Environmental Science and Pollution Research
Fig. 2 A m ounts of ash in office paper and in cellulose fibres after dissolving PCC ( a ); co m pounds identified in waste paper ( b )
A total of 138 che m ical co m pounds were identified in waste paper sa m ples using the TD-GC/MS m ethod. These co m pounds were classified into four groups based on their origin: those derived fro m 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 co m pounds and additives used during the paper m aking process to opti- m ize paper properties, including fragrances fro m essential oils and synthetic m usks. In ter m s of co m pound count, paper-derived substances were slightly m ore prevalent, accounting for 67 co m pounds co m pared to those originating fro m printing inks. Additionally, six co m pounds were found to originate fro m either paper or printing inks, potentially.
varied between 0.05 and 0.20 mm , with an average value of 0.11 ± 0.04 mm . One of the key para m eters of cellu- lose is its degree of crystallinity, as it directly influences m echanical strength, ther m al stability, and enzy m atic accessibility—properties critical for industrial process- ing and m aterial perfor m ance. In this study, two absorb- ance ratios derived fro m FTIR spectroscopy were used as indicators of crystalline and a m orphous phase distri- bution: A ၶၹ ᔐ ၾ /A ၽၾၻ (Oh et al. 2005) and A ၽၾၻ /A ၶ ᔎ ၺ ᔎ (Park et al. 2010). The band at 1429 c mၱ 1 corresponds to CH ᔐ vibrations in crystalline structures, whereas the 896 c mၱ 1 band represents C–H defor m ations in a m orphous regions. Additionally, the band at 1050 c mၱ 1 is associated with ordered, crystalline do m ains of cellulose. The m easured FTIR absorbance ratios were A ၶၹ ᔐ ၾ /A ၽၾၻ = 0.995 and A ၽၾၻ / A ၶ ᔎ ၺ ᔎ = 0.991, both suggesting a higher contribution of a m orphous regions co m pared to crystalline phases in the analysed sa m ple. The separated cellulose obtained fro m waste paper, char- acterized by an enhanced a m orphous structure as revealed by FTIR analysis, offers i m proved processability, ink disper- sion, and substrate flexibility. These properties are highly desirable for 3D printing technologies, m aking the m aterial suitable for bioco m posite fila m ents, printable gels, func- tional bioinks, and even food packaging applications.
Chemical compounds coming from virgin wood
A total of 31 che m ical co m pounds originating fro m vir- gin wood were identified in waste paper, having not been re m oved during the production process. These co m pounds were divided into four categories, ranked by abundance: plant and m icrobial m etabolites (14 co m pounds), deco m - position products of cellulose and lignin (9 co m pounds), terpenes and their oxidation products (6 co m pounds), and pesticides (2 co m pounds) (Table 2 and Table S1,Fig. 3). The highest concentrations of virgin wood-derived co m - pounds were found in office paper and m ixed paper sa m - ples. The group of wood extractives includes a variety of wood resins co m prising m onoterpenes, resin acids, fatty acids, fatty alcohols, sterols, stearyl esters, and triglycer- ides (Dou et al. 2023). Terpenes and their oxidative prod- ucts were quantified at 1361.25 ± 134.62 m g/kg in office paper and 126.98 ± 29.20 m g/kg in journal paper. Notably, (1S-endo)−1,7,7-tri m ethyl-bicyclo[2.2.1]heptan-2-ol and 2,6,6-tri m ethyl-bicyclo(3.1.1)heptane-2,3-diol—identi- fied as m ajor oxidation products of α-pinene—were also
Organic compounds in waste paper
The che m ical co m pounds identified in waste paper were categorized into six groups based on their origin: virgin wood-derived co m pounds, paper m aking additives, ink and paint co m pounds, ink and paper m aking co m pounds, and unclassified substances. A m ong these groups, ink-derived co m pounds exhibited the highest concentrations in m ixed paper and office paper sa m ples, averaging 11.03 ± 0.57 g/kg.
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