into alcohol was about 70% in the newspaper, cartons, colored paper, and disposable paper cups. An essential observation was the decolorization of the origami craft paper within 24 hours. The study was involved in enhancing the maximum Enzyme activity of cellulases from different cellulosic raw materials. Hence, it was achieved by JCB strain, optimization of pH, temperature, and acids for the biodegradation. The presence of peaks at 3200 and 2900 was a confirmation of ethanol bonds in the biodegradation reaction mixtures. [ABSTRACT FROM AUTHOR]

Self-powered electronic equipment has rapidly developed in the fields of sensing, motion monitoring, and energy collection, posing a greater challenge to triboelectric materials. Triboelectric materials need to enhance their electrical conductivity and mechanical strength to address the increasing demand for stability and to mitigate unpredictable physical damage. In this study, polyaniline-modified cellulose was prepared by means of in situ polymerization and compounded with polydimethylsiloxane, resulting in a triboelectric material with enhanced strength and conductivity. The material was fabricated into a tubular triboelectric nanogenerator (TENG) (G-TENG), and an electrocatalytic pretreatment of mixed office waste paper (MOW) pulp was performed using papermaking white water as the flowing liquid to improve the deinking performance. The electrical output performance of G-TENG is highest at a flow rate of 400 mL/min, producing a voltage of 22.76 V and a current of 1.024 μA. Moreover, the deinking effect of MOW was enhanced after the electrical pretreatment. This study explores the potential application of G-TENG as a self-powered sensor power supply and emphasizes its prospect as an energy collection device. [ABSTRACT FROM AUTHOR]

Flotation deinking is one of the most widely used techniques for the separation of ink particles from cellulose fibers during the process of paper recycling. It is a complex process influenced by a variety of factors, and is difficult to represent and usually results in models that are inconvenient to implement and/or interpret. In this paper, a comprehensive study of several machine learning methods for the prediction of flotation deinking performance is carried out, including support vector regression, regression tree ensembles (random forests and boosting) and Gaussian process regression. The prediction relies on the development of a limited dataset that assumes representative data samples obtained under a variety of laboratory conditions, including different reagents, pH values and flotation residence times. The results obtained in this paper confirm that the machine learning methods enable the accurate prediction of flotation deinking performance even when the dataset used for training the model is limited, thus enabling the determination of optimal conditions for the paper recycling process, with only minimal costs and effort. Considering the low complexity of the Gaussian process regression compared to the aforementioned ensemble models, it should be emphasized that the Gaussian process regression gave the best performance in estimating fiber recovery (R2 = 97.77%) and a reasonable performance in estimating the toner recovery (R2 = 86.31%).

Background The bleach-boosting capability of xylanases is well-known. The use of xylanase pre-treatment before the application of chemical bleach has multiple advantages including (i) lesser use of polluting chemicals of the traditional bleaching process; (ii) less damage to the cellulosic fbers, therefore better recyclability; and (iii) better brightness of chemical bleach. The major impediment in the application is the availability of commercial enzymes that are active at the elevated temperature and pH that exist during the industrial pulping process. In the present paper, xylanase having suitability for application in deinking is reported. Results The xylanase used showed high deinking potential. Optimal deinking was obtained at the xylanase dosing of 20U/g of the dried pulp at 60°C for a treatment time of 1h. It could bring about a 50% reduction in the usage of chemical bleach that was applied after xylanase pre-treatment. The comparison of FTIR spectra showed changes in intensity without signifcant changes in the functional group signatures implying that there is negligible damage to the fber strength in the xylanase pre-treatment process as compared to the chemical bleach process. Conclusion The xylanase used in this study was efective in deinking paper pulp and can be used for bio-bleaching of recycled paper. [ABSTRACT FROM AUTHOR]

Self-powered electronic equipment has rapidly developed in the fields of sensing, motion monitoring, and energy collection, posing a greater challenge to triboelectric materials. Triboelectric materials need to enhance their electrical conductivity and mechanical strength to address the increasing demand for stability and to mitigate unpredictable physical damage. In this study, polyaniline-modified cellulose was prepared by means of in situ polymerization and compounded with polydimethylsiloxane, resulting in a triboelectric material with enhanced strength and conductivity. The material was fabricated into a tubular triboelectric nanogenerator (TENG) (G-TENG), and an electrocatalytic pretreatment of mixed office waste paper (MOW) pulp was performed using papermaking white water as the flowing liquid to improve the deinking performance. The electrical output performance of G-TENG is highest at a flow rate of 400 mL/min, producing a voltage of 22.76 V and a current of 1.024 μA. Moreover, the deinking effect of MOW was enhanced after the electrical pretreatment. This study explores the potential application of G-TENG as a self-powered sensor power supply and emphasizes its prospect as an energy collection device.

On the market there are increased quantities of laminated cardboard packaging with glossy surface. Laminated packaging is being used for its appealing appearance. However, laminated paper treatment creates additional problems in the process of recycling of used product. Adhesives and foil are a specific issue in the separation of impurities in recycled paper. It is crucial that the paper packaging products contained in the paper for recycling are repulpable within standard operating time and equipment. In this research three methods (without chemicals, INGEDE 11 and their combination) of removing impurities from paper pulp are compared and their efficiencies are determined to gain deeper insight into the recycling process. The procedures determine the recyclability of existing printed material, as well as the possible adhesive and material improvements. A specific issue in the separation of impurities was the presence of adhesives as well as silver foil (BOPET metallized film) for lamination. All three applied procedures successfully separate impurity particles from paper pulp and printed laminated boxes in a more sustainable manner, without the use of chemical agents.

The present study develops an effective and sustainable catalytic system using mesoporous (KIT-6 and NbKIT-6) and microporous catalysts (ZIF-8) for the conversion of newspaper waste to value-added products such as TRS (Total reducing sugars) and 5-HMF (5-Hydroxymethyl furfural). The bio-based products were produced using green and biodegradable solvent Choline chloride in presence of sustainable catalysts under mild operating conditions at 1 atm pressure. The study demonstrated the potential of monophasic (Choline chloride and Catalyst) and biphasic (Choline chloride, Catalyst and Extracting solvent) system and revealed their comparative insights. It was observed that both the systems were highly effective but the purity and stability of products were higher in the biphasic system compared to the monophasic system. The synthesised catalysts possess high surface area 588.528, 534.414 and 351.85 m2/g with pore volume 0.7587, 0.3574 and 0.2362 cc/g for KIT-6, NbKIT-6 and ZIF respectively. The selected extracting solvents were found to be promising and the maximum 5-HMF yield was found to be 62.12%, 73.45% and 79.66% in DMSO medium using KIT-6 (160 °C, 135 min), NbKIT-6 (140 °C, 90 min) and ZIF-8 (140 °C, 105 min) catalysts respectively. Also, all the catalysts are reusable for up to five runs with minimal loss in catalyst activity. The proposed catalytic system will help to resolve the challenges associated with biorefineries in terms of product separation and recyclability of catalysts.

Recycling technology contributes to sustainability and has received considerable interest in fulfilling consumable products’ social demands, including papers. Recycled fibers are the primary source of the papermaking industry. Papers, valuable daily used materials, can be further recycled for further implementation. Here, we report a simple method for recycling waste papers for further use. Our method includes re-pulping, deinking, bleaching, and papermaking. The sample and the recycled papers were characterized by X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDS). XRD data shows the presence of cellulose and filler minerals in the sample and the recycled papers. FTIR analysis confirmed the presence of hydroxyl, carbonyl, and methyl functional groups in the recycled papers suggesting that the deinking and bleaching did not cause any structural changes. The fibrous structures were also sustained after recycling, as confirmed by SEM studies demonstrating that the recycling was successful and the papers can be further used and recycled. EDS analysis further confirmed the filler minerals in the sample paper with a trace amount of lead, which decreased upon bleaching the paper. The structure and properties of the sample and the recycled papers were quite similar, inferring that waste papers can be recycled again and different products from low to higher grade papers can be fabricated. [ABSTRACT FROM AUTHOR]

Cellulose nanocrystals (CNC) were successfully prepared from waste newspapers through a simple pretreatment and hydrolysis process. The Fourier transform infrared spectroscopy (FTIR) result for the CNC suggested that no new chemical bonds were formed during the preparation of CNC. X-ray diffraction results indicated that the crystallinities of the deinked and untreated waste newspapers were 66% and 73.8%, respectively. Greater smoothness of the deinked waste newspapers fibers could be clearly observed by scanning electron microscope (SEM), which was attributed to the removal of ink from the chemical treatment. The transmission electron microscopy (TEM) and atomic force microscopy (AFM) results of the CNC revealed a needle-like natural fiber with a length of 300 nm to 600 nm, a diameter of 10 nm to 30 nm, and an aspect ratio in the 10 to 60 range. The obtained CNC particles were found to improve the physical properties of paper sheets, specifically that of the tear, tensile, and burst indices. The maximum increase in the physical properties was achieved with a 5.5% CNC addition.

Beauveria bassiana is an entomopathogenic fungus widely used as a biopesticide for insect control; it has also been shown to exist as an endophyte, promoting plant growth in many instances. This study highlights an alternative potential of the fungus; in the production of an industrially important biocatalyst, xylanase. In this regard, Beauveria bassiana SAN01 xylanase was purified to homogeneity and subsequently characterized. The purified xylanase was found to have a specific activity of 324.2 U.mg-1 and an estimated molecular mass of ~37 kDa. In addition, it demonstrated optimal activity at pH 6.0 and 45 °C while obeying Michaelis-Menton kinetics towards beechwood xylan with apparent Km, Vmax and kcat of 1.98 mg.mL-1, 6.65 μM.min-1 and 0.62 s-1 respectively. The enzyme activity was strongly inhibited by Ag2+ and Fe3+ while it was significantly enhanced by Co2+ and Mg2+. Furthermore, the xylanase was shown to effectively deink wastepaper at an optimal rate of 106.72% through its enzymatic disassociation of the fiber-ink bonds as demonstrated by scanning electron microscopy and infrared spectroscopy. This is the first study to demonstrate the biotechnological application of a homogeneously purified glycosyl hydrolase from B. bassiana. [ABSTRACT FROM AUTHOR]

To reuse recycled cellulosic fibers in paper production, contaminated particles and other impurities of the fibers can be greatly removed using a de-inking stage which is considered as a supplementary step in waste paper recycling technology. The effect of using ultrasonic pretreatment on the deinking of old newspapers was investigated utilizing the common conventional chemical method across this research work. Experimental design method was served to optimize the amount of ultrasonic bath temperature and sonication time. Therefore, 13 tests were designed using Response Surface Methodology (RSM) and Central Composite Design with Design Expert 7.0.0 Trial software. Ultrasonic bath temperature and sonication time at three different levels (1, 0 and 1+) and two axial points (α + and α-) were used as independent variables, and the optical and mechanical properties of handsheets were used as dependent variables. Response surfaces and contour plots were served to show the interaction between the independent variables and the response variable. ANOVA test showed that the quadratic model is the best model to explain the interaction among the studied variables. The predicted values of the obtained model had much conformity with the experimental results (R2=0.98). According to ANOVA results, it can be concluded that the effect of each of the variables on the optimal properties is significant and the ultrasonic time is the most effective factor on the response. According to the results, the proposed optimum conditions to achieve the highest amount of mechanical and optical properties (43.43) are the ultrasonic bath temperature 47 oC and the ultrasonic time of 31 min.

Bu çalışmada, ofis (A4), kuşe, oluklu mukavva, NSSC (Nötral sülfit yarı kimyasal hamur), gazete ve karışım kâğıtları üzerine hamurlaştırma işlemleri yapılmıştır. Bu işlemin sonunda ise dövme ve ardından mürekkep giderme işlemi yapılmıştır. İşlem sonunda ise elde edilen test kâğıtlarına ise bazı testler yapılmıştır. Çalışmada, kontrol amaçlı standart yüzdürme metoduna göre mürekkep giderme işlemi yapılmıştır. Bu amaçla, sodyum hidroksit, hidrojen peroksit, sodyum silikat, oleik asit ve kalsiyum klorür ingede metoduna göre uyarlanarak kullanılmıştır.

Three approaches were examined for the reutilization of cold caustic extraction (CCE) lye. The term CCE lye refers here to the used NaOH solution with relatively high alkali content, which could be wasted if not reused properly. The results showed that CCE lye can be effectively applied in deinking, alkaline hydrogen peroxide bleaching, and oxygen delignification processes. The CCE lye improved the physical strength of the dried sheet of pulp, as the tensile index increased by 17.9% to 40.5%, the tear index increased by 2.9% to 22.2%, and the burst index increased by 10.5% to 41.0%. The results demonstrated the feasibility of integrating the CCE process of dissolving pulp production with regular pulping and bleaching processes. [ABSTRACT FROM AUTHOR]

Beauveria bassiana is an entomopathogenic fungus widely used as a biopesticide for insect control; it has also been shown to exist as an endophyte, promoting plant growth in many instances. This study highlights an alternative potential of the fungus; in the production of an industrially important biocatalyst, xylanase. In this regard, Beauveria bassiana SAN01 xylanase was purified to homogeneity and subsequently characterized. The purified xylanase was found to have a specific activity of 324.2 U·mg−1 and an estimated molecular mass of ~37 kDa. In addition, it demonstrated optimal activity at pH 6.0 and 45 °C while obeying Michaelis–Menton kinetics towards beechwood xylan with apparent Km, Vmax and kcat of 1.98 mg·mL−1, 6.65 μM·min−1 and 0.62 s−1 respectively. The enzyme activity was strongly inhibited by Ag2+ and Fe3+ while it was significantly enhanced by Co2+ and Mg2+. Furthermore, the xylanase was shown to effectively deink wastepaper at an optimal rate of 106.72% through its enzymatic disassociation of the fiber-ink bonds as demonstrated by scanning electron microscopy and infrared spectroscopy. This is the first study to demonstrate the biotechnological application of a homogeneously purified glycosyl hydrolase from B. bassiana.

Continuous efforts have been made in recent year to improve the process of paper recycling, as it is of critical importance for saving the wood, water and energy resources. Flotation deinking is considered to be one of the key methods for separation of ink particles from the cellulose fibres. Attempts to model the flotation deinking process have often resulted in complex models that are difficult to implement and use. In this paper a model for prediction of flotation performance based on Support Vector Regression (SVR), is presented. Representative data samples were created in laboratory, under a variety of practical control variables for the flotation deinking process, including different reagents, pH values and flotation residence time. Predictive model was created that was trained on these data samples, and the flotation performance was assessed showing that Support Vector Regression is a promising method even when dataset used for training the model is limited.

Compared with conventional chemical deinking, enzymatic deinking is a more environmentally compatible alternative for processing recovered paper. In this study, a bacterial isolate identified as Achromobacter xylosoxidans (designated as L2) was found to be a promising candidate for a paper deinking process. It showed endoglucanase, ß-glucosidase, endoxylanases, and filter paper degrading activities (FPase) with the maximal values of 2.60, 2.57, 3.08, and 24.58 U/mL, respectively. The optimal temperature and pH for FPase were determined to be 44 °C and pH 7.6. After two days of incubation with L2 at 130 rpm and 30 °C, the waste newspaper strips (0.5 cm × 5 cm) were disintegrated to debris with the average size of 3.5 mm (while that of the untreated without inoculation of L2 was 5.7 mm). The final brightness of the regenerated handsheets after incubation with L2 increased 3.7 units (31.4% ISO). The isolate and its complete lignocellulosic enzymes could be applied as deinking agents in the recycling of waste paper. [ABSTRACT FROM AUTHOR]

With the utilization of used newspaper into the paper making industry, bleaching has been an area of concern to obtain a balance between desired brightness and the amount of treatment it requires. Motivation of this study was to optimize bleaching of recycled newsprint fibers in terms of five variables namely hydrogen peroxide charge, amount of sodium hydroxide employed, pulp consistency, bleaching temperature, and bleaching time. Experimental work was conducted in the laboratory to simulate bleaching plant and it was found that higher peroxide charge is better for improvement in brightness, but it is uneconomical to increase peroxide charge indefinitely. The amount of hydrogen peroxide is added so that the residual peroxide at the end of the reaction is not less than 10% of the initially added peroxide. Sodium hydroxide provides alkalinity which is very important for making the fibers flexible and softening of ink particles but it also contributes to pulp yellowing if residual hydrogen peroxide contents are lesser than the minimum required value. So, for 16 kg t ^−1 of hydrogen peroxide, 6 kg t ^−1 of sodium hydroxide prevented the brightness reversion in this study. Higher pulp consistency is better but unavailability of very high consistency pulp mixer in the industry is a limiting factor for higher than 30% pulp consistency. Temperature and time are quite interrelated and, with the given bleaching conditions, a temperature of 95 °C with 10 min residence time was found to be optimum for this study. It was also observed that multiple pre-washings increase brightness and save bleaching chemicals.

The effect of changing the sequence of refining and enzymatic treatment on the properties of deinked pulp from mixed office waste paper (MOW) was investigated. The sequences included refining before and after enzymatic treatment. Refining was applied for 700 and 1500 revolutions, and the consistency of pulps during enzymatic treatment was 5, 8, and 13%. Enzymatic treatment was applied for 20, 40, and 60 min. After each of the sequences, the deinking stage was the same. When refining was applied after the enzymatic treatment, the freeness of pulp was greater than that of the pulp on which refining was conducted before the enzymatic treatment, at a constant refining speed. Better strength properties were produced when refining was carried out before the enzymatic treatment. Also, the results of testing the optical properties of deinked pulp showed that brightness and ERIC improved when refining was carried out before the enzymatic treatment.

Bu çalışmada, ofis kâğıtları üzerinde mürekkep giderme işlemi yapılmıştır. Bu işlem için farklı oranlarda kimyasal ve enzimler katılmış ve bunların etkileri analiz edilmiştir. Bu amaçla sodyum hidroksit, hidrojen peroksit sodyum silikat ve oleik asit’de uygun dozlarda kullanılmıştır. Çalışmada ayrıca ultrasonik enerjinin etkiside ayrıca incelenmiştir. Araştırma sonunda ise işlem sonunda elde edilen hamur ve atık çamur üzerinde organik ve anorganik madde analizleri yapılmıştır.

Bu çalışmada, yüzdürme metoduna göre mürekkep giderme işlemi uygulanmış baskılı ofis kâğıtları üzerinde taramalı elektron mikroskobu (SEM) ile görüntü analizleri yapılmıştır. Bu işlem için öncelikle bazı kimyasallar ile enzimler kullanılmıştır. Çalışmada ayrıca ultrasonik enerjiden de faydalanılmıştır. Çalışmada baskılı ofis kağıtlarının hamurlaştırma ve ardından uygulanan yüzdürme işlemi sonrası elde edilen numunelerden örnekler alınarak taramalı elektron mikroskobu yardımıyla (SEM) görüntü analizleri yapılmıştır. Bu analizler sayesinde baskılı ofis kağıtlarınına uygulanan ultrasonik, kimyasal katkılı, kimyasalsız ve enzim katkılı işlemler sonucu lif ve tonerde meydana gelen değişimler gözlemlenmiştir.

Bu çalışmada, yüzdürme metoduna göre mürekkep giderme işlemi uygulanmış baskılı ofis kâğıtları üzerinde taramalı elektron mikroskobu (SEM) ile görüntü analizleri yapılmıştır. Bu işlem için öncelikle bazı kimyasallar ile enzimler kullanılmıştır. Çalışmada ayrıca ultrasonik enerjiden de faydalanılmıştır. Çalışmada baskılı ofis kağıtlarının hamurlaştırma ve ardından uygulanan yüzdürme işlemi sonrası elde edilen numunelerden örnekler alınarak taramalı elektron mikroskobu yardımıyla (SEM) görüntü analizleri yapılmıştır. Bu analizler sayesinde baskılı ofis kağıtlarınına uygulanan ultrasonik, kimyasal katkılı, kimyasalsız ve enzim katkılı işlemler sonucu lif ve tonerde meydana gelen değişimler gözlemlenmiştir.Anahtar Kelimeler: Taramalı elektron mikroskobu (SEM), Enzimler, Mürekkep giderme, Ultrases

Bu çalışmada, ofis kâğıtları üzerinde mürekkep giderme işlemi yapılmıştır. Bu işlem için farklı oranlarda kimyasal ve enzimler katılmış ve bunların etkileri analiz edilmiştir. Bu amaçla sodyum hidroksit, hidrojen peroksit sodyum silikat ve oleik asit’de uygun dozlarda kullanılmıştır. Çalışmada ayrıca ultrasonik enerjinin etkiside ayrıca incelenmiştir. Araştırma sonunda ise işlem sonunda elde edilen hamur ve atık çamur üzerinde organik ve anorganik madde analizleri yapılmıştır.Anahtar Kelimeler: Organik madde, Anorganik madde, Mürekkep giderme, Ofis kağıdı

This research was conducted to investigate the bleaching of combined old newspapers (ONP) and old magazines (OMG) deinked pulp using sodium dithionite. The pulp was bleached using 0.5, 0.75, and 1% sodium dithionite and different times of 30, 60 and 90 minutes. The pulps were then refined to 300 ml, CSF freeness and standard handsheets were made from the refined pulps. The optical and mechanical properties of handsheets and the COD of bleaching effluent were measured according to TAPPI standard test methods. The results showed that the brightness of paper was increased significantly with increase in time and sodium dithionite charge. When the charge of bleaching agent increased, the mechanical properties of handsheets and COD load of bleaching effluent were increased and paper bulk and opacity decreased but these changes were not statistically significant. Increasing the bleaching time from 30 to 90 minutes resulted in a significant improvement in tensile, burst and tear indices but the opacity of paper was reduced.

Xylanase is a major enzyme used in the paper and pulp industries for biobleaching applications. There are possibilities for xylanase with better properties suitable for industrial applications. This paper focused on a potential xylanolytic fungus, Trichoderma viride VKF-3, obtained from a mangrove soil sample. Optimum conditions for xylanase production were tested by culturing T. viride VKF3 under varying carbon and nitrogen sources, medium pH, and incubation temperature. The isolate T. viride VKF3 achieved a maximum of 3.045 IU/mL of xylanase activity by utilizing coconut oil cake as a substrate. During purification, 84% yield was obtained with 40% ammonium sulphate. The enzyme activity was confirmed through zymogram analysis, and a band was observed at 14 kDa. The xylanase facilitated maximum hexenuronic acid release with a 30% enzyme dosage following 4 h of incubation. Moreover, the Kappa number tended to decrease with increased enzyme dosage and incubation time. There was a Δ brightness of 11% following 4 h of enzymatic treatment. Strength properties, such as the tensile, burst indices, and folding endurance, was improved during the xylanase assisted deinking of pulp. Hence, the present xylanase was found to be suitable for the biobleaching of newspaper waste via an eco-friendly process. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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.

Process waters in deinking mills often feature a strong coloration, due to dyes and pigments released from the recovered paper. This can usually be remediated by pulp bleaching treatment with appropriate chemicals. However, the red shade (from rhodamine dye) is resistant to conventional bleaching treatments. This largely limits the use of deinked pulp in white paper grades. In this review, the available technologies for process water decolorization are discussed (chemical methods, physico-chemical methods and biological treatments). Ozonation of the process water appears to be the most promising technique for decolorization of process water in deinking mills. Other emerging technologies such as photo-catalytic treatment or mineralization by white-rot fungi (after adsorption on low-cost agricultural residues) should be considered as well.

Enzymes are protein molecules with complex structures that accelerate the biochemical reactions. Activity of these chemical compounds is accomplished at limited range of pH, temperature and concentration. In this study, the effects of different concentrations of cellulose enzyme were investigated on deinking of old newsprint. Old newsprint (ONP) was repulped at 5% consistency for 10 minutes in disintegrator with total revolution number of 26500. Enzymatic treatments of recycled ONP pulp were done under constant conditions (10% consistency,treatment time of 15 minutes, pH range of 5-5.5) at different cellulose concentrations of 0.025, 0.05, 0.1 and 0.2% (based on oven-dry waste paper). The optical and physical properties of the standard paper (60g/m2) made at different concentrations of cellulose were evaluated in comparison with control pulp (untreated ONP pulp with cellulase). Overall, the results achieved by comparison the optical properties of the paper produced indicated that using cellulase in deinking of ONP led to increase the brightness and the yellowness and decrease the opacity. The brightness was improved to a maximum level of 47.5 ISO %, but the yellowness was decreased to a minimum level of 11.3 ISO %, while the brightness reduced and the yellowness increased at higher concentrations than 0.05% cellulase. The highest opacity of 99.3 ISO % was achieved using 0.1% cellulase even higher than control pulp. The results gained by comparison the physical properties of the paper showed that using cellulase resulted in decrease of paper calliper, air resistance and density and improve the freeness of pulp

In this study, deinking of waste newspaper was investigated by conventional and enzymatic methods. Conventional deinking was done in pulping times of 10, 20 and 30 minutes along with different processes of washing, flotation and combined washing/ flotation. Enzymatic deinking was accomplished at different charges of 0.025, 0.05, 0.1 and 0.2% cellulase enzyme (based on oven-dried waste paper), pulping times of 10,15 and 20 minutes, pH range of 5-5.5 along with one-stage washing process. Optimum compositions were selected from chemical and enzymatic treatments and then physical and mechanical properties of the paper produced in optimum conditions were compared. Achieved results from comparison of the physical properties of optimum chemical and enzymatic treatments showed that, the paper produced from deinked pulp by conventional method had higher calliper, bulk and porosity. Using of 0.1% cellulase resulted the papers with higher tensile and breaking length compared to chemical treatments. The papers could be produced with similar burst and tear indexes compared to chemical treatments using of 0.1% cellulose, as well.

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.

In this study, Deinking of old newspaper was investigated by chemical and enzymatic methods. Chemical treatment was done using chemicals at different times of 10, 20 and 30 minutes, consistency of 10%, temperature of 50±1!C along with washing, flotation and combination of washing/flotation. While, Enzymatic treatment was accomplished at different concentrations of 0.025, 0.05, 0.1 and 0.2% of cellulase enzyme (on the basis of oven dried waste paper), pH range of 5-5.5, different times of 10,15 and 20 minutes, consistency of 10%, temperature of 50±1!C along with washing. The results comparison of optimum chemical and enzymatic treatments showed that, deinked pulp by chemical method had higher brightness and yellowness. Also, deinked pulp by chemical method resulted the papers with higher bulk, higher caliper and higher air resistance.

The pulp and paper industry has started applying new, ecologically sound technology (biotechnology) in its manufacturing processes. Many interesting enzymatic applications have been proposed. Implemented technologies tend to change the existing industrial process as little as possible. Enzymes have great potentials in solving many problems associated with the use of recycled fiber, especially related to deinking, drainability, hornification, refining, and stickies. Based on the promising results of mill-scale trials, several mills in the world have started using enzymes for deinking. The potentials of cellulase enzymes have also been demonstrated for reducing the energy requirement in pulp refining, improving the machine runnability and stickies control when using recycled fiber. They have the important benefits in that they can be considered a “green” product. They are natural occurring compounds with little adverse impact on the environment. This paper deals with the importance of recycling of paper, problems associated with the recycling, and potentials of enzymes in solving these problems. A few case studies have also been included.

The effect of refining of recycled pulp on the optical, physical and mechanical properties of paper was investigated.The results showed that, except tear strength, all of mechanical strength of paper significantly increases by refining.While, by refining of recycled pulp the brightness increases but the opacity decreases.Also, caliper and roughness of paper decreases.Refining of recycled pulp result in increasing Porosity.