Oxygen atmosphere enhances ball milling remediation of petroleum-contaminated soil and reuse as adsorptive/catalytic materials for wastewater treatment.

Ball milling is an environmentally friendly technology for the remediation of petroleum-contaminated soil (PCS), but the cleanup of organic pollutants requires a long time, and the post-remediation soil needs an economically viable disposal/reuse strategy due to its vast volume. The present paper develops a ball milling process under oxygen atmosphere to enhance PCS remediation and reuse the obtained carbonized soil (BCS-O) as wastewater treatment materials. The total petroleum hydrocarbon removal rates by ball milling under vacuum, air, and oxygen atmospheres are 39.83%, 55.21%, and 93.84%, respectively. The Langmuir and pseudo second-order models satisfactorily describe the adsorption capacity and behavior of BCS-O for transition metals. The Cu2+, Ni2+, and Mn2+ adsorbed onto BCS-O were mainly bound to metal carbonates and metal oxides. Furthermore, BCS-O can effectively activate persulfate (PDS) oxidation to degrade aniline, while BCS-O loaded with transition metal (BCS-O-Me) shows better activation efficiency and reusability. BCS-O and BCS-O-Me activated PDS oxidation systems are dominated by 1O2 oxidation and electron transfer. The main active sites are oxygen-containing functional groups, vacancy defects, and graphitized carbon. The oxygen-containing functional groups and vacancy defects primarily activate PDS to generate 1O2 and attack aniline. Graphitized carbon promotes aniline degradation by accelerating electron transfer. The paper develops an innovative strategy to simultaneously realize efficient remediation of PCS and sequential reuse of the post-remediation soil.

Specific of mechanical alloying of solid-liquid binary system Fe-Ga and effect of different process control agents.

Mechanical alloying allows obtaining nonequilibrium structures in various systems, often possessing unique properties, including magnetic ones. Considering the unusual structural features of the magnetostrictive Fe-Ga alloy, this approach may be promising for this system. In this work, extensive experimental studies were carried out aimed at studying the features of mechanical alloying of Fe-Ga. The object of the study was the system Fe-20 wt% Ga in which disordered solid solution α-Fe(Ga) is formed. It was shown that high-intensity milling is an effective tool for mechanical alloying of solid-liquid binary system Fe-Ga, but a serious problem is a low powder recovery, less than 50 %. To solve this problem, various process control agents were tested. Their influence on powder recovery, process kinetics, particle size, carbon contamination, and magnetic properties was studied using a large set of techniques such as XRD, SEM, EDS, VSM, LIBS, and others. It has been shown that, based on a combination of factors, the optimal process control agent for this system is ethanol in an amount of 1 wt.

Beneficial utilization of ball-milled carbon sand to activate peroxymonosulfate oxidation: Quantitation of ROS using probe-based kinetic models and mechanism insights.

In this study, the oil sand was treated with an integrated process of pyrolysis and ball milling, and the obtained ball-milled carbon sand (BMCS) was utilized as peroxymonosulfate (PMS) activator to treat wastewater containing aniline (AN). Quenching experiments and electron paramagnetic resonance (EPR) confirmed the existence of sulfate radical (SO4∙-), hydroxyl radical (·OH) and singlet oxygen (O12) in the BMCS/PMS system. A probe-based kinetic model was constructed to describe the degradation process of pollutants in the BMCS/PMS system, quantified the exposure of each reactive oxygen species and their contributions to AN degradation. BMCS activated PMS to quickly produce SO4∙- and gradually generate ·OH. The O12 exposure showed a rapid increasing trend and the largest total exposure, while its contribution to AN degradation was small. Ball milling time and BMCS dosage demonstrated significant effect on the exposure of ·OH and O12. The main active sites for BMCS to activate PMS were iron oxides, defective carbon and oxygen-containing functional groups. This study provides a green and low-cost process for value-added transformation of pyrolytic residue of oil sand (PROS), so as to promote PROS treatment mode from harmless disposal to resource utilization.

Effective removal of Cr(VI) from water by ball milling sulfur-modified micron zero-valent iron：Influencing factors and removal mechanism.

To address the issues of ZVI's susceptibility to oxidation and aggregation, ball milling and Na2S·9H2O modification were employed on ZVI to enhance its efficiency in removing Cr(VI) from effluent. The characterization results expressed that S-mZVIbm had mesoporous and macroporous structures, enabling successful capture of Cr(VI). Moreover, S-mZVIbm had the highest adsorption capacity for Cr(VI) (350.04 mg/g) at pH = 2.00 and reached kinetic equilibrium within 420 min. Furthermore, the adsorption of Cr(VI) by S-mZVIbm conformed to the Avrami-fractional-order model, demonstrated that the adsorption process indicated a complex multi-adsorption process. Meanwhile, the adsorption also fit to Langmuir and Sips models, suggesting monolayer-level adsorption with heterogeneous sites located on S-mZVIbm. The S-mZVIbm could enhance Cr(VI) adsorption through various synergistic mechanisms, such as electrostatic interaction, chemical precipitation, surface complexation, and reduction. Overall, this research presented an innovative perspective for the modification of ZVI, and S-mZVIbm could be widely applied in the practical remediation of wastewater containing Cr(VI).

Toward the Production of Hydroxyapatite/Poly(Ether-Ether-Ketone) (PEEK) Biocomposites: Exploring the Physicochemical, Mechanical, Cytotoxic and Antimicrobial Properties.

The development of hydroxyapatite (HAp) and polyether ether ketone (PEEK) biocomposites has been extensively studied for bone repair applications due to the synergistic properties of the involved materials. In this study, we aimed to develop HAp/PEEK biocomposites using high-energy ball milling, with HAp concentrations (20%, 40%, and 60% w/v) in PEEK, to evaluate their physicochemical, mechanical, cytotoxicity, and antimicrobial properties for potential applications in Tissue Engineering (TE). The biocomposites were characterized by structure, morphology, apparent porosity, diametral compression strength, cytotoxicity, and antimicrobial activity. The study results demonstrated that the HAp/PEEK biocomposites were successfully synthesized. The C2 biocomposite, containing 40% HAp, stood out due to the optimal distribution of HAp particles in the PEEK matrix, resulting in higher compression strength (246 MPa) and a homogeneous microstructure. It exhibited antimicrobial activity against Staphylococcus aureus, Pseudomonas aeruginosa, and Escherichia coli, with no cytotoxicity observed. These properties make the C2 biocomposite promising for regenerative medicine applications, combining mechanical strength, bioactivity, and biocompatibility.

Microcrystalline Engineering of Anthracite-Based Carbon Via Salt-Assisted Ball Milling for Enhanced Sodium Storage Performance.

Coal-based carbon material, characterized by abundant resources and low cost, has gained considerable interests as a promising anode candidate for sodium-ion batteries (SIBs). However, the coal-based carbon generally shows inferior Na-storage performance due to its highly-ordered microstructure with narrow interlayer spacing. Herein, a salt-assisted mechanical ball-milling strategy is proposed to disrupt the polycyclic aromatic hydrocarbon structure in anthracite molecules, thereby reducing the microcrystalline regularity of the derived carbon during following pyrolysis process. In addition, the induced C─O─C bonds during ball-milling process can alter the pyrolysis behavior of anthracite and restrain the formation of surface defects. Consequently, in contrast to pristine anthracite-based pyrolytic carbon, which exhibits a Na-storage capacity of 198.4 mAh g-1 with a low initial Coulombic efficiency (ICE) of 65.1%, the ball-milling modified carbon assisted by NaCl salt (NAC), with enhanced structural disordering and reduced surface defects, demonstrate significantly improved Na-storage capacity of 332.1 mAh g-1 and ICE value of 82.0%. The NAC electrode also realizes excellent cycle and rate performance, retaining a capacity of 196.0 mAh g-1 at 1 C after 1000 cycles. Furthermore, when coupled with NaNi1/3Fe1/3Mn1/3O2 cathode, the assembled Na-ion full cell deliveres an exceptional electrochemical performance, highlighting its promising prospect as high-performance anode for SIBs.

Microstructure evolution and catalytic activity of AlCo1-xFeNiTiMox high entropy alloys fabricated by powder metallurgy route.

This investigation presents the synthesis of equiatomic and non-equiatomic AlCo1-xFeNiTiMox (x = 0, 0.1, 0.25 and 1.0) high entropy alloys fabricated by mechanical alloying. Mo partially replaced Co. Classic thermodynamic calculations, such as mixing enthalpy (ΔHmix), configurational entropy (ΔSmix), the atomic size difference (δ), entropy to enthalpy ratio (Ω), electronegativity difference (△χ), and valence electron concentration (VEC) were used. Considering δ, Ω and VEC parameters, a BCC solid solution and an intermetallic phase can be predicted due to the partial replacement of Co by Mo. X-ray and electron diffraction of equiatomic HEA without Mo content revealed that after 35 h of milling, a Fe-type BCC lattice phase was formed in the alloy and two L21 phases, in addition to a minimal amount of FCC phase. As the Mo content increased, the Fe-type BCC phase was steadily replaced by the Mo-type BCC phase and the Fe-type FCC phase, and two L21 phases were also developed. When the 5 at% Mo-containing (x = 0.25) alloy was further milled for 80 h, the amount of phases remained almost the same; only the grain size was strongly reduced. The influence of the Mo addition on the properties of studied alloys was also confirmed in the decolourisation of Rhodamine B using a modified photo-Fenton process. The decolourisation efficiency within 20 min was 72% for AlCoFeNiTi and 87% for AlCo0.75FeNiTiMo0.25 using UV light with 365 nm wavelength.

Mechanochemistry in Glycation Research.

Mechanochemistry by milling has recently attracted considerable interest for its ability to drive solvent-free chemical transformations exclusively through mechanical energy and at ambient temperatures. Despite its popularity and expanding applications in different fields of chemistry, its impact on Food Science remains limited. This review aims to demonstrate the specific benefits that mechanochemistry can provide in performing controlled glycation, and in "activating" sugar and amino acid mixtures, thereby allowing for continued generation of colors and aromas even after termination of milling. The generated mechanical energy can be tuned under specific conditions either to form only the corresponding Schiff bases and Amadori compounds or to generate their degradation products, as a function of the frequency of the oscillations in combination with the reactivity of the selected substrates. Similarly, its ability to initiate the Strecker degradation and generate pyrazines and Strecker aldehydes was also demonstrated when proteogenic amino acids were milled with glyoxal.

Enhanced the removal of norfloxacin by oxalated zero-valent iron with rich surface Fe(II) sites activating the chlorite.

Oxalic acid-modified ball-milled zero-valent iron (OA-ZVIbm) was employed to activate sodium chlorite (ClO2-) for the removal of norfloxacin (NOR). The complete removal of 20 mg/L NOR was achieved within 60 min by the OA-ZVIbm/ClO2- process. Compared with the ZVIbm/ClO2- process which was the ball-milled zero-valent iron (ZVIbm) activate sodium chlorite, the reaction activity of the OA-ZVIbm/ClO2- process was increased by 102.6 times. Through scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), electrochemical testing, and density functional theory (DFT) calculations, which has been confirmed that the introduction of oxalic acid can significantly increase the surface Fe(II) content of OA-ZVIbm, and accelerate the electron transfer rate of iron nuclei, thereby improve the efficiency of ClO2- activation for the removal of NOR. The role of various active species in NOR removal, which were •O2-, 1O2, Fe(IV), ClO2, and •OH, was elucidated through free radical quenching experiments, electron paramagnetic resonance (EPR) spectroscopy, and quantitative detection of active species. These active species all participated in the reaction, while •O2- played a dominant role in the reaction because it could transform into other active species, such as (•OH, 1O2). Inorganic anions and natural organic matter have no significant effect on the removal of NOR in the OA-ZVIbm/ClO2- process. The protonation of oxalic acid ensured its good pH applicability range (pH = 2-11), thus exhibiting excellent performance in NOR removal in real water bodies. This further demonstrates that OA-ZVIbm prepared by oxalic acid ball milling modification is an efficient ClO2- activator, offering promising prospects for antibiotic removal technology.

Co-production of cellulose and lignin by Taguchi-optimized one-pot deep eutectic solvent-assisted ball milling pretreatment of raw oil palm leaves.

This study explores an eco-friendly delignification technique for raw oil palm leaves (OPL), highlighting the optimized conditions of choline chloride-lactic acid deep eutectic solvent (DES)-mediated ball milling pretreatment to maximize the co-production yields of highly crystalline cellulose and lignin. Our five-level-four-factor Taguchi design identified the optimal reaction settings for cellulose production (85.83 % yield, 47.28 % crystallinity) as 90-minute milling, 1500 rpm, mill-ball size ratio of 30:10, ball-to-sample mass ratio of 20:1, DES-to-sample mass ratio of 3:1. Conversely, the maximal lignin extraction yield (35.23 %) occurred optimally at 120-minute milling, 600 rpm, mill-ball size ratio of 25:5, ball-to-sample mass ratio of 20:1 and DES-to-sample mass ratio of 9:1. Statistical results showed that milling frequency (p-value ≤ 0.0001) was highly significant in improving cellulose crystallinity and yield, while DES-to-sample mass ratio (p-value ≤ 0.0001) was the most impacting on lignin yield. The thermogravimetric method affirmed the elevated cellulose thermal stability, corroborating the enhanced cellulose content (40.14 % to 73.67 %) alongside elevated crystallinity and crystallite size (3.31 to 4.72 nm) shown by X-ray diffractograms. The increased surface roughness seen in micrographs mirrored the above-said post-treatment changes. In short, our optimized one-pot dual-action pretreatment effectively delignified the raw OPL to produce cellulose-rich material with enhanced crystallinity and lignin solidity.

Triphasic Hydroxysilylation of Alkenes by Mechanically Piezoelectric Catalysis.

The 1,2-hydroxysilylation of alkenes is crucial for synthesizing organosilicon compounds which are key intermediates in material science, pharmaceuticals, and organic synthesis. The development of strategies employing hydrogen atom transfer pathways is currently hindered by the existence of various competing reactions. Herein, we reported a novel mechanochemical strategy for the triphasic 1,2-hydroxysilylation of alkenes through a single-electron-transfer pathway. Our approach not only circumvents competitive reactions to enable the first-ever 1,2-hydroxysilylation of unactivated alkenes but also pioneers the research in mechanic force-induced triphasic reactions under ambient conditions. This gentle method offers excellent compatibility with various functional groups, operates under simple and solvent-free conditions, ensures rapid reaction time. Preliminary mechanistic investigations suggest that silylboronate can be transformed to a silicon radical by highly polarized Li2TiO3 particles and oxygen under ball-milling condition.

Creation of fully degradable and mechanically robust poly(4-hydroxybutyrate) films by filling modified starch.

Chemically synthesized poly(4-hydroxybutyrate) (P4HB) is a new generation of biomass-derived and degradable semi-crystalline polymer with good comprehensive properties, but high costs limit its application. Starch, as an inexpensive natural polymer, can reduce the cost of P4HB products. However, starch lacks thermoplastic behavior and has poor compatibility with P4HB, thus its extensive use will inevitably impair the mechanical properties of P4HB. In this study, the ball-milling starch grafting process is adopted, which can simultaneously solve the two major deficiencies of starch, and the prepared ball-milling starch-g-polycaprolactone (BSt-g-PCL) has thermoplasticity and better compatibility with P4HB. BSt-g-PCL can melt near 55 °C, and the interweaving of its molecular chains with P4HB reduces the binding energy (Einteraction) of both, making the phase interface blurred or even disappear. Therefore, the elongation at break retention (REB) of P4HB/BSt-g-PCL can increase from 37.1 % to 74.3 % compared to P4HB/starch at the same filling (70 Phr). Additionally, BSt-g-PCL can exert the effect of accelerating P4HB degradation and still make it maintain excellent anti-aging ability. The ball-milling starch graft process provides a simple and effective method for the preparation of inexpensive fully biodegradable P4HB composite films with excellent mechanical properties.

General synthesis of high-entropy oxides and carbon-supported high-entropy oxides by mechanochemistry.

High-entropy oxides (HEOs) have been receiving a lot of attention due to their excellent properties. However, current common methods for preparing HEOs usually involve high-temperature processes. The development of green synthesis techniques remains an important issue. Carbon-supported HEOs have shown excellent performance in electrochemical energy storage in recent years. Crucially, the traditional methods cannot synthesize carbon-supported HEOs under N2 or air atmospheres. Toward this end, a universal method for preparing carbon-supported HEOs was proposed. During this process, without high-temperature post-treatment, high-entropy LaMnO3 could be synthesized in 2 hours using the mechanical ball-milling method. Furthermore, this method was universal and has been proved in the synthesis of a series of HEOs such as PrVO3, SmVO3, and MgAl2O4. The LaMnO3 species synthesized by this method exhibit excellent catalytic performance in CO combustion and could maintain a conversion rate of over 97% for 350 hours. Subsequently, carbon-supported HEOs could be obtained with 0.5 hours of additional ball-milling, offering significant advantages over traditional methods. This process provides a potential method to synthesize carbon-supported HEOs.

Solid Dispersions Obtained by Ball Milling as Delivery Platform of Etodolac, a Model Poorly Soluble Drug.

Poor water solubility of drugs is a limiting factor for their bioavailability and pharmacological activity. Many approaches are known to improve drug solubility, and among them, the physical method, solid dispersions (SDs), is applied. SDs are physical mixtures of a drug and a carrier, sometimes with the addition of a surfactant, which can be obtained by milling, cryomilling, spray-drying, or lyophilization processes. In this study, solid dispersions with etodolac (ETD-SDs) were prepared by the milling method using different carriers, such as hypromellose, polyvinylpyrrolidone, copovidone, urea, and mannitol. Solubility studies, dissolution tests, morphological assessment, thermal analysis, and FTIR imaging were applied to evaluate the SD properties. It was shown that the ball-milling process can be applied to obtain SDs with ETD. All designed ETD-SDs were characterized by higher water solubility and a faster dissolution rate compared to unprocessed ETD. SDs with amorphous carriers (HPMC, PVP, and PVP/VA) provided greater ETD solubility than dispersions with crystalline features (urea and mannitol). FTIR spectra confirmed the compatibility of ETD with tested carriers.

Technologies for Mechanical Recycling of Carbon Fiber-Reinforced Polymers (CFRP) Composites: End Mill, High-Energy Ball Milling, and Ultrasonication.

Carbon fiber reinforced polymer (CFRP) composites have very high specific properties, which is why they are used in the aerospace, wind power, and sports sectors. However, the high consumption of CFRP compounds leads to a high volume of waste, and it is necessary to formulate mechanical recycling strategies for these materials at the end of their useful life. The recycling differences between cutting-end mills and high-energy ball milling (HEBM) were evaluated. HEBM recycling allowed us to obtain small recycled particles, but separating their components, carbon fiber, epoxy resin, and CFRP particles, was impossible. In the case of mill recycling, these were obtained directly from cutting a CFRP composite laminate. The recycled materials resulted in a combination of long fibers and micrometric particles-a sieving step allowed for more homogeneous residues. Although long, individual carbon fibers can pass through the sieve. Ultrasonication did not significantly affect HEBM recyclates because of the high energy they are subjected to during the grinding process, but it was influential on end mill recyclates. The ultrasonication amplitude notably impacted the separation of the epoxy resin from the carbon fiber. The end mill and HEBM waste production process promote the presence of trapped air and electrostatics, which allows recyclates to float in water and be hydrophobic.

Regulating the Pore Structure of Biomass-Derived Hard Carbon for an Advanced Sodium-Ion Battery.

Biomass-derived hard carbon materials are attractive for sodium-ion batteries due to their abundance, sustainability, and cost-effectiveness. However, their widespread use is hindered by their limited specific capacity. Herein, a type of bamboo-derived hard carbon with adjustable pore structures is developed by employing a ball milling technique to modify the carbon chain length in the precursor. It is observed that the length of the carbon chain in the precursor can effectively control the rearrangement behavior of the carbon layers during the high-temperature carbonization process, resulting in diverse pore structures ranging from closed pores to open pores, which significantly impact the electrochemical properties. The optimized hard carbon with abundant closed pores exhibits a high specific capacity of 356 mAh g-1 at 20 mA g-1, surpassing that of bare hard carbon (243 mAh g-1) and hard carbon with abundant open pores (129 mAh g-1 at 20 mA g-1). However, the kinetic analysis reveals that hard carbon with open pores shows better sodium-ion diffusion kinetics, indicating that a balance between the closed and open pores should be considered. This research offers valuable insights into pore design and presents a promising approach for enhancing the performance of hard carbon anode materials derived from biomass precursors.

Nanoscale Stolephorus sp. powder fabrication using high-energy milling for bioactive materials in dentistry.

BACKGROUND: The application of natural products in dentistry has been widely explored. Anchovy (Stolephorus in Latin) has been examined for its bioactive content (calcium, phosphorus and fluoride) as an agent for bone stimulation and tooth development, topical fluoridation and pulp capping. Ball milling has been used to prepare calcium oxide nanoparticles from snakehead fish bone. OBJECTIVES: The aim of the study was to reduce the particle size of Stolephorus sp. powder to the nanoscale using high-energy ball milling for 8, 12 and 24 h, and to analyze the optimal milling time by comparing the powder characteristics. MATERIAL AND METHODS: The Stolephorus sp. were oven-dried at 50°C for 6 h, after which the entire fish were crushed into powder. The fish powder was produced by blending the material for 5 min and passing it through a 200-mesh sieve. The remaining dried fish was blended again for 5 min until it passed through the sieve. The top-down approach to the particle size reduction was performed using high-energy milling at 3 distinct time points (8, 12 and 24 h). The characteristics of the powder were evaluated using a particle size analyzer, a Fourier-transform infrared spectrometer (FTIR) and scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS). RESULTS: The Stolephorus sp. powder contained 64.50% protein, 7,420 mg/kg sodium, 28,912 mg/kg calcium, and 1,924 mg/kg magnesium. The high-energy milling process resulted in a reduction of the particle size from the microscale to the nanoscale. The analysis of the average particle size and polydispersity index indicated that 24 h of milling showed the most optimal results. Furthermore, the functional groups exhibited no significant alteration at 3 milling times (p ≥ 0.05, FTIR analysis). CONCLUSIONS: The high-energy milling method has the potential to reduce the particle size of Stolephorus sp. powder to the nanoscale at the 8- and 24-h milling periods. The powder resulting from the 24-h milling process had a size of 789.3 ±170.7 nm, smooth size distribution, good size uniformity, a polydispersity index of 0.763, no significant change in organic and inorganic compound content, and a calcium/phosphorus ratio that was the closest to that of hydroxyapatite (HAp).

Effects of ball milling treated wheat flour and maltodextrin on the texture and oil absorption properties of fried batter-coated cashews and almonds.

In this study, the effects of wheat flour treated with ball milling (BM) and maltodextrin on the oil absorption and textural characteristics of fried batter-coated cashews and almonds (BCAs) were investigated. The result showed that the crystallinity of the starch granules in wheat flour decreased after the BM treatment. Furthermore, the ΔH of the batter decreased as the BM time was elongated, but the addition of maltodextrin had no significant impact on ΔH. Both BM-treated wheat flour and maltodextrin increased the fracturability and decreased the oil content of the fried BCAs' batter. The addition of BM-treated wheat flour and maltodextrin decreased the oil content of the batter from 28.93% to 18.75% for batter-coated cashews and from 30.92% to 18.61% for batter-coated almonds. Overall, the addition of BM-treated wheat flour and maltodextrin in batter is an effective approach to decrease oil content and improve the textural quality of fried BCAs.

Mechanochemical comparison of ball milling processes for levofloxacin amorphous polymeric systems.

This study aimed to investigate the amorphization capabilities of levofloxacin hemihydrate (LVXh), a fluoroquinolone drug, using a polymer excipient, Eudragit® L100 (EL100). Ball milling (BMing) was chosen as the manufacturing process and multiple mill types were utilized for comparison purposes. The product outcomes of each mill were analyzed in detail. The solid-state of the samples produced was comprehensively characterized by Powder X-ray Diffraction (PXRD), In-situ PXRD, Differential Scanning Calorimetry (DSC), Solid-State Fourier Transform Infrared Spectroscopy (FT-IR), and Dynamic Vapor Sorption (DVS). The crystallographic planes of LVXh were investigated by in-situ PXRD to disclose the presence or absence of weak crystallographic plane(s). The mechanism of LVXh:EL100 system formation was discovered as a two-step process, first involving amorphization of LVXh followed by an interaction with EL100, rather than as an instantaneous process. DVS studies of LVXh:EL100 samples showed different stability properties depending on the mill used and % LVXh present. Overall, a more sustainable approach for achieving full amorphization of the fluoroquinolone drug, LVXh, was accomplished, and advancements to the fast-growing world of pharmaceutical mechano- and tribo-chemistry were made.

Ball milling nano-sized biochar: bibliometrics, preparation, and environmental application.

Nano-sized biochar, which is a small structure prepared from biochar by grinding, has surpassed traditional biochar in performance, showing enhanced effects and potential for a wide range of environmental applications. Firstly, this paper visualizes and analyzes the literature in this field by CiteSpace to clarify the development trend of nano-sized biochar. The review intuitively shows the most influential countries, the most productive institutions, and the most concerned hot spots in the field of nano-sized biochar. Secondly, these hotspots in environment management are summarized by keywords and clustering: (1) The application of ball milling is a modification scheme that researchers have paid attention to, and it is also a key method for preparing biochar nanomaterials. It has a more dispersed structure and can support more modified materials. (2) Nano-sized biochar in the comprehensive utilization of water, soil, and plants was discussed and is a small range of application modification methods. (3) The bidirectional effects of nano-sized biochar on plants were analyzed, and the challenges in its application were listed. Finally, the economic management of nano-sized biochar and the relationship between microorganisms are the focus of the next research.