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.

When the coronavirus disease 2019 (COVID-19) pandemic spread globally, wearing face masks in public became one of the most effective protective measures. Subsequently, due to the increasing demand for face masks, researchers explored feasible approaches to optimize their efficiency. The outcome of this research provides insights into the adsorption performance of four commercial face mask filter inserts with activated carbon layers (ACL). The results showed that the ACL of the inserts has very low Brunauer, Emmett, and Teller (BET) surface areas (2–33 m²/g) and low carbon percentages (19–31%). Physical adsorption analysis revealed non-uniform micropore size distributions in all samples. In addition, non-woven structures were obtained through scanning electron microscopy (SEM). The experimental outcomes show that the ACL in the purchased face masks is low-quality adsorbent and not pure carbonaceous material; polymeric components may be predominant.

This study investigates the efficacy of biochar derived from Southern Yellow Pine for the removal of polystyrene (PS) microplastics (0.2 µm) from aqueous solutions. Raw biochar was produced via carbonization and subsequently activated using CO ₂ at temperatures ranging from 550 to 850°C for activation times of 1–4 h, and was sieved into uniform-sized adsorbents between 300 and 425 μm. The effects of these activation parameters on the biochar's physicochemical properties and microplastic adsorption performance were systematically evaluated. Surface characterization through N ₂ adsorption, ultimate and proximate analyses, and FTIR revealed that activation significantly enhanced the specific surface area and porosity. The Brunauer–Emmett–Teller (BET) surface area increased from 235.6 m ² /g for raw biochar to a maximum of 600.2 m ² /g for biochar activated at 850°C for 1h. Batch adsorption experiments demonstrated a strong correlation between surface area and adsorption capacity. The biochar activated at 850°C exhibited the highest microplastic removal efficiency of 99%, significantly outperforming the raw biochar and samples activated at lower temperatures. These findings highlight that thermal activation is a critical step for enhancing biochar’s properties and that tuning activation parameters, particularly temperature, is key to optimizing its performance for microplastic remediation in wastewater.