Cork Granules Research Articles

Treatment of a textile effluent by adsorption with cork granules and titanium dioxide nanomaterial

ABSTRACTThis study aimed to explore the efficiency of two adsorbents, cork granules with different granulometry and titanium dioxide nanomaterial, in the removal of chemical oxygen demand (COD), colour and toxicity from a textile effluent. The adsorption assays with cork were unsatisfactory in the removal of chemical parameters however they eliminated the acute toxicity of the raw effluent to Daphnia magna. The assay with TiO2 NM did not prove to be efficient in the removal of colour and COD even after 240 min of contact; nevertheless it also reduced the raw effluent toxicity. The best approach for complete remediation of the textile effluent has not yet been found however promising findings were achieved, which may be an asset in future adsorption assays.

Drying kinetics of granulated cork: Effect of air drying stream conditions and granule size

Granulated cork is a by-product of natural cork stoppers manufacturing which is incorporated into highly valued products such as agglomerated cork stoppers and expanded cork insulation. Prior to this, the cork granules must be dried.This work presents an experimental study for the characterization of wet granulated cork drying kinetics with different morphologies: a powder and granules with different sizes (2–2.8, 2.8–4 and 4–5.6 mm). A drying process with hot air stream flowing tangentially to the solid was used for a systematic analysis of the influence of air stream conditions (temperature and flowrate) on drying kinetics. Under these conditions, the influence of the stream temperature was much more relevant than its velocity with the drying time almost halving when the temperature rose from 35.0 °C to 56.5 °C. The drained humid solid with higher granulometry was dried entirely during a falling drying rate period. All others products presented a constant drying rate period before the falling drying rate period.The results revealed that the falling drying rate period is conditioned by water migration through the solid and presents a similar shape for all products. Thus, the behavior can be described by a single characteristic drying curve, allowing predicting drying rate as a function of the solid normalized humidity, despite the cork granules dimensions. This normalized curve is a useful tool for dryer equipment dimensioning in the cork manufacturing industry.To predict the time of drying for defined air drying conditions, a simple procedure was proposed using the characteristic drying rate obtained.

Added-value for wood bark as a coating layer for flooring tiles

Worldwide more than 50% of the bark amount is used for energy generation. In this research, physico-mechanical and surface properties of flooring tiles coated with thin layers made of larch bark are presented for the first time. Two types of adhesives were involved to bond the bark particles, namely polyurethane and a formaldehyde-free tannin-hexamine resin.Larch (Larix decidua Mill.) bark was used to produce layers with 3 mm thickness at three levels of density, from 0.6 to 0.8 g/cm³, to coat standard high density fiberboard (HDF) as core material. Mechanical and physical properties of the specimens including surface soundness, Brinell hardness, dimensional stability, abrasion resistance, cross-cut test, resistance to chemicals and fire resistance of the bark coated panels were determined and compared with the properties of industrial multilayered boards with granulated cork as wear layer. Overall, excepting the Brinell hardness, all the properties of the boards produced with wear layer made of larch bark were lower compared to cork-based coated control. Surface soundness of panels with larch wear layer was 30% or 60% lower compared to control. Both thickness swelling and water absorption after 24 h of the panels were too high. Neither polyurethane nor formaldehyde-free tannin adhesive influenced better the panel's properties. Surface properties were similar to control. Although mechanical properties of the samples considered in this work were inferior to those of typical flooring material coated with cork layer, it can be stated that such a little used material like bark may have a useful potential as a value-added product for such application.

Furosemide removal in constructed wetlands: Comparative efficiency of LECA and Cork granulates as support matrix

The removal efficiency of LECA and cork granulates as support matrix for pharmaceuticals active compounds in a constructed wetland system was investigated using the diuretic drug Furosemide. Kinetics studies were performed testing three different concentrations of Furosemide in an ultrapure water matrix, along seven days. LECA achieved higher removal values compared to cork granulates. However, cork granulates presented a higher removal in the first 24 h of contact time compared to the other adsorbent. The kinetic studies showed that LECA and cork granulates have different adsorption behaviours for Furosemide which is controlled by different adsorption mechanisms. Both materials showed good removal efficiencies and a combination of the two should be further explored in order to applied both materials as support matrix to cope with different furosemide concentrations.

Cork ‐ a natural material for linalool controlled release

AbstractControlled release of aromatic mixtures to the atmosphere is a requirement for scented systems for indoor applications. The product must smell nice, but also be able to last, slowly releasing the perfume over time. Several adsorption materials have been used, for this purpose. In this study, cork was investigated as a potential perfume adsorbent for application in scented drawer sachets and equivalent products. Cork was selected due to its adsorption properties and because it is a natural, renewable, sustainable material. Granulated cork is a significant by‐product in cork industries and it was chosen for adsorption in this work. Linalool, an enantiomeric monoterpene alcohol and one of the main components of several essential oils, was selected as the model compound for adsorption studies.Activated carbon (AC) was used as the reference material. The sorption of linalool to granulated cork and AC was evaluated by HS‐SPME‐GC‐FID. The linalool isotherm on cork was shown to follow a Brunauer‐Deming‐Deming and Teller, Type IV model. The isotherm data on AC can be adjusted to Langmuir and Freundlich models. A maximum adsorption capacity of 3.9x103μg/g was achieved for AC. Desorption studies were performed. Linalool was still released from granulated cork after three equilibrium stages of desorption, whereas only two desorption values were obtained for AC from the equilibrium with highest linalool concentration. Thus, AC demonstrated good adsorption but not good desorption properties. Sorption and desorption studies of linalool from granulated cork, showed that granulated cork could be an excellent material allowing controlled release of the aroma.

A design tool for resource-efficient fabrication of 3d-graded structural building components using additive manufacturing

Abstract The construction sector is under increasing pressure to improve its efficiency and effectiveness, reducing environmental impacts, material use and costs. A computational tool was developed to design and fabricate functionally graded building components. The material composition was defined based on voxel determination in order to design building elements with varying material stiffness. A cement-based conceptual building wall was investigated with a varied material composition, using two different lightweight aggregates, a granulated cork one and the other with expanded clay. This functionally graded material concept applied to lightweight building components will allow producing resource-efficient graded building components tailored to specific loading conditions, minimizing waste generation, emissions and resource consumption.

Substrate influence on aromatic plant growth in extensive green roofs in a Mediterranean climate

Green roofs have been described as technical solutions to overcome urban environmental problems, such as decrease of vegetation and stormwater management. In the present study, two pilot 20 m2 extensive green roofs were implemented in an urban Mediterranean region, at a 1st storey on a warehouse building structure, in order to test the adequacy of different substrates for supporting aromatic plants (Lavandula dentata, Helichrysum italicum, Satureja montana, Thymus caespititius and Thymus pseudolanuginosus). Experimental substrates included expanded clay and granulated cork as main components, supplemented with organic matter and crushed egg shell. A commercial substrate that obeys to FLL guidelines was also tested. Plant growth was assessed and compared within each platform. All experimental substrates proved to be adequate for vegetation growth, with the combination of 70% expanded clay, 15% organic matter and 15% crushed egg shell showing the best results regarding plant establishment and growth over time. Water runoff quality parameters - turbidity, pH, conductivity, NH4 +, NO3 −, PO4 3− - met standard values required for water reuse for non-potable purposes, such as toilet flushing or irrigation. Preliminary qualitative thermographic measurements comparing surface temperature of different plant species and the substrate showed that temperature of vegetation surface was lower than substrate, reinforcing green roofs benefits of lowering air temperature in their surroundings. The present research shows that aromatic vegetation combined with clay substrates are suitable for green roofs located in countries of the Mediterranean region.

Growing substrates for aromatic plant species in green roofs and water runoff quality: pilot experiments in a Mediterranean climate.

Green roof technology has evolved in recent years as a potential solution to promote vegetation in urban areas. Green roof studies for Mediterranean climates, where extended drought periods in summer contrast with cold and rainy periods in winter, are still scarce. The present research study assesses the use of substrates with different compositions for the growth of six aromatic plant species - Lavandula dentata, Pelargonium odoratissimum, Helichrysum italicum, Satureja montana, Thymus caespititius and T. pseudolanuginosus, during a 2-year period, and the monitoring of water runoff quality. Growing substrates encompassed expanded clay and granulated cork, in combination with organic matter and crushed eggshell. These combinations were adequate for the establishment of all aromatic plants, allowing their propagation in the extensive system located on the 5th storey. The substrate composed of 70% expanded clay and 30% organic matter was the most suitable, and crushed eggshell incorporation improved the initial plant establishment. Water runoff quality parameters - turbidity, pH, conductivity, NH4+, NO3-, PO43- and chemical oxygen demand - showed that it could be reused for non-potable uses in buildings. The present study shows that selected aromatic plant species could be successfully used in green roofs in a Mediterranean climate.

Dynamic mechanical analysis and creep-recovery behavior of agglomerated cork

The mechanical behavior of agglomerated cork, made of cork granules bound with polyurethane moisture-cured adhesive is investigated and compared to natural cork in the small strain regime (strain <5%). Dynamic mechanical analysis (DMA) of the agglomerated material revealed two distinct thermal transitions, one at −45 °C, related to the glass transition of polyurethane, and one at 3 °C, associated with melting of suberin, a natural polyester that is the main component of cork’s cell walls. Natural cork showed the latter transition to occur at a higher temperature range, between 10 and 25 °C, probably due to a different crystalline arrangement being formed upon cooling the cork granules under pressure in the mold. The storage modulus of agglomerated cork was found to be similar to that of natural cork. Creep and recovery experiments were well described by Burgers model and Weibull distribution function, respectively. Agglomerated cork showed higher instantaneous creep strain and viscous flow than natural cork, probably due to relative displacement and slippage of the granules being allowed by the binder. In all cork materials, not all the instantaneous creep strain was instantaneously recovered. A fraction underwent delayed recovery and another turned into permanent strain. This behavior was associated with the deformation of corrugations in the cork cell walls. Cyclic creep-recovery tests showed for all cork materials recoveries above 90%, except for the first cycle.

Elastic properties of packing of granulated cork: Effect of particle size

Cork is a natural raw materials used in numerous traditional and innovative applications among which the most famous are cork stoppers, insulation boards, and wall and floor covering. Cork exhibits a relatively homogeneous honeycomb structure composed of polyhedron cells filled with gas, which gives its specific properties such as elasticity or hydrophobic behavior. Mechanical properties of cork have been studied from a long time. However, in many industrial applications cork is increasingly used as granulate (>200μm) or powder (<200μm) obtained by milling processes. By generating failure in the raw material, the comminution of cork could damage cells and induce modifications in the mechanical behavior of cork particles but the relation between the size of the particles and the mechanical properties of the packaging is still little known. In this study, we investigate the effect of cork particles size reduction on the mechanical properties of the packing. To this end, eighteen discrete size fractions of cork from 0 to 25μm to 2.5–3mm, generated by impact milling were characterized in term of shape, loaded density, and elastic recovery. Experiments show that impact milling mainly affects the elastic properties of particles less than 200μm. The mechanical behavior of cork particles was also described by model based on a mixing law taking in account the size and the shape of particles and the amount of damaged cells in the particles. The fitting of the model to the experimental data suggests that the elastic properties of the packing of cork particles have to be related to the content of damage cells more than to their size.

Mineral oil recovery from cork granules by a mechanical compression method: Compression cycles analysis

The aim of this study was to investigate the recovery of mineral oil from oil-loaded regranulated cork (RGC) particles by a mechanical compression method using a pneumatic press, as well as to evaluate their possible reuse in consecutive loading/compression cycles. The oil-impregnated RGC was inserted into a cylindrical compression barrel, and then compressed using a conical piston. The recovered oil percentage (%RO) was evaluated as function of the applied mechanical compression pressure (p = 0.2–0.7 MPa), compression time (tC = 1, 3 and 5 min), waiting time between each compression (tW = 1 min or tW = tC), height of the compression barrel filled with RGC particles (H ≤ 12.4 cm)/mass of RGC particles saturated with oil (mSO) and number of compressions (1 ≤ NC ≤ 3). Two configurations of the cylindrical barrel were used: a) only perforated at the bottom and b) perforated at the bottom and in the cylindrical surface. A higher oil recovery was achieved using the second configuration since oil flows in the axial and radial directions, decreasing the distance that oil has to travel to come out the barrel. The particles reusability was tested in ten cycles of saturation/compression using the optimized compression variables (p = 0.5 MPa, NC = 3, tC = 3 min, tW = 1 min and H ∼ 12.4 cm).

The influence of cork on the thermal insulation properties of home textiles

Novel strategies and technologies to obtain home textiles with thermal insulation properties are increasingly being researched as a strategic approach in the textile industry. The fabric conductivity and heat resistance are two important parameters to take into consideration in order to obtain a structure with improved performance. It is widely accepted that thermal insulation fabrics that resist heat flow possess still air in their structure. The higher is the thickness of the fabric, the bigger is the air entrapped in the structure and thus better is their thermal insulation properties. Nevertheless, these types of textiles face a critical challenge that is obtaining a structure with decreased thickness, without losing the thermal insulation properties required to provide comfort to users. The main objective of this work was to develop different low thickness fibrous structures with improved thermal insulation properties by incorporating cork particles within nonwoven structures. The nonwoven fabrics were produced with wool and hollow polyester fibers and the cork particles were incorporated within the structure in the process of nonwoven fabrication. Nonwoven structures have been prepared in different compositions including 75 % of wool and 25 % of hollow polyester blended with cork granules with sizes ranging from 1-2 and 2-5 mm using as a control an agglomerated cork of 0.8 mm. After production, samples were tested for their thermal behaviour using Alambeta equipment. Results have shown that nonwoven composition comprising cork particles greatly influences the thermal performance, and enables for obtaining a low weight material with improved thermal insulation properties.

Feasibility of alkali-activated mining waste foamed materials incorporating expanded granulated cork

Feasibility of alkali-activated mining waste foamed materials incorporating expanded granulated cork

English

This work presents an experimental study to determine the mechanical properties in bending, tension, compression and shear of a new sandwich material based on natural materials (jute and cork). The sandwich material is made basically of natural materials whose soul is agglomerated cork white (located in Jijel, East of Algeria) and the skins are woven jute with ortho phthalic polyester resin. Agglomerated white cork granules with medium density were used (cork boards with thicknesses of 10, 20 and 30 mm). The bending tests were performed on standard samples that were cut elaborate sandwich plates. The sandwich material prepared was tested for 3 and 4 flex points which indicate the stress, strain, bending stiffness, shear strength and failure mode. It was also found that a core thickness of 10 mm has better results compared to 20 and 30 mm. The results of this study allow us to develop a variety of agglomerated cork white product in for the development of low-density sandwich panels for use in the field of insulation and field of construction. Key words: Cork, jute, resin, sandwich, mechanical characteristics.

Floating faeces: Effects on solid removal and particle size distribution in RAS

The removal of solid wastes originating from faecal matter is one of the decisive challenges for future fish farming, in particular given the current emphasis on water reuse in aquaculture. This study compared solid waste removal performance in replicate recirculating systems in which the only difference was the removal concept being deployed. Rainbow trout (Oncorhynchus mykiss) of the test group were fed an innovative diet supplemented with 2.5% cork granules (0.5–1mm) resulting in buoyant faecal casts (density values below 1.00gcm−3). These were removed directly from the tank by a low cost slotted pipe at the water surface. The control group was fed a conventional diet, identical to the experimental feed except that it lacked the cork additive. The resulting solids in both systems were removed by sedimentation in a classic manure pit, which was drained to the drum filter twice a day. Wastewater from both treatments was mechanically cleaned by a drum filter and biologically treated by a moving bed bioreactor before being returned to the tanks.The cork treatment led to a substantially higher solid load being delivered to the drum filter via the wastewater outflow than in the control system. The average removal efficiency of cork-treated wastes was more than twice that achieved in the control system (59% vs. 25%). Total suspended solid (TSS) in the backwash stream of the drum filter was about five times greater in the cork diet treatment. There was no significant difference in the particle size distribution or TSS load of water passing the 100μm gauze of the drum filter in the two systems. Cork supplementation did not affect growth or mortality of rainbow trout. The present study shows that the application of floating faeces is an exciting prospect in recirculating aquaculture systems, offering significant improvements in solid removal efficiency.

On the Use of Vibro-Compressed Units with Bio-Natural Aggregate

The paper deals with the use of vibro-compressed units with bio-natural components on construction. The proposed mix design of vibrated blocks consist of cork granules and/or hemp shives, with the aim to substitute polymeric elements or expanded clay, together with the use of natural hydraulic lime (NHL) as binder. An experimental campaign is presented, with mechanical tests to evaluate the influence of each component on flexural and compression behavior. The proposal is also investigated from a productive point of view, considering how it can be harmonized in the productive process of lightweight aggregate concrete units without modifications in the productive process. The tested elements could perform a certain reduction of the carbon impact, maintaining interesting mechanical properties. The application of the proposed units in several contexts, as separating elements joined with structural components, is considered to improve rehabilitation or to obtain higher performances in buildings.

A carbon footprint simulation model for the cork oak sector

In the present study, a simulation model for the calculation of the carbon footprint of the cork oak sector (CCFM) is developed for the first time. A life cycle approach is adopted including the forest management, manufacturing, use and end-of-life stages. CCFM allows the user to insert the cork type used as raw material and its respective quantity and the distances in-between the various stages. The user can choose among different end-of-life destination options for the used cork products. The option of inserting different inputs, allows the use of the present simulation model for different cork oak systems, in different countries and with different conditions. CCFM allows the identification of the stages and products with the greatest carbon footprint and thus, a better management of the sector from an environmental perspective. The Portuguese cork oak sector is used as an application example of the model. The results obtained showed that the agglomeration industry is the hotspot for the carbon footprint of the cork sector mainly due to the production of the resins that are mixed with the cork granules for the production of agglomerated cork products. The consideration of the biogenic carbon emissions and sequestration of carbon at the forest in the carbon footprint, resulted to a great decrease of the sector's carbon footprint. Future actions for improvement are suggested in order to decrease the carbon footprint of the entire cork sector. It was found that by decreasing by 10% the emission factor of the agglomeration and transformation industries, substituting the transport trucks by more recent ones and by decreasing by 10% the cork products reaching the landfilling end-of-life destinations (while increasing the quantities reaching incineration and recycling), a decrease of the total CF (excluding the biogenic emissions and sequestration) of the entire cork industry by 10% can be achieved.

Parametric Analysis to Study the Influence of Aerogel-Based Renders' Components on Thermal and Mechanical Performance.

Statistical models using multiple linear regression are some of the most widely used methods to study the influence of independent variables in a given phenomenon. This study’s objective is to understand the influence of the various components of aerogel-based renders on their thermal and mechanical performance, namely cement (three types), fly ash, aerial lime, silica sand, expanded clay, type of aerogel, expanded cork granules, expanded perlite, air entrainers, resins (two types), and rheological agent. The statistical analysis was performed using SPSS (Statistical Package for Social Sciences), based on 85 mortar mixes produced in the laboratory and on their values of thermal conductivity and compressive strength obtained using tests in small-scale samples. The results showed that aerial lime assumes the main role in improving the thermal conductivity of the mortars. Aerogel type, fly ash, expanded perlite and air entrainers are also relevant components for a good thermal conductivity. Expanded clay can improve the mechanical behavior and aerogel has the opposite effect.

Properties of the Compressed-Stabilized Earth Brick Containing Cork Granules

This paper investigates the mechanical properties and thermal conductivity of the compressed-stabilized earth brick containing cork granules. First part of paper highlights the influence of mass percentage of cement and dune sand on maximum dry density, the optimal water content and mechanical strengths. The results show that composition (58% soil, 30% dune sand, 12% cement) assures maximum dry density of 1.75 T/m3 with a compressive strength in the dry state of 2.87 MPa at 28 days. Then a test of static compaction is performed on this composition for four levels of applied stresses. The results show that compaction of 10 MPa has increased maximum dry density a rate of 0.23%, which corresponds to rate of increase of the compression strength in the dry state of 46.69%. Second part examines the effect of the addition of the cork granules in mass relative to the dry soil and which is suffered a the static compaction with the different applied stresses levels on the mechanical properties, maximum dry density and thermal conductivity of optimized mixture. The results indicate that for a static compacting of 10 MPa and 12% of cork granules, the dry density decreases an rate of 1.50%, the compressive strength in the wet state decreases an rate of 7.41% at 28 days and the thermal conductivity in the dry state significantly decreases an rate of 55% relative to optimized mixture without the incorporation of the cork granulates which improves therefore thermal insulation.

Release of phenolic compounds from cork stoppers and its effect on protein-haze

Cork stoppers contain low molecular weight phenols, mainly as ellagic tannin, whose role in the protein stability of white wine has been not elucidated. The release of cork phenols from cork granules, disks and stoppers of different quality classes (A and D) in synthetic wine was investigated as well as its effect on animal gelatin, lysozyme and wine protein. Amounts of cork phenolic compounds up to 115 and 179 µg/cm2 were released within two weeks for best and worst quality cork disks, respectively, indicating the cork quality can strongly affect the phenolic compounds release. Similar trend was found for cork stoppers even if the concentration of phenolic compounds was lower (68 µg/cm2). Protein-haze was observed in presence of both animal gelatin and lysozyme (50 mg/l) when the phenol level exceeded 30 and 9 mg/l, respectively, whereas no effect on wine protein was observed. This research suggests that even if the overall amount of phenolic compounds released from cork stoppers is low, protein-haze can be achieved when the bottle is stored horizontally and motionless due to the high phenols concentration close to the cork stopper.