Cork Waste Research Articles

Cork waste valorization as reinforcement in high-density polyethylene matrix

In this paper, we investigated the use of cork wastes, generated by cork industry in Algeria, as reinforcement in a high density polyethylene matrix. Different formulations with loading rates of 10, 20 and 30 wt%) were elaborated by incorporating a compatibilizing agent (PE-g-AM) to solve the problem of incompatibility between hydrophobic matrix and hydrophilic fiber. Initially HDPE / cork flour composites blend in a calendar before preparing plates having an average thickness of 2 and 3 mm by compression at 190 °C. These were characterized by various techniques: mechanical tests (tensile test, Charpy impact test and Shore D hardness), rheological tests (Melt flow index) and physical characterization (Water absorption).

Construction of a Self-Supporting Catalyst Based on Bionic Honeycomb Communication Channel from Biomass Cork Waste for Hydrogen Evolution

Construction of a Self-Supporting Catalyst Based on Bionic Honeycomb Communication Channel from Biomass Cork Waste for Hydrogen Evolution

Influence of Waste Cork with Thinner on the Rheological Properties of Asphalt

Over the last two decades, the rapid and continued deterioration of the transportation network has been regarded as a major issue. There are many measures that can be taken to reduce this deterioration and improve road specifications, including improving road design, using higher quality materials, and using more efficient construction methods. This study is concerned with three principles: including investigating the impact of using waste paste on the rheological properties of bitumen; the environmental pollution that is a global problem; and the economic benefits as a result of the reusing of waste materials such as corks to produce new reusable materials like Modified-Asphalt. In this research, cork has been melted by thinner and mixed with asphalt to get a good paste with weight percentages of 1%, 3%, 5%, and 7%. After conducting the necessary tests on the samples, it was found that the addition of waste paste to virgin bitumen has softened the bitumen by decreasing the hardness and adhesiveness of the bitumen by increasing penetration with increasing cork paste content. The findings show that the current procedure can be used in cold regions because it requires less hard asphalt than that used in hot regions. It can also be used with natural asphalt, like natural rock asphalt, in various percent to give asphalt with suitable properties for use in roofing and paving roads.

Production of Lightweight Concrete by Using Polystyrene (cork) waste

There are two important subjects in the local and global areas, the first is the environmental pollution and the second is economic advantages of recycling and reusing of industrial materials. One of the most important industrial materials is cork waste. Because of many good properties of cork, like compressibility and a good ability to mould according to human needs, this material become as an important material in several life categories. This research work includes production of new type of light weight concrete and studies the mechanical and thermal properties. Several proportions of raw materials were used to produce this type of concrete. This study is intended to produce light weight concrete with low thermal conductivity so that it can be used for concrete masonry units. Polystyrene aggregate was added as percentages by weight of cement to improve the thermal properties of this type of concrete. Mechanical, and thermal tests with difference ages were made in this work. For polystyrene concrete with polystyrene cement ratio (p/c) of (2.67 – 6)%, the 28-day compressive strength range is from (4.31 – 2.67)MPa, flexural strength range is from (3.05-1.719) MPa, density range is from (1493-1213) kg/m3, and thermal conductivity range is from (0.91-0.782)% as a percentage by that of reference mix. The study show suitability of this type of concrete to be used in concrete masonry units of non-bearing walls.

Low-temperature pyrolysis products of waste cork and lignocellulosic biomass: product characterization

In recent years, there has been growing interest in the pyrolysis of biomass due to economic and environmental reasons. Low-temperature pyrolysis is one of the most straightforward and low-cost pyrolysis processes that may be used to produce added-value biochars as well as liquid and gas products from waste biomass. Lignocellulosic biomass obtained from the fractionation of Quercus cerris bark including cork-rich and phloem-rich granules were subjected to low-temperature pyrolysis (250–325 °C) and the resulting pyrolysis products were examined. The results showed that 59–90% biochar, 8–24% bio-oil, and 2–16% gas products could be obtained from the waste cork, while phloem results in 53–89% biochar, 8–21% bio-oil, and 3–30% gas. The produced chars are rich sources of calcium, magnesium, and potassium and these elements are concentrated in the char as the pyrolysis temperature increases. The pyrolysis condensates contain high amounts of lignin-derived phenolic compounds with 2-methoxy phenol being the most abundant compound.

Thermo-mechanical and physical properties of waste granular cork composite with slag cement

Construction industry consumes a lot of energy either through the materials used or by heating and cooling. Insulation materials using waste materials could help reduce the energy consumption. Waste cork is abundant in Mediterranean countries and is rarely used as a construction material. Cork presents excellent thermal and acoustic performance and could be used in heat insulation for roof elements. This paper aims to investigate the mechanical and thermal properties of cement composites with waste cork under different curing conditions. The effect of including granulated blast furnace slag on these composites was also studied. The results indicate that the strength of cork cement composite is adequate and meets the standards requirements for heat insulation elements.

Reducing the Environmental Impact of Cork Waste by Improving Natural Asphalt as Water Proofing Material

This research is concern with two principles, a) the environmental pollution which is the global problem b)the economic benefits as a result of reusing of waste material such as corks to produce new reusable materiallike Modified-Asphalt. In this research cork has melted by benzene and mixed with Hit Natural Asphalt toget good paste with weight percentages of 0%, 10%, 20%. The properties of Modified –Asphalt have beenstudied after and before adding coke. The results revealed that adding coke by 29% can make the Modified–Asphalt meets the international specifications (ASTM D312) and Iraqi specifications (88-1196) as a Waterproofing material.

Microporous carbon nanoflakes derived from biomass cork waste for CO2 capture

Porous structure design is considered to be a promising strategy for the development of effective sorbents for CO2 capture. Herein, a series of carbon nanoflakes with large surface area (up to 2380 m2/g) and high micropore volume (up to 0.896 m3/g) were synthesized from a renewable precursor, cork dust waste, to capture CO2 at atmospheric pressure. The nanoflakes exhibited superior CO2 uptake performance at 1 bar with the maximum capacity of 7.82 and 4.27 mmol/g at 0 and 25 °C, respectively, in sharp contrast to previously reported porous carbon materials. The existence of large numbers of narrow micropores with the pore width less than 0.86 nm and 0.70 nm play a critical role in the CO2 uptake at 0 and 25 °C, respectively. Moreover, the CNFs exhibited good recyclability and high selectivity for CO2 uptake from the mixture of CO2 and N2. By taking advantage of the unique hollow honeycomb cell, the three-layered cell wall structure, as well as the unique chemical composition of a cork precursor, such delicate microporous carbon nanoflakes were able to be achieved by simple thermal pretreatment combined with chemical activation. This bioinspired precursor-synthesis route poses a great potential for the facile production of porous carbons for a variety of diverse applications including CO2 capture.

Chemical characterization, bioactive and fuel properties of waste cork and phloem fractions from Quercus cerris L. bark

Waste biomass composed of cork-rich and phloem-rich granules obtained from the fractioning of Quercus cerris L. bark were characterized for bulk density, chemical composition, bio-active components, ash composition, and higher heating value.Bulk density of the fractions relate to their cork content and deceases with smaller particle size due to a cork enrichment in the finer particles. The bulk density may therefore be used as an indicator of suberin content of waste cork and phloem fractions. Waste cork fractions are rich sources of lipophilic and polar extracts while waste phloem fractions contain high amount of polar extracts. The polar extracts of both biomass fractions showed very high antioxidant capacities with IC50 values between 2.5 and 7.3 μg extract mL-1 for cork fractions and 5.8 and 11.7 μg extract mL-1 for phloem fractions.Higher heating values in waste cork fractions increase with decreasing particle size and ranged between 20 and 22 MJ kg-1. A biorefinery scheme was developed for the valorization of the waste cork and phloem fractions based on their physical, chemical, bioactive, and higher heating values.

Low-temperature biochars from cork-rich and phloem-rich wastes: fuel, leaching, and methylene blue adsorption properties

Waste cork and phloem fractions from the bark of Turkey oak (Quercus cerris) were subject to low-temperature pyrolysis between 250 and 325 °C and residence times of 30 or 60 min. The fuel, leaching, and methylene blue adsorption properties of the produced biochars were evaluated for the first time. The results indicate that cork and phloem containing bark fractions have a promising potential for the production of biochars. The pyrolysis process reduces the bark wastes and contributes to their efficient use. The cork and phloem biochars produced above 300 °C showed promising H/C and O/C atomic ratios that were comparable with lignite. Methylene blue adsorption on cork and phloem biochars was inversely affected by pyrolysis temperature and residence time. Activated carbons for soil amendment applications may be produced from the biochars via a steam activation method with optimum temperature and residence time of approximately 300 °C and 30 min in order to harness the nutrient release while avoiding the potential of toxicity from phenolic leaching.

Converting industrial waste cork to biochar as Cu (II) adsorbent via slow pyrolysis

Cork is light, porous, carbon-rich, and renewable, which leads to competitive advantages in the preparation of biochar, as compared to other biomass material. In this work, we propose to convert cork powder into cork-based biochar as Cu (II) adsorbent via slow pyrolysis, thereby providing a reliable and simple method for recycling cork industrial waste. The physicochemical properties of cork-based biochar prepared under different pyrolysis temperatures (450, 550, 650, and 750 °C) and pyrolysis time (0.5, 1.0, 1.5, and 2.0 h) were characterized by elemental analysis, FT-IR, XRD, N2 adsorption and SEM. The adsorption capacity of cork-based biochar on heavy metal ions was further evaluated by Cu ion adsorption testing. Results showed that the cork-based biochar produced under conditions of higher pyrolysis temperature and time, has higher aromaticity and lower polarity, larger specific surface area, and enhanced Cu ion adsorption capacity. The maximum specific surface area of cork-based biochar prepared at 750 °C for 0.5 h was 392.5 m2/g, which surpasses most other biochars reported in previous studies, which are beneficial to the application of wastewater management. The SEM image demonstrated that the biochar retains the special hollow polyhedral cell structure of raw material cork. Furthermore, a large number of pores formed on the cell wall after high temperature pyrolysis, and the cells are connected with each other through these open pores. Finally, cork-based biochar exhibits superior Cu ion adsorption capacity (18.5 mg/g) with a shorter equilibrium time (4 h), which gives it a competitive advantage to similar adsorbents.

Conversion of waste cooking oil into biodiesel using heterogenous catalyst derived from cork biochar

In this study, a heterogeneous catalyst prepared by pyrolysis of waste cork (Quercus suber) was used for the transesterification of waste cooking oil (WCO). Physicochemical properties of the synthesized biochar catalyst were studied using BET, SEM, FTIR, and XRD. The experiment results demonstrate that heterogeneous catalyst synthesized at 600 °C showed maximum fatty acids methyl esters (FAMEs) conversion (98%) at alcohol:oil (25:1), catalyst loading (1.5% w/v) and temperature 65 °C. Biodiesel produced from WCO (Canola oil) mainly composed of FAMEs in following order C18:1 > C18:2 > C16:0 > C18:0 > C20:0. Properties of produced biodiesel were analysed as cetane number (CN) 50.56, higher heating value (HHV) 39.5, kinematic viscosity (ʋ) 3.9, and density (ρ) 0.87.

Biomimetic calcium carbonate with hierarchical porosity produced using cork as a sustainable template agent

Calcium carbonate has many applications in different fields; its use in environment remediation is particularly considered, due to its non-toxicity and potentially high efficiency. The structure, morphology and surface features of calcium carbonate can greatly affect its performance. Hierarchical porosity, in particular, can be beneficial for several functional properties. In this study, we report the synthesis of biomorphic calcium carbonate using a sustainable template agent – waste cork powder. Pyrolysed cork powder was infiltrated by an appropriate calcium-containing salt and successively thermally treated. Selected precursors, different impregnation-solution concentrations and thermal conditions were tested. The resulting materials were characterised by XRD, Raman spectroscopy and SEM. Surface area and porosity features were studied by BET analysis, with a detailed study on the effect of synthesis on the mesoporosity of the materials, average sizes varying between 4−15 nm. The most valuable results were achieved with calcium acetate followed by pyrolysis performed for relatively short time period. This maintained the porous 3D honeycomb cork structure made of ∼20 μm hexagonal cells, while consisting of highly mesoporous single-phase CaCO3. Such samples showed the highest surface area ever reported for CaCO3 prepared using a plant-based template; moreover, it also exhibited a dual-scale hierarchical porosity as, in addition to micrometer scale cellular macroporosity, it contained a significant mesoporosity in the cell walls, with a very narrow range of 3.6–3.9 nm.These promising characteristics enable the potential employment of cork-derived CaCO3 for environment remediation.

Environmental and socio-economic assessment of cork waste gasification: Life cycle and cost analysis

Catalonia is one of the most important world producers of cork, a natural material from which wine stoppers, champagne stoppers and derived products are produced. Within this process, approximately 15% of the extracted raw cork ends up as forestry waste, while considerable shares of the processed cork are also considered cork residues, as for instance defective stoppers or agglomerate plates. Indeed, cork residues are usually sent to landfill with no recovery or second use.In this study, gasification is used as a thermal strategy to convert cork wastes into energy, in order to demonstrate the valorisation of cork waste. This contributes to the implementation of the Waste Framework Directive (2008/98/CE) following the objectives and goals of the Roadmap for a Resource-Efficient Europe. Technological, R&D and industrial partners were gathered under the framework of the LIFE + Ecorkwaste Project and thus, a gasification plant with capacity to treat 15 kg of cork residues per day was designed. The ultimate goal was to develop and optimize the experimental procedure so that the gasification plant could be implemented at an industrial scale. In order to assess the environmental, techno-economic and social impacts of this technology, life cycle assessment (LCA) and life cycle cost (LCC) were performed, as well as a socio-economic matrix integrating various aspects of the technique was developed. The functional unit was the production of 1 MWh by means of cork valorisation through gasification technology and a comparison with the conventional scenario of using the national electricity grid was performed. Three scenarios of possible management strategies for the produced wastes were modelled for the LCA using Simapro Developer and two scenarios of different operation regimes were considered for the LCC under the CAPEX-OPEX concept. As main findings it was shown that the gasification strategy has a sustainable profile with lower environmental impacts than the conventional scheme of energy production. Moreover, this thermal scheme entails lower costs than the conventional scheme and allows net savings in the order of several hundred thousand €, for a 20-year lifespan of the plant.

Waste-based biosorbents as cost-effective alternatives to commercial adsorbents for the retention of fluoxetine from water

The goal of this study is to demonstrate that waste-based biosorbents can be cost-effective and green alternatives to commercial adsorbents for the retention of pharmaceuticals. Adsorption kinetics and equilibrium measurements allowed the determination of the adsorption capacity of commercial adsorbents (GAC - granular activated carbon and two synthetic zeolites) and waste-based biosorbents (SCG - spent coffee grounds, pine bark and cork waste) for the retention of fluoxetine from water. For commercial adsorbents, the maximum adsorption capacities followed the order GAC (233.5 mg/g) > zeolite 13× (32.11 mg/g) > zeolite 4A (21.86 mg/g), while for low-cost biosorbents, the sequence was SCG (14.31 mg/g) > pine bark (6.53 mg/g) > cork waste (4.74 mg/g). The economic feasibility of the adsorbents/biosorbents was examined through a detailed cost analysis. Commercial adsorbents present higher costs per gram of fluoxetine removed (6.85 €/g, 3.13 €/g and 1.07 €/g zeolite 4 A, zeolite 13× and GAC, respectively) when compared to low-cost biosorbents (0.92 €/g, 0.41 €/g and 0.16 €/g for pine bark, cork waste and SCG, respectively). It was found that SCG is the most economically viable option for fluoxetine removal, while cork waste, the second less expensive, is the most environmentally friendly biosorbent since its preparation does not generate any solid or liquid wastes. This manuscript demonstrates that the conversion of waste materials into adsorbents has a double environmental benefit for both improving waste management and protecting the environment.

Granulated cork with bark characterised as environment-friendly lightweight aggregate for cement based materials

The cork industry generates large quantities of waste, which has been studied for the application in the construction industry. However, the literature refers to it as cork waste (granulated or dust) in general, and its features have not been clearly specified. However, cork waste includes several by-products with different characteristics depending on the stage of process which they are generated in. The main goal of this study is to investigate the specific characteristics of one of those by-products that is granulated cork with bark, in order put to use as a lightweight aggregate in the construction industry. In this paper, its surface chemical properties are studied, by the first time, employing Fourier Transformed Infrared Spectroscopy and Energy Dispersive X-ray Spectroscopy and they are compared to those of cork. The chemical functional groups that are present at the granule surface, carbonyl and hydroxyl groups, are able to interact with cement components and water by important intermolecular chemical forces such as hydrogen bonds or dipole-dipole. The microstructure of grains is evaluated through image analysis, Scanning Electron Microscopy. The found cellular structure gives rise to density and absorption values similar to those of commercial lightweight aggregates and provides thermal insulating properties to this material. Then this material presents suitable properties to find a use as lightweight aggregate for concrete or mortar. The optimal replacement of aggregate by granulated cork with bark would contribute to a sustainable manufacture of cork providing an outlet for this waste.

Recycled Plastic and Cork Waste for Structural Lightweight Concrete Production

The use of waste materials as lightweight aggregates in concrete is highly recommended in seismic risk areas and environmentally recommended. However, reaching the strength needed for the concrete to be used structurally may be challenging. In this study four dosages were assayed: the first two-specimen had high cement content (550 and 700 kg/m3 respectively), Nanosilica, fly ash and superplasticizer. These samples were high performance, reaching a strength of 100 MPa at 90 days. The other two mixtures were identical but replaced 48% of the aggregates with recycled lightweight aggregates (30% polypropylene, 18.5% cork). To estimate its strength and durability the mixtures were subjected to several tests. Compression strength, elasticity modulus, mercury intrusion porosimetry, carbonation, attack by chlorides, and penetration of water under pressure were analyzed. The compression strength and density of the lightweight mixtures were reduced 68% and 19% respectively; nonetheless, both retained valid levels for structural use (over 30 MPa at 90 days). Results, such as the total porosity between 9.83% and 17.75% or the chloride ion penetration between 8.6 and 5.9 mm, suggest that the durability of these concretes, including the lightweight ones, is bound to be very high thanks to a very low porosity and high resistance to chemical attacks.

A sustainable multi-function biomorphic material for pollution remediation or UV absorption: Aerosol assisted preparation of highly porous ZnO-based materials from cork templates

For the first time, highly porous ZnO-based biomorphic materials were synthesised using cork as a natural sustainable template. In the first step, waste cork powder was pyrolysed and converted into inorganic carbon. This template was then infiltrated using a novel approach employing an aerosol of zinc-containing solutions. The infiltrated powders were calcined to convert the precursors into zinc oxide. Depending on temperature, these could form either a ZnO-graphite composite material, or pure ZnO. Their morphology, porosity, microstructure and composition were characterised; their optical band gap energies, ability to adsorb and photodegrade organic pollutants and UV absorption were also assessed. When heated to 350 °C they maintained the 3D porous cork structure, producing a graphite-containing composite material, with both physical adsorption and photocatalytic activity (Eg = 3.19 eV), suitable for environmental remediation. When heated to 700 °C, the powders were pure ZnO (no graphite), and they absorbed in the UV region, hence suitable for use as sunscreen. Doped ZnO ecoceramics were also produced, using silver and aluminium. An addition of 1 mol% Ag improved photocatalysis under solar light. Conversely, adding 2 mol% Al and calcining at 700 °C deactivated photocatalysis, but maintained strong UV absorption, producing a safer sunscreen material (no generation of free radicals). This is the first time that photocatalytic or UV absorption properties of any wood-derived biomorphic material or ecoceramic have been reported.

The use of forest-based materials for the efficient energy of cities: Environmental and economic implications of cork as insulation material

Cork is a very interesting forest-based material for many industrial sectors as a natural and renewable material with a high geographical concentration in the Iberian Peninsula. Currently stoppers for beverages are its most valuable application, but the properties of the cork are an excellent opportunity to eco-innovate. Natural materials are being studied as potential sustainable solutions for building sector to reduce environmental impact and energy use of cities. This study introduces and evaluates the environmental and economic implications of using cork insulation boards as a solution for retrofit buildings in Barcelona metropolitan area.Results demonstrate a high potential of retrofit buildings with cork insulation boards from an environmental and economic perspective, therefore the present capacity of cork oak forest sector in Catalonia is not ready to absorb the potential demand that could be generated, as less than 50% of forests are not managed and harvested. This is also an opportunity for this sector to diversify its market and develop other products that can fit into many other sectors. The use of cork wastes and by-products to produce granulates would be a relevant circular economy strategy in order to substitute other non-renewable materials.

A novel study on the influence of cork waste residue on metakaolin-zeolite based geopolymers

The effect of industrial waste from the cork industry on the strength and adsorption properties of zeolite-metakaolin based geopolymers has been studied. Cork residue 20% by weight was added to geopolymers that contained 0%, 25%, 50%, 75% replacement of metakaolin by zeolite in the structure. The SiO2/Al2O3 and Na2O/Al2O3 molar ratios were kept at 1 to reduce the environmental impact of sodium silicate and sodium hydroxide to the minimum. The compressive strength evolution after 1, 14 and 28days in water and the heavy metals (Cd2+, Cr3+, Cu2+, Pb2+, and Zn2+) adsorption of the geopolymers were determined. It was found that addition of zeolite and cork residue in minor amounts concurrently aided in increasing the compressive strength of geopolymers. The adsorption properties, however, were dominated by the presence of cork residue and metakaolin which resulted in increasing adsorption of all heavy metal cations with increasing metakaolin in the structure. The adsorption was well fitted by the Langmuir model with R2>0.98 and the trend of adsorption was found to be Pb2+>Cd2+>Cu2+, Zn2+>Cr3+. The significant improvement in compressive strength, as well as adsorption capacity observed with the addition of cork waste residue, connotes that it can be efficient as filler in geopolymers.