Colloid Mill Research Articles

Facile preparation of nanochitins via acid assisted colloid milling in glycerol

A facile route was developed for the production of nanochitins. Acid-assisted glycerol swelling at 120 °C and low-intensity colloid milling were found to be sufficient for the successful nanofibrillation of purified chitin. The glycerol together with a small amount of sulfuric acid was employed to break the hydrogen bonds between the chitin fibrils, and then the excessively swelled chitin bundles were easily disassembled to the nanoscale through mechanical disintegrations. Despite their good dispersibility in glycerol, the prepared nanochitins were also well-dispersed in acidic and neutral aqueous solutions. Optimal reaction conditions such as the amount of sulfuric acid and processing time for colloid milling were determined to be 0.64% w/w sulfuric acid (based on the whole reaction system) and 2 h, respectively. Under the optimal conditions, nanochitins with a fibril width of less than 50 nm and length of several microns were obtained with high yield (approximately 85%).

Structural characteristics and functional properties of fiber-rich by-products of white cabbage modified by high-energy wet media milling

The recovery of residues and by-products of the food industry plays an important role in terms of sustainable management. For this reason, the aim of this study was to analyse the effect of wet milling parameters on dietary fiber concentrates of white cabbage by products or, more precisely, the stalks of cabbage. The input of hydraulic shear-energy during wet milling process leads to a partial modification of the structure of fiber components to obtain compounds with high water- and oil-binding properties. Furthermore, the wet milling parameters affect the functional properties of the fiber concentrates. A mathematical model was developed which relates the functional properties to the parameters of the colloid mill such as slurry concentration, milling time, agitation speed and particle size distribution. A slurry of the grounded material is forced into the milling gap. Grinding is autogenous as a result of collisions between rotating particles. All of the material in the process stream is being grounded finer than the gap setting and grinding can be optimized by adjusting mill operating parameters. The identification of the relations between milling parameters and functional properties is necessary in order to comprehend the processing characteristics of the material in the context of fiber enriched food products manufacturing.

Production of starch aerogel in form of monoliths and microparticles

Pea and amylomaize starches were used to produce aerogel in form of monoliths and microparticles. The formation of starch gel was investigated, and we showed that each starch needed a different pasting temperature for its complete dissolution. The gelation kinetics was investigated with oscillatory rheometry for both systems as a function of the starch concentration. The gelation and retrogradation temperature of the starch gel were varied and its impact on the final aerogel evaluated. The emulsion gelation was carried out batch wise in a stirred vessel with different impeller geometries, concentrations of surfactant (Span80 and PGPR) and stirring rates. A particle size prediction approach based on idealized flow (Couette, 2D hyperbolic and turbulent) during the emulsification was proposed. A semi-continuous set-up for the emulsion gelation was developed in which the emulsification occurs in a single pass through a colloid mill and the gelation is triggered in-line with a counter-current heat exchanger.Graphical abstract.

Preparation of Microfibrillated Cellulose from Wood Pulp through Carbamate Modification and Colloid Milling

This paper studies a new convenient method to prepare microfibrillated cellulose from a bleached eucalyptus kraft pulp. First, the wood pulp was reacted with urea to produce cellulose carbamate (CC), and then the CC was treated with colloid mill in an acidic medium. A feasible preparation process for CC was to soak the pulp with the urea solution, and then the cellulose pulp was dewatered, dried, and reacted with urea at high temperatures above the melting point of urea. The Kjeldahl method, infrared spectroscopy, and solid 13C NMR were used to confirm the effectiveness of the reaction. On the basis of CC with the degree of substitution, DS = 0.123, the aqueous suspension with 2% content of CC at pH values of 1, 3, or 7 was severally ground by a colloid milling. After centrifugation, the nanocellulose carbamate fiber (CCNF) in the supernatant was obtained. X-ray diffraction showed that CC and CCNF had the same crystal form as the cellulose pulp, but the crystallinity decreased successively. The nanometer diameter of the CCNF fiber was observed with scanning electron microscopy. Results showed that when the pH value of the CC suspension decreased during the colloid milling, the crystallinity of the CCNF decreased along with the decrease of fiber diameter, and the zeta potential of the supernatant increased. This indicated that carbamate side groups of CC were protonated at low pHs and the cation repulsion between cellulose molecular chains enhanced the driving force of the pulp separation to CCNF. Interestingly, the thermal stability of CCNF is comparable to that of the original cellulose, and the enhancement effect of CCNF on starch can be clearly observed even at a relatively low loading of CCNF.

The nutritional components and physicochemical properties of brown rice flour ground by a novel low temperature impact mill

A low temperature impact mill (LTIM) was created and used for grinding brown rice. The nutritional components and physicochemical properties of the resulting flour were investigated and compared with those ground by traditional wet colloid mill (CM) and dry high-speed universal grinder (HUG). It was found that LTIM produced a fine flour with unimodal particle size distribution, and well retained non-starch nutrients. Especially, the phenolic content of flour prepared by LTIM was two times higher than that prepared by CM. LTIM also led to less damaged starch content than HUG. The damaged starch content related well with the thermal and gel hydration properties. Interesting, comparing the particle size distribution before and after enzymolysis, it was found that LTIM could pulverize dietary fiber of brown rice efficiently. The results from this study indicated that the LTIM may provide a promising technology for pulverizing brown rice thus open its new applications.

Cellulose fibrillation and interaction with psyllium seed husk heteroxylan

Fibrillated cellulose (FC) and its mixture with psyllium seed husk powder (PSY) were investigated to broaden the applications of these two materials by a novel combination. Purified cellulose was processed by a colloid mill and relatively stable suspensions were obtained. An FC suspension shows localised concentrations appearing as flocculates, which can be promoted by heating or centrifugation.The structures of unheated mixtures of FC and PSY appear to be binary phase dispersions while, after heat treatment, FC fibres were incorporated into PSY gels and form composites. Fibrillation on the FC surface does not influence the structure and rheological property of the composite mixtures while fibre disintegration contributes to a denser structure and higher moduli. Fluorescent images show the attachment of PSY heteroxylan aggregates on cellulose and fibrillated cellulose fibres. The interaction is weak and time-dependent because G’ during cooling was higher than that during heating, and declined back to the same value as the start of heating during an isothermal test at 20 °C. PSY was fractionated according to temperature and only F60 (fraction at 60 °C) clearly associates with the unfibrillated cellulose fibres, possibly via long arabinan sidechains (similar to hairy pectin) or/and backbone (via interaction with helical domains or/and conformational compatibility). The interaction was promoted by fibrillation, potentially trapping PSY heteroxylan aggregates within the cellulose dispersion. With further fibrillation, smaller FC fibres were generated and form interpenetrating particles with whole PSY or PSY fractions. Highly fibrillated cellulose has a higher surface area and smaller fibrils, which significantly increased the interaction resulting in a clumped structure.

Influence of dispersity of reinforcing polymer to the polymer-fiber composite materials’ rigidity

This research aims at validation of the technological approaches to the provision of penetrating the polymer binder into the structure of the filament carrier in order to construct a developed interfacial layer in the form of molecular brushes. Brush “bristles”, enshrined by the outer end in the layer of the copolymer binder, can give elastic properties to the composite material obtained by duplicating the shell material with reinforced adhesive interlining materials.As a large part of the interlining materials range comprises a mixture of polyester fiber with cotton or viscose, the problem of accessibility of textile liner web for reinforcing polymer is originally considered in relation to the cellulosic component, which has a developed system of pore spaces.This work defines the technical possibility of regulating the elastic-deformation properties of the fused panels of garment by changing the degree of reinforcing polymer (RP) dispersion fineness, providing different terms for penetration into the structure of fiber material. To change the capacity of the RP to penetrate into the fiber structure a method of ultra-dispergation was used by the mechanical activation of hydrosols in a colloid mill. There is an experimental prove of the decisive role of the reinforcing polymer penetration into the pore spaces of the cellulose component of the interlining material for the formation the branched comb structure of interfacial layer, which provides a comprehensive improvement in the ability of materials to form the bulk shape of the garment and its preservation while distorting.

Study on the Dispersion of Aramid Pulp in Epoxy Resin System

In order to improve the uniformity of dispersion of aramid pulp (AP) in an epoxy resin (EP) system containing the EP and curing agent, a series of treatments including the surface cleaning, colloid mill grinding, freeze-drying of APs were carried out in this article. In addition, the composites were prepared by mixing the untreated and treated APs and EP system with the AP mass fractions of 0, 0.1, 0.3, 0.5 and 0.7%. The APs and their dispersion behaviors in EP system were characterized by scanning electron microscope (SEM), fiber quality analyzer, specific surface area tester and optical microscope, moreover, the impact strength and section morphology of composites after impact damage were tested and characterized by a universal material testing machine and SEM.

Producing a novel edible film from mushrooms (L. edodes and F. velutipes) byproducts with a two-stage treatment namely grinding and bleaching

For realizing the high-valued utilization of agricultural by-products and investigating the feasibility of their functional production, we focused on developing biodegradable/edible films based on insoluble dietary fibers (IDF) derived from dried Lentinus edodes (L. edodes) stems and aged Flammulina velutipes (F. velutipes) with a two-stage treatment containing physical processing (colloidal milling and PFI grinding) and chemical treatment (hydrogen peroxide bleaching). Undergoing the bleaching treatment, the IDFs with a reduced size and regular shape effectively improved the performances of edible films. Scanning electron micrographs showed that the bleached L. edodes (BLF) film displayed a smoother surface and more compact internal structure compared to the others. Furthermore, BLF film possessed the highest tensile strength (24.37 ± 0.88 MPa) and an effective barrier to water vapor (0.253 ± 0.016 g mm/m2· h· kpa) and oxygen (10.03 ± 0.97 meq/kg). This study demonstrated that the insoluble fiber dissociated from edible mushroom byproducts has good potential for producing the edible films.

Preparation of carbon nanotubes/polyethersulfone antistatic composite materials by a mixing process

AbstractIn this work, a facilitated physical dispersion technology was employed to prepare polymer‐based antistatic composites using polyethersulfone (PES) as matrix and the acidulated multiwalled carbon nanotube (MWCNT) as nanofillers, scattering the PES resin in the deionized water contained MWCNT by the colloid mill to obtain MWCNT/PES emulsion and the MWCNT/PES composites were prepared by melt processing. The influence of dispersion technology about the MWCNT/PES composites on the mechanical, thermal, and electrical properties was investigated in detail. The morphology of the MWCNT/PES emulsion was investigated by transmission electron microscopy and scanning electron microscope, respectively. The results showed that the MWCNT nanoparticles were encapsulated in the PES microspheres homogeneously. In addition, the obtained MWCNT/PES composites showed higher glass transition temperature (T g) and initial thermal decomposition temperature (T5%). More importantly, the tensile strength and surface resistance of 3 wt% MWCNT/PES composites were up to 112 MPa and 106 Ω/m, respectively. Therefore, these high‐performance polymer‐based antistatic composites will have potential application in electronic devices applied with high temperature conditions.

Impact of oil type and pH value on oil-in-water emulsions stabilized by egg yolk granules

The aim of this study was to investigate the effect of oil type, i.e. sunflower, rapeseed, peanut and corn oil on the emulsification effect. Knowledge about the impact of the different oils on the emulsification process in a head-to-head comparison is lacking. The hypothesis was that various oils as such or with their special compositions of by-products will have an impact on the properties of the resulting emulsion. As a novel aspect, a single fraction of egg yolk (EY), i.e. the egg yolk granules, were used as emulsifier. Because of their different sources and production processes, the oils differ in composition of fatty acids, degree of saturation and contain various surface-active components like cell membrane fragments, phospholipids and vitamins which influence the emulsification process and therefore the emulsions. In addition, the pH value of the aqueous phase was varied in a broad range. The dynamic interfacial tension between oil and water as well as the adsorption behavior of granules at the interface was analyzed by drop shape analysis. Oil-in-water emulsions with high ratio of dispersed phase (80%) were produced using a colloid mill. The resulting particle size distribution was determined by laser diffraction. There were significant differences in interfacial tension and adsorption of surface-active components at the interface among the oils due to their composition, fatty acid chain length and ratio of mono-, di-, and triglycerides, resulting in different droplet sizes ascribable to the oils. A correlation could be found for the initial decrease of the analytically measured interfacial tension at the oil-water interface and the resulting emulsion droplet size. Furthermore, it could be shown that the droplet size of the emulsions decreased with increasing pH-value of the continuous phase.

Equipment desing automation at asphalt-concrete production modernization

The relevant task in the field of road construction and maintenance is gradual transition to the production of asphalt-concrete mixtures on polymer-bitumen binders. Most asphalt-concrete plants of small and medium capacity consider this transition as challenging due to a relatively high cost of the specialized equipment for polymer-bitumen binders production. Most proposed techniques involve the utilization of colloid mills. The practice of such mills operation shows that production lines experience long downtime periods due to the necessity of preventive maintenance and repair. A promising direction in polymer-bitumen binders manufacture is to use polymer waste materials for the bitumen modification. This provides the reduction of the modified binder costs and the solution of environmental problems. The paper deals with the problem of asphalt-concrete plants modernization to obtain polymer-bitumen binders in its own production using agitated mixers common in the chemical industry. Optimization problem is formulated for design and operating parameters of such equipment to provide required quality indicators for the resulting polymer-bitumen binders. Algorithmic and software assistance is developed to solve the set problem. The proposed technical solutions were tested when solving the modernization problems regarding the process diagram of the asphalt-concrete plant to release products on polymer-bitumen binder of its own production.

The technology of improving industrial processing quality of mango puree

This paper aims at improving the industrial processing quality and studying on the processing method of decreasing high spot rate and choosing optimal Hainan mango cultivars for the processing of mango puree. Mango cultivars of the 'Jinhuang', 'Parthenon', 'Ivory' and 'Imperial concubine' were selected to research raw material processing suitability from three aspects including the puree yield rate, nutrient content and temperature sensitivity. The processing technology was improved by using wet ultrafine treatment evaluated from taste, color and heterochromatic spots, etc. Results showed that the 'Imperial concubine' was optimal for processing of mango puree. Mango protoplasmic delicate degree increased significantly and the spot rate dropped more than 90% by adopting the colloid mill and homogenizer joint processing.

Hydro-mechanical processing of brewer's spent grain as a novel route for separation of protein products with differentiated techno-functional properties

Hydro-mechanical processing using a colloid mill with a large gap setting leads to the preferential breakup of the residual aleurone and endosperm tissues of brewer's spent grain, forming a protein rich fines material with small particle size around 1–10 μm. This fraction can be separated from the coarser husk fraction by centrifugation, giving a protein product with enhanced techno-functional properties. The fines have good stability in aqueous suspensions, with potential for stabilising other particulate materials in food or drink formulations. The fines particles can stabilise oil-water emulsions, possibly through a Pickering mechanism, which may also support use in food applications. Fines suspensions have strong shear-thinning behaviour, which may be beneficial from a textural or transport perspective. Spray drying of fines suspensions is shown to avoid particle coalescence, which is important for effective resuspension on rehydration. The high surface area of the fines also leads to more efficient digestion by proteases. A novel hydro-mechanical milling process has been investigated for separation of a protein fine fraction from brewer's spent grain having enhanced techno-functional properties. The small particle size of the fines would be a key attribute for formulation in shake or smoothie products, where sensory attributes of the product would not be compromised and the properties of the fines could confer stability against settling. Applications may be found for the fines material as an ingredient in spreads and sauces or infant purees, in-particular where it might be used to stabilise of products based on oil-water emulsions. The market for protein-rich ingredients for foods and drinks is already established in the fitness and well-being market, as derived from other vegetable or cereal sources such as hemp, pea or rice. This controlled pre-milling step is also shown to lead to greater rate and extent of protease digestion of spent grain, which may be of value for generation of protein and peptide products for well-being and cosmetics applications. • Hydro-mechanical processing is used to create a unique protein rich fines material with small particle size around 1-10 μm. • The protein rich fine fraction can be physically separated from the coarser husk fraction by centrifugation. • Aqueous suspensions of protein rich fines might be used to stabilise other particulate materials in food or drink formulations. • The protein rich fines may stabilise oil-water emulsions by a Pickering type mechanism, also leading to food applications. • Protein rich fines suspension have strong shear-thinning behaviour, beneficial for texture and for flow and transport.

Nanostructuring sodium silicate solutions applied as binding substance of molding sands in foundry

The present paper deals with the effect of sodium silicate solution dispersion on the strength of molding sand. The authors proposed the method for modifying sodium silicate solution widely used as a binding substance while producing expendable molds in foundry, provided chemical agents are not included in the molding sand composition. Nanostructurization of sodium silicate solutions is carried out under the integral action, including hydrodynamic, acoustic and magnetic impacts, in the colloidal mill. As a result of processing, there was the obtained solution of uniform gravimetric composition providing lower sodium silicate content in molding sands up to 4.5 % without loss of strength.

Asphalt emulsion formulation: State of the art of formulation, properties and results of HIPR emulsions

Abstract As a way to make pavements more economic, less polluting, and with lower energy consumption bitumen emulsions can be used. The formulation of bitumen emulsions is a complex task and they are usually produced using colloid mills. This method presents several limitations; the maximum bitumen concentration of the dispersed phase, 69%, being the most significant. The HIPR (High Internal Phase Ratio) method must be used for higher bitumen concentrations. With this second method, apart from it being possible to obtain concentrated emulsions, with a volume fraction higher than 70%, it is possible to control the distribution and average droplet diameter of the emulsion. This control is achieved by changing variables such as the volume fraction, the concentration and type of surfactant and the temperature of the dispersed phase, the type of bitumen used, and mechanical variables such as the rotational speed and time employed. The current study aims to review the state-of-the-art of the manufacture of bitumen in water emulsions, with a special emphasis on the concentrated bitumen emulsions manufactured following the HIPR method.

Influence of mechanical pretreatment to isolate cellulose nanocrystals by sulfuric acid hydrolysis

The mechanical pretreatments intensities on characteristics of cellulose nanocrystals (CNC) prior to acid hydrolysis was evaluated. The cellulose was submitted to mechanical pretreatment as: magnetic stirring (CNCst), blending (CNCbl) or grinding by 20 (CNC20x) and 40 (CNC40x) passages in a super mass colloid mill. Then, all samples were submitted to H2SO4 hydrolysis and the CNC were evaluated by total mass yield (TMY%), rheological behavior, size distribution for width/length (WD), crystallinity index (CI%), OSO3- substitution degree (SD) and zeta potential (ζ). After hydrolysis samples exhibited the same SD (190 ± 5 mMol·kg-1), ζ (-55 ± 3 mV) and CI% (65 ± 2), differing only in TMY% and WD. The CNCst showed TMY% of 85%, WD of 8 ± 5 nm and 100-800 nm, with presence of cellulose nanofibers (CNF), suggesting incomplete hydrolysis. The CNCbl and CNC20x revealed TMY% of 65 ± 1, but differed in WD of 8 ± 5 nm and 300 ± 200 nm and 8 ± 5 nm and 200 ± 170 nm, respectively. The results showed that the grinding mechanical pretreatment is mandatory for CNF isolation, but not for CNC. Stability profile after the hydrolytic procedure, CI%, morphology and similar character generated CNC with adequate features and good yield, by simple mechanical stirring or blending, reducing the production's cost and allowing industrial-scale production.

PMB quality problems based on its morphology and used equipment

In the first part of the study, a direct relationship is established between the influence of the morphology of PMB (polymer modified binder) on the totality of its consumer properties and its tendency to destruction. The second part of the study is devoted to the influence of technological equipment used for the production of polymer modified binder on its properties. It was experimentally established that having the same initial components, PMB of completely different quality were obtained at the output. According to the degree of increase in rigidity (penetration value at 25 °C), obtained PMBs can be conditionally positioned as follows: prepared using a paddle mixer, a colloid mill, and an extruder. It is proved that the high elastic properties of PMB can be achieved by using paddle mixers that do not damage the long polymer macromolecules during the process. However, such binders are prone to delamination. To eliminate this negative aspect, the use of additional crosslinking agents is necessary. PMB prepared using an extruder has lost its elastic abilities, has become tough, with a high rate of cohesive strength. Thus, it is noted that when designing PMB compositions, it is necessary to carefully choose not only the raw material base but also the technological equipment for its preparation.

A continuous approach to the emulsion gelation method for the production of aerogel micro-particle

Aerogel micro-particles have a wide range of applications demonstrated at lab-scale in numerous publications, but material in a larger amount needs to be produced to allow for industrial tests and prototyping. In this work, we propose a continuous emulsion-gelation process able to produce gel micro-particles in sizeable quantities, demonstrating the industrial relevance of such approach. Alginate is taken as a model gelling system and two gelation mechanisms are demonstrated. Alginate solution and oil are pumped together through a progressive cavity pump and fed to a colloid mill to produce alginate in oil emulsion in one pass. The gelation in emulsion is then carried in-line via a controlled injection of a gelation trigger (acetic acid or calcium chloride). The gel microparticles are separated from the oil via sedimentation or centrifugation and partitioning into an ethanol solution. Further solvent exchange to ethanol and supercritical drying with CO2 yielded aerogel microparticles with large specific surface area. The size of the emulsion droplets is directly related to the final aerogel particles size. The influence of the emulsification parameters on the droplet size is thus discussed and assessed using critical capillary number values from the literature. To complete this task, the dynamic interfacial tension of the alginate-paraffin oil-Span80 system was measured and the rheology of the alginate solution and of the emulsion assessed.

A novel method to prepare lignocellulose nanofibrils directly from bamboo chips

Nanocelluloses, including cellulose nanocrystals (CNCs), bacterial nanocellulose (BNC), and cellulose nanofibrils (CNFs), have attracted much attention in recent years all over the world. However, commercial applications of nanocelluloses are still limited due to the high cost of nanocelluloses. In this study, we developed a novel method to prepare lignocellulose nanofibrils (LCNF) directly from bamboo chips (BC), which can readily be scaled up. The method developed consists of three primary steps, which are as follows: glycerol pretreatment, screw extrusion, and mechanical refining/milling in a colloid mill. Glycerol can readily penetrate into bamboo chips and it is used as an effective reaction medium for fibrillation and delignification. The LCNF yield is about 77.2% based on bone dry bamboo chips. The morphology of the LCNF was investigated by transmission electron microscopy (TEM), which shows that the LCNFs have a diameter of 20–80 nm and a length of several thousand nanometers. X-ray diffraction (XRD) analysis shows that the crystallinity of the LCNF was 52.7%, which was slightly lower than that of the bamboo raw material. This process can be easily scaled up for commercial production of LCNF.