Volume 39, Issue 2

The valorization of newspaper waste through adsorption-driven processes using activated carbon presents a promising avenue for sustainable waste management. This comprehensive review explores the advances and prospects of using activated carbon to enhance the value of newspapers. The fundamental properties of activated carbon, its unique adsorption mechanisms, and its interaction with contaminants commonly found in newspapers, such as ink dyes, heavy metals, and organic pollutants, are also discussed. Applications of activated carbon-treated newspapers span across air and water purification, soil enrichment, and odour control. The paper critically evaluates the environmental benefits of this approach, comparing it with conventional disposal methods. Furthermore, challenges associated with implementing activated carbon-assisted valorization and potential strategies for overcoming them are discussed. Real-world case studies highlight successful projects, shedding light on this innovative waste management solution’s economic viability and technological feasibility. This review concludes by emphasizing the role of adsorption-driven valorization in transforming newspaper waste into a valuable resource, addressing environmental concerns, and shaping future research directions.

The utilization of mulch stands as a paramount approach in the management of wind erosion and the stabilization of soil and drifting sands. This study aimed to explore the impact of various concentrations of spent liquor (20 %, 30 %, and 50 % v/v) derived from SO 2 –ethanol–water (SEW) fractionation of Eucalyptus wood on the physical and mechanical properties of sand. These properties encompassed moisture content, thickness, temperature, electrical conductivity (EC), wind erodibility, penetration resistance, and seed germination. The findings revealed that the highest compressive strength (0.76 MPa) was attained with mulch consisting of 50 % SEW spent liquor, resulting in a 3.3-fold increase in penetration resistance compared to the control treatment. Furthermore, the 20 % concentration of spent liquor did not adversely affect the germination of black saxaul ( Haloxylon ammodendron ), whereas the lowest seed germination rate was associated with the 50 % concentration. Based on the measured parameters, the optimal mulch treatment for stabilizing drifting sands was identified as mulch with a 50 % (v/v) concentration. This study underscores the efficacy of SEW spent liquor in dust control and mitigating its environmental impacts, thus highlighting its potential in sustainable soil management practices.

The effects of different hot air speeds and temperatures on the drying characteristics of half-ripe rice paper were investigated by hot air convection drying experiments. The thin-layer drying experiments were carried out at three different combinations of air speeds of 1.97 m/s, 3.00 m/s, and 3.90 m/s and temperatures of 85 °C, 100 °C and 115 °C. The results show that among the 10 drying kinetic models selected, the Modified Page model is the most suitable model to describe the drying characteristics of the thin layer of half-ripe rice paper; the whole drying process exists obvious ascending, constant and descending processes; the effective moisture diffusion coefficient of half-ripe rice paper is in the range of 1.52656 × 10 −9  m 2 /s–3.15816 × 10 −9  m 2 /s, whose size increases with the increase of the hot wind speed and temperature. Its magnitude increases with the increase of wind speed and temperature; the drying activation energy of half-ripe rice paper is 6.55 kJ/mol calculated by Arrhenius equation.

This study delves into the dynamic evolution of solids content in a pilot-scale through air drying tissue machine, aiming to enhance comprehension and refine optimization strategies for tissue manufacturing. It focuses on development of solids content throughout the process. Analyzing the interaction between process parameters and solids content provides deeper insights into water removal dynamics. The research employs solid contents monitoring techniques in pilot scale, offering a detailed view of solids content evolution from the wet web’s inception to the final tissue product. It significantly highlights the impact of key parameters, particularly pulp refining, on solids content across all positions of the pilot machine. Additionally, the study emphasizes the influence of vacuum system configurations, identifying the relationship between energy expended in the vacuum system and evaporation energy. Furthermore, the results indicate that compression and air displacement dewatering in vacuum boxes are less speed-sensitive compared to heat-driven evaporation in the TAD- and Yankee cylinders. Solid contents at all positions in the tissue machine correlates between various dewatering elements. Optimizing site-specific dewatering and evaporation strategies can potentially save drying energy in the Yankee drying phase which hold promise for enhanced energy and resource utilization, aligning with demands for sustainable manufacturing practices.

Foam-forming technique imparts ceramic fiber paper with excellent uniformity, low density, and high porosity, but its strength loss must be compensated. Herein, a flexible and rigid foam-formed ceramic fiber network was manufactured by using different strength improvement methods and simultaneously investigated their strength and thermal insulation properties. Sufficient strength (1136 kPa) was achieved by combining Polyvinyl alcohol (PVA) 2 % and Polyester (PET) 3 %. However, the tensile strength of fiber networks would decrease under the contribution of inter-fiber bonding area reduced when the fiber length was longer than 24 mm. Benefiting from the developed flocculation system (aluminum sol-anionic polyacrylamide-carboxymethylcellulose), the strength of the foam-formed ceramic fiber network was 20 kPa, the retention rate increased from 75 % to 88 %, and the average aggregation factor of fillers in the Z direction was 0.67. By adjusting the ratio and Z -directional distribution of functional fillers, the sintered foam-formed paper with a tensile strength of 1300 kPa and compressive strength of 1000 kPa could be obtained. The thermal insulation performance (thermal conductivity 0.03252 W/(m·K)) was similar to the quartz fiber paper reinforced silica airgel, and the flame resistance was better than the commercialized aluminum silicate wool board.

Evaluation of physical and mechanical heterogeneity in commercial paperboards is needed to promote their use in structural applications, especially within the field of packaging. Understanding the range of their behaviors is needed to compete with other materials in the current marketplace and expand in others. This work describes the physical and stiffness heterogeneities of twelve commercial materials using tensile tests in the cross-machine direction and several inverse analyses. The effects of grammage, thickness, and apparent density on tensile stiffness were evaluated in both the linear elastic and nonlinear regimes. Thickness and density provided the best explanation for elastic heterogeneous behavior in most of the materials; local grammage was not the best descriptor for any material. The analyses used here were not able to provide a good explanation of the nonlinear behavior, which was attributed to the development of large shear strains within the materials as they neared failure. This work provides a methodology for additional heterogeneous behavior examinations.

Due to a shortage of resources, exploring new biomass fillers has become critical for paper making. In this study, we reported an eco-friendly strategy for fabricating low-cost and efficient recycled paper with high mechanical properties using corrugated cardboard waste paper and harmless municipal sludge (HMS). First, the characteristics of HMS, including the particle size, pH, specific surface area, organic functional groups and organic component content, were analyzed. Then, the influence of the amount of HMS on the properties of the recycled paper was studied. Finally, the strengthening mechanism of biomass filling recycled paper was discussed. The results showed that HMS, a biomass filler for recycled paper preparation, exhibited excellent physical and chemical properties, with a median particle size of 6.395 μm, a surface area of 39.974 m 2  g −1 and organic functional groups. The tensile index of the recycled paper with 30 % HMS was 13.10 Nm/g, which was 16.4 % greater than that of the unfilled paper and showed better thermal stability. This excellent performance could be attributed to the uniform distribution of HMS on the fiber surface, which improved the accessibility of hydrogen bond formation between fibers. Thus, this study proved that HMS was an excellent biomass filler for producing recycled paper.

In the present study, a nanocellulose acetate and acrylate polymer composite membrane was formed by the phase transfer technique. The physical and mechanical properties, water flux, and desalination performance of the achieved composite membrane were investigated. When 3 % (w/w) acrylate polymer, 10 % acetylated nanocellulose, and 0.3 % mass fraction of TiO 2 were used for the formation of the membrane, the obtained product could reach a tensile strength of 1.97 N/mm 2 and a pure water flux of 51 L/(m 2  h). Moreover, the composite membrane achieved a desalination rate of 92.4 %. Thus, the obtained composite membrane could meet the performance requirements for the treatment of industrial wastewater.

Liquid mulching film is an emerging film material to replace the traditional plastic film, which causes wide public concern. In this study, a graft copolymer (LS-AA) was synthesized from sodium lignosulfonate (LS) by free radical polymerization, which was added as enhancer to the cationic starch (CS) solutions to obtain the CLA based film. The grafting conditions was optimized by response surface methodology (RSM) for the preparation of LS-AA, after that the LS-AA was characterized by FTIR, XRD, and TG. The highest grafting rate was obtained under the reaction conditions of 80 °C for 2.6 h with the mass ratio of monomer and LS of 5.5/5 at initiator dosage of 1 %. The fabricated liquid mulching film with addition of LS-AA showed outstanding anti-ultraviolet, biodegradation, anti-erosion, which provided theoretical base and practical references for popularizing and application of liquid mulching film in the dust prevention and sand fixation.

The preparation of biodegradable mulch film with paper-based materials has become a significant focus in mulch film development due to the serious pollution caused by plastic mulch film. This study utilized the esterification cross-linking reaction of LA, PVA, and GA to coat the surface of paper as the substrate. FTIR, TGA, XRD, SEM, tensile testing, and oxygen, water vapor barrier performance tests were performed. The optimal conditions for film preparation were determined to be a 10 % PVA aqueous solution, 5 % GA content, and a PVA/LA/GA ratio of 1:2:1. The resulting film paper exhibited a dry strength of 6.52 kN/m, a wet strength of 0.23 kN/m, a tearing degree of 969.35 mN, a Cobb value of 12.04 g/m 2 , a water vapor transmission rate of 573.27 g m −2 24 h −1 , and an oxygen transmission rate of 7.373 cm 3  m −2 24 h −1 . After a 6-week landfill degradation test, the film showed a degradation rate of 25.3 %, while still maintaining a tensile strength of 1.89 kN/m. Field application tests in greenhouses confirmed that the film paper facilitated the growth of strawberry, its mechanical and barrier properties suitable for a biodegradable paper mulch.

The resource utilization of fly ash has always been a popular topic in the field of solid waste recycling. This paper is based on the three-phase reaction system of “fly ash (s)-[Ca(OH) 2 –H 2 O/ethanol] (l)-CO 2 (g)”, using the bubble carbonization method to carry out heterogeneous phase reaction with fly ash as the core crystallized to form a fly ash-based calcium carbonate composite with higher brightness. The composite material is used in the filling of paper instead of calcium carbonate filler. Based on the previous research of our team, we focused on exploring the addition of miscible wettability additives (ethanol and acetone) to improve the wettability of the reaction system, thereby improving the whitening and modification effect of fly ash. The results showed that the addition of ethanol and acetone can significantly improve the coating effect of fly ash, however, acetone is slightly toxic, more volatile, and expensive than ethanol, so ethanol is more suitable as a wetting agent to be added to the reaction system. Under the optimal coating conditions, when the ratio of ethanol and water is 1:1, the brightness of fly ash can reach 71.62 % ISO, which is 17.29 % ISO higher than that without ethanol.

Using cellulosic micro/nanofibrils (MFC/NFC) in developing films for coatings and packaging has aroused industrial interest to replace plastic. This study proposes functionalizing packaging films composed of hybrid suspensions of 80 % titica vine ( Heteropsis flexuosa ) and 20 % Pinus to improve their mechanical properties. The MFC/NFC were produced by mechanical fibrillation and adding proportions of 1, 2.5, and 5 % of nanolignin, vegetal tannin, and synthetic termite saliva. Both suspensions had concentrations of 1 % (w/w). The MFC/NFC were evaluated for energy consumption, microstructural, and stability, while the films were for physical, optical, barrier, and mechanical properties. Films with nanolignin 2.5 % obtained lower WVP and degradation in water, with greater hydrophobicity and puncture strength. The treatment with tannin 1 % obtained higher density and lower porosity, while termite saliva 1 % presented higher tensile strength at around 53.1 MPa. The additives improved the quality index of the MFC/NFC (>51.1 points). It is concluded that adding different binders can help expand the use of MFC/NFC. New studies are essential to seek pre-treatments or alternative fibrillation methods to increase their application and efficiency for fiber cell wall fibrillation, in addition to the need for a deeper analytical understanding of the interactions of additives with cellulose.

Paper cultural relics, as the carriers of human civilization, inevitably deteriorate during the long-term storage. The restoration of those damaged or aged paper cultural relics is an important part of cultural relics protection. How to obtain the fiber with high permanence property is the key to the repair paper used to cultural relic restoration. Herein, in order to obtain high permanence lignocellulosic fiber, nano-CaCO 3 was introduced inside the Wikstroemia bast fiber by in-situ mineralization. Under accelerated aging condition, the microstructure, chemical structure, crystallinity, degree of polymerization, variation of pH, alkali reserve and mechanical strength of the fiber before and after mineralization were studied. The results showed that nano-CaCO 3 had no obvious effect on the properties of paper prepared from those mineralized fibers, but it can effectively neutralize the acid generated inside the fiber, slow down the degradation rate of cellulose and improve the permanence of the paper during the aging process. It provides a new insight for the manufacture of repair paper for cultural relics restoration.

Complete utilization of different agricultural wastes is a great challenge before human society. The present study reports the valorization of rice straw for simultaneous production of reducing sugars and paper. The rice straw was first pre-extracted with water under different reaction conditions sequentially followed by papermaking. A maximum total reducing sugars (TRS) upto 12.38 % was extracted through aqueous pre-treatment. The pulped biomass was assessed for paper properties viz., tensile index, tear index, burst index, Kappa no. and brightness. For untreated rice straw tensile index, tear index and burst index were recorded within a range of 30.9–35.8 N m/g; 2.25–2.62 mN m 2 /g and 1.91–2.35 kN/g respectively where as it were ranged from 31.1 to 33.7 N m/g, 2.02–2.51 mN m 2 /g and 1.78–2.08 kN/g respectively for pretreated rice straw. Moreover, for untreated rice straw, kappa number and brightness were recorded in a range from 20.7 to 26.6 and 32.4 to 36.7 % ISO respectively, whereas for pre-treated rice straw it ranged from 19.1 to 26.3 and 31.6 to 35.5 % ISO respectively. High performance liquid chromatography (HPLC) analysis and field emission gun scanning electron microscopy (FESEM) were further employed during the study. In overall, extraction of underutilized sugars prior to pulping may prove as an efficient route for apt utilization of sugars followed by papermaking in near future.