Removal of fillers and chemical reagents from waste paper for its sustainable use

Vol.:(0123456789) Environmental Science and Pollution Research https://doi.org/10.1007/s11356-025-37133-5 RESEARCH ARTICLE Removal offillers andchemical reagents fromwaste paper forits sustainable use MarekKucbel1 · HelenaRaclavská1· JanaRůžičková1· MichalŠafář1· PavelKantor1· KarolinaSlamová2· JarmilaDrozdová3 Received: 25 March 2025 / Accepted: 21 October 2025 © The Author(s) 2025 Abstract Waste paper represents a valuable secondary source of cellulose fibres, contributing to the reduction of virgin wood consumption in paper production. To support sustainable development objectives, the integration of natural fibres with synthetic polymers is increasingly explored across industrial sectors. Reliable use of waste paper materials requires baseline data on pollutant content and migration potential. In this study, cellulose fibres were separated using 0.2M acetic acid (CH3COOH) extraction, followed by washing. This method effectively removed precipitated calcium carbonate-based filler from office paper, achieving an extraction efficiency of 86%. A total of 138 compounds were identified in waste paper, originating from: virgin wood (n = 31), paper manufacturing and recycling processes (n = 19 + 15 fragrance compounds), and printing inks (n = 67), with solvents (n = 25) forming the largest subgroup. Additional substances were associated with surface treatments and ink formulations. Compound hazard profiles were assessed using the Globally Harmonized System (GHS). The identified substances were, among others, persistent organic pollutants, including benzophenone, butylated hydroxytoluene, and bis(2-ethylhexyl) phthalate, bisphenol A, and bisphenol S, while solvents exhibited the highest proportion of hazardous classifications. Following CH3COOH extraction, concentrations of hazardous solvents were reduced by 93%, indicating the method’s potential for pollutant mitigation in fibre recovery. Keywords Waste office paper· Cellulose fibres· Precipitated calcium carbonate· Organic pollutants· Health hazards Abbreviations AT Acute toxicity BD 1,3-Butadiene BHT Butylated hydroxytoluene BPA Bisphenol A CIS Cooled injection system CMC Carboxymethyl cellulose CNs Cellulose nanocrystals DEHP Bis(2-ethylhexyl) phthalate DEHT Bis(2-ethylhexyl) terephthalate DiBP Dibutyl phthalate DINP 2,6-Diisopropylnaphthalene DOIP Bis(2-ethylhexyl) ester 1,3-benzenedicarboxylic acid Responsible Editor: Weiming Zhang * Marek Kucbel [email protected] Helena Raclavská [email protected] Jana Růžičková [email protected] Michal Šafář [email protected] Pavel Kantor pav[email protected] Karolina Slamová [email protected] Jarmila Drozdová drozdo[email protected]stecb.cz 1 CEET/ENET Centre, VSB–Technical University ofOstrava, 17. listopadu 15/2172, Ostrava-Poruba70800, CzechRepublic 2 Institute ofForeign Languages, VSB–Technical University ofOstrava, 17. listopadu 15/2172, Ostrava-Poruba70800, CzechRepublic 3 Department ofMechanical Engineering, Faculty ofTechnology, Institute ofTechnology andBusiness inČeské Budějovice, Okružní 517/10, ČeskéBudějovice37001, CzechRepublic Environmental Science and Pollution Research EH Environmental hazards EuPIA European Printing Ink Association GHS Globally Harmonized System of Classification and Labelling of Chemicals HH Health hazards I Irritant KODAFLEX TXIB 2,2,4-Trimethyl-1,3-pentanediol diisobutyrate OP Office paper PAC Polyaluminium chloride PCC Precipitated calcium carbonate PES Polyester PPCs Plant fibre/plastic composites STD Standard deviation stickies Organic sticky contaminants US EPA United States Environmental Protection Agency UV Ultraviolet Introduction In the Czech Republic, 40–50 kg of waste paper is produced per person/year. According to Milbrandt etal. (2024), the largest share of the waste paper is achieved by cardboard (44%); compostable paper, food-soiled paper products, towels, and napkins (21%); other papers, books and aseptic containers (18%); newspapers (6%); high-grade office paper (6%); and journals (5%). Increasing paper consumption produces more waste paper. Thus, the extraction of pulp from paper waste can reduce negative impacts on forest ecosystems (Hanafiah etal. 2019). Waste paper is a significant raw material whose value can be efficiently increased according to the rules of the circular economy. While the largest proportion of recycled cellulose fibres is still used for paper production and products (for example, pressed fibres), a sharp increase has been seen mainly in biodegradable food transport packaging (Andrade etal. 2022) based on plant fibre/ plastic composites (PPCs). The potential safety risk of plant fibres is the crucial distinction between PPCs and common plastic materials (Zhang And Weng 2021). Despite the rapid development of technologies for processing cellulose fibres and cellulose nanocrystals (CNs) in the packaging industry, there are some doubts about the safety of these products made from waste cellulose fibres in connection with releasing volatile migrants from packaging or printing (An etal. 2024). However, systematic research on migration methods and safety assessment is still insufficient, and further studies are needed regarding the main safety risks and migration patterns. For further utilization of cellulose fibres, their quality is a determining factor. Standard technologies for recovering cellulose fibres from waste paper include disintegration using sodium hydroxide (NaOH), followed by coarse screening of mechanical impurities and a deinking process involving flotation and washing. Flotation enables the removal of fillers and inks, while washing eliminates residual microparticles from the suspension. These procedures may be modified through enzymatic treatment (Singh etal. 2020) and thermomechanical dispersion. However, when removing fillers, especially precipitated calcium carbonate (PCC), flotation may not be sufficiently effective. PCC particles are typically smaller than 5 µm, which is below the optimal separation range of flotation. In addition, PCC is hydrophilic and therefore poorly adheres to air bubbles; this limitation, however, can be overcome with the use of collectors (Hubbe And Gill 2016). The choice of chemical reagent depends on the intended application of the cellulose fibres. Strong acids such as hydrochloric acid (HCl) cause hydrolysis of glycosidic bonds within cellulose, leading to fibre shortening and reduced crystallinity, particularly in amorphous regions (Habibi etal. 2010). In contrast, low concentrations of acetic acid do not affect the crystalline structure of cellulose, nor do they result in acetylation (Hu etal. 2018). Acetic acid was therefore selected for its gentle effect on the fibres and its selective reactivity with PCC. The reaction yields soluble calcium acetate, which can be easily removed by washing. This approach minimizes both the risk of cellulose degradation and the technological and environmental concerns associated with the use of aggressive mineral acids. In addition to the standard recycling of waste paper, the subject of interest is increasing its value in the form of new products, such as the production of cellulose nanocrystals (CNs). Many reactive chemical groups are present on the surface of CNs, allowing physical adsorption, surface modification, and chemical vapour deposition. This ensures the use of CNs in a wide range of applications, both in their original state and based on other chemical modifications (Rashid etal. 2023). These properties make it possible for them to be applied extensively in the industry, including construction, cuisine, telecommunications, the automotive industry, medication, the cosmetic industry, and the production of carbon nanotubes, representing another rod-shaped nanomaterial with excellent mechanical and electrical conductivity performance (Yang etal. 2022; Mohammad Firman etal. 2023). In the environment, CNs are used as the hybrid bio-sponge sorbent with magnetic bimetallic Fe3O4@ TiO2 for coloured water treatment and oil–water separation (Assanvo etal. 2023). Moreover, CNs and CNFs have been widely investigated for wastewater remediation due to their high surface area and the possibility of changing the surface chemistry. Functionalized nanocellulose has shown excellent sorption capacity for heavy metals (e.g. Pb2+, Cr6+, and Cd2+), dyes, pesticides, and oil residues. Forms such Environmental Science and Pollution Research as aerogels, membranes, and hydrogels have been applied in various water purification strategies (Abdelhamid 2024; Yang etal. 2024). There is increasing use of environmentally sustainable products based on the use of cellulose fibres in the construction industry, where bio-compound (natural fibre) has the function of reinforcement in polymer matrix composites as it increases the mechanical strength of composites (Uppal etal. 2022). Cellulose fibres have recently been used in soil protection against erosion (Ishak etal. 2021) or in the production of hydrogels, which have a hydrophilic structure with the ability to retain large amounts of water within their three-dimensional networks (Ioelovich 2021). The hydrogels have a more comprehensive application; they can be used in biomedicine, hygiene, pharmaceutics, food processing, chemistry, physical chemistry, water purification, agriculture, and other areas. Cellulose fibres obtained from waste paper may be contaminated with additives that are used in paper production or are part of printing inks and adhesives. A higher degree of evaluation of cellulose fibres requires their higher purity (Pivnenko etal. 2015). Up to 348 compounds that may be present in paper material are listed in the literature (Pivnenko etal. 2016). Up to 157 potentially hazardous compounds may be present in paper material. A total of 133 chemical substances have been assigned to the printing industry, the majority of which are solvents and polymer resins used in inks, pigments, and dyes. Chemical compounds that cannot be assigned to either paper production or the printing industry could potentially be by-products or contaminants introduced into the production cycle through recycled paper (Pivnenko etal. 2016). Information on the occurrence of pollutants in waste paper should be crucial in deciding how to further apply the cellulose fibres used, especially considering their potential use for the food packaging industry. There is a lack of published data on the ability of weak organic acids to target additives used in paper production. Our findings are supported by the results of Lee etal. (2011), Singh etal. (2020), and Itkor etal. (2024), all of which confirm that mild acids alone are capable of significantly reducing additive content in separated cellulose fibres. The article aims to identify compounds that occur in waste paper and come from virgin wood (e.g. pesticides) or paper production technology, as well as the use of printing inks. It can provide the missing information on the potential risks involved in using cellulose fibres from waste paper. The second objective was to assess the impact of removing calcium carbonate on the quality of the cellulose fibres from the point of view of their further potential use. The originality of this research lies in the systematic identification of a broad spectrum of organic pollutants present in waste paper and the verification of an extraction method capable of removing hazardous compounds effectively, without deteriorating the quality of cellulose fibres. Through the application of TD-GC/MS and acetic acid treatment, the study uncovers previously undetectable compounds embedded within the paper matrix. It confirms their origin from printing inks and virgin wood. This approach demonstrates that waste paper, particularly office paper, can be transformed into a highly pure cellulose source suitable for further technological use. The work contributes new evidence supporting sustainable paper decontamination and offers an analytically supported method to improve recyclability and safety in circular material flows. Materials andmethods Materials andtheir pre‑treatment forfurther analysis Separated samples of waste paper (office paper, magazines, and cardboard) were obtained from Smolo Co., a company specializing in waste management. Three samples collected at 1-month intervals were analysed. Three office paper samples were collected at monthly intervals from the shredding facility operated by Archivace Skartace Co. in Ostrava, which provides paper shredding services within the city (Moravian-Silesian Region, Czech Republic). This company processes approximately 540 tonnes of office paper annually. During each sampling session, 100 kg of waste office paper was collected and reduced on-site to a final weight of 10 kg. The sample was then transported to the laboratory, where it was quartered to the required weight of 1 kg (Hennebert And Beggio 2021). These prepared samples were used for chemical analysis and cellulose fibre separation. Samples of magazines, cardboard, and mixed paper were obtained from the sorting line operated by Smolo Co. The sorting line produces approximately 150 kg/h of cardboard, 7.5 kg/h of magazine paper, and 30 kg/h of mixed paper. On a single day, 120 kg of cardboard, 24 kg of mixed paper, and 10 kg of magazine paper were collected. Sampling was conducted three times. After collection, cardboard and mixed paper samples were shredded to obtain 10 kg portions. The magazine paper was not quartered. The chemical analysis results reported represent the average values obtained from three independent samples. Waste paper samples were cut into smaller pieces (approximately 1 cm). To decompose carbonates, a mixture of 20 g of office paper and 500 mL of 0.2 M CH₃COOH was prepared. The use of acetic acid does not represent a novel extraction method; however, it is well documented that this approach enables the recovery of cellulosic fibres with minimal damage, specifically, without significant loss Environmental Science and Pollution Research of crystallinity or cleavage of glycosidic bonds. Importantly, acetic acid allows for the simultaneous removal of both PCC and organic additives, without compromising the cellulose structure. In contrast, traditional acid or alkaline treatments (e.g. NaOH and HCl) often exhibit limitations in selectively removing both fillers and additives while preserving fibre integrity. The sample of waste paper was disintegrated for 1 min using the Vorwerk Thermomix TM6 (Vorwerk Engineering, Wuppertal, Germany) and then separated in a centrifuge (Beckman Avanti JXN-26, Beckman Coulter, Brea, California) at 8000 rpm. The acid–base reaction of the solution was determined according to ISO 10523 (International Organization for Standardization 2008). Calcium ion concentration (Ca2⁺, mg/L) was analysed following ISO 6058 (International Organization for Standardization 1984). The cellulose sample was subsequently rinsed with 500 mL of deionized water (once or twice). The selection of a suitable extraction agent and its concentration (HCl, H₃PO₄, and CH₃COOH) was based on the studies by Phipps and Lorusso (2001) and Kim and Kim (2018). Methods The ASTM E1755-01(2020) “Standard Test Method for Ash in Biomass” (oxidation at 575 ± 25 °C) was applied (ASTM International 2020). This method is suitable for determining ash content in materials such as office waste, boxboard, and newsprint. Moisture content was determined according to ISO 18134-3:2023 (International Organization for Standardization 2023). The calcium (Ca) concentration in both embossed cellulose and waste paper was measured using the US EPA Method 6200, “Field Portable X-ray Fluorescence Spectroscopy for the Determination of Elemental Concentrations in Soil and Sediments,” employing the Innov-X Delta Professional analyzer (Olympus Innov-X, USA). Identifying minerals in ash and the character of cellulose fibres was performed using the auto-emission scanning electron microscope FEI Quanta-650 FEG (manufactured by FEI Co., Hillsboro, USA). The mineralogical phase composition of fillers was analysed by X-ray diffraction (Bruker Advance D8 X-ray diffractometer). The chemical composition and crystallinity of the separated cellulose were analysed using a Fourier transform infrared (FTIR) spectrometer (FT-IR Nicolet 6700, Thermo Scientific). Measurements were conducted using the attenuated total reflectance (ATR) technique across a spectral range of 4000 to 525 cm⁻1, with a resolution of 4 cm⁻1. Each sample was scanned 64 times, and the resulting spectra were compared to assess structural differences and compositional features. The TD-GC/MS method (Gerstel, Mülheim an der Ruhr, Germany) was used for the identification of organic compounds in the feedstock. A sample of 300 µg of paper/ cardboard/magazine was placed into a glass sampling tube along with an internal standard (1,3,5-tri-tert-butylbenzene). Thermal desorption was performed using a unit (Gerstel, Mülheim an der Ruhr, Germany) in the temperature range 50 to 300 °C for 5 min, with a heating rate of 60 °C/min. Volatilized organic compounds were concentrated in a cooled injection system (CIS) at − 10 °C and subsequently separated on a non-polar HP5 ms column (60 m × 0.25 mm × 0.25 µm) under a temperature programme: 40 °C (2 min) to 310 °C (10 min), at a rate of 10 °C/min. Identification and quantification of organic compounds were performed using a mass spectrometer (Agilent 5977 B, Santa Clara, USA) within a scan range of m/z 50–650, using external calibration with certified standards. GC/MS quantification of compounds was performed by external standards with the addition of 1 µl of internal standard (1,3,5-tri-tert-butylbenzene) by the calibration curve method. The construction of calibration curves was carried out by the program Mass Hunter-MS Quantification. Processing ofresults fromTD‑GC/MS A comprehensive search of the literature, PubChem databases, and additional online sources was conducted to identify the origin of the detected compounds. This included information from the “European Printing Ink Association (EuPIA), Inventory List – Version January 2011,” which catalogues packaging ink raw materials applied to the nonfood contact surfaces of food packaging. The potential hazards of the identified compounds were assessed according to the “Globally Harmonized System of Classification and Labelling of Chemicals” (GHS Rev. 10, 2023), a guideline for the classification and labelling of hazardous substances. To characterize the broadest possible range of identified chemical compounds, the use of GHS hazard categories was selected as the only viable and consistent method for communicating their potential risks across international datasets, since GHS-based databases contain information on hundreds of thousands of substances, including many that are not registered in the EU. This approach allowed us to retrieve relevant hazard data for a large number of organic compounds. For each compound, hazard information from the PubChem database was consulted, with emphasis on the GHS hazard statements: health risks, environmental risks, and irritants—the latter being considered part of health risks. Classification into hazard categories was performed using the comprehensive category system provided by the United Nations Economic Commission for Europe. In cases where a compound was associated with risks in all three categories, only one hazard class was reported, following a predefined prioritization: health risks > environmental risks > irritants. Environmental Science and Pollution Research Results Paper composition A wide variety of chemicals are used in paper production, selected to optimize paper properties and maximize production efficiency while complying with environmental regulations. The specific grade of paper being produced also influences chemical selection. One strategy for promoting environmental sustainability in the paper industry involves creating a novel composite material by combining paper with polyester, including the potential use of waste products (Sheeju Selva Roji etal. 2024). The incorporation of short-cut polyester fibres (polyethylene terephthalate) enhances the wet strength of the paper, enabling its use in high-humidity environments without disintegration. This polyester addition facilitates the production of fibrereinforced paper, commonly used in cardboard boxes and paper bags. In order to improve adhesion between cellulose and synthetic fibres, a vinyl-acrylic binder is applied. Furthermore, when paper is used as a packaging material, its hydrophobic properties are of particular importance. These can be achieved through surface treatment with silane-modified starch (Manoharan etal. 2021; Majka etal. 2023). The properties of paper are also influenced by the presence of residual extractives and adhesive substances known as “stickies.” In addition to the primary components—hemicellulose, cellulose, and lignin—wood contains a range of extractives. The proportion of these major components varies depending on the paper type. For office paper, cellulose ranges from 61.8% to 79.2%, hemicellulose from 3.5% to 12.6%, and lignin from 2.0% to 9.2% (De Oliveira etal. 2023). In cardboard, the cellulose content is lower (56.9%), while lignin is higher, up to 17.8%, and hemicellulose accounts for approximately 10.7% (Vukoje and Rožić 2018). Extractives typically represent 2–5% of softwood composition and include waxes, fats, terpenes and terpenoids, fatty acids (e.g. palmitic and stearic acids), monosaccharides, alkaloids, and phenolic compounds such as simple phenols, lignans, flavonoids, tannins, and stilbenes (N’Guessan etal. 2023). The presence of extractives is known to diminish pulp quality. These compounds are soluble in various neutral solvents. Depending on the pulping technology used, up to 85% of extractives may be removed during processing (Lehr etal. 2021). Organic sticky contaminants affect both the papermaking process and the quality of the final paper product. These contaminants—including polyvinyl acetate polymers, styrene-butadiene rubber, polyamines, and paraffin waxes derived from wood extractives—vary depending on the paper grade (Wang etal. 2023). They originate primarily from the addition of coating binders during production, but may also come from recycled paper containing printing inks, such as styrene-butadiene rubber and polyvinyl acrylate. Odorous compounds can arise during both the technological processing of paper and its ageing. The papermaking process occurs in a moist and temperature-sufficient environment rich in nutrients. The increased use of recycled paper contributes to these conditions, promoting microbial development. Recycled fibres often contain residues from sizing agents, coatings, starches, polymers, and adhesives, all of which are nutrientrich (Czerny And Buettner 2009). Anaerobic decomposition of these compounds leads to the formation of volatile fatty acids, which are major contributors to unpleasant odours. To suppress microbial growth and mitigate odour, biocidal agents are introduced, including essential oils that not only provide fragrance but also possess antibacterial properties. Odour-inducing compounds may be released as a result of microbial degradation of lignin and the autooxidation of cardboard. These include odour-active aldehydes such as hexanal, heptanal, octanal, and nonanal (Czerny And Buettner 2009). Paper degradation caused by natural ageing leads to the formation of low molecular weight compounds, including, among others, formic, acetic, lactic, propionic, and levulinic acids (Jablonsky etal. 2012), which also contribute to odour emissions. Another source of odour precursors may be unsaturated lipids present in cardboard used for food packaging. Ultraviolet (UV) curable inks containing photoinitiators are commonly applied in the printing of cellulose-based packaging materials (Pugh And Guthrie 2000), influencing the rate and extent of lipid oxidation. Fragrances are incorporated to prevent the spread of unpleasant odours associated with paper ageing, food storage, or during the manufacturing of scented paper products. Scent can be added by embedding solid or liquid fragrances during the papermaking process, by introducing fragranceloaded nano/microspheres directly into the pulp, or through microencapsulation, whereby encapsulated compounds are adsorbed onto the paper surface (Rungwasantisuk And Raibhu 2020). Common encapsulated fragrance agents include lavender essential oil, vanillin, citronella oil, and orange oil. These are delivered using carriers such as chitosan, carboxymethylcellulose, or the triblock copolymer polyethylene oxide–polypropylene glycol–polyethylene oxide (PEO–PPO–PEO). Recently, encapsulated fragrances with antibacterial properties have also been introduced into paper products (Perinelli etal. 2020). Fillers The most common fillers in paper production are minerals, either of natural origin or produced synthetically. Calcite is Environmental Science and Pollution Research widely used as a filler, available both in its natural form and as synthetic precipitated calcium carbonate (PCC). Fillers are incorporated into cellulose fibres at the early stage of the papermaking process. The quantity of filler used depends on the intended application of the paper. For office paper, filler content typically ranges between 5 and 30%. For PCC specifically, the recommended maximum concentration is 20–25%, depending on the paper grade (Dölle 2021). Notably, certain products, such as Kleenex, contain no fillers at all. When fillers are used as substitutes for cellulose fibres, several advantages are commonly cited: reduced consumption of natural fibres, lower drying energy costs, and modified paper properties. Incorporating fillers enhances brightness and opacity due to their particle size characteristics. Depending on the polymorphous phase contained in PCC, fillers can affect friction and pore size (Hubbe And Gill 2016), as well as surface smoothness and ink absorption in papermaking (Jimoh etal. 2018). Beyond their role as fillers, PCC is also utilized as a coating material. For effective performance in paper production, calcite should exhibit a highly uniform particle size distribution. At least 75 wt.% of particles should have a diameter below 1 μm for coatings, or below 5 μm when used as fillers (Dhar etal. 2020). The particle size of PCC can be reduced through the addition of organic compounds, such as ethylene glycols, which also promote the formation of highly aggregated crystals (Konopacka-Łyskawa etal. 2017). PCC modification is carried out using chemical agents like chitosan, acetic acid, carboxymethyl cellulose (CMC), and alum (Al2(SO4)3·nH2O), improving physical characteristics (Jimoh etal. 2018; Ghosh etal. 2020). Alterations in crystal morphology have also been achieved using ammonium carbamate and urea (Liendo etal. 2022). The use of CMC and polyaluminium chloride (PAC) for encapsulating PCC fillers has been shown to enhance paper properties, particularly brightness and opacity (Mousavipazhouh etal. 2018). Differences in mineralogical composition and filler content are presented in Table1, with filler proportions corresponding to the measured ash content (Fig.1). All three forms of calcium carbonate are employed in office paper production. In journal-grade papers, synthetic dicalcium silicate derived from fly ash has emerged as a significant filler component, recently introduced to the paper industry, particularly for high-quality applications (Song etal. 2018; Qiu etal. 2020). Printing inks Modern printing inks typically consist of pigments (5–30%); binders (15–50%), which may include oils, resins, or various types of varnishes; solvents (15–65%); and excipients (< 10%) such as drying agents, chelating compounds, and other additives that influence ink properties. Common chemicals found in printing inks include 1-octane, 2-butanone, butyl acetate, citric acid, cyclohexanone, dichloromethane, ethyl acetate, ethylene glycol, gum arabic, isopropanol, methyl isobutyl ketone (used as dilution solvents), n-heptane, organic pigments, phthalate esters, polybutylene terephthalate resin, soybean oil, toluene, xylene, and polyvinyl acetate (used as adhesives and glues) (Tsai etal. Fig. 1 Ash (dicalcium silicate) after combustion of journals at 815 °C (a); ash (micro-calcite) after combustion of office paper (b) Environmental Science and Pollution Research 2016). Enhancements in ink adhesion and overall printing performance can be achieved through the incorporation of polyurethane-based polymers (Liu etal. 2022). Separation ofcellulose fibres andtheir basic characterization Waste paper cellulose is typically obtained through a combination of chemical and mechanical processes. The three most commonly used methods include pre-hydrolysis (using either alkali or mineral acid), alkaline pulping (typically with NaOH), and subsequent bleaching using hydrogen peroxide (H2O2) or sodium hypochlorite (NaOCl) (Hanafiah etal. 2019; Gunjan etal. 2023). These conventional processes are technically demanding; therefore, in our study, we opted for a simpler approach: releasing cellulose fibres by dissolving the filler material, PCC. Precipitated calcium carbonate, a synthetically produced filler commonly present in waste paper, exhibits properties distinct from those of natural calcite. It contains all three polymorphous modifications of calcium carbonate: calcite + aragonite + vaterite. Recent studies highlight PCC’s higher purity, controlled morphology, and surface modifiability, making it more suitable for industrial processing and the effective release of cellulose fibres (Kim etal. 2021). Given these differences, our research focused on identifying the most effective dissolution method to release the embedded cellulose fibres. Mineralogical analysis of office paper (Table1) confirms that the filler consists exclusively of various crystalline forms of calcium carbonate (CaCO₃), which are soluble in slightly acidic environments. The dissolution of calcium occurs according to the reactions described in Eqs. (1–4) Phipps and Lorusso (2001): (1) CaCO 3(s) ↔Ca2+(aq) + CO2− 3 (aq) Kso = [Ca 2+ ][CO 2− 3 ] The amount of calcium (Ca) extracted depends on several factors, including solvent type and concentration, particle size, and the solid-to-liquid (S/L) ratio. For paper sludge, Ca concentration in solution increased up to pH 5.5, where maximum leachability was observed, reaching 54% when using 0.7 M HCl or CH3COOH at an S/L ratio of 1:25 (Kim and Kim 2018). In the case of office paper leaching, hydrochloric acid (HCl) concentrations above 0.12 M caused the solution pH to drop below 5. Similarly, when acetic acid was applied, pH fell below 5 at concentrations exceeding 0.2 M CH₃COOH. Acetic acid at 0.2 M demonstrated higher efficiency in carbonate removal, as evidenced by ash reduction and decreased Ca content in the embossed cellulose fibres (Fig.2). At this concentration, Ca removal efficiency reached 95% and was further improved to 98.5% following subsequent washing. The removal of carbonates to isolate pure cellulose fibres in an acidic medium is effective for office paper, cardboard, and mixed paper, where carbonates represent the primary filler component. The potential applications of separated cellulose are largely determined by its physicochemical properties, including crystallinity, purity, particle or fibre size, surface chemistry (presence of hydroxyl groups), thermal stability relevant for composite manufacturing, and its reactivity/modifiability enabling functionalization. The fibre dimensions were influenced by the applied disintegration method. The lengths ranged from 0.88 to 5.93 mm, with an average of 2.87 ± 1.38 mm. The widths (2) H+ (aq) + CO 2− 3 (aq) ↔HCO − 3 (aq) K1= [HCO − 3]∕[CO 2− 3]][H +] (3) H+ (aq) + HCO − 3 (aq) ↔CO2(aq) +H 2O(l) K2= [CO2]∕[HCO − 3][H +] (4) CO 2 (aq) ↔CO2 (g) K H = P(CO2)∕[CO2 ] Table 1 Mineral composition of fillers in different kinds of used paper (weight %) determined by the X-ray diffraction method Mineral phase Chemical formula Office paper Journals Cardboard Mixture wt. % Anhydrite CaSO40.40 ± 0.18 0.12 ± 0.04 C2Sα Polymorphic dicalcium silicate (2CaO*SiO2) 0.63 ± 0.28 10.25 ± 3.57 0.33 ± 0.15 Portlandite Ca(OH)26.81 ± 3.23 1.09 ± 0.42 Lime CaO 2.56 ± 0.87 0.88 ± 0.36 0.24 ± 0.11 Calcite CaCO3–trigonal 9.08 ± 2.55 11.30 ± 13.20 10.19 ± 3.56 6.88 ± 2.19 Vaterite CaCO3–hexagonal 1.09 ± 0.22 3.40 ± 0.78 Aragonite CaCO3–orthorhombic 1.11 ± 0.38 Talk Mg3Si4O10(OH)20.05 ± 0.02 Quartz SiO20.27 ± 0.14 Ash 14.47 ± 2.87 29.05 ± 10.87 10.87 ± 2.26 11.70 ± 3.37 Environmental Science and Pollution Research varied between 0.05 and 0.20 mm, with an average value of 0.11 ± 0.04 mm. One of the key parameters of cellulose is its degree of crystallinity, as it directly influences mechanical strength, thermal stability, and enzymatic accessibility—properties critical for industrial processing and material performance. In this study, two absorbance ratios derived from FTIR spectroscopy were used as indicators of crystalline and amorphous phase distribution: A₁₄₂₉/A₈₉₆ (Oh etal. 2005) and A₈₉₆/A₁₀₅₀ (Park etal. 2010). The band at 1429 cm⁻1 corresponds to CH₂ vibrations in crystalline structures, whereas the 896 cm⁻1 band represents C–H deformations in amorphous regions. Additionally, the band at 1050 cm⁻1 is associated with ordered, crystalline domains of cellulose. The measured FTIR absorbance ratios were A₁₄₂₉/A₈₉₆ = 0.995 and A₈₉₆/ A₁₀₅₀ = 0.991, both suggesting a higher contribution of amorphous regions compared to crystalline phases in the analysed sample. The separated cellulose obtained from waste paper, characterized by an enhanced amorphous structure as revealed by FTIR analysis, offers improved processability, ink dispersion, and substrate flexibility. These properties are highly desirable for 3D printing technologies, making the material suitable for biocomposite filaments, printable gels, functional bioinks, and even food packaging applications. Organic compounds inwaste paper The chemical compounds identified in waste paper were categorized into six groups based on their origin: virgin wood-derived compounds, papermaking additives, ink and paint compounds, ink and papermaking compounds, and unclassified substances. Among these groups, ink-derived compounds exhibited the highest concentrations in mixed paper and office paper samples, averaging 11.03 ± 0.57 g/kg. A total of 138 chemical compounds were identified in waste paper samples using the TD-GC/MS method. These compounds were classified into four groups based on their origin: those derived from waste paper, printing inks, paper/ printing inks (where the origin could not be distinguished), and unknown sources. Within the waste paper group, two subcategories were defined: virgin wood-derived compounds and additives used during the papermaking process to optimize paper properties, including fragrances from essential oils and synthetic musks. In terms of compound count, paper-derived substances were slightly more prevalent, accounting for 67 compounds compared to those originating from printing inks. Additionally, six compounds were found to originate from either paper or printing inks, potentially. Chemical compounds coming fromvirgin wood A total of 31 chemical compounds originating from virgin wood were identified in waste paper, having not been removed during the production process. These compounds were divided into four categories, ranked by abundance: plant and microbial metabolites (14 compounds), decomposition products of cellulose and lignin (9 compounds), terpenes and their oxidation products (6 compounds), and pesticides (2 compounds) (Table2 and TableS1,Fig.3). The highest concentrations of virgin wood-derived compounds were found in office paper and mixed paper samples. The group of wood extractives includes a variety of wood resins comprising monoterpenes, resin acids, fatty acids, fatty alcohols, sterols, stearyl esters, and triglycerides (Dou etal. 2023). Terpenes and their oxidative products were quantified at 1361.25 ± 134.62 mg/kg in office paper and 126.98 ± 29.20 mg/kg in journal paper. Notably, (1S-endo)−1,7,7-trimethyl-bicyclo[2.2.1]heptan-2-ol and 2,6,6-trimethyl-bicyclo(3.1.1)heptane-2,3-diol—identified as major oxidation products of α-pinene—were also Fig. 2 Amounts of ash in office paper and in cellulose fibres after dissolving PCC (a); compounds identified in waste paper (b) Environmental Science and Pollution Research Table 2 Chemical compounds contained in virgin wood paper, including their classification according to GHS criteria Group by origin Chemical compound Office papers Journal Cardboard Mixture GHS classification "Stickies" mg/kg HH EH Irritant AVG STD AVG STD AVG STD AVG STD Terpenes and their oxidation products 1-Methyl-4-(1-methylethyl)−1,3-cyclohexadiene 2.15 0.24 73.06 14.92 19.73 4.22 ✓ 1,3,3-Trimethyl2-oxabicyclo[2.2.2]octan-6-ol 55.95 8.54 182.21 37.27 472.33 87.69 5-Pentadecanone 255.26 52.20 57.69 9.37 214.94 22.56 71.67 22.16 ✓ (1S-endo)−1,7,7-Trimethyl-bicyclo[2.2.1]heptan2-ol 414.83 41.14 11.20 2.56 10.72 2.37 351.55 89.31 2,6,6-Trimethyl-bicyclo(3.1.1)heptane-2,3-diol 489.67 37.65 129.38 87.66 Exo-2-hydroxycineole 201.49 15.23 15.42 2.27 Decomposition of cellulose, lignin, and lignocellulose 2-Ethyl-5-propylcyclopentanone 19.99 7.61 48.78 6.98 2,3,3,4-Tetramethyl-pentane 214.60 27.85 95.21 23.46 ✓ 2-Hexadecanone 401.20 31.33 116.47 20.15 345.45 49.54 115.54 33.78 ✓ 1-(4-Hydroxy-3-methoxyphenyl)−2-propanone 1194.49 523.20 202.47 52.27 ✓ 2-Methoxy-4-propylphenol 38.65 8.37 Coniferyl aldehyde 871.83 211.60 721.32 137.64 Levoglucosenone 167.13 37.98 878.25 214.35 Octadecane 28.60 4.39 46.54 12.55 Pentacosane 102.00 20.55 166.60 38.37 135.30 35.72 ✓ Pesticides 1,2-Dihydro-3H-1,2,4-triazol-3-one 210.50 32.46 288.97 102.16 ✓ 3-Oxo-2-pentyl-cyclopentaneacetic acid methyl ester 432.54 27.24 224.48 27.36 322.43 34.36 238.04 74.33 ✓ Plant a microbial metabolite 2-Pentadecanone 412.61 17.56 129.29 41.33 295.47 31.37 152.83 32.64 ✓ 2′,4′-Dihydroxypropiophenone 24.15 4.27 ✓ 2,6-Pyridinedicarboxylic acid 9.47 32.33 ✓ 3-Ethyl-3-octanol 35.63 4.21 54.45 2.23 21.83 5.11 3-Undecanone 23.36 4.24 190.22 52.33 58.88 7.31 4,6′-Dimethoxy-2′-(tert.-butyldimethylsilyl)oxychalcone 10.08 1.56 23.25 4.61 30.43 6.14 2,4-Dihydroxy-6-methyl-benzaldehyde 2464.54 412.70 2237.22 567.42 ✓ Benzoic acid pentyl ester 80.77 10.35 19.93 3.27 26.81 5.39 Heneicosane 131.29 22.57 50.65 8.56 113.12 22.37 82.73 11.13 ✓ Octacosane 189.62 39.41 69.30 24.21 144.14 17.12 157.19 21.54 ✓ ✓ Allyl ethyl ester oxalic acid 77.51 26.86 1409.59 523.78 Environmental Science and Pollution Research Table 4 (continued) Chemical compound Office papers Journals Cardboard Mixture GHS classification mg/kg HH EH Irritant AVG STD AVG STD AVG STD AVG STD Diethylene glycol 145.21 42.38 110.29 24.70 ✓ 2-Hexyl-1-decanol 59.63 11.13 Methyl tetradecanoate 70.20 25.23 57.75 17.77 21.62 8.74 ✓ 2-Ethylhexanoic acid 275.01 105.68 258.37 11.76 2-Propanamine 160.64 76.55 16.73 3.23 133.93 34.95 ✓ 2,3-Dihydro-1,1,3-trimethyl-3-phenyl-1H-indene 16.92 3.34 13.42 2.48 ✓ Dodecyl acrylate 140.64 54.84 70.88 6.56 174.61 88.91 61.10 5.76 ✓ 2-Ethylhexyl2 metylbenzoate 238.84 80.38 201.65 102.44 84.79 11.64 1-(Phenylmethoxy)-naphthalene 212.96 41.37 149.19 45.09 1,1′-[1,2-ethanediylbis(oxy)]bisbenzene 133.40 28.55 486.84 249.92 ✓ 1-Dodecanol 309.44 88.60 184.15 23.55 ✓ Bisphenol S 14.89 7.98 3.60 1.05 ✓ 1,2-Ethanediol monobenzoate 74.50 30.33 9.21 4.66 30.69 8.56 11.18 1.33 ✓ N,N′-Methylenebis-2-propenamide 56.41 8.34 60.02 2.55 ✓ Benzophenone 23.39 8.01 53.78 21.49 ✓ 2-Pyrrolidinone 278.30 55.68 ✓ 1,3-Diacetin 11.55 2.07 18.09 4.62 Bis(2-ethylhexyl) phthalate 118.83 ✓ Bisphenol A 6.73 ✓ Hexanedioic acid, dioctyl ester 53,96 29,44 ✓ Nonanoic acid 848.05 196.50 231.66 89.92 1419.61 594.11 ✓ Benzoic acid, undecyl ester 87.47 33.56 93.47 14.42 32.57 7.33 Methyl hexadecanoate 477.88 98.93 252.91 102.14 372.96 103.78 294.71 82.55 ✓ 1,3,5-Triazine-2,4(1H,3H)-dione 93.05 42.81 32.51 3.18 ✓ 4-Methyl-1,3-isobenzofurandione 28.91 3.30 32.52 2.55 ✓ Phthalic anhydride 460.48 104.55 ✓ 5-(1,1-Dimethylethyl)−1,3-benzenedicarboxylic acid 33.94 17.31 ✓ Isothiocyanatocyclohexane 114.93 48.03 23.03 5.88 44.78 3.36 ✓ Methylphosphonic acid 2TMS derivative 502.32 266.55 8.91 1.90 80.80 15.89 n-Decanoic acid 692.10 284.44 142.23 29.34 290.90 36.66 ✓ Diethyl(decyloxy)borane 74.73 13.30 2.56 52.86 31.14 (6-Isopropyl-3,4-bis(methylamino)−2,4,6-cycloheptatrienylidene)malononitrile 129.79 286.78 111.01 Environmental Science and Pollution Research carbonless copy paper dyes (Coltro etal. 2021). In the present study, DINP concentrations reached 240 ± 24 mg/kg in office paper, while journal-derived waste samples exhibited significantly lower levels of 86 ± 17 mg/kg. The highest concentrations among compounds monitored under the Globally Harmonized System (GHS) were associated with irritants, reaching approximately 12 g/kg. These substances were proportionally distributed between those originating from printing inks and virgin wood. Virgin wood contributed four compounds formed during cellulose thermal degradation, such as 2-ethyl-5-propylcyclopentanone (Ojha And Vinu 2015), and additional compounds resulting from lignin depolymerization, including 2-methoxy-4-propylphenol (Zhang etal. 2018). Within the plant and microbial metabolite group, seven compounds demonstrated irritant properties; for example, 2-pentanone, which also functions as a biocidal agent (Tyśkiewicz etal. 2019). A total of 25 irritant compounds were linked to printing inks. Among these, nine were solvents and three were polymeric resins. Each of the three categories (slip agents, plasticizers, and dispersants) contained two compounds. The remaining compounds were distributed across other ink-related functional groups, including photoinitiators, thermal stability agents, coalescing agents, anti-evaporation agents, photoionization compounds, binders, and wetting agents—each represented by a single substance. Nineteen compounds classified as health hazards (HH) were identified in waste paper. The highest number of HH compounds (16) was found in mixed paper materials, which also exhibited the greatest concentrations. Office paper contained ten HH compounds, journals eight, and cardboard the fewest. Among all HH substances, phthalic anhydride had the highest concentrations in mixed paper, reaching 460.5 ± 75.5 mg/kg. In terms of environmental hazards (EH), 12 compounds were identified across the samples. All were present in mixed paper material, nine in office paper, and only six in cardboard. Journal waste exhibited the lowest concentrations of EH compounds. As with HH substances, most EH compounds originate from printing inks. However, pesticides derived from virgin wood also contribute significantly to EH classifications in waste paper. The presence and concentrations of HH and EH compounds play a crucial role in determining the feasibility of further utilizing cellulose fibres obtained from recycled paper. Effect ofremoval ofprecipitated calcium carbonate fromoffice paper onthequality ofcellulose fibres Pure cellulose fibre extraction was performed using 0.2 M acetic acid (CH3COOH), as detailed in the “Materials and their pre-treatment for further analysis” section. This procedure applies only to office paper, where PCC is the sole filler. Organic compounds were analysed via the TD-GC/MS method, as in previous sections. Following PCC removal, Table 4 (continued) Chemical compound Office papers Journals Cardboard Mixture GHS classification mg/kg HH EH Irritant AVG STD AVG STD AVG STD AVG STD (4aS-trans)−1,2,3,4,4a,9,10,10a-octahydro-1,1,4a-trimethyl-7-(1-methylethyl) phenanthrene (Abieta-8,11,13-triene) 55.63 23.84 ✓ AVG average value, EH environmental hazard, HH health hazard, STD standard deviation Environmental Science and Pollution Research a total of 31 compounds were identified in the office paper sample (Table6). Eight compounds were identified both in cellulose fibres and in the original waste paper. Removed amounts of compounds ranged between 4 and 90% (Table6). An additional ten compounds were newly detected exclusively in the cellulose fibres. Their possible formation is described in TableS5. Furthermore, 13 compounds were probably formed through mutual interactions between detected substances or as a result of acetic acid–mediated transformations during the leaching process. The newly identified compounds found in the cellulose fibres are presumed to have originated from polymer coatings, adhesives, Table 5 Chemical compounds utilized for paper making and also for printing inks, including their classification according to GHS criteria AVG average value, EH environmental hazard, HH health hazard, STD standard deviation Chemical compound Office paper Journals Cardboard Mixture GHS classification mg/kg HH EH Irritant AVG STD AVG STD AVG STD AVG STD 2-Phenoxyethanol 753.31 247.85 427.55 77.37 321.84 112.35 ✓ 2-Butanone 20.72 4.22 23.65 2.44 ✓ 2,2,4-Trimethyl-1,3-pentanediol diisobutyrate 374.15 82.13 213.85 44.79 84.16 5.56 172.25 18.93 ✓ Bis(2-ethylhexyl) terephthalate 8.54 1.88 11.96 2.42 Diisobutyl phthalate 15.23 3.12 647.91 184.39 ✓ Dimethyl phthalate 21.36 4.24 169.53 44.47 ✓ Fig. 5 Division of compounds using GHS classification for each paper type (a, b, and c); the total distribution of compounds identified by TD-GC/MS according to GHS classification (d) Environmental Science and Pollution Research Table 6 Chemical compounds in office paper determined after extraction with acetic acid (OP-CH3COOH) and in original waste office paper (OP) in mg/kg Matrix Chemical compounds CAS OP-CH3COOH STD Waste paper Removed Origin/Use GHS classification mg/kg mg/kg mg/kg % HH EH I AT Paper/ink 3,5,5-Trimethyl-hexanoyl chloride 36727–29-4 761.75 112.41 Production of esterified cellulose nanofibres ✓ 4-Methoxy-1,3-benzenediamine 615-05−4 49.52 6.54 Acrylic fibres (nylon, polyester) ✓ Virgin wood 1-(1H-imidazol-4-yl)−1-pentanone 69393-15−3 28.86 14.12 Alkaloid 1-Methyl-4-(1-methylethyl)−1,3cyclohexadiene*99-86−5 7.21 1.22 73.06 90.1 Component of terpenoid, α-terpinene ✓ 1H-Naphtho[2,1-b]pyran, 3-ethenyldodecahydro-3,4a,7,7,10a-pentamethyl-, [3S-(3.alpha.,4a.alpha.,6a.beta.,10a. alpha.,10b.beta.)]- 3.05 0.56 Essential oil compounds with antioxidant activities 1,2,4-Triazine-3,5(2H,4H)-dione* 461-89−2 34.07 7.23 35.51 4.04 Metabolite of the herbicide metribuzin 4-Methyl-2-hexanone 105-42−0 33.00 17.24 Natural substances and extractives ✓ 1,3,3-Trimethyl-2-oxabicyclo[2.2.2] octan-6-ol*18679-48−6 716.57 241.50 1082 33.8 Biooxidation of cineole 1,3,3-Trimethyl-2-oxabicyclo[2.2.2] octan-6-ol, acetate 72257-53−5 142.00 23.14 Formed through acetylation 5-Acetyldihydro-2(3H)-furanone 29393-32−6 203.01 27.29 Natural substances and extractives ✓ Hexacosane 630-01−3 90.03 14.32 Natural products—compounds of "Stickies" ✓ Tricosane 638-67−5 54.25 17.38 Natural products—compounds of "Stickies" Paper 1,2-Ethanediol diformate 629-15−2 71.09 16.27 pH regulating agent Table2137-89−3 47.84 21.25 Plasticiser for paper and cardboard products. Replacement of DEHP ✓ 1,6-Dioxacyclododecane-7,12-dione 777-95−7 15.98 4.32 Production of polyurethane, adhesives in multilayer packaging materials ✓ 2-Oxooctanoic acid 328-51−8 816.17 156.15 Surface tension ✓ N,N′-Methylenebis-2-propenamide*110-26−9 11.51 1.27 60.02 80.8 Paper making ✓ Dihydro-5-pentyl-2(3H)-furanone*104-61−0 359.08 82.33 754.35 52.4 Fragrance mostly for cellulose cardboard 5-Heptyldihydro-2(3H)-furanone*104-67−6 174.60 33.12 408.22 57.2 Fragrance mostly for cellulose cardboard ✓ 5-Hexyldihydro-2(3H)-furanone* 706-14−9 222.05 47.54 298.50 25.6 Fragrance Dicyandiamide 461-58−5 73.36 18.26 Improvement in ink absorption, flame retardant in the paper industry ✓ Octadecanal 638-66−4 120.66 21.97 Biologically active pheromones ✓ Sec-butyl acetate 105-46−4 47.87 23.47 Paper processing, solvent for nitrocellulose lacquers Environmental Science and Pollution Research or surface treatments, where they were chemically bound or incorporated within the paper matrix. Upon leaching with acetic acid, these layers underwent degradation, releasing the compounds. Owing to their polar and reactive nature, the compounds then interacted with cellulose and became detectable within the fibre matrix, even though they had not been directly identified in the original waste paper. Following the removal of PCC, enhanced access to cellulose fibres enabled the identification of eight compounds derived from virgin wood and eight compounds originating from printing inks. Two of the ink-related compounds— 1,3-cyclohexanedione and 2-acetyl-resorcinol—were formed through the conversion of resorcinol, originally present in the untreated office paper. Four additional substances were identified as solvents. Bis(2-(dimethylamino)ethyl) ether was detected as an additive specific to UV-printing applications. Another compound, 3-butene-1,2-diol, represents the primary degradation product of 1,3-butadiene (BD), used in ink resin formulations. Furthermore, eight newly identified compounds in OP–CH3COOH were associated with various functional roles in paper production (Table6). Two additional compounds were found to originate either from printing inks or paper materials. The first, 4-methoxy1,3-benzenediamine, is employed in both ink production and the synthesis of polyester fibres, which may serve as alternatives to natural fibres. The second, 3,5,5-trimethylhexanoyl chloride, functions as a plasticizer and is also utilized in the production of esterified cellulose nanofibres. According to the Globally Harmonized System (GHS) classification, 4 compounds identified in the waste paper samples fall under health hazards (HH), 1 compound is categorized as an environmental hazard (EH), 2 exhibit acute toxicity, and 13 are classified as irritants. Figure6 illustrates a 79% reduction in the total concentration of identified compounds between untreated office paper (OP) and acetic acid-treated samples (OP–CH3COOH), including a significant decrease in GHS-classified hazardous substances. Additionally, as shown in Table6, no persistent organic pollutants were detected in OP–CH3COOH. These results demonstrate that extraction using 0.2 M acetic acid followed by washing yields a highly purified cellulose fibre product, suitable for further applications (Fig.7). The newly identified compounds were released from the cellulose matrix during acid extraction and subsequently detected using the TD-GC/MS method. Although thermal desorption is generally expected to release most compounds during TD-GC/MS analysis, its reliability diminishes when analytes are structurally embedded within the cellulose. Thermal decomposition of cellulose occurs at temperatures ranging from 440 to 580 °C under oxidative conditions and 280–380 °C in an inert atmosphere (Shen etal. 2013), both of which exceed the operational temperature of the thermal desorption unit used in the analytical setup. * Designation of chemicals identified in the original waste paper, AT acute toxicity, EH environmental hazard, HH health hazard, I irritant, OP office paper, STD standard deviation Table 6 (continued) Matrix Chemical compounds CAS OP-CH3COOH STD Waste paper Removed Origin/Use GHS classification mg/kg mg/kg mg/kg % HH EH I AT Printing inks 1,3-Cyclohexanedione* 504-02−9 9.91 0.86 53.53 81.5 Decomposition product of resorcinol, a polymeric dispersant for ink jet ✓ 2-Ethyl-1-butanol 97-95−0 26.70 13.14 Solvent for printing inks ✓ 3-Butene-1,2-diol 497-06−3 250.06 51.97 The major metabolite of 1,3-butadiene, used for the ink ✓ 3-Heptanone 106-35−4 354.09 52.29 Solvent for paint ✓ Bis(2-(dimethylamino)ethyl) ether 3033-62−3 103.10 22.86 UV printing ingredients ✓ Cyclopentane 287-92−3 34.72 12.21 Non-polar solvent Ethyl cyanoacetate 105-56−6 25.05 4.27 Ethyl acetate, a solvent for resins in inks ✓ 2-Acetyl-resorcinol 699-83−2 51.02 11.11 Produced by the chemical reaction of acetic acid ✓ Σ All compounds 116 175 2070 864 Environmental Science and Pollution Research Conclusion Following acetic acid (CH₃COOH) treatment, 31 of the original 138 compounds identified in waste office paper remained embedded in the cellulose fibres. The purpose of this study was to document the presence of natural organic substances derived from virgin wood that persist despite conventional paper manufacturing processes. These compounds constitute up to 40.4 ± 5.8% of the total organic content in office paper. Notably, approximately 39% of virgin wood-derived compounds were classified as “stickies”, which can interfere with paper recycling operations. The extraction procedure using CH₃COOH, followed by thorough washing, resulted in a 92% reduction in compounds classified as health hazards (HH). This includes the effective removal of persistent organic pollutants such as di(2-ethylhexyl)phthalate (DEHP), bisphenol A (BPA), and benzophenone. Additionally, compounds categorized as environmental hazards (EH) were reduced by 92.6%, Fig. 6 Comparison of concentrations of identified compounds in waste office paper and office paper (OP) extracted in CH3COOH (a); decrease in concentrations of hazardous and not identified compounds after extraction in CH3COOH (b) Fig. 7 Cellulose fibres before (a) and after extraction (b) with CH3COOH and washing with distilled water in the scanning electron microscope Environmental Science and Pollution Research irritants by 83%, and substances with unknown hazard classifications by 80%. These findings demonstrate that the removal of precipitated calcium carbonate enables the recovery of highly purified cellulose fibres from office paper, suitable for further technological applications. The chemical data indicate significantly reduced levels of additives (contaminants) following fibre separation. Nonetheless, to confirm the safety of these fibres for foodcontact applications, additional experimental validation is required, particularly through migration testing and assessments of functional performance. Moreover, our approach avoids the use of stronger corrosive acids or chlorine-based bleaching agents, which pose greater risks to workers and the environment. A preliminary risk assessment suggests that, with proper process design, acetic acid treatment can be safely implemented at scale, while offering improved material purity and reduced chemical hazards compared to conventional deinking and extraction processes. Supplementary Information The online version contains supplementary material available at https:// doi. org/ 10. 1007/ s1135602537133-5. Author contribution All authors contributed to the study conception and design. Conceptualization: Helena Raclavská, Jana Růžičková; Marek Kucbel. Data curation: Jana Růžičková, Michal Šafář, Jarmila Drozdová. Formal analysis: Michal Šafář, Pavel Kantor. Investigation: Helena Raclavská, Jana Růžičková, Marek Kucbel. Methodology: Helena Raclavská, Jana Růžičková. Software: Pavel Kantor, Jarmila Drozdová. Supervision: Helena Raclavská, Jana Růžičková. Validation: Helena Raclavská, Jana Růžičková. Visualization: Pavel Kantor, Michal Šafář. Writing—original draft: Helena Raclavská, Karolina Slamová, Jana Růžičková, Michal Šafář, Marek Kucbel, Jarmila Drozdová. Writing—review and editing: Helena Raclavská, Karolina Slamová. Funding The article was supported by the TACR project Innovative solutions for sustainable energy, National Center for Energy II (TN02000025) − PB1.07 Research on the application of the principles of Green Deal for non-recyclable waste based on biomass in the conditions of the Czech Republic. This article is supported by the ESF in “Waste as an alternative source of energy” project, reg. nr. CZ.02.01.01/00/23_021/0008590 within the Programme Johannes Amos Comenius. Data availability All data generated or analysed during this study are included in this published article. Declarations Ethical approval Not applicable. Consent to participate Not applicable. Consent for publication Not applicable. Competing interests The authors declare no competing interests. Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. 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