Preparation of lignin-based hydrogels, their properties and applications.

Polymers obtained from biomass are a concerning alternative to petro-based polymers because of their low cost of manufacturing, biocompatibility, ecofriendly and biodegradability. Lignin as the second richest and the only polyaromatics bio-polymer in plant which has been most studied for the numerous applications in different fields. But, in the past decade, the exploitation of lignin for the preparation of new smart materials with improved properties has been broadly sought, because lignin valorization plays one of the primary challenging issues of the pulp and paper industry and lignocellulosic biorefinery. Although, well suited chemical structure of lignin comprises of many functional hydrophilic and active groups, such as phenolic hydroxyls, carboxyls and methoxyls, which provides a great potential to be applied in the preparation of biodegradable hydrogels. In this review, lignin hydrogel is covered with preparation strategies, properties and applications. This review reports some important properties, such as mechanical, adhesive, self-healing, conductive, antibacterial and antifreezing properties were then discussed. Furthermore, herein also reviewed the current applications of lignin hydrogel, including dye adsorption, smart materials for stimuli sensitive, wearable electronics for biomedical applications and flexible supercapacitors. Overall, this review covers recent progresses regarding lignin-based hydrogel and constitutes a timely review of this promising material.

Bacterial Performance in Crack Healing and its Role in Creating Sustainable Construction.

Building practices began with human civilization. Cement is the most commonly used building construction material throughout the world. These traditional building materials have their own environmental impact during production, transportation, and construction, but also have limitations on building quality and cost. Biological construction materials are currently emerging technology to combat emissions from the construction sector. Different civil and biotechnology researchers have turned to microorganisms for the production of bio construction materials that are environmentally friendly, socially acceptable, and economically feasible but can also produce high strength. Scanning electron microscope (SEM) and X-Ray diffraction (XRD) are the most characterization methods used to observe and ensure the production of calcite precipitate as bacterial concrete. As compared to conventional concrete, bacterial concrete was greater by 35.15% in compressive strength, 24.32% in average tensile strength, and 17.24% in average flexural strength, and it was 4 times lower in water absorption and 8 times lower in acid resistivity than conventional concrete. Genetic engineering has great potential to further enhance the mechanical strength of bacterial concrete for use in crack repairs in existing buildings.

Mycelium-Based Composite: The Future Sustainable Biomaterial.

Because of the alarming rate of human population growth, technological improvement should be needed to save the environment from pollution. The practice of business as usual on material production is not creating a circular economy. The circular economy refers to an economic model whose objective is to produce goods and services sustainably, by limiting the consumption and waste of resources (raw materials, water, and energy). Fungal-based composites are the recently implemented technology that fulfills the concept of the circular economy. It is made with the complex of fungi mycelium and organic substrates by using fungal mycelium as natural adhesive materials. The quality of the composite depends on both types of fungi and substrate. To ensure the physicochemical property of the fabricated composite, mycelium morphology, bimolecular content, density, compressive strength, thermal stability, and hydrophobicity were determined. This composite is proven to be used for different applications such as packaging, architectural designs, walls, and insulation. It also has unique features in terms of low cost, low emission, and recyclable.

Comparative Utilization of Dead and Live Fungal Biomass for the Removal of Heavy Metal: A Concise Review.

Human and industrial activities produce and discharge wastes containing heavy metals into the water resources making them polluted, threatening human health and the ecosystem. Biosorption, the process of passive cation binding by dead or living biomass, represents a potentially cost-effective way of eliminating toxic heavy metals from industrial wastewater. The abilities of microorganisms to remove metal ions in solution have been extensively studied; in particular, live and dead fungi have been recognized as a promising class of low-cost adsorbents for the removal of heavy metal ions. The biosorption behavior of fungal biomass is getting attention due to its several advantages; hence, it needs to be explored further to take its maximum advantage on wastewater treatment. This review discusses the live and dead fungi characteristics of sorption, factors influencing heavy metal removal, and the biosorption capacities for heavy metal ions removal and also discusses the biosorption mechanisms.