Chemical Deinking Research Articles

Recycling of printed Xerographic paper using Aspergillus assiutensis enzyme cocktail: an integrated approach to sustainable development.

To overcome the human and animal survivability risk, sustainable development is the only option on earth that can be achieved through the maximum use of renewable environmental resources. Recycling of waste paper is an emerging waste management approach to conserve natural resources. Herein, we studied enzyme-mediated process to recycle the xerographic paper by using the crude fungal extract from indigenously isolated fungi identified asAspergillus assiutensis. The fungal enzyme cocktail has been characterized for the production of multiple enzymes namely cellulase, amylase, xylanase, pectinase, and protease. All these enzymes have pH optima in the acidic range and except cellulase and all the enzymes are stable from 10 to 80C. In the zymogram analysis, pectinase, xylanase, amylase, and cellulase were detected at 68kDa, ~ 54kDa, 38kDa, and 30kDa, respectively. Also, the presence of protease was confirmed by the clear zone at 68, 31, and 16kDa. A 26% decrease in the kappa number and reduction in Hex A of the pulp was observed on the treatment of the pulp with enzyme as compared to the control pulp without any treatment. The physical and chemical properties of the pulp were also improved by enzyme-mediated pulping as compared to the control The physiochemical parameter of the effluent like TDS was reduced (397ppm) significantly in comparison to chemical deinking process and it was within the permissible limit. BOD and alkalinity were reduced when the enzymes and chemical dosage were used in combination. These results indicate that chemi-enzymatic deinking is most promising to reduce or remove the pollution parameters including ink and this approach can be used in the paper and pulp industry for sustainable development.

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.

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.

Storage of Documents as a Function of Sustainability

Sustainability is a premise that has been implemented in all technologies, industries, and service activities to have as little impact on the environment as possible. Typography as a profession made its contribution by creating eco fonts. In each country, the law regulates the lifespan of the storage of everyday business documents. One of the ways to reduce the impact on the environment is to reduce the consumption of ink, which can be achieved by printing the document with more sustainable fonts. By using the mentioned fonts when creating documents, the user should not notice a visual difference, and the document should have the same level of readability. Earlier research on ecological standards was only related to the environmental acceptability of materials, i.e., inks or printing substrates. Using eco fonts, each ink can have a reduced environmental impact. The more environmentally friendly fonts, Ryman Eco and Ecofont Sans, were tested in this experiment. Arial as a standard sans serif font and Times New Roman as a standard serif font were used as reference fonts. In the research, coverage data of different document samples created with different types of typeface and spacing are interpreted to investigate the possibility of saving ink. As eco fonts have been used since the end of the previous and beginning of this century, some stored documents are certainly ready for waste management, which is almost always recycled. By recycling document samples, the optical characteristics of laboratory paper sheets obtained by chemical deinking flotation were investigated. Another aim of the investigation is to provide insight into the quality of recycled fibres after the recycling process.

Elucidating the potential of cellulases isolated from a locally isolated strain (NSF-2) in paper and pulp industry

The potential of enzyme cellulases which are known to all has made it pave its way in the field of present-day biotechnology and bio-based emerging industries. For the purpose of human consumption of enzymes, it makes it even more demanding to perform highly precised purification method. Our study deals with the characterization and applicability of cellulases fabricated by a locally isolated strain (NSF-2). The enzyme was purified using standard purification techniques. The isolated enzyme was observed to be of molecular weight 75KDa Purified enzyme showed the best activity at pH5, 50 °C and 3 % substrate concentration. The gene isolated from cellulase enzyme of about 1.2 Kb was amplified from selected isolate. Salts like SDS, urea, EDTA were perceived to have a regressive effect on enzyme activity while tween 20 and tween 100 were neutral towards enzyme. Hg2+ was found to be the most potent inhibitor and Ca2+ was found to be the most potent inhibitor and most significant activator of the enzyme respectively. The waste paper was deinked with isolated enzyme, sodium silicate (5 %) and NaOH (2 %). Various techniques like FTIR, SEM, fluorescence micrographs and fluorescence spectroscopy were performed to study the quality of the deinked paper. The results obtained for cellulase deinking were comparable to sodium silicate treatment but better as compared to NaOH treated paper. Although, the results of enzymatic deinking were similar to the results obtained in sodium silicate treatment but the enzymatic technology proved to be an advantageous technology as compared to chemical deinking as a reduction in dewatering step, declined chemical load in waste water, save capital cost and less energy consumption. The enzyme was found to be highly suitable for application in deinking industries which are in accordance with the observations.

Producing Direct Food Packaging Using Deinked Office Paper Grades—Deinkability and Food Contact Suitability Evaluation

Paper recycling is the most eco-efficient waste management option, since the use of recycled fibers reduces the need for virgin wood fiber and lowers energy consumption, and hence has a positive effect on the environment. The use of recycled paper is by far the highest in the packaging industry. In food packaging production, recycled paper is often favored over paper and board made from virgin fibers. However, due to the possible hazardous chemicals that can be found in recycled paper, there is a dilemma of how to overcome food safety issues while making food packaging more circular. The objective of the study was to determine if deinked office paper grades could be used as an alternative fiber source in the production of food packaging white top linerboards. For that purpose, three different types of digitally printed papers were submitted to a chemical deinking flotation in laboratory conditions, and the handsheets formed after each recycling trial were tested on the suitability for direct food contact. Evaluation of deinkability for each group of recycled prints was performed, as well. Deinkability was evaluated by calculating the flotation yield, pulp’s brightness and whiteness increase, ink elimination factor, determination of residual ink area, as well as ash content elimination. Food safety evaluation was performed by determining the content of heavy metals (Cd, Pb, Hg, and Cr VI), primary aromatic amines, diisopropylnaphthalenes (DIPN), phthalates, and polychlorinated biphenyls (PCB) from aqueous or organic solvent extracts of recycled paper pulp. The fastness of the fluorescent whitening agents was determined, as well. Of all evaluated deinking flotation efficiency parameters, only flotation yield and ash reduction by flotation were positively assessed. High content of residual ink particles detected after the flotation stage indicates that the flotation was not a successful method for the elimination of disintegrated ink particles, which was also confirmed by deficient results of ink elimination measurements and whiteness increase. Flotation proved to be the least efficient in the recycling of inkjet prints, where the lowest ink elimination, whiteness, and brightness values were achieved. As far as food safety assessment of deinked pulp is concerned, all tested deinked handsheets were found suitable to be used in direct contact with foods.

Partial purification of bacterial cellulo-xylanolytic enzymes and their application in deinking of photocopier waste paper

The potential of alkaline cellulo-xylanolytic enzymes from non-pathogenic Bacillus subtilis strain was tested for deinking of photocopier waste paper. Cellulase and xylanase play a crucial role in deinking of different types of waste paper. Partial purification of cellulo-xylanolytic enzymes was carried out using ultrafiltration followed by ammonium sulfate precipitation. The ultrafiltered enzyme was used for deinking the photocopier waste paper along with chemical deinking. An enzyme dose of 0.6 IU/g and reaction time of 60 min for ultrafiltered cellulo-xylanolytic enzyme significantly increased deinking efficiency, tear index (9.52%) and folding endurance (5±2%) as compared to chemical deinking. There was improvement in strength properties such as tear index and double-fold along with freeness of pulp (18%). There was slight decrease in tensile index (0.6%) and burst index (16%) while ISO brightness remained unaffected. Enzymatic deinking (74.3%) by ultrafiltered cellulo-xylanolytic from Bacillus subtilis was found significant over conventional chemical deinking.

PRODUCTION, OPTIMIZATION AND DEINKING CAPACITY OF ALKALINE CELLULASE PRODUCED FROM MUCOR CIRCINELLOIDES WSSDBS2F1

An alkaliphilic Mucor circinelloides WSSDBS2F1 strain, with the ability to produce endoglucanase and exoglucanase enzymes, was isolated from decomposing bagasse, originating from a sugar processing mill in Punjab, India, and then screened. A pH range of 7-11, temperature of 30-60 °C, incubation period of 4-12 days, different lignocellulosic waste and nitrogen sources were investigated for optimum production of cellulase enzyme. Response Surface Methodology (RSM) was the statistical tool used for optimization of endoglucanase and exoglucanase production, following the one-factor-at-a-time approach. The optimized endoglucanase was further evaluated for its ability to deink waste paper, compared to chemical deinking. It was found that the enzymatically deinked pulp had high ISO brightness, tensile, burst and tearing strength, as compared to chemically deinked and control pulps. Scanning electron microscopy and Fourier transform infrared spectroscopy (FTIR) were also used to confirm the action of the endoglucanase enzyme on waste paper.

A comparative study of conventional chemical deinking and environment-friendly bio-deinking of mixed office wastepaper

Bio-deinking is an environmentally friendly process that improves the pulp and paper properties and reduces chemical consumption during the recycling of waste paper. This study was performed to evaluate the efficacy of enzyme by Penicillium sp. AKB-24. Chemical deinking of MOW showed freeness (CSF), pulp brightness (ISO), deinking efficiency, and dirt count by 426±4 ml, 75.55±0.1%, 82.13±0.7%, and 733±24 mm2/m2 respectively at optimum repulping parameters. The physical strength properties including burst index, tear index, tensile index and double fold numbers were found 2.97±0.14 kPa.m2/g, 11.14±0.61 mN.m2/g, 46.60±1.99 N.m/g, and 36±2 respectively during chemical deinking of MOW. The deinking chemicals including NaOH, Na2SiO3, and H2O2 were replaced with crude enzyme by Penicillium sp. AKB-24 during enzymatic deinking of MOW. Enzymatic deinking of MOW resulted in an improvement in pulp freeness by 18.30% compared to chemical deinking while the dirt count value decreased by 32.60% during enzymatic deinking of MOW. Physical strength properties such as burst index, tensile index, and double fold numbers were improved by 16.07%, 14.54% and 8.57% respectively while tear index was decreased by 11.61% during enzymatic deinking of MOW compared to chemical deinking.

Effects of cellulase enzyme in deinking of Solvent-Based inks from mixed office wastes

The effects of cellulase enzymes (Trichoderma reesei) in flotation deinking of mixed office wastes (MOW) on the deinking efficiency, physical and optical properties of the papers were investigated. In order to determine the effects of cellulase, conventional chemical deinking was also performed and compared with enzymatic deinking. After deinking processes, the handsheets were produced to determine deinking efficiency and physical and optical properties. Dirt particle analyses, Effective Residual Ink Concentrations (ERIC) and deinking efficiency (IEERIC) were determined to clearly understand effects of cellulase on deinking of MOW. IEERIC values of papers obtained from enzymatic and chemical deinked pulps were 11.9 and 62.0%, respectively. Use of cellulase enzyme by itself was not as effective as conventional deinking. Furthermore, optical properties of enzymatic deinked papers were lower than those of chemical deinked papers. These negations were eliminated by combining enzymatic and chemical deinking processes. Chemical charge used in conventional deinking were reduced by half with using cellulase. Properties of papers obtained from this deinking process were better than both enzymatic and chemical ones. This suggests that using cellulase enzyme in deinking process of MOW have a great potential as an alternative to chemical conventional deinking per se.

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.

A cleaner process of deinking waste paper pulp using Pseudomonas mendocina ED9 lipase supplemented enzyme cocktail

Lipase enzyme has a critical role in deinking process along with other lignocellulosic enzymes. In this paper, we try to demonstrate the role of lipase in the enzyme cocktail used for enzymatic deinking. For this, we identified a potential lipolytic bacterium, Pseudomonas mendocina ED9 isolated from elephant dung with a molecular weight of 35kDa. During the Box-Benhken model optimization, a maximum lipase activity of 105.12U/g, which was 12.36-fold higher than the initial enzyme activity and 1.3-fold higher than the activity obtained during the Plackett Burman design, was achieved. A maximum lipase activity of 105.12U/g was obtained after optimization. Ammonium sulphate (60%) precipitation resulted in a specific activity of 68.19U/mg with a 1.4-fold purification and yield of 64%. Lipase from P. mendocina ED9 exhibited a Km of 0.5306mM and Vmax of 25.0237μmol/min/mg. A Δ brightness of approximately 14.5% were achieved during the enzymatic deinking using cocktail comprised of cellulase, xylanase and lipase. This reports the significant role and efficacy of lipase in enzyme cocktails for deinking applications. This formulation will reduce the pollution and environmental toxicity of conventional chemical 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.

An efficient eco-friendly approach for recycling of newspaper waste.

In this study, a chemical reduction strategy was explored for deinking of newspaper waste using xylano-pectinolytic catalysts. A remarkable reduction of 40% in toxic chemicals consumption was obtained by introducing this enzymatic approach of deinking along with improved level of various physical and optical properties. Similarly, a reduction of 18.89% and 17.68% in BOD, COD values of effluent has also been noticed. This combined deinking methodology also resulted in a gain of 5.82% in breaking length, 6.45% in tear factor, 8.57% in burst factor and 9.64% in viscosity, which greatly improved the quality of the handsheets. The study revealed that enzymatic deinking followed by chemical deinking with 40% less chemicals consumption, could be an effective method for reducing the negative impact over the environment caused by 100% deinking chemicals. This is the first report of newspaper waste deinking using xylano-pectinolytic catalysts produced concurrently in the same production media by a bacterial isolate using agricultural wastes as carbon sources.

Laccase based de-inking of mixed office waste and evaluation of its impact on physico-optical properties of recycled fiber

The de-inking ability of the crude laccase (benzenediol: oxygen oxidoreductase, EC 1.10.3.2) produced by a white rot fungus Peniophora sp. (NFCCI-2131) was tested using mixed office waste paper. In addition, the impact on physical and optical properties of the de-inked pulp, and the chemical load of the effluent generated during laccase based de-inking process was also analyzed. In the present study, 2.5 U/ml laccase was produced by the fungus under submerged culture conditions. Laccase (10 U/g of air dried pulp) was found to improve the tensile strength of recycled pulp by 1.7-fold, de-inking efficiency by 1.5-fold, opacity by 3.84%, and brightness by 5.83%. Scanning electron microscopy analysis revealed less rupturing of cellulose fibers and increased detachment of ink particles from the surface of the fibers in comparison to chemical de-inking. Fourier-transform infrared spectroscopy analysis of laccase treated pulp revealed degradation of the guaiacyl group and a high degree of deformation in methyl group of lignin. The biochemical and chemical oxygen demand (BOD and COD) were found to be reduced by 52 and 36% respectively, in the effluent generated after crude laccase based de-inking of mixed office waste.

Studies on the environmentally friendly deinking process employing biological enzymes and composite surfactant

In this study, biodegradable cardanol polyoxyethylene ether (CPE) was applied to the field of flotation deinking of mixed office waste paper (MOW), and its combination with fatty alcohol polyoxyethylene ether (AEO-9), fatty alcohol polyoxyethylene ether sulfate (AES) as a composite surfactant was also investigated for a green deinking process. The prepared composite surfactant was applied to the traditional alkaline chemical deinking. Moreover, the effect of cutinase on the deinking of MOW was also evaluated for the first time. Cutinases and amylases combined with the previously employed complicated surfactants were utilized to replace traditional chemicals for neutral deinking. The deinking effect and the environmental impact of these two deinking methods were evaluated in detail. The results showed that the surfactant composed of CPE/AEO-9/AES with a mass ratio of 1:1:1 can be used in traditional alkaline deinking, which could effectively improve the deinking pulp quality. Moreover, cutinase/amylase/surfactants deinking system could further enhance the deinking pulp quality. When pulped mixed office waste paper was treated with 0.2% of surfactants, 10 U g−1 of cutinase, 5 U g−1 of amylase at 50 °C for 30 min, the brightness of the deinked papers reached 92.24% ISO with an ink removal rate of 92.63%, tensile index of 24.83 N m g−1, and tear index of 9.48 mN m2 g−1. According to this study, cutinase and amylase combined with cardanol polyoxyethylene ether and other surfactants provide an environmentally friendly and effective deinking strategy.

Biodeinking of mixed ONP and OMG waste papers with cellulase

Development of qualitative properties and surface modification of mixed recycled 70% old newspaper and 30% old magazine pulp after enzymatic treatment with commercial cellulase was evaluated. The results of the present research demonstrated that the quality of the pulp and paper obtained from cellulase deinking process was comparable or even better than that from the chemical deinking. Under mild conditions of cellulase deinking (charge of 0.025–0.1% and duration time of 20 min, the paper with similar opacity as well as the increased brightness and whiteness values were obtained in comparison with non treated pulp or chemical one. Increasing reaction time to 30 min (at higher levels than 0.25% cellulase) and also enhancing the charge of cellulase to more than 0.1% (at different reaction times) were not advisable due to weak optical features of paper produced. The highest deinking efficiencies of 11.77 and 10.04% were obtained in enzymatic runs with cellulase (C2T2 and C1T3, respectively) but it was 9.3% for chemical deinking process (run of Cc). Increase in duration from 10 to 30 min at the maximum cellulase charge (0.2%) has been negatively influenced tensile index, breaking length, stretch and stiffness. In general, the best strength properties were obtained at middle charges of cellulase (0.025–0.05%) and duration times of 10–20 min. All strength characteristics were severely declined for run C4T3 (charge 0.2% and reaction time of 30 min). Run of C3T2 (charge 0.1% and reaction time of 20 min) was resulted in the higher tensile index (by 22%), stretch (by 9%) and stiffness (by 42%) compared to chemically deinked pulp. Cellulose crystallinity obtained by FTIR and XRD spectra was remarkably increased up to 0.2% cellulase but reduced severely at higher charges than 0.2% cellulase which implied declining the strength properties. In addition, FESEM micrographs of recycled fibers treated at different cellulase charge and duration times revealed surface modification and morphological changes like external fibrillation, peeling, fine production as well as rougher fiber surface due to cellulase act on the fiber surface. With increasing enzyme charge and duration time to some extent, fiber fibrillation have been developed and appearing much fibrils may result in the increased hydrogen bonding, number and contact area between fibers and consequently paper strength properties. However in harsh conditions particularly higher cellulase charges, the fiber structure is degraded, more fines appeared on fiber surface and strength properties are declined (especially tear resistance) due to a possible reduction in average fiber length.

Safety Evaluation of Deinked Pulp Containing Offset Thermochromic Inks

Evaluating the safety of thermochromic inks for offset lithography in deinked pulp samples is a major area of investigation. In this study, three offset inks were analyzed – one that dries by absorption and two that dry by oxypolymerization of vegetable oils. Inks were printed separately on strips of white uncoated paper, and the prints were recycled by chemical deinking flotation. Thermochromic inks, handsheets, filter pads, and process waters obtained from deinking were tested for the presence of heavy metals, while concentrations of bisphenol A (BPA), total organic compounds, and antimicrobial agents were examined in handsheets and filter pads. The concentration of heavy metals cations was determined from ashes of undeinked and deinked pulp handsheets as well as from ashes of blank paper, flotation froth, and process water filtrates. BPA originates from thermochromic inks, and a 50% reduction of BPA was noticed in the samples after flotation. Considering the results, deinked pulp is undesirable due to the presence of BPA. Despite the presence of BPA, there was no release of toxic components from deinked pulp.

Comparison of cutinases in enzymic deinking of old newsprint

In this study, the impact of cutinases from Thermobifida fusca and Fusarium solani pisi on the deinking of old newsprint were evaluated for the first time. When repulped old newsprint was treated with 8 U/g of T. fusca cutinase at pH 8 and 60 $$^{\circ }$$ C for 30 min, the brightness of the deinked papers reached 42.01%. With 8 U/g F. solani cutinase at pH 8.5 and 35 $$^{\circ }$$ C for 30 min, the brightness reached 41.62%. These brightness values are higher than that achieved using chemical deinking by 5.13 and 4.38%, respectively. These brightness values were also superior to that achieved using commercial lipase in this study and those previously reported using cellulases, hemicellulases, and laccase, which were higher than that achieved using chemical deinking by 2–4%. The mechanical properties of the deinked paper, including tensile index, tear index, and burst index, were also measured. The results showed that the two cutinases had different effects on the paper fibers. In summary, both T. fusca and F. solani pisi cutinases were able to remove ink from old newsprint more efficiently than alkaline chemistry or other enzymes. This study provides a potential strategy to deink efficiently old newsprint using cutinase.

Deinkability of thermochromic offset inks

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.