Structural evaluation of chitosan-modified precipitated calcium carbonate composite fillers for papermaking applications

Papers with high filler contents enabled by nanocelluloses as retention and strengthening agents

The development of economic and functional papers relies on the introduction of functional filler particles but faces several challenges, especially the low filler retention and inferior mechanical properties. This study introduces plant-based cellulose nanofibrils (CNFs) as dual-function retention and strengthening agents, offering a sustainable alternative to petroleum-based polymer additives. Precipitated calcium carbonate (PCC), a widely used filler, is selected as the model system. The effects of CNF dosage, aspect ratio, and surface carboxyl content on the filler flocculation process were systematically investigated, with additional enhancement achieved through cationic ion crosslinking to improve filler bridging. Remarkably, a superior filler retention rate (>90 %) and filler-tensile factor (2.0) were achieved for the final papers at very low CNF dosage (1 %), surpassing most literature data. Detailed analyses of filler morphology and distribution elucidated the structure-property relationships underlying this performance. Furthermore, the versatility of the approach was demonstrated with other functional fillers, imparting properties such as flame retardancy, oil/water separation, high brightness, and soluble organic pollutant absorption. Overall, this study reveals the critical feature of CNFs in simultaneously improving filler retention and mechanical properties, demonstrating their high potential for their applications in the papermaking industry.

Exploring the potential of chitosan/aragonite biocomposite derived from cuttlebone waste: Elaboration, physicochemical properties and in vitro bioactivity

Cuttlefish bone biowaste is a potential source of a composite matrix based on chitin and aragonite. In the present work, we propose for the first time the elaboration of biocomposites based on chitosan and aragonite through the valorization of bone waste. The composition of the ventral and dorsal surfaces of bone is well studied by ICP-OES. An extraction process has been applied to the dorsal surface to extract β-chitin and chitosan with controlled physico-chemical characteristics. In parallel, aragonite isolation was carried out on the ventral side. The freeze-drying method was used to incorporate aragonite into the chitosan polymer to form CHS/ArgS biocomposites. Physicochemical characterizations were performed by FT-IR, SEM, XRD, 1H NMR, TGA/DSC, potentiometry and viscometry. The ICP-OES method was used to evaluate in vitro the bioactivity level of biocomposite in simulated human plasma (SBF), enabling analysis of the interactions between the material and SBF. The results obtained indicate that the CHS/ArgS biocomposite derived from cuttlefish bone exhibits bioactivity, and that chitosan enhances the bioactivity of aragonite. The CHS/ArgS biocomposite showed excellent ability to form an apatite layer on its surface. After three days' immersion, FTIR and SEM analyses confirmed the formation of this layer.

A comprehensive review of chitosan applications in paper science and technologies

Using environmentally friendly biomaterials in different aspects of human life has been considered extensively. In this respect, different biomaterials have been identified and different applications have been found for them. Currently, chitosan, the well-known derivative of the second most abundant polysaccharide in the nature (i.e., chitin), has been receiving a lot of attention. This unique biomaterial can be defined as a renewable, high cationic charge density, antibacterial, biodegradable, biocompatible, non-toxic biomaterial with high compatibility with cellulose structure, where it can be used in different applications. This review takes a deep and comprehensive look at chitosan and its derivative applications in different aspects of papermaking.

Ultrasonic-assisted production of precipitated calcium carbonate particles from desulfurization gypsum

This study aimed to investigate the effect of ultrasonic application on the production of precipitated calcium carbonate (PCC) particles from desulfurization gypsum via direct mineral carbonation method using conventional and venturi tube reactors in the presence of different alkali sources (NaOH, KOH and NH₄OH). The venturi tube was designed to determine the effect of ultrasonication on PCC production. Ultrasonic application was performed three times (before, during, and after PCC production) to evaluate its exact effect on the properties of the PCC particles. Scanning electron microscope (SEM), X-ray diffraction (XRD), Atomic force microscope (AFM), specific surface area (SSA), Fourier transform infrared spectrometry (FTIR), and particle size analyses were performed. Results revealed the strong influence of the reactor types on the nucleation rate of PCC particles. The presence of Na⁺ or K⁺ ions in the production resulted in producing PCC particles containing only calcite crystals, while a mixture of vaterite and calcite crystals was observed if NH₄⁺ ions were present. The use of ultrasonic power during PCC production resulted in producing cubic calcite rather than vaterite crystals in the presence of all ions. It was determined that ultrasonic power should be conducted in the venturi tube before PCC production to obtain PCC particles with superior properties (uniform particle size, nanosized crystals, and high SSA value). The resulting PCC particles in this study can be suitably used in paint, paper, and plastic industries according to the ASTM standards.