Review Articles

The use of lignocellulosic residues as feedstocks for biofuels production represents an economic and ecofriendly option, since they are generated as byproducts or wastes from different industrial areas. Nevertheless, a pretreatment method aimed at eliminating the lignin content of these residues must be performed. This is required in order to increase cellulose bioavailability, which favors the production of reducing sugars through microbial or enzymatic attack. Some performed pretreatments can be classified as physical, chemical, and physicochemical methods. Although such methods are the most used pretreatments, they are expensive and generate or make use of harmful compounds. Biological methods, by the action of microorganisms or their enzymes for lignin content reduction, may be regarded as an alternative, being cheaper and more friendly to the environment than the aforementioned methods. However, until now, biological pretreatments have not shown the same yield as the previously mentioned methods in both sugar recovery and biofuel production. In that sense, the aim of this work is to review the efficiency of these methods, with the goal of clarifying their advantages and disadvantages for improvement of biofuel production.

Polyamidoamine epichlorohydrin (PAAE) is the preeminent permanent wet strength additive used in papermaking. Wet strength additives are used to improve paper resistance to a rupture force in wet environments. The invention of PAAE in 1957 was an innovation, as it improved paper properties by giving superior wet strength in humid or wet conditions. It was rapidly adopted by the industry. Despite PAAE’s long history, the mechanism of PAAE interaction with fiber has not been fully understood. Therefore, fundamental understanding of PAAE mechanism needs to be investigated to improve its utilization in making sustainable paper products. These areas include an understanding of repulping methods and optimal PAAE dosages for better cost and performance. This paper investigates different generations of PAAE, the application method, and its impact on paper recyclability. Three generations of PAAE are currently on the market with at least two newer iterations under development. Critical application parameters that need to be understood include determination of the bonding mechanism, optimal dosage, and retention parameters. The main drawback of PAAE application is it makes paper recycling difficult. Several repulping methods are proposed for better recyclability and sustainability in the papermaking process.

This paper reviews the positive attributes and challenges of bamboo usage in carbon absorption, water, and wastewater purification. Bamboo can serve as a habitat for a variety of creatures and supports a diversified ecology. Bamboo roots can cast a fibrous net into the ground to prevent soil erosion and degradation. As the water passes through this woven mesh, the bamboo roots act as a filter, drawing toxins and other contaminants out of the water. Bamboo can treat wastewater effectively in free-water surface, horizontal flow, and vertical flow constructed wetlands. Bamboo charcoal has exceptional filtering properties for cleaner drinking water and better air quality. Additionally, bamboo can be used to form cellulose-based membranes. Bamboo is a renewable resource for creating paper, furniture, and building materials. Bamboo has various benefits. Thus, bamboo forests offer opportunities for rural communities to thrive economically.

Fungi are a diverse group, and they are essential for health, the economy, and food. Interest in these organisms has increased because of the importance and effect of their chemical components viz., phenolic compounds, which are considered an alternative source of antioxidants. Antioxidants are compounds that prevent cell damage and can help prevent or counteract certain diseases (cardiovascular, neurodegen-erative, cancer, etc.) because they can improve cell function (changes in enzyme activity, enzyme patterns, membrane fluidity, and responses to stimuli), among others. To date, no adverse side effects have been reported. The difference in production is due to several factors, such as the growth environment, nutrition, cell age, the part from where the phenolic compounds are obtained (pileus, stipe, or mycelium), the extraction method, etc. This article aims to provide an overview of wild edible mushrooms, to promote the study of their antioxidant capacity, and to better understand the nutraceutical potential of edible mushrooms consumed in different parts of the world.

Lignin, with its carbon content of up to 60%, can be an ideal precursor for the preparation of carbon materials. Carbonaceous materials obtained from lignin can be transformed into porous and structural morphologies at different scales, providing a biomass approach to energy conversion and storage in batteries. Focusing on lignin-derived carbon materials, this paper summarizes the different morphologies and structures of lignin-based carbon obtained through different preparation methods, and the different electrochemical properties exhibited by these materials as electrode materials for rechargeable batteries (lithium-ion batteries, sodium-ion batteries, lithium-sulphur batteries, etc.). In addition, the development prospects and challenges of lignin-based carbon materials in the field of rechargeable batteries are summarized, providing ideas for the next step in the design and development of high-performance lignin-based carbon-based electrode materials.

Chitosan can serve as a natural alternative to petroleum-based components in food packaging; however, the mechanical and barrier properties of pure chitosan film possess certain limitations. This paper presents a comprehensive review on the mechanical and barrier properties of composite films formed by combining chitosan-based films with plasticizers, polysaccharides, proteins, and lipids. These composite films often exhibit superior mechanical strength and enhanced barrier performance compared to pure chitosan film, thereby expanding the potential applications of chitosan in food packaging. Chitosan represents an ideal raw material for developing innovative biofilms that can cater to diverse packaging requirements for various food products while offering promising prospects for broad application.

In recent years, thermosensitive polysaccharide-based injectable hydrogels have gained increasing attention in biomedical applications, including wound healing, drug delivery, and cartilage repair. These hydrogels have favorable biocompatibility, biodegradability, and tunable physical and chemical properties. Thermosensitive polysaccharide-based injectable hydrogels are a class of intelligent soft matter material. They can undergo a reversible liquid-solid transition when exposed to temperature stimuli. Therefore, their precursor solutions can be accurately inserted into target sites with irregular geometries in a minimally invasive way and then transformed into gels in situ by the organism’s temperature stimulation to deliver biologically active molecules. This review summarizes the recent developments of thermosensitive injectable polysaccharide-based hydrogels. The focus is on the mechanism of sol-gel phase transition, as well as the design and preparation of thermosensitive polysaccharides and their applications in biomedical fields. In addition, the outlook of the challenges in biomedical applications is provided at the end of the paper.

The production of cashew nuts has been increasing globally, leading to a greater volume of waste materials that require proper management. Nevertheless, cashew nutshells (CNS), currently considered waste by most processors, offer a noteworthy opportunity for alternative applications owing to their distinct physical, chemical, and thermal properties.  This article reviews alternative applications for CNS that can leverage these properties, while evaluating research gaps. The potential uses are classified into three categories: material development, energy production, and substance absorption. In the materials segment, various examples are discussed where CNS serves as raw material to synthesize biopolymers, cementitious materials, and a broad range of composites. The energy production section discusses various processes that utilize CNS, including pyrolysis, gasification, and briquette production. The absorption section presents CNS and activated carbon derived from CNS as effective absorbents for liquid-phase and gas-phase applications. While this review highlights numerous research-level possibilities for CNS utilization, only a few of these options have been implemented within the industry. Consequently, further research is essential, particularly in CNS characterization, economic and environmental assessment, and real-life implementation, to broaden and enhance the integration of this biomass into applications that can contribute to the value of both its production and processing chain.

The potential of paper and paperboard as fiber-based materials capable of replacing conventional polymer-based materials has been widely investigated and evaluated. Due to paper’s limited extensibility and inherent heterogeneity, local structural variations lead to unpredictable local mechanical behavior and instability during processing, such as mechanical forming. To gain a deeper understanding of the impact of mechanical behavior and heterogeneity on the paper forming process, the Finite Element Method (FEM) coupled with continuum modeling is being explored as a potential approach to enhance comprehension. To achieve this goal, utilizing experimentally derived material parameters alongside stochastic finite element methods allows for more precise modeling of material behavior, considering the local material properties. This work first introduces the approach of modeling heterogeneity or local material structure within continuum models, such as the Stochastic Finite Element Method (SFEM). A fundamental challenge lies in accurately measuring these local material properties. Experimental investigations are being conducted to numerically simulate mechanical behavior. An overview is provided of experimental methods for material characterization, as found in literature, with a specific focus on measuring local mechanical material structure. By doing so, it enables the characterization of the global material structure and mechanical behavior of paper and paperboard.

Carbon quantum dots (CQDs) are an emerging type of multifunctional nanomaterial. They have unique optical and electronic properties based on their quantum size effect and limiting effect. The carbon quantum dot prepared from biomass is green and environmentally friendly, and it can also achieve a high comprehensive utilization of undervalued biomass wastes. Biomass carbon quantum dots with abundant surface functional groups and good biocompatibility show great potential in ion detection and bioimaging. This review paper focuses on the synthesis methods of CQDs from biomass and the perspective of their applications in recent years, as well as the challenges in the future.