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Wood and Wood Modification
Published in Dick Sandberg, Andreja Kutnar, Olov Karlsson, Dennis Jones, Wood Modification Technologies, 2021
Dick Sandberg, Andreja Kutnar, Olov Karlsson, Dennis Jones
The trunk has an outer covering, called bark, which protects the wood from extremes of temperature, drought, and mechanical injury. Bark constitutes, on average, about 10% of the volume of a tree, but this figure varies depending on tree species and age. The bark usually refers to tree tissues outside the cambium. It includes a number of different tissues, but bark can simply be divided into the inner bark (phloem and cork cambium) and the outer bark (cork layer). The relatively light-coloured inner bark is living tissue that conducts sugars downwards from the leaves. The dark-coloured and dry outer bark includes only dead tissue and is more or less impermeable to water and gases with an insulating function. The cell walls in the cork layer contain suberin, a waxy substance which protects the stem against water loss and the invasion of insects into the stem, and prevents infection by bacteria and fungal spores. The cork produced by the cork cambium is normally only one cell layer thick and it divides periclinally (parallel to the tissue surface) to the outside, producing cork. Like wood, bark is anisotropic with regard to dimensional stability and strength. Its thermal properties and heating value are similar to those of wood.
Green fabrication of biodegradable cork membrane for switchable separation of oil/water mixtures
Published in Journal of Dispersion Science and Technology, 2021
Yanbiao Zhou, Kaige Qu, Lihui Zhang, Xiaoqiang Luo, Binghua Liao
Dried cork was ground into a fine powder (40–60 mesh) and the powder was used for the analysis of suberin, lignin and polysaccharides. The suberin content of cork powder was determined by NaOCH3-CH3OH depolymerization. 1.5 g cork powder was refluxed for 3 hours with 250 mL 3% NaOCH3 in CH3OH, filtrated and the residue refluxed again with 100 mL CH3OH for 15 minutes. The mixture was filtered, acidified to pH 6 with 2 M H2SO4 and dried under vacuum. After the addition of 100 mL H2O to the residue, the suspension was extracted with 200 mL CHCl3 three times. The combined CHCl3 extracts were dried over Na2SO4, and the solvent was removed by vacuum distillation.[19]
Treatment of a textile effluent by adsorption with cork granules and titanium dioxide nanomaterial
Published in Journal of Environmental Science and Health, Part A, 2018
Margarida Castro, Verónica Nogueira, Isabel Lopes, Maria N. Vieira, Teresa Rocha-Santos, Ruth Pereira
For a better assessment of the capacity and adsorption properties of the cork granules, it would be required a characterization of its surface. This chemical characterization would be essential to understand the mechanisms of adsorption, which are dependent on the functional groups in the surface of the adsorbent.[5] As stated by the supplier of the cork, the granules were subjected to a thermal treatment with steam at 400°C, which according to Neto et al.[28] can decompose the lignin and suberin affecting the proprieties of cork. The changes caused by the heat treatment in the cork structure could have chemically stabilized the cork surface since aromatic molecules typically exhibit a larger chemical stability compared to non-aromatic similar molecules, decreasing the adsorption capacity. Also according to Pintor et al.,[5] the compounds that were degraded with the heat treatment, the suberin and the lignin, were those that can be responsible for increasing the diffusion capacity of hydrophobic compounds to the cork, and increase the affinity to remove the organic pollutants from water. So it is important to evaluate the adsorption capacity of cork without this heat treatment, however it is known that it is important to perform a treatment to the cork to reduce their ability to induce colour and toxicity by the release of some organic compounds, such as phenolic compounds, including tannins.[29]
Pharmaceutical and Personal Care Products (PPCPs) in the environment: Plant uptake, translocation, bioaccumulation, and human health risks
Published in Critical Reviews in Environmental Science and Technology, 2021
S. Keerthanan, Chamila Jayasinghe, Jayanta Kumar Biswas, Meththika Vithanage
Plants take up water along with dissolved solute such as minerals, organic compounds like PPCPs through the roots from the rhizosphere by passive diffusion. Generally, the passage of PPCPs through the plant starts at root hairs. Once PPCPs enter into root hairs, PPCPs reach the xylem/phloem through cortex, endodermis, and Casparian strip (Miller et al., 2016). The movement of PPCPs from root hair to xylem/phloem has been demonstrated by several pathways. (1) the movement of water and solute occurs through the space outside the cell membrane (apoplastic movement), (2) flux of water along with solute occurs through the cell cytoplasm (symplastic movement), and (3) the water and solute flow occurs via the vacuoles in cells (vacuolar movement) (Öztürk et al., 2016; Zhang & Zhu, 2009). Mainly, hydrophobic PPCPs move toward the xylem/phloem via the apoplastic movement, whereas the movement of hydrophilic PPCPs occurs via the symplastic movement (Zhang & Zhu, 2009). However, the apoplastic movement gets stopped at the Casparian strip because the deposition of lignin and suberin on the Casparian strip cell walls blocks the passive movement of water and solute. At this point, the flux of water and solute via apoplastic movement is forced into the symplastic movement (Cui & Schröder, 2016). Once the PPCPs reach the xylem/phloem, they get translocated upward to the aerial parts of the plant, such as stems, leaves, or fruits. Mainly, the water and PPCPs are pulled toward the leaves by the combined action of transpiration steam, capillary action, and root pressure. Apart from this, the hydrophobic PPCPs are translocated to the shoot via the xylem sap, which contains latex-like-proteins which bind with hydrophobic PPCPs (Goto et al., 2019). The solubility enhancement of triclocarban and endosulfan in zucchini and soybean xylem sap was observed when those solubilities are compared with deionized water (Garvin et al., 2015).