The small-amplitude and finite-amplitude propagation characteristics of laser line source excited and laser detected Scholte waves are investigated. Acoustic waves with Mach numbers up to 0.054 are observed at the interface between water and glass. In our case of a hard solid–liquid interface, the Scholte wave propagates very much like a bulk wave, for which the simple-wave equation holds. The experimental results are well fitted with this model, extended with an attenuation term. An anomalously large (compared with low amplitude viscous effects) attenuation reveals possible leakage of energy from the Scholte wave to bulk waves, through a mechanism of nonlinear mixing between the different wave modes and viscosity induced turbulence.

Polyethylene microplastics (PE MPs) pose a severe threat to aquatic ecosystems and human health, demanding urgent, sustainable remediation strategies. While the electro-Fenton process is widely used for treating refractory pollutants in wastewater, its standalone application remains inadequate for PE MPs due to their stable chemical structure and complex molecular chains. This study introduces a green and sustainable magnetite-activated persulfate electro-Fenton (Mt-PS-EF) system designed to address these limitations while aligning with circular-economy principles. By synergizing Fe₃O₄ catalysis, persulfate activation, and electrochemical processes, the Mt-PS-EF system achieves efficient PE MP degradation through hydroxyl (·OH) and sulfate (SO₄·⁻) radical-driven oxidation. Under optimized conditions (60 mg/L PE, 40 mM persulfate, 150 mg Fe₃O₄, 20 h treatment), a 90.6% degradation rate was attained, with PE MPs undergoing chain scission, surface erosion, and release of low-molecular-weight organics. Crucially, the magnetic property of magnetite facilitated the recovery and reuse of the catalyst, significantly reducing material costs and minimizing waste generation. By integrating catalytic efficiency with resource recovery, this work advances scalable, eco-friendly solutions for microplastic pollution mitigation, directly contributing to UN Sustainable Development Goals (SDGs) 6 (Clean Water) and 14 (Life Below Water). The findings highlight the potential of hybrid electro-Fenton technologies in achieving sustainable wastewater treatment and plastic waste management.

Nano- and microplastic contamination poses a growing challenge to aquatic environments, driving the need for efficient and sustainable removal technologies. In this study, carbon–silica hybrid nanoparticles (CSNPs) were synthesized from rice husk-derived black liquor via controlled lignin–silica self-assembly followed by thermal carbonization, providing a waste-recycling biorefinery route for value-added material production. Structural characterizations revealed that carbonization generates a hierarchically porous carbon–silica hybrid with enhanced surface area. The CSNPs exhibited rapid and size-dependent adsorption toward nano- and microplastics (200–1000 nm), with optimal performance observed for 500 nm particles. Microscopic observations further demonstrated a size-adaptive capture mechanism, involving pore filling and surface adsorption for nanoplastics and aggregate-assisted encapsulation for larger microplastics. This study highlights CSNPs as low-cost and effective adsorbents for broad-spectrum plastic removal while offering a sustainable pathway for the high-value utilization of black liquor and rice husk biomass in water purification applications.