Volume 21 Issue 3

The enzymatic breakdown of lignin generates a spectrum of aromatic monomers — including vanillin, guaiacol, syringaldehyde, vanillic acid, ferulic acid, and p-coumaric acid — that serve as platform chemicals for pharmaceuticals, fragrances, resins, and bio-based polymers. However, its complex and recalcitrant structure necessitates highly efficient enzymatic systems for depolymerization. This review systematically classifies ligninolytic enzymes into five functional categories: laccases, peroxidases (including manganese peroxidases, lignin peroxidases, and versatile peroxidases), cytochrome P450s, dye-decolorizing peroxidases (DyPs), and auxiliary enzymes, evaluating their distinct roles and synergies in lignin breakdown. Laccases emerge as particularly versatile biocatalysts due to their widespread occurrence, broad substrate specificity, and operational flexibility under diverse conditions. Peroxidases drive critical oxidative reactions, while DyPs represent a functionally robust peroxidase class with superior stability under extreme pH, temperature, and pressure. Complementary enzymes such as etherases and lignin-mimetic systems further expand the toolbox for lignin valorization. To overcome inherent limitations of native enzymes, protein engineering strategies were highlighted to enhance catalytic efficiency, stability, and substrate affinity. Additionally, enzyme immobilization on advanced matrices (e.g., metal-organic frameworks) is discussed as a breakthrough approach to improve reusability and reaction scalability. These integrated advancements pave the way for sustainable lignin valorization.

Biogas produced through the anaerobic digestion of organic biomass is a renewable energy source with significant potential to replace fossil fuels. However, impurities such as carbon dioxide, hydrogen sulfide, and water vapor reduce its calorific value and cause operational challenges. Upgrading is therefore essential to increase methane concentration and biogas quality. Among various upgrading technologies, adsorption using activated carbon offers a practical, low cost, and energy efficient alternative. Activated carbon derived from lignocellulosic biomass exhibits high surface area (up to 3000 m²/g), tunable pore structure, and resistance to moisture saturation, making it suitable for carbon dioxide and methane separation. Activation techniques, both physical (using carbon dioxide or steam) and chemical (using potassium hydroxide or phosphoric acid), significantly influence surface functional groups and pore distribution. Natural and synthetic binders such as bentonite clay, methyl cellulose, and polyvinyl alcohol can enhance mechanical strength and adsorption stability in humid conditions. This review considers the structure, activation, and adsorption mechanisms of biomass derived activated carbon for biogas purification. Future research directions include hybrid composite development, functional surface modification, and performance evaluation under industrial biogas conditions. Overall, activated carbon represents a sustainable and efficient adsorbent supporting the transition toward cleaner and low carbon energy systems.

The transition toward a circular economy has established biodegradable polymer composites as a critical platform for active food packaging. This review systematically examines the structural design, functional mechanisms, and application performance of natural biopolymer matrices, including polysaccharides and proteins. Physicochemical coupling among polymer-network architecture, interfacial interactions, and active-agent dispersion governs the integration of antimicrobial, antioxidant, gas-barrier, UV-shielding, moisture-regulating, and stimuli-responsive functions. Particular emphasis is placed on controlled mass transfer and release kinetics at active packaging interfaces. Active-agent delivery is governed by molecular diffusion, polymer-network relaxation, carrier structure, and microenvironmental triggers such as pH, humidity, and temperature, which collectively determine the effective concentration and duration of antimicrobial and antioxidant activity. These structure–release–function relationships are further evaluated in high-moisture foods, respiring fruits and vegetables, and low-moisture or lipid-rich products. In addition, this review discusses the major constraints on industrial translation, including the migration and regulatory compliance of intentionally and non-intentionally added substances, nanoparticle safety, environment-dependent biodegradation, life cycle impacts, and thermomechanical challenges associated with continuous processing. Future development should move beyond passive material substitution toward the integrated design of active and intelligent packaging, scalable manufacturing, food-specific performance validation, and multi-objective optimization of functionality, safety, cost, and end-of-life behavior.

The utilization of starch-based bioplastics as renewable and environmentally friendly alternatives to replace traditional petroleum plastics has gained significant traction in recent years due to their biodegradability, renewability, and cost-effectiveness. However, their widespread industrial applications are hindered by shelf-life constraints, high moisture sensitivity, and poor performance when subjected to variations in microbial and temperature changes. In addition, starch-based bioplastics are formulated in complex mixtures, which may result in process-related toxicity. This review critically investigates these performance issues in depth, including toxicity potential, shelf-life, microbial resistance development, thermal stability, and physical appearance. Particular emphasis is placed on the safety of natural starch sources, the influences of environmental conditions on degradation behavior, and the incorporation of natural additives to enhance material properties. By considering these factors, this review aims to facilitate the development and selection of sustainable, safer, and environmentally friendly starch-based bioplastics for diverse future applications.

This review article considers factors contributing to the development of problematic levels of foam, as well as ways to control foam, with emphasis on two critically important unit operations in pulp and paper manufacturing plants, namely the brownstock washing system and the paper machine. In general terms, hard-to-break foam bubbles can be expected when an aqueous system is subject to a means of air entrainment (such as agitation), when an air phase is present, when there are surface-active agents present, and when the solution also contains significant levels of water-soluble polymers. Brownstock washers and paper machines have all of these ingredients, and sometimes they are at problematic levels. The resulting stabilized foam bubbles can hurt production rates, interfere with displacement of pulping liquor from the fiber mat during washing, and contribute to blemishes in paper products. Considerable progress has been made over many years in understanding these phenomena and also in understanding the work of foam-control products. Engineers in modern pulp and paper mills can make use of efficient foam-control products as well as monitoring equipment. This article provides a tutorial review of such issues, based on published findings.

Establishing an economically efficient supply chain for biomass feedstock is a critical prerequisite for achieving large-scale bioenergy development under China’s “dual carbon” strategy. Focusing on agro-forestry residue feedstocks, this paper systematically reviews the technologies and models for the key stages of their collection, storage, and transportation (CST) system. The inherent physicochemical characteristics of biomass, such as low bulk density and high moisture content, constitute a fundamental physical bottleneck that constrains its economic viability. To this end, pretreatment technologies, with densification at their core, are widely recognized as a critical technological stage for enhancing logistics efficiency and achieving value addition. In contrast to the technological optimization of individual stages, systemic integration strategies—such as establishing a hybrid “decentralized-centralized” supply chain model and employing multi-modal transport—represent a more effective pathway to achieving whole-chain cost reduction and efficiency enhancement. Through a systematic integration of research in this field, this paper emphasizes that the key to resolving CST bottlenecks lies in adopting a whole-chain perspective that involves the deep coupling of essential pretreatment technologies with innovative supply chain organizational models.