Solvent-free Ball Milling Research Articles

Adsorption and Photocatalytic Degradation Properties of Bimetallic Ag/MgO/Biochar Nanocomposites

The Ag/MgO/biochar nanostructures were fabricated using a solvent-free ball milling process as an effective adsorbent. Development of functional materials capable of completely removing organic pollutants from water and their adequate adsorption present challenges. The addition of MgO nanoparticles diffused equally on biochar surfaces in the biochar matrix, according to various characterization data. In decomposing biochar and compressing MgO, powdered metal enhanced mesopores and macropores of nanocomposites. XPS analysis indicates the potential synthesis of modified biochar nanocomposites. Adequate amounts of MgO added to biochar improved the ability of the nanocomposites to remove methylene blue (M.B.) through photosynthesis and adsorption. Photocatalytic analysis was carried out for the proposed novel composites to remove tetracycline (T.C.) subjected to different conditions. The photodegradation efficiency was found 80.26% for TC concentration, 50 ppm, H2O2 of 100 mM pH: 5-6 of Ag/MgO/biochar (0.01 g) at 25° temperature. Treatment of various organic wastewaters by metal oxide/biochar nanocomposites with strong adsorption and photocatalytic degradation capabilities is made possible by this research.

Synthesis of γ Phase and Amorphous Solid Dispersion of Glycine from α-Glycine During the Solvent-Free Ball Milling Process.

Nano α-glycine crystals, γ-glycine crystals, and amorphous solid dispersion (ASD) of glycine were prepared through solvent-free ball milling of commercial α-glycine. The solid-state polymorph conversion of glycine from α to γ was completely realized by ball milling with 0.2 wt.% NaCl for 1h or by ball milling with 0.02 wt.% NaCl for 1h with subsequent storage for one week. The ASD of glycine was prepared by ball milling α-glycine with an equal amount of CaCl2 for 1 h. We studied the effect of inorganic salt types and their concentrations on the extent of polymorph conversion and amorphization of glycine in our experiments. This solvent-free ball milling method could be used for the synthesis of polymorphs and amorphous phase of drugs and other organic materials.

Green Synthesized Carbon Quantum Dots/Cobalt Sulfide Nanocomposite as Efficient Electrode Material for Supercapacitors

In the present work, carbon quantum dots/CoS2 nanocomposite (CQDs/CoS2) was prepared through a solvent-free ball milling route followed by solvothermal treatment. The CQDs were prepared first by a green catalyst-free microwave-assisted procedure from glycerol, as a single precursor, with a quantum yield of ∼16%. Then, a ball mill–hydrothermal combination method was used to synthesize CQDs/CoS2 with edged bricklike morphology. Benefiting from advantageous features of large specific surface area (427.2 m2 g–1), unique nanostructure with high mesoporosity, and greater electronic conductivity, the as-synthesized CQDs/CoS2 nanocomposite electrode material displays a rather high specific pseudocapacitance, about 808 F g–1 at 1 A g–1 current density, a high rate capability with 83.9% capacity retention rate at 20 A g–1, and good cycling stability of 98.75% over 10 000 charge/discharge cycles at 1 A g–1. The attained results support the suitability of CQDs/CoS2 nanocomposite as a desired material for future high-performance electrochemical energy storage devices.

Sulfamic acid catalyzed oxonium-ene reactions under ball milling conditions: Straightforward access to highly functionalized Oxabicyclo[3.2.1]octenes

Herein, we report a facile green procedure for the synthesis of oxabicyclo[3.2.1]octenes using sulfamic acid as catalyst under solvent-free ball milling conditions. A series of aldehydes or epoxides underwent oxonium-ene reaction with (−)-terpinen-4-ol under optimized conditions to produce a variety of oxabicyclo[3.2.1]octene derivatives. The excellent selectivity, higher isolated yields of the products, use of mild catalyst and solvent-free ball milling conditions, and recyclability are the major advantages of the present procedure.

Ball-milled, solvent-free Sn-functionalisation of wood waste biochar for sugar conversion in food waste valorisation

The use of biomass wastes for biochar production is a promising waste management option, and biochars can be potentially applied in the food waste recycling industry to produce value-added chemicals. In this study, an advanced Sn-functionalised biochar catalyst was synthesised via a novel solvent-free ball milling protocol to facilitate the isomerisation of glucose to fructose. Raw wood biomass (W) and its derived biochars pyrolysed at low (LB, 400 °C) and high (HB, 750 °C) temperatures were investigated as catalyst supports. The interactions between Sn and the carbonaceous supports were related to the surface chemistry of the catalysts. The raw W had a functional group-enriched surface, which provided more active sites for anchoring Sn, resulting in higher metal loading on the support compared to LB and HB. The annealing temperature was another critical factor determining the amount and speciation of loaded Sn. Catalytic conversion experiments indicated that SnW annealed at 750 °C exhibited the best fructose yield (12.8 mol%) and selectivity (20.2 mol%) at 160 °C for 20 min. The catalytic activity was mainly determined by the quantity and nature of active Sn sites. This study elucidated the roles of the carbon support and its surface chemistry for synthesising biochar-supported catalysts, highlighting a simple and green approach for designing effective solid catalysts for sustainable biorefineries.

Solvent-free synthesis of mesoporous platinum-aluminum oxide via mechanochemistry: Toward selective hydrogenation of nitrobenzene to aniline

Mesoporous alumina (meso-Al2O3) supported noble metal catalysts have been widely used in heterogeneous catalysis. However, these catalysts are generally prepared via wet chemistry, which suffers from several drawbacks, such as: excessive use of solvents and time-consuming drying process. In this manuscript, a mechanochemical method for solid-state processing between aluminum isopropoxide and block copolymers (P123) were introduced to synthesize meso-Al2O3 supported platinum catalyst (Pt/m-Al2O3). The resulting Pt-meso-Al2O3 catalyst shows high surface area (up to 465 m2/g) and uniform pore size (~3.9 nm). Interestingly, the solvent-free ball milling method enables the processing of bulky micrometer-scale Pt precursors into well dispersed Pt nanoparticles (~4.8 nm). Moreover, Pt/m-Al2O3 catalyst affords good performance in the selective hydrogenation of nitrobenzene to aniline (Conversion: >99%, Aniline Selectivity: >99%). This mechanochemical route provides a solvent-free and one-step method for synthesizing meso-Al2O3 supported noble metal catalysts.

Toughening Effect of Rodlike Cellulose Nanocrystals in Epoxy Adhesive

Epoxy structural adhesives have been used extensively in the automotive and aerospace industries to bond assembly parts. Much effort has been devoted to enhancing the mechanical properties of epoxy resin by incorporating fillers. Among a variety of fillers investigated for this purpose, nanocelluloses are regarded as a promising type of emerging green filler material because of their excellent mechanical and physicochemical properties. Indeed, nanocelluloses have been used as a filler for polymer nanocomposites. However, the toughening and reinforcing effects of nanocelluloses on rigid epoxy adhesives have not yet been fully revealed, particularly from the perspective of adhesive bonded joints. Here we report that epoxy adhesive containing cellulose nanocrystal (CNC) aggregates produced using a solvent-free ball milling method achieves drastically improved adhesive strength and fracture toughness compared with that of the reference adhesive without CNCs. The epoxy adhesive containing CNC aggregates exhibi...

Solvent-free pulverization and surface fatty acylation of pulp fiber for property-enhanced cellulose/polypropylene composites

Abstract Cellulosic fibers have the potential serving as lightweight and bio-based reinforcement in polymer composites but they suffer from difficulties in obtaining adequate dispersion and a strong interface in the matrixes. The hydrophilic and aggregating nature of the cellulose fiber are the main reasons responsible for the poor processing and mechanical performance. Here we proposed that cellulose fibers be subjected to mechanochemical activation and functionalization to prepare surface modified cellulose powders for properties-improved polypropylene (PP) composites. Specifically, mechanochemical ball milling was used to simultaneously pulverize, activate, and surface modify pulp fibers to produce property-tuned cellulose particles for reinforcing. Acetic-oleic mixed anhydrides were used as esterifying agents for improved processing ability and surface hydrophobicity. The mechanochemical esterification, crystallinity and thermal stability of the modified samples were characterized. Cellulose particles with different degree of substitutions (DS) were obtained and then compounded with PP matrix to prepare composite specimens. The melt processability, matrix crystallization behavior, mechanical performance, composite morphology and water absorption of the composites were investigated. The results reveal that cellulose could be effectively esterified during the solvent-free ball milling reaction, with the successful grafting of both the acetyl group and the fatty acyl group. The modified cellulose particles improved the melt processability, promoted the matrix crystallization temperature and decreased the moisture uptake of the composite. Particle composite produced with a higher level of DS exhibited better processability, higher elongation at break, lower modulus, and better water repellency than those of the lower DS particle reinforced one.

Preparation and toughening of mechanochemically modified lignin-based epoxy

In this work, succinylated lignin (SA-KL) was prepared by reacting a kraft lignin and succinic anhydride (SA) through a solvent-free ball milling process. A bisphenol A/F epoxy resin (DER 353) cured with a commercial alicyclic anhydride and SA-KL (~38 wt% in the composition) exhibited a flexural strength of 48.8 MPa and modulus of 3.62 GPa but a low impact strength of 6.7 kJ/m2 which were comparable to the properties of many anhydride cured epoxies. Toughening of the lignin-based epoxy resin with a carboxyl-terminated butadiene acrylonitrile (CTBN) liquid rubber was investigated. Introduction of the CTBN rubber significantly increased the impact strength and fracture toughness but resulted in reduction of flexural strength. A ductile-brittle transition was observed at 5–12 wt% CTBN rubber. Examination of the fracture surfaces by scanning electron microscopy suggests that rubber particle cavitation and massive shear yielding of the epoxy matrix were the dominant toughening mechanisms. Incorporation of CTBN had little change to the thermal stability of the lignin-based epoxy. This study introduces a green method for synthesis of lignin-derived polyacid and a viable approach for achieving balanced mechanical and thermal properties for lignin-based epoxy materials.

Mechanochemical activation of phlogopite to directly produce slow-release potassium fertilizer

Phlogopite, one trioctahedral mica, was activated by solvent-free ball milling to serve directly as slow-release potassium fertilizer. Before the final breakdown of the crystal structure, phase transformation of trigonal phlogopite into monoclinic by milling at 300 rpm for 120 min was observed for the first time. Different solubility of the amorphous product and monoclinic crystalline product in water or 2% citric acid was also obtained. The content of water soluble potassium (quick acting potassium) and 2.0% citric acid soluble one (slow release potassium) in the products could be easily changed by adjusting the milling speed depending on the requirement for plant growth. 100.0% K extraction in 2.0% citric acid solution from the amorphous sample and near 30% K extraction in water from the sample milled at 300 rpm was achieved. Several analytical methods such as XRD, SEM, FT-IR and TG-DTG were used to characterize the activated sample and to understand the reason for the easier dissolution of potassium. The proposed process was economical and environment-friendly, which could help to maintain a balanced supply of potassium fertilizer for sustainable development of agriculture by compensating partially current high-cost chemical fertilizer.

Mechanochemical Decomposition of Crystalline Cellulose in the Presence of Protonated Layered Niobium Molybdate Solid Acid Catalyst.

Direct depolymerization of crystalline cellulose into water-soluble sugars by solvent-free ball milling was examined in the presence of a strongly acidic layered metal oxide, HNbMoO6 , resulting in full conversion with 72 % yield of water-soluble sugars. Measurements by 13 C cross-polarization magic angle spinning NMR spectroscopy and X-ray diffraction revealed that amorphization of cellulose occurred rapidly within 10 min. Scanning electron microscopy equipped with an energy dispersive X-ray indicated that the substrate and the catalyst were well mixed during milling. The time course of the product distribution showed that most of the resultant water-soluble sugars were produced not by successive degradation of oligosaccharides but by direct depolymerization of cellulose chains. The products included glucose, mannose, and cello-oligomers, as well as anhydrosugars. Addition of small amounts of polar solvents increased the sugar yield, whereas further addition of water decreased the selectivity to anhydrosugars. Calculations of the mechanical energy required for the ball-milling process showed that 0.02 % was utilized for the chemical transformation under the conditions examined in this study.

“Solvent-Less” Mechanochemical Approach to the Synthesis of Pyrimidine Derivatives

Modified ZnO NPs were synthesized through a sol–gel route with an aromatic capping agent to provide a highly efficient catalyst, NS-5, for the one-pot multicomponent synthesis of various pyrimidine derivatives using a solvent-free ball milling technique. Greenness of the present method was evaluated by calculating an Ecoscale score and E-factor. Characteristics of the method include use of a recyclable catalyst, scale-up to a multigram scale, and ease of product isolation.

Manganese (III) acetate mediated synthesis of polysubstituted pyrroles under solvent-free ball milling

Under solvent-free ball milling conditions, a simple and mild method was developed for efficient synthesis of 2,5-dimethyl-3,4-dicarboxylate-pyrroles and N-substituted 3,4-diphenylpyrroles via condensation-annulation of amines with acetoacetate and 2-phenylacetaldehyde, respectively. The use of cheap and safe Mn(OAc)3 as a mediator, no use of commonly employed acetic acid as solvent, short reaction time and readily available starting materials make this protocol a good alternative to traditional synthesis of polysubstituted pyrroles.

Green High-Yielding One-Pot Approach to Biginelli Reaction under Catalyst-Free and Solvent-Free Ball Milling Conditions

A simple, green, and efficient approach was used to synthesize 3,4-dihydropyrimidines derivatives. We showed that the application of the planetary ball milling method with a ball-to-reagent weight ratio of 8 for the Biginelli reaction provides 3,4-dihydropyrimidines derivatives with excellent yields (>98%) in a short reaction time from the one-pot, three-component condensation of aldehydes, ethyl acetoacetate, and urea (or thiourea).

Ball Milling Assisted Solvent and Catalyst Free Synthesis of Benzimidazoles and Their Derivatives.

Benzoic acid and o-phenylenediamine efficiently reacted under the green solvent-free Ball Milling method. Several reaction parameters were investigated such as rotation frequency; milling balls weight and milling time. The optimum reaction condition was milling with 56.6 g weight of balls at 20 Hz frequency for one hour milling time. The study was extended for synthesis of a series of benzimidazol-2-one or benzimidazol-2-thione using different aldehydes; carboxylic acids; urea; thiourea or ammonium thiocyanate with o-phenylenediamine. Moreover; the alkylation of benzimidazolone or benzimidazolthione using ethyl chloroacetate was also studied.

Monofunctionalized Cobaltocenium Compounds by Dediazoniation Reactions of Cobaltoceniumdiazonium Bis(hexafluorophosphate)

Monofunctionalized cobaltocenium salts are obtained for the first time from cobaltoceniumdiazonium bis(hexafluorophosphate) with various nucleophiles via Sandmeyer-type and related reactions. For successful conversions, reaction conditions are quite critical: either standard solution chemistry in nitromethane or solvent-free ball milling proved necessary, depending on the type of reactant. By this synthetic approach valuable synthons such as iodocobaltocenium and azidocobaltocenium salts are accessible that open up new vistas in cobaltocenium chemistry. Spectroscopic characterization by NMR, IR, HRMS, and single-crystal structure analysis as well as the results of electrochemical studies are reported. Derivatives with two reversible reductions show the expected relation of the half-wave potentials with the Hammett substituent parameter σp of the respective substituent with a slightly larger slope for the first reduction. The carboxylic acid (reductive deprotonation of the −COOH functionality), the iodo (p...

ChemInform Abstract: Cascade Oxa‐Michael—Henry Reaction of Salicylaldehydes with Nitrostyrenes via Ball Milling: A Solvent‐Free Synthesis of 3‐Nitro‐2H‐chromenes.

Cascade oxa-Michael–Henry reactions of salicylaldehyde derivatives with β-nitrostyrenes catalyzed by potassium carbonate via solvent-free ball milling are demonstrated. The corresponding 3-nitro-2H-chromene products were obtained in moderate to excellent yields. This method offers significant advantages, particularly in terms of high yields, short reaction times and mild conditions.

Cascade Oxa-Michael–Henry Reaction of Salicylaldehydes with Nitrostyrenes via Ball Milling: A Solvent-Free Synthesis of 3-Nitro-2H-chromenes

Cascade oxa-Michael–Henry reactions of salicylaldehyde derivatives with β-nitrostyrenes catalyzed by potassium carbonate via solvent-free ball milling are demonstrated. The corresponding 3-nitro-2H-chromene products were obtained in moderate to excellent yields. This method offers significant advantages, particularly in terms of high yields, short reaction times and mild conditions.

In(III) triflate-catalyzed detritylation and glycosylation by solvent-free ball milling

A highly efficient In(III) triflate-assisted method for the detritylation of O-trityl derivatives of carbohydrates, phenols, and alcohols using solvent-free mechanochemical method is described. In the case of carbohydrates, further reaction in the presence of an acceptor sugar leads to highly efficient glycosylation in the same pot resulting in the formation of the desired glycoside-product in very high yields. The method was applied successfully to the synthesis of a combinatorial library of galactose-based (1,6)-linked cyclohexa-, hepta-, and octasaccharides on gram scale.

Highly efficient protection of alcohols as trityl ethers under solvent-free conditions, and recovery catalyzed by reusable nanoporous MCM-41-SO3H

An efficient method was developed for the protection of alcohols as trityl ethers using triphenylmethanol in the presence of nanoporous MCM-41-SO3H as a heterogeneous catalyst under solvent-free ball-milling at room temperature. Low catalyst loading, high efficiency, reusability are among the advantages of this new solvent-free and environmentally friendly method. The deprotection of the produced trityl ethers was also efficiently achieved using the same catalyst in wet acetonitrile.