The aim of this work was to determine the influence of the conventional offset printing technique and digital electrophotography printing with liquid toner (LEP) on some optical properties of recycled fibres. A series of LEP prints was made with the variation of the negative voltage of the developing drum (−200 V, −280 V, −350 V, and −430 V) after calibration of the machine and achieving standard densitometry values. Besides deinkability aspects, the quality of wastewater effluents after process of prints recycling was observed in order to make a conclusion regarding how different printing techniques, conditions in printing process, and different types of inks can affect the wastewater effluents. Results of image analysis showed that by increasing the negative voltage of developing drum in LEP printing technique, the formation of large ink particles on handsheet from recycled pulp increases. Depending on the size of the negative voltage of the developing drum, under the same experimental conditions, handsheets made from LEP recycled fibres have lower whiteness gain, brightness gain, and ΔERIC of handsheets compared to those made from the offset prints. In addition, a certain correlation was found between IE_ERIC (ink elimination), chemical oxygen demand (COD), and total organic carbon (TOC) of wastewater effluents after recycling of LEP prints and offset prints as well. Organic water pollution parameters (COD and TOC) showed higher values in wastewater after recycling of offset prints compared to recycling of LEP prints.

Labels are a crucial component of products, offering informational content and attractive visuals; therefore, the durability of the print is an important quality requirement. On the other hand, in accordance with eco-design, the recyclability of printed labels is vital. In our research, the focus was on the assessment of the durability, recyclability, and deinkability of printed label paper equipped with printed RFID tags. The determined color fastness of electrophotographic prints affected by various environmental factors showed good resistance to dry rubbing and, in most cases, light and moist–heat treatment, confirming the applicability of digital printing on self-adhesive biodegradable paper labels. In the second part of this study, recyclability was assessed, and a comparison between the deinkability of the offset and digital prints and two conductive functional inks was conducted. Good deinkability was observed for the printed RFID antennas on both the offset and electrographic prints, with only a small deterioration in optical properties, especially when nano-silver conductive ink was used. The study highlights the importance of the selection of materials and printing techniques when considering the environmental impact of printed electronics. The results showed that INGEDE 11 is a suitable deinking method for printed RFID antennas on offset and electrographic prints.

In the process of paper recycling, certain amounts of metals can be found in the cellulose suspension, the source of which is mainly printing inks. The paper industry often uses different technologies to reduce heavy metal emissions. The recycling of laminated packaging contributes to the formation of sticky particles, which affects the concentration of heavy metals. This study aimed to determine the mass fraction of metals in the different phases of the deinking process to optimize the cellulose pulp’s quality and design healthy correct packaging products. In this research, the deinking flotation of laminated and non-laminated samples was carried out by the Ingede 11 method. As a result of the study, the mass fractions of metals in cellulose pulp were divided into four groups according to the mass fraction’s increasing value and the metals’ increasing electronegativity. The quantities of metals were analyzed using Inductively Coupled Mass Spectrometry (ICP-MS). The separation of metals from cellulose pulp is influenced by the presence of adhesives and the electronegativity of the metal. The results of the study show that the recycling process removes certain heavy metals very well, which indicates the good recycling potential of pharmaceutical cardboard samples.

Adhesive modification with nanoparticles affects multiple adhesives properties, making it essential to evaluate and compare changes across all key characteristics—existing positive and limiting properties. This study investigates the impact of silica (SiO₂) and titanium dioxide (TiO₂) nanoparticles on the elasticity and aging resistance of PVAc adhesive. Tensile properties were determined according to ISO 527-3:2018, with Young’s moduli of elasticity $\left({\rm E}\right)$, and stress–strain curves for neat PVAc, nano-SiO₂ PVAc, and nano-TiO₂ PVAc adhesive. Material toughness ($U_T$), failure stresses $\left({\sigma }_f\right)$, and failure strains $\left({\epsilon }_f\right)$ were also calculated. After UV exposure (0, 48, and 96 h), according to ISO 9142:2003, samples were characterized by Fourier-transform infrared spectroscopy (FTIR). Analysis of variance (ANOVA) was performed to determine if there is a statistically significant difference in material toughness between neat PVAc and nano-modified PVAc adhesives, as well as changes in FTIR spectra of paper–adhesive samples before and after UV exposure. The Bonferroni post hoc test was used to identify specific group differences. The results showed that SiO₂ nanoparticles improved PVAc elasticity by 9.15%, while TiO₂ nanoparticles reduced elasticity by 44.47%. FTIR analysis revealed similar behavior in both nano-modified and neat PVAc adhesives after UV exposure, indicating that aging resistance was preserved with the addition of SiO₂ or TiO₂.

Packaging appearance is important in a competitive market. Designers strive to create products that attract customers and often use laminated packaging, due to the attractive appearance and quality characteristics of the material. The circular economy in the recycling of cardboard packaging helps to reduce waste, saves natural resources and increases the quality of the environment. All of the above contributes to sustainable production, but the quality and properties of the obtained recycled paper materials should not be ignored. Recycling of laminated cardboard packaging often has a negative impact on the quality of recycled paper, due to the formation of sticky particles that can affect the optical properties of recycled paper and the efficiency of the recycling process. This article provides insight into the influence of each stage of production of packaging intended for pharmaceutical products on the properties and characteristics of recycled paper. The standard INGEDE 11 deinking method was used to remove dyes and other impurities from the pulp. The obtained optical results of the characteristics of recycled laboratory sheets obtained from laminated and non-laminated cardboard samples were compared in order to determine the impact of each stage of box production on the quality of the paper pulp. The acquired knowledge can be applied in the design phase of a more sustainable product, and laminated materials can be used in luxury products or to increase the functionality of the packaging. Designing for recycling will contribute to an increase in the quality of the obtained paper mass, which is directly related to an increase in the productivity of recycling and the sustainability of the packaging production process.

This study investigates the effects of aging and recycling on the optical properties of paperboard, which is key to advancing circular economy practices in packaging. Methods included deinking flotation of cardboard made from sea algae and eco-conventional cardboard of unexposed and exposed samples in a xenon test chamber. Optical measurements were performed on the obtained laboratory paper sheets. Measurements for the chromatic coefficients ΔL*, Δa* and Δb*, as well as the CIE whiteness from comparison of the fluorescent component in the cardboard, were carried out under two light sources, D65 and UV. Regression analysis was used to quantify the statistical significance of these changes over time, i.e., in the aging process. The results revealed significant effects of both aging and recycling on the chromatic coefficients, with ΔL* and Δa* decreasing, while Δb* initially increased before decreasing. The influence of the fluorescent component is reduced by recycling the samples. Opacity measurements showed an initial increase in values that decreased with the aging of the samples, which indicates structural changes in the material. This research contributes to the circular economy by providing insight into the durability and optical properties of recycled cardboard, helping to develop sustainable packaging solutions.