Resin Grains Research Articles

Isolation and identification of olive tree leaf phenols through a resin adsorption/desorption process

Agricultural by-products contain substantial amounts of phenolics with significant antioxidant properties. In this work, a method to recover high concentrations of phenolic substances from a typical agricultural by-product, such as olive tree leaves, was investigated. Phenolic compounds previously separated through extraction and fractionated on a membrane array: Ultrafiltration (UF)-Nanofiltration (NF)-Reverse Osmosis (RO), were examined, alongside standard compounds. More specifically, the NF concentrate fraction, which contained the low molecular weight organics (simple phenols, carbohydrates) was treated by sorption/desorption processes in a cylindrical column packed with XAD16 N resin. The aim of this study was to optimize the isolation and the enrichment of phenolic compounds through their selective adsorption on resin grains. Standard compounds such as gallic acid and glucose were tested to study the sorption and desorption kinetics of phenol and carbohydrate families and the sorption parameters were estimated using the Thomas model. The results showed that XAD16 N resin selectively adsorbed phenolic compounds over carbohydrates. This was evident by the adsorption capacity exhibited by the resin when treating the glucose and gallic acid solutions. Regarding the NF concentrate fraction of olive leaf phenols, after the adsorption step, the adsorbed hydrophilic carbohydrates were removed by desorption using pure water. Immediately afterwards, an alcohol/water mixture was introduced to recover and extract the phenolic compounds. To identify the distinct phenols, a thorough liquid chromatography study was performed on the sorption and desorption samples collected at the outlet of the packed column, identifying the different time frame each phenol left the system.

Abrasion-resistant superhydrophilic objects with anisotropic water transport capacities prepared by a selective laser sintering 3D printing strategy

Liquid directional manipulation has been widely used in the fields of microfluidic, microreactor, liquid separation and collection, sewage treatment. Most studies based on the construction of gradient structures on the substrate surface realized liquid directional transportation, but their fragile surfaces are vulnerable to external forces and can only transport thin water film according to the array thickness. Here, we report that abrasion-resistant superhydrophilic objects with anisotropic water transport capacities can be one-step constructed by selective laser sintering (SLS) the composites of hydrophilic glass beads (GBs) and thermoplastic phenol–formaldehyde resin (PF) grains. The long interlayer micro-slits between the adjacent printing layers cooperated with the inserted hydrophilic GBs formed long capillary channels, resulting in anisotropic water transport abilities on different printing surfaces. In addition, the abrasion-resistant ability endowed superhydrophilic mechanical stability. Furthermore, water could climb about ∼26 cm along the horizontal printed sample, showing excellent anti-gravity water transport ability. Finally, we demonstrated that the printed evaporators with diverse salt-resistant structures not only maintain long-term salt resistance, but also possess high evaporation efficiency. The superhydrophilic materials proposed in this study will lead the design and preparation of liquid directional transport materials and provide advanced inspiration for 3D printing functional materials.

Terahertz 3D bulk metamaterials with randomly dispersed split-ring resonators

Abstract While optical systems using terahertz wave are expected to achieve beneficial applications, at present, the materials of the optical elements that compose them must be selected from limited choices. In this study, we propose a three-dimensional bulk metamaterial in which metal microstructures are dispersed in the bulk resin randomly. A bulk metamaterial was designed and fabricated, in which split-ring resonators known as typical metamaterials were dispersed in cyclo-olefin polymer. In the fabrication method, a resin sheet containing split-ring resonators was first prepared and then diced into resin grains containing a single split-ring resonator. Finally, they were filled in a mold and solidified with a resin solution to obtain the target bulk metamaterial. The optical properties of the fabricated bulk metamaterial were measured by terahertz time-domain spectroscopy. The measurement results confirmed that the refractive index deviated from the original refractive index of the cyclo-olefin polymer due to the resonance of split-ring resonators, suggesting that the proposed bulk metamaterials could be used as a new optical material in the terahertz band.

ARTIFICIAL NEURAL NETWORKS FOR PREDICTING THE GENERATION OF ACETALDEHYDE IN PET RESIN IN THE PROCESS OF INJECTION OF PLASTIC PACKAGES

The industrial production of preforms for the manufacture of PET bottles, during the plastic injection process, is essential to regulate the drying temperature of the PET resin, to control the generation of Acetaldehyde (ACH), which alters the flavor of carbonated or non-carbonated drinks, giving the drink a citrus flavor and putting in doubt the quality of packaged products. In this work, an Artificial Neural Network (ANN) of the Backpropagation type (Cascadeforwardnet) is specified to support the decision-making process in controlling the ideal drying temperature of the PET resin, allowing specialists to make the necessary temperature regulation decisions for the best performance by decreasing ACH levels. The materials and methods were applied according to the manufacturer's characteristics on the moisture in the PET resin grain, which may contain between 50 ppm and 100 ppm of ACH. Data were collected for the method analysis, according to temperatures and residence times used in the blow injection process in the manufacture of the bottle preform, the generation of ACH from the PET bottle after solid post-condensation stage reached residual ACH levels below (3-4) ppm, according to the desired specification, reaching levels below 1 ppm. The results found through the Computational Intelligence (IC) techniques applied by the ANNs, where they allowed the prediction of the ACH levels generated in the plastic injection process of the bottle packaging preform, allowing an effective management of the parameters of production, assisting in strategic decision making regarding the use of temperature control during the drying process of PET resin.

The effects of initiators mixture on suspension polymerization of vinyl chloride and its comparison with other productivity-enhancing procedures

Molecular and morphological properties of poly(vinyl chloride) (PVC) grains produced by suspension polymerization of VCM in the presence of a mixture of fast, mild and slow initiators (named as Cok process) was experimentally investigated in a pilot-scale reactor. In contrast to nonisothermal and fast initiator dosage process, using initiators mixture has the smallest influence on molecular weight and polydispersity index compared to the control process. It is found that Cok-PVC grains have the lowest cold plasticizer absorption and porosity among productivity-enhancing processes. Scanning electron microscopy showed that the particles produced by Cok process are more regularly shaped, with a smoother surface compared with the control resin. All three productivity-enhancing techniques lead to an apparent quality enhancement, higher flowability and greater bulk density of final grains when compared with control resin grains. While both nonisothermal and fast initiator dosage polymerization process broaden the particle size distribution (PID) of final PVC grains, applying Cok process produces particles with the same PID as a control process. In comparison with nonisothermal trajectory and continuous fast initiator dosage system, the Cok polymerization process leads to the most delay of motionless conversions, fusion time and the formation of a three-dimensional skeleton of primary particles as well.

Laser Granulometer as an Useful Tool for Selection of Appropriate Membranes Used in the MIEX® DOC-UF/MF Hybrid Process

In the study, particle size distribution of the MIEX® resin was presented. Such analyses enable to determinate whether presence of fine resin fraction may be the reason for unfavorable membrane blocking during water purification by the hybrid MIEX®DOC-microfiltration/ultrafiltration systems. Granulometric analysis of resin grains using the laser diffraction particle size analyzer (laser granulometer) was carried out as well as the microscopic analysis with scanning electron microscope. The following samples were analyzed: samples of fresh resin (a fresh resin – not used in water treatment processes) and samples of repeatedly used/regenerated resin that were collected to analysis during mixing and after sedimentation process. Particle size distribution was slightly different for fresh resin and for repeatedly used/regenerated resin. The grains sizes of fresh resin reached approximately 60 μm (d10), 120 μm (d50) and 220 μm (d90). Whereas the sizes of repeatedly used/regenerated resin were about 15 μm (d10), 40 μm (d50) and 115-130 μm (d90). The smallest resin grains sizes were in the range of 0.3-0.45 μm. This ensures that the ultrafiltration membranes retain all resin grains, even the smallest ones. Whereas the microfiltration membranes must be appropriately selected to guarantee full separation of the resin grains and at the same time to exclude a membrane pores blocking.

Preparation of Highly Tough Ethylene Vinyl Acetate (EVA) Heterogeneous Cation Exchange Membranes and Their Properties of Desalination

A manufacturing method has been devised to prepare novel heterogeneous cation exchange membranes by mixing ethylene vinyl acetate (EVA) copolymers with a commercial cation exchange resin. Optimum material characteristics, mixture ratios and manufacturing conditions have been worked out for achieving favorable membrane performance. Ion exchange capacity, electrical resistance, water uptake, swelling ratio and tensile strength properties were measured. SEM analysis was used to monitor morphology. Effects of vinyl acetate (VA) content, melt index (MI) and ion exchange resin content on properties of heterogeneous cation exchange membranes have been discussed. An application test was carried out by mounting a selected membrane in a membrane capacitive deionization (MCDI) system to investigate its desalination capability. 0.92 meq/g of ion exchange capacity, 8.7 Ω.㎠ of electrical resistance, 40 kgf/ ㎠ of tensile strength, 19% of swelling ratio, 42% of water uptake, and 56.4% salt removal rate were achieved at best. VA content plays a leading role on the extent of physical properties and performance; however, MI is important for having uniform distribution of resin grains and achieving better ionic conductivity. Overall, manufacturing cost has been suppressed to 5-10% of that of homogeneous ion exchange membranes.

The influence of ultrasounds on the process of uranium desorption

In the present paper, we have studied the intensification of the desorption process of the complex anions of uranium U(VI), from ion exchange resins under the action of the ultrasonic field. The dynamics of uranium desorption from the anionic resins Purolite A600U/3472 and PM 611 was analyzed, both in standard conditions and with ultrasounds. The use of ultrasounds leads to the substantial growth of desorption kinetics and of the uranium recovery degree. The tests for stability of the resin grains size, mechanical resistance and the capacity of loading with uranium, after the repeated action of the ultrasounds field, emphasized the physical-chemical stability of resins used in the experiment (loading capacity of untreated resin 30.36 mgU/g resin and treated in continuous ultrasonic field 30.85 mgU/g resin).

The influence of ultrasounds on the process of uranium desorption

In the present paper, we have studied the intensification of the desorption process of the complex anions of uranium U(VI), from ion exchange resins under the action of the ultrasonic field. The dynamics of uranium desorption from the anionic resins Purolite A600U/3472 and PM 611 was analyzed, both in standard conditions and with ultrasounds. The use of ultrasounds leads to the substantial growth of desorption kinetics and of the uranium recovery degree. The tests for stability of the resin grains size, mechanical resistance and the capacity of loading with uranium, after the repeated action of the ultrasounds field, emphasized the physical-chemical stability of resins used in the experiment (loading capacity of untreated resin 30.36 mgU/g resin and treated in continuous ultrasonic field 30.85 mgU/g resin).

Teflon-HPLC: A novel chromatographic system for application to isotope geochemistry and other industries

Traditional column chromatography techniques are restricted by several factors, including limitations on column length, resin grain size, elution time, and a general inability to slowly ramp up or down reagent concentrations along a gradient. Likewise, most existing high-performance liquid chromatography (HPLC) systems are not amenable to certain column chromatography techniques that require highly concentrated acids.Here, we outline the development of a Teflon HPLC (T-HPLC) system for application to a wide variety of chromatography problems. The primary factors that set the T-HPLC system apart from any currently available chromatography procedure are the following: 1) a fluid flow path enclosed entirely by Teflon, 2) fully automated elution schemes controlled by computer software, which allows for fresh mixing of reagents for each elution step, and fine scale gradient/ramp elutions, 3) temperature control of the entire system (up to 80°C) for enhanced chemical separations and, 4) a modular design making the system easily adaptable to a variety of separation schemes.The effectiveness of the T-HPLC system is tested on two column techniques that are of particular interest to the geochemistry/cosmochemistry communities. The first application involves the separation of Ni from Mg, which is required for high precision Ni isotopic studies and for investigating the abundance of the extinct 60Fe radionuclide. The T-HPLC system greatly simplifies and improves upon the classical technique. In a single pass on an 80cm long column, we achieve excellent separation of Ni from Mg, with a much improved time frame (10h versus 70h). The second application is the separation of the individual rare earth elements from each other. The isotopic compositions of the multi-isotopic REEs (La, Ce, Nd, Sm, Eu, Gd, Dy, Er, Yb and Lu) may hold important information about nucleosynthetic processes, cosmic-ray exposure effects in meteorites and airless bodies, and mass fractionation effects. For this application, we also developed a computer simulation that uses experimentally determined partition coefficients to simulate an elution curve in order to optimize the actual column elution scheme. Overall, we were able to achieve excellent separation of the multi-isotopic REEs from each other.Although the two applications that we explore are in the fields of geochemistry/cosmochemistry, the modular design and adaptability make the T-HPLC system useful to a wide array of scientific fields and industries.

Removal of uranium anionic species from aqueous solutions by polyethylenimine–epichlorohydrin resins

The removal of uranium anionic species from aqueous solutions (initial concentration: 10–2,000 mg/L) by a low- and a high molecular weight polyethylenimine–epichlorohydrin resins was studied in the absence of background electrolytes at initial pH (pHinit) 8 to10. The amount of the sorbed U was determined spectrophotometrically using the Arsenazo III method. The maximum uptake was observed at pHinit 8 using both resins. The maximum uptake capacity observed was 221 and 388 mg U/g for the low- and high molecular weight resin respectively. The uptake data were modeled using a number of 2- and 3- parametric isotherm equations (Langmuir, Freundlich, Langmuir–Freundlich, Toth and Redlich–Peterson). The kinetics of the uranium removal was also studied and modeled using the pseudo-first and pseudo-second order equations. The surface and interior of the resin grains were examined after the sorption experiments by scanning electron microscopy/energy dispersive spectroscopy.

A novel electrochemical ion exchange system and its application in water treatment

A novel electrochemical ion exchange system with porous cylinder electrodes is proposed for treatment of wastewater. This system can be used for desalination without the costly ion-exchange membrane and extra chemical reagents. Since the electrodes are completely uniform and no ion-exchange membrane was used in this system, it can be operated by switching anodes and cathodes flexibly for eliminating the scaling on the surface of electrodes. The strong base ion-exchange resin grains placed among the anode and cathode have played as supporting electrolyte, which is capable for the treatment of wastewater with low conductivity. The concentrated and neutralized anolyte containing chlorine is effective for disinfection and contaminants removal. Under the experimental conditions, the removal percentage of total dissolved salts was 83% and the removal percentage of chemical oxygen demand was 92% without consumption of extra chemical reagents.

Preparation of a heterogeneous hollow‐fiber affinity membrane having a mercapto chelating resin and its recovery of Hg2+ cations

AbstractA kind of heterogeneous hollow‐fiber affinity filter membrane with a high chelating capacity for Hg2+ was prepared by phase separation with blends of a mercapto chelating resin and polysulfone as the membrane materials, N,N‐dimethylacetamide as the solvent, and water as the extraction solvent. The adsorption isotherms of the hollow‐fiber affinity filter membrane for Hg2+ were determined. The heterogeneous hollow‐fiber affinity filter membrane was used for the adsorption of Hg2+ cations through the coordination of the mercapto group and Hg2+ cations, and the effects of the morphology and structure of the affinity membrane on the chelating properties were investigated. The chelating conditions, including the chelating resin grain size, pH value, concentration of the metallic ion solution, mobile phase conditions, and operating parameters, had significant effects on the chelating capacity of the hollow‐fiber affinity filter membrane. The results revealed that the greatest chelating capacity of the hollow‐fiber affinity filter membrane for Hg2+ was 1090 μg/cm2 of membrane under appropriate conditions, and the adsorption isotherms of Hg2+ could be described by the Langmuir isotherm. The dynamic chelating experiments indicated that the hollow‐fiber affinity membrane could be operated at a high feed flow rate and that large‐scale removal of Hg2+ could be realized. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008

Preparation of a heterogeneous hollow‐fiber affinity membrane modified with a mercapto chelating resin

AbstractA high‐quality, heterogeneous hollow‐fiber affinity membranes modified with mercapto was prepared through phase separation with blends of a chelating resin and polysulfone as membrane materials, poly(ethylene glycol) as an additive, N,N‐dimethylacetamide as a solvent, and water as an extraction solvent. The effects of the blending ratio and chelating resin grain size on the structure of the hollow‐fiber affinity membrane were studied. The effects of the composition of the spin‐cast solution and process parameters of dry–wet spinning on the structure of the heterogeneous hollow‐fiber affinity membrane were investigated. The pore size, porosity, and water flux of the hollow‐fiber affinity membrane all decreased with an increase in the additive content, bore liquid, and dry‐spinning distance. With an increase in the extrusion volume outflow, the external diameter, wall thickness, and porosity of the hollow‐fiber affinity membrane all increased, but the pore size and water flux of the hollow‐fiber affinity membrane decreased. It was also found that the effects of the internal coagulant composition and external coagulant composition on the structure of the heterogeneous hollow‐fiber affinity membrane were different. The experimental results showed that thermal drawing could increase the mechanical properties of the heterogeneous hollow‐fiber affinity membrane and decrease the pore size, porosity, and water flux of the heterogeneous hollow‐fiber affinity membrane, and the thermal treatment could increase the homogeneity and stability of the structure of the heterogeneous hollow‐fiber affinity membrane. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007

Impact of surface properties on the dust grain charging

Dust grains are common in the space environment and being immersed in plasma, they become charged. It is well known that a motion of grains in space is driven mainly by electrodynamic forces and thus the grain charge is important for processes like the coagulation or dust cloud formations. Among other charging currents, emission processes are very important for setting the dust charge. It is believed that emission processes are connected exclusively with surface properties of dust grains but it is not evident for the surfaces covered by a very thin layer of different material (e.g., oxidized metal). For this reason, we investigate surface effects experimentally. Our experiment is based on an 3D electrodynamic trap. We caught a single dust grain for several days inside the vacuum vessel and exposed it to the electron/ion beam and studied charging/discharging processes. We have chosen spherically shaped melamine formaldehyde resin grains of a diameter 2.35 μm either with a clean surface or covered with a thin nickel film. An advantage of these samples is that the properties of bulk and surface materials are completely different. The effect of a surface modification was studied for ion and electron field emissions. We determined field intensities needed for significant emission currents as well as effective work functions for charged dust grains of particular material.

Ion beam effects on dust grains

Our experimental set-up allows us to keep a single dust grain trapped in a high-vacuum chamber for hours or days and to affect it by electron or ion beams. It apparently makes possible to study each particular charging process separately but, as our results have shown, the influence of emissions from the surfaces surrounding the experimental space cannot be neglected in interpretation of results.The paper is devoted to experimental and theoretical investigations of ion field emission from spherical non-conducting monodisperse melamine resin grains with diameters of 2.35(m∼1×10-14kg), 4.97, and 9.78μm that were exposed by the ion beam with energies ranging from 0.3 to 5keV. We present the methodology of the determination of different charging currents as well as the determination of a grain size. These quantities are then used for estimation of equilibrium potentials. Results obtained using He ions show that ion field emission from the investigated grains can be recorded at field intensities of the order of 109V/m and strongly depends on a history of the grain charging.

Study on preparation of heterogeneous polysulfone affinity filter membrane and its sorption properties for Hg2+

AbstractHigh quality heterogeneous polysulfone affinity flat filter membranes having chelating groups were prepared by phase separation by the use of blends of chelating resin and polysulfone as membrane materials, N,N‐dimethylacetamide as the solvent, and water as the extraction solvent. The effects of blending ratio, chelating resin grain size, and temperature of casting solution on the structure of affinity membranes were investigated. The sorption process of an affinity filter membrane for Hg2+, adsorbed under various chelating conditions such as chelating resin grain size, pH value, and the concentration of the metallic ion solution, was also studied. The results revealed that the greatest chelating capacity of an affinity filter membrane for Hg2+ was 1050 μg/cm2 per membrane under appropriate conditions, and the sorption isotherms of Hg2+could be expressed by the Freundlich sorption model. Dynamic chelating experiments indicated that the Hg2+ could be extracted with the affinity filter membrane and reextracted under acidic conditions. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 908–915, 2003

An Unusual Dinosaur Coprolite from the Campanian Aguja Formation, Texas

ABSTRACT The diversity of cranial and postcranial elements of dinosaur remains, early mammals and palynomorphs in the Aguja Formation (Campanian) rivals many other Upper Cretaceous localities. Recently, a large, globular reptilian multi-tier coprolite, 5.9 in. (15 cm) in length, 3.5 in. (9 cm) in width, and 4.7 in. (12 cm) in height, of an unknown origin, was collected from the upper shale member of the Aguja Formation in Big Bend National Park, Brewster County, Texas. This rare and unusual find provides for the first evaluation of a large coprolite of this kind from the southwestern United States. The coprolite consists of at least ten individual, somewhat cylindrical or tubular, anisopolar units that curve into half-moon shapes. Organic inclusions include inner and outer bark tissue, conifer wood fragments, amber resin and pollen grains from assorted angiosperms. Inorganic inclusions consist of sand grains, manganese oxide, and secondary infillings of pyrite, fibrous-like chalcedony, iron-stained carbonate and white calcite. The size and structure and contents suggest that this coprolite was deposited by an herbivorous dinosaur.

Frequency dependent conductivity of agglomorated spheres having a conducting surface

Charge carrier diffusion in an agglomeration of non-conducting resin grains covered with a layer of small conducting particles occurs on two scales, on single spherical grain surfaces and between different grains. Measurements of the frequency dependent permittivity between 5 Hz and 0.5 THz have been performed. The analysis allows to distinguish between the two contributions to the conductivity of the system.

Distinct element simulation of grain alignment in mushy-state forging of magnets

A method for simulating the motion of grains in mushy-state forming of magnets is proposed on the basis of the distinct element method. The grains of the magnet are modelled to be a lot of elliptical elements, and the effect of the liquid phase on the motion of the grains is treated as viscous resistance to the movement. The motion of individual grains is obtained by solving the equations of motion for a time increment under the action of the elastic repulsive, frictional and viscous forces. Macroscopic plastic deformation of a metallic capsule containing the magnet is calculated by the viscoplastic finite element method, and the obtained motion of the interface between the capsule and magnet is used as a boundary condition in the distinct element simulation. The motion of grains in mushy-state plane-strain upsetting of a rare earth magnet contained in a steel capsule is chosen as an example of the simulation. The degree of grain alignment due to the upsetting increases as the reduction in height increases. The calculated degree of grain alignment agrees well with that for a model experiment using acrylic resin grains and a plasticine capsule.