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The inherent complexity of cellulose, hemicellulose, and lignin contributes to the recalcitrance of lignocellulosic biomass, resulting in a low conversion efficiency and high cost of bioethanol conversion. Pretreatment methods that disrupt the plant cell structure of lignocellulose, such as straw, can significantly enhance the conversion efficiency. In this study, we utilized an acid-assisted mechanocatalytic depolymerization technique to pretreat rice straw, and the results demonstrated a significant disruption of the cellulose structure of the straw. Compared to the untreated straw, the particle size of pretreated straw reduced from 279 μm to 11.8 μm, the crystallinity of cellulose decreased from 43.05% to 22.71%, the specific surface area increased by 177%, and the surface oxygen-to-carbon ratio (O/C) ratio was enhanced by 75%. The changes in microstructure enabled the pretreated straw to achieve a total sugar yield of over 95% within 12 h of enzymatic hydrolysis, significantly superior to the 36.24% yield from untreated straw, the 45.20% yield from acid impregnated straw, and the 73.25% yield from ball milled straw. Consequently, acid-assisted mechanocatalytic depolymerization emerges as a highly effective pretreatment strategy to enhance both the enzymatic hydrolysis and the overall conversion efficiency of rice straw. [ABSTRACT FROM AUTHOR]

Amid escalating global concerns regarding plastic pollution, a multitude of strategies for the removal of microplastics and nanoplastics (MPs/NPs) have been rigorously explored. Biochar, distinguished by its elevated specific surface area, complex porosity, and robust stability, has emerged as a promising candidate for the adsorption of MPs/NPs from the environment. This review introduces biochar modification techniques to augment the adsorption capabilities of biochar-based adsorbents, encompassing acid/base modification, metal modification, ball milling modification, and surfactant modification. The mechanisms of MPs/NPs adsorption by biochar are discussed in detail. Besides, the influence of environmental factors on the adsorption behavior of biochar adsorbents is also analyzed. Lastly, future research directions and innovative strategies are proposed aiming to provide comprehensive assistance in exploring the potential applications of biochar. In addition to pursuing enhanced removal efficiency of MPs/NPs through biochar, the challenges of biochar regeneration and substance leaching are also discussed by introducing constructive strategies, such as constructing catalytic degradation systems and enhancing adsorbent stability through calcination, to bolster the sustainability of biochar-based environmental remediation approaches. Conclusively, biochar presents a significant avenue for the environmental amelioration of MPs/NPs, with its deployment in environmental stewardship warranting deeper exploration. [Display omitted] • Microplastic/nanoplastic can be effectively removed by biochar. • An overview of the adsorption mechanism of microplastic/nanoplastic on biochar. • Key environmental factors influencing biochar adsorption are discussed. • The future challenges and perspectives of biochar development are summarized. [ABSTRACT FROM AUTHOR]

• The deconstruction of cell walls in molecular-level during ball milling was evaluated. • Mechanical fragmentation could efficiently modify the supramolecular structure of cellulose-hemicelluloses-lignin matrix. • Ball milling led to the depolymerization of the complex polymeric structure of cell wall, especially the polysaccharides. • Micromorphology features of corn stover were significantly changed by mechanical action. In this work, the deconstruction mechanism of corn stover cell wall polymers during ball milling was evaluated. The characterization showed that ball milling not only brought about the dissociation of the cross-linked cellulose-hemicellulose-lignin complex but also led to the depolymerization of the cell-wall polymers especially the carbohydrates. Micromorphology characterization revealed that mechanical treatment disrupted the orderly fibrillar matrices with a porous structure. The breakage of β-1,4 glycosidic bonds in cellulose and the decomposition of arabinoxylans indicated the modification in polysaccharide chains. The degradation of lignin-carbohydrate complex (LCC) linkages and the cleavage of β-O-4′ linkages in lignin approved the partial degradation of lignin. In conclusion, mechanochemistry is an efficient force to make the polymers in plant fibers more digestible. [ABSTRACT FROM AUTHOR]

Highlights • Carbonization and ball milling enhancement of Pb(II) adsorption on WS-CK verified. • Carbonization markedly contributes to precipitation mechanism of Pb(II) adsorption. • Carbonization and ball milling enhance ion exchange mechanism of Pb(II) adsorption. • Competition exists between ion exchange and precipitation during Pb(II) adsorption. Abstract Straw biomass is a promising adsorbent for the removal of heavy metals. To improve its Pb(II) adsorption capacity and elucidate competition of adsorption mechanisms (e.g., ion exchange and precipitation), the Pb(II) adsorption mechanisms for wheat straw (WS-CK), wheat straw-biochar (WS-BC), and ball-milled wheat straw-biochar (WS-BC + BM) samples were investigated in detail by EDX, XRD, and FTIR. The results implied that the Pb(II) adsorption capacities at an adsorbent dosage of 0.2 g/L onto WS-CK, WS-BC, and WS-BC + BM were 46.33, 119.55, and 134.68 mg/g, respectively. This indicates that carbonization and ball milling are efficient techniques for improving the adsorption capacity of Pb(II) onto wheat straw, as WS-BC and WS-BC + BM exhibited adsorption capacities comparable to other commonly used bioadsorbents. Carbonization contributed significantly to precipitation (e.g., PbCO 3 and Pb 3 (CO 3) 2 (OH) 2). Furthermore, competition existed between ion exchange and precipitation during the Pb(II) adsorption process. With relative lower adsorbent dosages, carbonization and ball milling enhanced ion exchange capacity. [ABSTRACT FROM AUTHOR]