Plastics are widely used across various industries due to their flexibility, cost-effectiveness, and durability. This extensive use has resulted in significant plastic pollution, with microplastics (MPs) becoming pervasive contaminants in water bodies worldwide, adversely affecting aquatic ecosystems and human health. This review explores the surface characteristics of carbon-based adsorbents, including biochar, activated carbon, carbon nanotubes (CNTs), and graphene, and their influence on MP removal efficiency. Key surface characteristics such as the carbon content, surface area, pore size, and particle size of adsorbents influenced adsorption efficiency. Additionally, hydrophobic interaction, van der Waals forces, π–π interactions and electrostatic interaction were found to be mechanisms by which microplastics are trapped onto adsorbents. Modified biochar and activated carbon demonstrated high adsorption efficiencies, while CNTs and graphene, with their high carbon contents and well-defined mesopores, showed outstanding performance in MP removal. Although a high surface area was generally associated with better adsorption performance, modifications significantly enhanced efficiency regardless of the initial surface area. This review emphasizes the importance of understanding the relationship between surface characteristics and adsorption efficiency to develop optimized adsorbents for MP removal from wastewater. However, challenges such as the lack of standardized testing methods, variability in biochar performance, and the high cost of regenerating carbon adsorbents remain. Future research should focus on developing cost-effective production methods, optimizing biochar production, and exploring advanced modifications to broaden the application of carbon adsorbents. Integrating advanced adsorbents into existing water treatment systems could further enhance MP removal efficiency. Addressing these challenges can improve the effectiveness and scalability of carbon-based adsorbents, significantly contributing to the mitigation of microplastic pollution in wastewater.

Carbon and graphene family nanomaterials have attracted more attentions and interests in the asphalt modification research due to their superior mechanical properties. This paper provides the state-of-art review of various graphene synthesis methods (chemical vapour deposition, exfoliation, thermal decomposition, unzipping, and reduction of graphite oxide) and recent studies on typical carbon and graphene family nanomaterials (nanoplatelets and graphene oxide) and carbon nanotube used for asphalt modification towards road engineering application. The effect of each nanomaterial on the asphalt binder is explored with respect to the rutting resistance (high-temperature property), fatigue cracking resistance (intermediate temperature property), and thermal cracking resistance (low-temperature property), respectively. Additionally, various blending methods for dispersing nanomaterials into the asphalt and the cost-effectiveness of each graphene family material are discussed.

This paper provides an in-depth and comprehensive review of the incorporation of fibres in asphalt pavements, focusing on the use of fibres in asphalt materials in respect to fibre classification, dosages, methods of incorporation and handling, performance evaluation, critical issues and sustainability. The type of fibre determines important properties that are crucial to the effectiveness in its incorporation into asphalt. As fibre and asphalt are two of the oldest engineering materials that are still in high demand today, this paper provides insights on the challenge and future study on the fibre-reinforced asphalt pavement. Further studies are recommended on the compatibility between fibres and asphalt mixtures, quality control of fibres in mixtures, extraction and harvesting fibres in a cost effective and sustainable manner, quantification of cost effectiveness and environmental impacts of fibre-reinforced asphalt pavements, true roadway performances with fibres deterioration in the harsh environment, as well as recyclability at its end-of-life.