Addition Of Vermiculite Research Articles

Influence of vermiculite on performance of flyash-based fibre-reinforced hybrid composites as friction materials

Flyash-based fibre-reinforced hybrid phenolic composites filled with vermiculite were fabricated and characterized for their physical, thermal, mechanical and tribological performance. The performance were evaluated in terms of their friction-fade, friction-recovery, maximum disc temperature rise and wear behaviour on a Krauss friction tester conforming to the Regulation-90 as per the Economic Commission for Europe (ECE) norms. The fade behaviour has been observed to be optimally dependent on the flyash–vermiculite combination whereas the recovery remained broadly unaffected at ∼112 ± 14%. Addition of vermiculite has contributed to the reduction in the maximum disc temperature rise whereas it enhanced the frictional amplitude, i.e. μ max– μ min. The wear behaviour remains closely related to the trend observed in fade. The addition of vermiculite has caused an increase in the post-braking onset of degradation temperature of the surface composition as compared to the pre-braking composition. The analyses of friction and wear performance of the composites were carried out and major factors influencing the tribo-performance were identified. Worn surface morphology investigation using scanning electron microscope has revealed that the addition of vermiculite alters the compositional interactions at the braking interface leading to flyash–vermiculite combination specific topographical attributes responsible for tribo-performance evolution.

Accumulation of heavy metals from contaminated soil to plants and evaluation of soil remediation by vermiculite

We evaluated the distribution of 15 metal ions, namely Al, Cd, Cu, Cr, Fe, La, Mn, Ni, Pb, Sc, Ti, V, Y, Zn and Zr, in the soil of a contaminated site in Piedmont (Italy). This area was found to be heavily contaminated with Cu, Cr and Ni. The availability of these metal ions was studied using Tessier’s sequential extraction procedure: the fraction of mobile species, which potentially is the most harmful for the environment, was much higher than that normally present in unpolluted soils. This soil was hence used to evaluate the effectiveness of treatment with vermiculite to reduce the availability of the pollutants to two plants, Lactuca sativa and Spinacia oleracea, by pot experiments. The results indicated that the addition of vermiculite significantly reduces the uptake of metal pollutants by plants, confirming the possibility of using this clay in amendment treatments of metal-contaminated soils. The effect of plant growth on metal fractionation in soils was investigated. Finally, the sum of the metal percentages extracted into the first two fractions of Tessier’s protocol was found to be suitable in predicting the phytoavailability of most of the pollutants present in the investigated soil.

Copper removal from sludge permeate with ultrafiltration membranes using zeolite, bentonite and vermiculite as adsorbents

The aim of this work is to examine copper removal from sludge permeate with the use of low-cost minerals of Mediterranean origin combined with ultrafiltration membranes. The minerals used were zeolite (clinoptilolite), bentonite and vermiculite. Activated sludge was enriched with 0.01 N (317.7 ppm) of Cu(II). Fixed concentrations of minerals were added to sludge and the pH value was adjusted at 5.5. The mixture was agitated for 2 hours at 800 rpm at room temperature and was then filtered through a batch ultrafiltration system for 1 hour. This experiment was repeated, for comparison purposes, with sludge enriched with 0.01 N of Cu(II) with no mineral addition. The results showed that ultrafiltration membranes with no mineral addition were able to remove a significant amount of copper with removal efficiencies ranging from 59.4-78.3%. The addition of 10 g/l and 20 g/l of bentonite combined with ultrafiltration membranes resulted in removal efficiencies of 94.9% and 99.4% respectively and that of 10 g/l and 20 g/l of vermiculite in removal efficiencies of 93.8% and 96.8%, respectively. The ion exchange capacity of minerals followed the order bentonite > vermiculite > zeolite. Furthermore, membrane fouling was investigated. The addition of zeolite and bentonite reduced membrane fouling, while the addition of vermiculite did not impact on fouling. The use of low-cost minerals in combination with ultrafiltration membranes can be employed to treat industrial wastewater, resulting in a final effluent with very low copper concentrations.

EFFECTS OF DIFFERENT COMPOUND SUBSTRATES ON GROWTH, YIELD AND FRUIT QUALITY OF CUCUMBER

The effects of eleven different peat-containing substrates on growth, yield and fruit quality of cucumbers (Cucumis sativus L.) were studied in an eco-organic type soilless culture system during a 17-week greenhouse experiment. The results showed that physical characteristics of all substrates were within acceptable ranges of plant growth and development, but pH and EC values were beyond the optimal ranges when coal ash was over 25% in the mixture. The best seedling performance was obtained in the mixture of peat to coal ash 3:1 (T3), followed by 1:1 peat/coal ash (T6), 1:1:1 peat/vermiculite/coal ash (T8), and 3:1 peat/perlite (T2) treatment. Highest cucumber yield and fruit quality were obtained by the mixture of peat to vermiculite 1:1 (T4). And plants grown in 3:1 peat/vermiculite (T1), 3:1 peat/perlite (T2), 3:1 peat/coal ash (T3) had better yield than in 100% peat. The results indicate that addition of vermiculite, perlite and coal ash to peat resulted in a better seedling growth, higher yield and better quality of fruit probably owing to increasing water-holding capacity and aeration of peat, which demonstrates that inorganic substances such as vermiculite, perlite and coal ash could partially replace peat.

Preparation and Properties of Polypropylene/Organo-Vermiculite Nanocomposites

Polypropylene/organo-vermiculite (OVMT) nanocomposites with different clay loadings were prepared via melt-mixing using a twin-screw extruder. The vermiculite was premodified with maleic anhydride by ball milling. The resultant polypropylene/OVMT nanocomposites possess an intercalated structure as confirmed by both wide-angle X-ray diffraction (WAXD) and transmission electron microscopy (TEM). The mechanical property tests show that the tensile and flexural strength of these nanocomposites increase dramatically with the OVMT loading; the fracture toughness remains almost unchanged and the Charpy impact strength decreases slightly. Finally, differential scanning calorimetry (DSC) and WAXD results show that the addition of vermiculite can induce the β crystal structure of polypropylene.

Effect of vermiculite addition on compost produced from Korean food wastes

To evaluate the effect of vermiculite addition on composting food wastes from Korean households, food wastes were composted in three small bins to which different additives were added. The following three bins were employed: in Case I, only recycled compost was composted; in Case II, food wastes with recycled compost; and in Case III, food wastes with recycled compost and vermiculite. In the experiment performed for 30 days, it was confirmed that the supplementary addition of vermiculite to the composting mixture did not significantly improve the weight loss rate and the decomposition rate of food wastes. Due to dilution through the use of inorganic vermiculite, the vermiculite addition reduced the organic matter concentration of the composting mixtures. Vermiculite addition did not raise the pH value. Weight losses of roughly 70% were observed based on calculating moisture loss as well as dry food waste loss and not considering additives, while dry food waste loss was 29.4% and 35.8% with and without the addition of vermiculite, respectively. For these experiments, the major portion of the weight loss was the loss of water. The results indicate a need to differentiate between weight loss percentages and decomposition percentages, and a need to indicate if either of these percentages includes or excludes the mass of additives.

Structure and properties of polyamide‐6/vermiculite nanocomposites prepared by direct melt compounding

AbstractPolyamide‐6 (PA6)/vermiculite nanocomposites were fabricated through the direct melt compounding of maleic anhydride‐modified vermiculite (MAV) with PA6 in a twin‐screw extruder followed by injection molding. The structure and morphology of the nanocomposites were determined by X‐ray diffraction and scanning and transmission electron microscopy techniques. The results revealed the formation of intercalated and exfoliated vermiculite platelets in the PA6 matrix. Tensile measurement showed that the tensile modulus and strength of the nanocomposites tended to increase with increasing vermiculite content. The thermal properties of the nanocomposites were determined by dynamic mechanical analysis, differential scanning calorimetry, and thermogravimetry measurements. The storage modulus of the PA6–MAV nanocomposites increased to almost twice that of the neat PA6. The thermal stability of the nanocomposites increased dramatically, and this was associated with the addition of vermiculite. The effect of the addition of maleic anhydride on the formation of the PA6–vermiculite nanocomposites was examined. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 2860–2870, 2002

Micropropagation of Shinano Walnut(Juglans regia L.).

Micropropagation of three cultivars of Shinano walnut (Juglans regia L.) was performed by using DKW medium. Nodal segments (explants) produced new shoots on DKW medium supplemented with 5μM BA and 0.05μM IBA. When subcultured, shoots grew better on the above medium with agar than they did with Gelrite. There was a significant difference in the growth of shoots among the cultivars. To induce roots, IBA-treated shoots were transferred to a rooting medium, a Gelrite-solidified DKW medium with macroelements reduced to 1/4 strength, with or without vermiculite. The addition of vermiculite to the medium improved the rooting percentage and promoted the development of a good root system. All regenerated plantlets were successfully acclimatized.

Novel Preparation and Properties of Polypropylene−Vermiculite Nanocomposites

A novel approach to the preparation of polymer nanocomposites utilizing a low-molecular-weight reactive modifying reagent has been developed in this study. This is the first report on the fabrication of in situ nanocomposites using maleic anhydride as a reactive reagent that acts both as a modifying additive for the polymeric matrix and as a swelling agent for the silicate. Accordingly, polypropylene−vermiculite nanocomposites with an intercalated or exfoliated structure can be achieved by simple melt mixing of maleic anhydride-modified vermiculite with polypropylene. The nanocomposite structure is evidenced by the absence of vermiculite reflections in the X-ray powder diffraction patterns. Tensile tests show that the tensile modulus and strength of the nanocomposites tend to increase dramatically with vermiculite addition. Such enhancement in mechanical properties results from the formation of intercalated and exfoliated vermiculite reinforcement in the composites. Finally, the thermal properties of the ...

European earwig, Forficula auricularia L. (Dermaptera: Forficulidae), as a predator of the redlegged earth mite, Halotydeus destructor (Tucker) (Acarina: Penthaleidae)

The European earwig, Forficulaauricularia L., consumed the redlegged earth mite, Halotydeusdestructor (Tucker), under laboratory conditions. Although female earwigs consumed more mites at the lowest density of 25 mites per petri dish, there was no difference between males and females at the two higher densities of 50 and 75 mites per dish. The addition of vermiculite to the dish to simulate habitat diversity had a negative impact on the consumption rate.

Convenient and effective methods for in vitro cultivation of mycelium and fruiting bodies of Lentinus edodes

Three strains were selected from 18 commercial strains of the shiitake mushroom, Lentinus edodes , on the basis of rate and density of mycelial growth. Comparison of biomass production between stationary and shake flask cultures was strain-dependent, strain Le-465 producing higher yields from shaken than stationary cultures while no differences were recorded in Le-11 and Le-103. Among 5 media tested for mycelial growth yield, a molasses medium gave the highest biomass after 14 d, but by day 28 yield from that medium was the second lowest. By day 28, a chemically defined medium was the best for biomass yield. Homogenization of mycelia provided an excellent uniform source of inoculum for replicate trials. Homogenization of the inoculum increased the yield of mycelium by day 28, when fruiting started. Chemically-defined media were best for fruiting of L. edodes . There was not much difference in fruiting performance between cultures incubated at a uniform 25 °C and those incubated in a 14/22° cycle. Supplementation of flask cultures with vermiculite promoted growth and fruiting. In flask cultures kept in a normal incubator a cotton stopper, as opposed to one made of plastic foam, was most suitable for growth and fruiting. Inclusion of a carbon dioxide trap was not necessary. The best fruiting in vitro was obtained by inoculation on to solid supports, like a wire mesh or agar, in crystallizing dishes which were kept within a plastic chamber whose air-flow and humidity could be regulated with air-vents and an air-pump. Under such conditions, vermiculite addition to the media did not enhance fruiting.

Effects of Soil Amendments and Fertilizer Levels on the Establishment of Silver Maple

In developing a landscape, establishment of woody ornamentals is a major concern. Most recommendations suggest the use of some form of soil amendment (4, 17). Others go so far as to recommend digging the planting hole a year in advance and filling it with leaves and organic matter to form a composted planting media (3). However, their recommendations are seldom referenced by research findings. The same is true for the addition of fertilizers. Some authors maintain fertilizer should not be applied to newly planted landscape material the first year. They state that it takes year for new feeder roots to develop (4, 5, 8). Other advocate the use of diluted solutions of soluble fertilizers, but fail to mention rate and frequency of application (6, 10, 17). Allison and Anderson (1), using sawdust for soil improvements, observed harmful effects on crop yields when sawdust was applied alone. It depleted nitrogen in the form of ammonia and nitrates. Rigby (8) used ground pine bark as a growing medium for container nursery stock. His results showed the newly planted material required additional nitrogen fertilizer for the first few months. Gartner, et. al., (11) worked with several species of plant material and various mixes of hardwood bark, soil and perlite. The decomposition of the bark in the mix caused a severe nitrogen deficiency that was not corrected by normal fertilization practices. Later studies by Gartner, Meyer and Saupe (12) demonstrated that a slow release fertilizer incorporated in bark-amended mixes prevented nitrogen deficiencies. Allison and Murphy (2) and Matkin (15) found that hardwoods decomposed at a faster rate than softwoods (40-50% in 60 days) and the hardwoods were attacked more readily by the microorganisms and consequently required more immediate nitrogen. In further studies with wood by-products, Viljoen and Fred (22) and Lunt (14) reported that there was no toxic effects on plants due to sawdust and woodchips. Joiner and Conover (13) found that shredded pine bark proved to be an accessible, inexpensive substitute for peat as the organic component of soil mixtures with sand for container-grown pittosporum. Salter and Williams (19) studied the moisture characteristics and crop yields from sandy loam soils amended with farmyard manure and peat. Yield differences between the peat and control plots were small and inconsistent. Feustal and Byers (9) studied the moisture absorbing and retaining capacities of peat-soil mixtures. They stated that moisture retention properties alone should not be the basis for incorporating peat with soil. They did not recommend it as a soil amendment. Pellet (16) found that the addition of peat, vermiculite or sawdust to the soils of central Minnesota resulted in no better growth of landscape plants than unamended soil. In agreement with Pellet, Townsend (21) used a 50% sandy loam soil and 50% peat mixture and tested the effects of soil amendments on the growth and productivity of highbush blueberries. The unamended control plot yielded larger plants and better fruit over a five year period than the peat amended soils. Smalley, Pritchett and Hammond (20) found similar results in experiments with bermudagrass putting greens. However, they found that the addition of vermiculite to a loamy fine sand putting-green soil increased yield significantly. It was not advantageous to

Carnation Production in Vermiculite Amended Media1

Abstract ‘Cardinal Sim’ carnations were grown for 2 years in 6 media combinations that were supplemented with 2 particle sizes of vermiculite. The addition of vermiculite resulted in significantly higher K levels in carnation foliage the first year than in control plants. The positive effect of vermiculite persisted through the second year but at a lower level. A combination of 1-1-1 by volume sphagnum peat moss, perlite and #4 vermiculite was as good a growing medium as the control soil when compared on a total production and quality index basis.

Fixation of Hydroxy‐Aluminum Polymers by Vermiculite

AbstractThe addition of vermiculite to hydroxy‐aluminum (OH‐Al) solutions prepared by the controlled addition of NaOH to AlCl3 results in the fixation of OH‐Al polymers by the clay. With solutions of NaOH/Al molar ratios = 0.3 to 2.1, the polymers held by the clay are of nearly constant composition, very close to the formula [Al6(OH)12]6+ (single ring) or [Al10(OH)22]8+ (double ring). The polymers are present in a single layer in the interlayer space. All specimens give a strong 14Å. X‐ray diffraction peak of similar intensity on K+ saturation even though the proportion of cation‐exchange positions occupied by the OH‐Al polymers varies from 24% to 61% on an equivalent basis.With solutions of NaOH/Al = 2.25 to 2.70, the polymers held by clay gradually increase in size and decrease in net positive charge per Al atom with increasing NaOH/Al ratio. The polymers are also present in a single layer in the interlayer space, but it takes more Al atoms and a longer time for the polymers in this group to produce a 14Å. peak of an intensity corresponding to that obtained when the Al is in the form of single or double ring units. In those specimens in which the amount of Al fixed is not sufficient to hold the vermiculite layer apart effectively, the Al polymer‐vermiculite layer is randomly interstratified with K‐vermiculite, and the resultant X‐ray diffraction patterns vary widely, some appearing as though X‐ray amorphous components were present.For all of the above mentioned specimens, no noticeable change has been found in the composition of the polymers held by clay minerals during aging up to 6 months. No crystalline Al(OH)3 was detected in any of these specimens. It is concluded that vermiculite functions as an anion which has a strong affinity for OH‐Al polymers and which inhibits the formation of gibbsite in soils.At NaOH/Al = 3, no OH‐Al polymer is found in the interlayer space but crystalline Al(OH)3 forms outside the clay lattice within two weeks.