Exhaustive valorization of cashew nut shell waste as a potential bioresource material

Abstract In this paper, we report extraction of cashew nut shell liquid (CNSL) from cashew nut shell waste (CNSW) and further use of residues for generation of activated carbon for removal of heavy metals and methylene blue (MB). Solvent extraction yielded 24.6 ± 0.4%, 38.2 ± 0.4% and 40.1 ± 0.9% fo...

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Autores principales: James Nyirenda, Kadango Zombe, George Kalaba, Chipo Siabbamba, Inyambo Mukela
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Publicado: Nature Portfolio 2021
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spelling oai:doaj.org-article:81d07f3cbba04bbcbadca6eb98fd939a2021-12-02T17:47:03ZExhaustive valorization of cashew nut shell waste as a potential bioresource material10.1038/s41598-021-91571-y2045-2322https://doaj.org/article/81d07f3cbba04bbcbadca6eb98fd939a2021-06-01T00:00:00Zhttps://doi.org/10.1038/s41598-021-91571-yhttps://doaj.org/toc/2045-2322Abstract In this paper, we report extraction of cashew nut shell liquid (CNSL) from cashew nut shell waste (CNSW) and further use of residues for generation of activated carbon for removal of heavy metals and methylene blue (MB). Solvent extraction yielded 24.6 ± 0.4%, 38.2 ± 0.4% and 40.1 ± 0.9% for petroleum ether, hexane and ethanol respectively. Phytochemical screening showed presence of alkaloids, carbohydrates, saponins, phenols, tannins, flavonoids, amino acids, terpenoids, proteins, steroids, glycosides and carboxylic acids. The CNSL had a pH of 3.2, viscosity (104.6 ± 1.8 mPa s), moisture (6.5%), ash (1.6 ± 0.1%), refractive index (1.52 ± 0.001), specific density (0.9561 ± 0.0002 g/cm3), acid value (118.7 ± 9.2 mg KOH/g), free fatty acid value (60.1 ± 4.7%), saponification number (138.1 ± 3.2 mg KOH/g) and iodine value (188.1 ± 2.3 mgI 2/100 g). The average percentage removal of Cu (II), Pb (II), Cd (II) and Zn (II) was 99.4 ± 0.5, 95.4 ± 1.5, 99.5 ± 0.1, 98.4 ± 0.1%, and removal efficiency of MB at 50, 150, 250 and 350 mg/L was 99.63, 97.66, 96.48 and 94.81%, respectively. Equilibrium data were best described by the Freundlich isotherm model. The maximum monolayer adsorption capacity was 12.1 mg/g. The adsorption kinetics conformed to pseudo-second-order model. ∆G° was negative and a ∆H° of + 22.76 kJ/mol indicated that adsorption was endothermic. The ΔS° (+ 0.086 kJ/mol/K) showed that there was spontaneous interaction of the solution and adsorbate. These results show that CNSW is a potential bioresource for CNSL production for use in the paints, varnishes, surface coatings, agrochemicals and ethnomedicine industries. Residual shells can be exploited as fuels or converted to activated carbon for use as low-cost filters in water purification.James NyirendaKadango ZombeGeorge KalabaChipo SiabbambaInyambo MukelaNature PortfolioarticleMedicineRScienceQENScientific Reports, Vol 11, Iss 1, Pp 1-14 (2021)
institution DOAJ
collection DOAJ
language EN
topic Medicine
R
Science
Q
spellingShingle Medicine
R
Science
Q
James Nyirenda
Kadango Zombe
George Kalaba
Chipo Siabbamba
Inyambo Mukela
Exhaustive valorization of cashew nut shell waste as a potential bioresource material
description Abstract In this paper, we report extraction of cashew nut shell liquid (CNSL) from cashew nut shell waste (CNSW) and further use of residues for generation of activated carbon for removal of heavy metals and methylene blue (MB). Solvent extraction yielded 24.6 ± 0.4%, 38.2 ± 0.4% and 40.1 ± 0.9% for petroleum ether, hexane and ethanol respectively. Phytochemical screening showed presence of alkaloids, carbohydrates, saponins, phenols, tannins, flavonoids, amino acids, terpenoids, proteins, steroids, glycosides and carboxylic acids. The CNSL had a pH of 3.2, viscosity (104.6 ± 1.8 mPa s), moisture (6.5%), ash (1.6 ± 0.1%), refractive index (1.52 ± 0.001), specific density (0.9561 ± 0.0002 g/cm3), acid value (118.7 ± 9.2 mg KOH/g), free fatty acid value (60.1 ± 4.7%), saponification number (138.1 ± 3.2 mg KOH/g) and iodine value (188.1 ± 2.3 mgI 2/100 g). The average percentage removal of Cu (II), Pb (II), Cd (II) and Zn (II) was 99.4 ± 0.5, 95.4 ± 1.5, 99.5 ± 0.1, 98.4 ± 0.1%, and removal efficiency of MB at 50, 150, 250 and 350 mg/L was 99.63, 97.66, 96.48 and 94.81%, respectively. Equilibrium data were best described by the Freundlich isotherm model. The maximum monolayer adsorption capacity was 12.1 mg/g. The adsorption kinetics conformed to pseudo-second-order model. ∆G° was negative and a ∆H° of + 22.76 kJ/mol indicated that adsorption was endothermic. The ΔS° (+ 0.086 kJ/mol/K) showed that there was spontaneous interaction of the solution and adsorbate. These results show that CNSW is a potential bioresource for CNSL production for use in the paints, varnishes, surface coatings, agrochemicals and ethnomedicine industries. Residual shells can be exploited as fuels or converted to activated carbon for use as low-cost filters in water purification.
format article
author James Nyirenda
Kadango Zombe
George Kalaba
Chipo Siabbamba
Inyambo Mukela
author_facet James Nyirenda
Kadango Zombe
George Kalaba
Chipo Siabbamba
Inyambo Mukela
author_sort James Nyirenda
title Exhaustive valorization of cashew nut shell waste as a potential bioresource material
title_short Exhaustive valorization of cashew nut shell waste as a potential bioresource material
title_full Exhaustive valorization of cashew nut shell waste as a potential bioresource material
title_fullStr Exhaustive valorization of cashew nut shell waste as a potential bioresource material
title_full_unstemmed Exhaustive valorization of cashew nut shell waste as a potential bioresource material
title_sort exhaustive valorization of cashew nut shell waste as a potential bioresource material
publisher Nature Portfolio
publishDate 2021
url https://doaj.org/article/81d07f3cbba04bbcbadca6eb98fd939a
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AT georgekalaba exhaustivevalorizationofcashewnutshellwasteasapotentialbioresourcematerial
AT chiposiabbamba exhaustivevalorizationofcashewnutshellwasteasapotentialbioresourcematerial
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