Document Type : Review Article


1 Tabriz University of Medical Sciences, Tabriz, Iran

2 Islamic Azad University, Tabriz Branch

3 Division of Food Sciences, Institute of Animal Reproduction and Food Research of the Polish Academy of Sciences, Olsztyn, Poland


The shell of walnut fruit is an agricultural byproduct generated in considerable amounts upon the processing of fruit to obtain its valuable kernel. Walnut is recognized as an appreciated tree nut belonging to the Juglandaceae family. The fruit is mainly composed of a kernel, seed coat, shell, and husk. In recent years, the shell portion of walnut fruit has been widely used in the development of different high–value materials. In this regard, high carbon and low ash contents of the walnut shell (WS) make it a suitable material and inexpensive waste agricultural product for the activated carbon (AC) preparation. In this review, recent developments in the preparation of AC from the shell of walnut fruit and the characterization methods are highlighted. Additionally, the applications of AC mainly in the removal of different hazardous materials such as heavy metals (HMs) ions, dyes as well as pharmaceuticals and other dangerous materials are comprehensively discussed.


[1]      Harrison, R. M., Pollution: Causes, effects and control, Royal Society of Chemistry, Cambridge, (2001).
[2]      Marsh, H. and Rodriguez-Reinoso, F., Activated carbon, Elsevier, Wallingford, United Kingdom, (2006).
[3]      Schröder, E., Thomauske, K., Weber, C., Hornung, A. and Tumiatti, V., “Experiments on the generation of activated carbon from biomass”, Journal of Analytical and Applied Pyrolysis, 79 (1), 106 (2007).
[4]      Jahanban-Esfahlan, A., Jamei, R. and Jahanban-Esfahlan, R., “The importance of almond (Prunus amygdalus L.) and its by-products”, Food Chem., 120 (2), 349 (2010).
[5]      Martinez, M. L., Torres, M. M., Guzman, C. A. and Maestri, D. M., “Preparation and characteristics of activated carbon from olive stones and walnut shells”, Industrial Crops and Products, 23 (1), 23 (2006).
[6]      Yagub, M. T., Sen, T. K., Afroze, S. and Ang, H. M., “Dye and its removal from aqueous solution by adsorption: A review”, Advances in Colloid and Interface Science, 209, 172 (2014).
[7]      Jahanban-Esfahlan, A., Jahanban-Esfahlan, R., Tabibiazar, M., Roufegarinejad, L. and Amarowicz, R., “Recent advances in the use of walnut (Juglans regia L.) shell as a valuable plant-based bio-sorbent for the removal of hazardous materials”, RSC Advances, 10, 7026 (2020).
[8]      Azat, S., Busquets, R., Pavlenko, V., Kerimkulova, A., Whitby, R. L. and Mansurov, Z., “Applications of activated carbon sorbents based on greek walnut”, Applied Mechanics and Materials, 467, 49 (2014).
[9]      Sun, K. and Chun Jiang, J., “Preparation and characterization of activated carbon from rubber-seed shell by physical activation with steam”, Biomass and Bioenergy, 34 (4), 539 (2010).
[10]  Okada, K., Yamamoto, N., Kameshima, Y. and Yasumori, A., “Adsorption properties of activated carbon from waste newspaper prepared by chemical and physical activation”, Journal of Colloid and Interface Science, 262 (1), 194 (2003).
[11]  Juan, Y. and Ke-Qiang, Q., “Preparation of activated carbon by chemical activation under vacuum”, Environmental Science and Technology, 43 (9), 3385 (2009).
[12]  Li, X., Wang, G. -Z., Li, W. -G., Wang, P. and Su, C. -Y., “Adsorption of acid and basic dyes by sludge-based activated carbon: Isotherm and kinetic studies”, Journal of Central South University, 22 (1), 103 (2015).
[13]  Lozano-Castello, D., Lillo-Rodenas, M., Cazorla-Amorós, D. and Linares-Solano, A., “Preparation of activated carbons from Spanish anthracite: I. Activation by KOH”, Carbon, 39 (5), 741 (2001).
[14]  Ichcho, S., Khouya, E., Fakhi, S., Ezzine, M., Hannache, H., Pallier, R. and Naslain, R., “Influence of the experimental conditions on porosity and structure of adsorbents elaborated from Moroccan oil shale of Timahdit by chemical activation”, Journal of Hazardous Materials, 118 (1), 45 (2005).
[15]  Tsai, W. -T., Chang, C. and Lee, S., “A low cost adsorbent from agricultural waste corn cob by zinc chloride activation”, Bioresource Technology, 64 (3), 211 (1998).
[16]  Martinez, M. L., Labuckas, D. O., Lamarque, A. L. and Maestri, D. M., “Walnut (Juglans regia L.): Genetic resources, chemistry, by-products”, Journal of the Science of Food and Agriculture, 90, 1959 (2010).
[17]  McGranahan, G. and Leslie, C., “Walnuts (Juglans)”, Acta Horticulturae, Genetic Resources of Temperate Fruit and Nut Crops, 290, 907 (1991).
[18]  Wani, M. S., Hussain, A., Ganie, S. A., Munshi, A. H., Lal, E. P. and Gupta, R. C., “Juglans regia-A review”, International Journal of Latest Research in Science and Technology, 5 (1), 90 (2016).
[19]  Arcan, I. and Yemenicioğlu, A., “Antioxidant activity and phenolic content of fresh and dry nuts with or without the seed coat”, Journal of Food Composition and Analysis, 22 (3), 184 (2009).
[20]  Fukuda, T., Ito, H. and Yoshida, T., “Antioxidative polyphenols from walnuts (Juglans regia L.)”, Phytochemistry, 63 (7), 795 (2003).
[21]  Zhang, Z., Liao, L., Moore, J., Wu, T. and Wang, Z., “Antioxidant phenolic compounds from walnut kernels (Juglans regia L.)”, Food Chemistry, 113 (1), 160 (2009).
[22]  Labuckas, D. O., Maestri, D. M., Perelló, M., Martínez, M. L. and Lamarque, A. L., “Phenolics from walnut (Juglans regia L.) kernels: Antioxidant activity and interactions with proteins”, Food Chemistry, 107 (2), 607 (2008).
[23]  Pereira, J. A., Oliveira, I., Sousa, A., Ferreira, I. C. F. R., Bento, A. and Estevinho, L., “Bioactive properties and chemical composition of six walnut (Juglans regia L.) cultivars”, Food and Chemical Toxicology, 46 (6), 2103 (2008).
[24]  Jahanban-Esfahlan, A., Ostadrahimi, A., Tabibiazar, M. and Amarowicz, R., “A comparative review on the extraction, antioxidant content and antioxidant potential of different parts of walnut (Juglans regia L.) fruit and tree”, Molecules, 24 (11), 2133 (2019).
[25]  Roufegarinejad, L., Amarowicz, R. and Jahanban-Esfahlan, A., “Characterizing the interaction between pyrogallol and human serum albumin by spectroscopic and molecular docking methods”, Journal of Biomolecular Structure and Dynamics, 37 (11), 2766 (2019).
[26]  Kornsteiner, M., Wagner, K. -H. and Elmadfa, I., “Tocopherols and total phenolics in 10 different nut types”, Food Chemistry, 98 (2), 381 (2006).
[27]  Mishra, N., Dubey, A., Mishra, R. and Barik, N., “Study on antioxidant activity of common dry fruits”, Food and Chemical Toxicology, 48 (12), 3316 (2010).
[28]  Yang, J., Liu, R. H. and Halim, L., “Antioxidant and antiproliferative activities of common edible nut seeds”, LWT-Food Science and Technology, 42 (1), 1 (2009).
[29]  Almario, R. U., Vonghavaravat, V., Wong, R. and Kasim-Karakas, S. E., “Effects of walnut consumption on plasma fatty acids and lipoproteins in combined hyperlipidemia”, The American Journal of Clinical Nutrition, 74 (1), 72 (2001).
[30]  Salcedo, C. L., López de Mishima, B. A. and Nazareno, M. A., “Walnuts and almonds as model systems of foods constituted by oxidisable, pro-oxidant and antioxidant factors”, Food Research International, 43 (4), 1187 (2010).
[31]  Prior, R. L. and Cao, G., “Antioxidant phytochemicals in fruits and vegetables: Diet and health implications”, HortScience, 35 (4), 588 (2000).
[32]  Lavedrine, F., Zmirou, D., Ravel, A., Balducci, F. and Alary, J., “Blood cholesterol and walnut consumption: A cross-sectional survey in France”, Preventive Medicine, 28 (4), 333 (1999).
[33]  Chauhan, A., Essa, M. M., Muthaiyah, B., Chauhan, V., Kaur, K. and Lee, M., “Walnuts-rich diet improves memory deficits and learning skills in transgenic mouse model of Alzheimer's disease”, Alzheimer's and Dementia, 6 (4), S69 (2010).
[34]  Feldman, E. B., “The scientific evidence for a beneficial health relationship between walnuts and coronary heart disease”, The Journal of Nutrition, 132 (5), 1062S (2002).
[35]  Fraser, G. E., Sabate, J., Beeson, W. L. and Strahan, T. M., “A possible protective effect of nut consumption on risk of coronary heart disease: The Adventist Health Study”, Archives of Internal Medicine, 152 (7), 1416 (1992).
[36]  Hu, F. B. and Stampfer, M. J., “Nut consumption and risk of coronary heart disease: A review of epidemiologic evidence”, Current Atherosclerosis Reports, 1 (3), 204 (1999).
[37]  Ros, E., “Nuts and novel biomarkers of cardiovascular disease”, The American Journal of Clinical Nutrition, 89 (5), 1649S (2009).
[38]  Kris‐Etherton, P. M., Zhao, G., Binkoski, A. E., Coval, S. M. and Etherton, T. D., “The effects of nuts on coronary heart disease risk”, Nutrition Reviews, 59 (4), 103 (2001).
[39]  Carvalho, M., Ferreira, P. J., Mendes, V. S., Silva, R., Pereira, J. A., Jerónimo, C. and Silva, B. M., “Human cancer cell antiproliferative and antioxidant activities of Juglans regia L”, Food and Chemical Toxicology, 48 (1), 441 (2010).
[40]  Kris-Etherton, P. M., Hu, F. B., Ros, E. and Sabaté, J., “The role of tree nuts and peanuts in the prevention of coronary heart disease: Multiple potential mechanisms”, The Journal of Nutrition, 138 (9), 1746S (2008).
[41]  Nagel, J. M., Brinkoetter, M., Magkos, F., Liu, X., Chamberland, J. P., Shah, S., Zhou, J., Blackburn, G. and Mantzoros, C. S., “Dietary walnuts inhibit colorectal cancer growth in mice by suppressing angiogenesis”, Nutrition, 28 (1), 67 (2012).
[42]  Nergiz-Ünal, R., Kuijpers, M. J. E., de Witt, S. M., Heeneman, S., Feijge, M. A. H., Garcia Caraballo, S. C., Biessen, E. A. L., Haenen, G. R. M. M., Cosemans, J. M. E. M. and Heemskerk, J. W. M., “Atheroprotective effect of dietary walnut intake in ApoE-deficient mice: Involvement of lipids and coagulation factors”, Thrombosis Research, 131 (5), 411 (2013).
[43]  Shabani, M., Nazeri, M., Parsania, S., Razavinasab, M., Zangiabadi, N., Esmaeilpour, K. and Abareghi, F., “Walnut consumption protects rats against cisplatin-induced neurotoxicity”, Neurotoxicology, 33 (5), 1314 (2012).
[44]  Jahanban-Esfahlan, A., Davaran, S., Moosavi-Movahedi, A. and Dastmalchi, S., “Investigating the interaction of juglone (5-hydroxy-1, 4-naphthoquinone) with serum albumins using spectroscopic and in silico methods”, Journal of the Iranian Chemical Society, 7 (14), 1527 (2017).
[45]  Ji, Y. -B., Qu, Z. -Y. and Zou, X., “Juglone-induced apoptosis in human gastric cancer SGC-7901 cells via the mitochondrial pathway”, Experimental and Toxicologic Pathology, 63 (1), 69 (2011).
[46]  Kiran Aithal, B., Sunil Kumar, M., Nageshwar Rao, B., Udupa, N. and Satish Rao, B., “Juglone, a naphthoquinone from walnut, exerts cytotoxic and genotoxic effects against cultured melanoma tumor cells”, Cell Biology International, 33 (10), 1039 (2009).
[47]  Xu, H. L., Yu, X. F., Qu, S. C., Qu, X. R., Jiang, Y. F. and Sui, D. Y., “Juglone, from Juglans mandshruica Maxim, inhibits growth and induces apoptosis in human leukemia cell HL-60 through a reactive oxygen species-dependent mechanism”, Food and Chemical Toxicology, 50 (3), 590 (2012).
[48]  Akbari, V., Jamei, R., Heidari, R. and Jahanban-Esfahlan, A., “Antiradical activity of different parts of walnut (Juglans regia L.) fruit as a function of genotype”, Food Chemistry, 135 (4), 2404 (2012).
[49]  Stampar, F., Solar, A., Hudina, M., Veberic, R. and Colaric, M., “Traditional walnut liqueur-cocktail of phenolics”, Food Chemistry, 95 (4), 627 (2006).
[50]  Oliveira, I., Sousa, A., Ferreira, I. C. F. R., Bento, A., Estevinho, L. and Pereira, J. A., “Total phenols, antioxidant potential and antimicrobial activity of walnut (Juglans regia L.) green husks”, Food and Chemical Toxicology, 46 (7), 2326 (2008).
[51]  Ghasemi, K., Ghasemi, Y., Ehteshamnia, A., Nabavi, S. M., Nabavi, S. F., Ebrahimzadeh, M. A. and Pourmorad, F., “Influence of environmental factors on antioxidant activity, phenol and flavonoids contents of walnut (Juglans regia L.) green husks”, Journal of Medicinal Plants Research, 5 (7), 1128 (2011).
[52]  Fernández-Agulló, A., Pereira, E., Freire, M. S., Valentão, P., Andrade, P. B., González-Álvarez, J., Pereira, J. A., “Influence of solvent on the antioxidant and antimicrobial properties of walnut (Juglans regia L.) green husk extracts”, Industrial Crops and Products, 42, 126 (2013).
[53]  Jahanban-Esfahlan, A., Ostadrahimi, A., Tabibiazar, M. and Amarowicz, R., “A comprehensive review on the chemical constituents and functional uses of walnut (Juglans spp.) husk”, International Journal of Molecular Sciences, 20 (16), 3920 (2019).
[54]  Wei, Q., Ma, X., Zhao, Z., Zhang, S. and Liu, S., “Antioxidant activities and chemical profiles of pyroligneous acids from walnut shell”, Journal of Analytical and Applied Pyrolysis, 88 (2), 149 (2010).
[55]  Wei, Q., Ma, X. H., Zhao, Z. and Zheng, T., “Preparation, chemical constituents analysis and antimicrobial activities of pyroligneous acids of walnut shell”, Transactions of the Chinese Society of Agricultural Engineering, 24, 276 (2008).
[56]  Zhai, M., Shi, G., Wang, Y., Mao, G., Wang, D. and Wang, Z., “Chemical compositions and biological activites of pyroligneous acids from walnut shell”, Bioresources, 10 (1), 1715 (2015).
[57]  Mathias, E. V. and Halkar, U. P., “Separation and characterization of lignin compounds from the walnut (Juglans regia) shell oil using preparative TLC, GC–MS and 1H NMR”, Journal of Analytical and Applied Pyrolysis, 71 (2), 515 (2004).
[58]  Qin, W., Xihan, M. and Tao, Z., “Preparation, chemical constituents analysis and antimicrobial activities of pyroligneous acid of walnut shell”, Transactions of the Chinese Society of Agricultural Engineering, 2008 (7), (2008).
[59]  Ma, X., Wei, Q., Zhang, S., Shi, L. and Zhao, Z., “Isolation and bioactivities of organic acids and phenols from walnut shell pyroligneous acid”, Journal of Analytical and Applied Pyrolysis, 91 (2), 338 (2011).
[60]  Zheng, Z. -F., Zou, J. -C., Hua, B., Zhang, H. J. and Wang, R., “Study on the constituents of walnut shell”, Journal of Southwest Forestry College, 26 (2), 33 (2006).
[61]  Wang, Y., Zhai, M., Yan, T. and Hao, F., “Chemical compositions and biological activity of pyroligneous acids of walnut shell”, Acta Bot. Boreal.-Occident. Sin., 31 (11), 2321 (2011).
[62]  Jahanban-Esfahlan, A. and Amarowicz, R., “Walnut (Juglans regia L.) shell pyroligneous acid: Chemical constituents and functional applications”, RSC Advances, 8, 22376 (2018).
[63]  Pitschmann, A., Zehl, M., Atanasov, A. G., Dirsch, V. M., Heiss, E. and Glasl, S., “Walnut leaf extract inhibits PTP1B and enhances glucose-uptake in vitro”, Journal of Ethnopharmacology, 152 (3), 599 (2014).
[64]  Verma, R. S., Padalia, R. C., Chauhan, A. and Thul, S. T., “Phytochemical analysis of the leaf volatile oil of walnut tree (Juglans regia L.) from western Himalaya”, Industrial Crops and Products, 42, 195 (2013).
[65]  Almeida, I. F., Fernandes, E., Lima, J. L., Costa, P. C. and Fernanda Bahia, M., “Walnut (Juglans regia L.) leaf extracts are strong scavengers of pro-oxidant reactive species”, Food Chemistry, 106 (3), 1014 (2008).
[66]  Amaral, J. S., Seabra, R. M., Andrade, P. B., Valentao, P., Pereira, J. A. and Ferreres, F., “Phenolic profile in the quality control of walnut (Juglans regia L.) leaves”, Food Chemistry, 88 (3), 373 (2004).
[67]  Hosseini, S., Fallah Huseini, H., Larijani, B., Mohammad, K., Najmizadeh, A., Nourijelyani, K. and Jamshidi, L., “The hypoglycemic effect of Juglans regia leaves aqueous extract in diabetic patients: A first human trial”, DARU Journal of Pharmaceutical Sciences, 22 (1), 19 (2014).
[68]  Hosseini, S., Mehrzadi, S., Najmizadeh, A. R., Kazem, M., Alimoradi, H. and Fallah Huseini, H., “Effects of Juglans regia L. leaf extract on hyperglycemia and lipid profiles in type two diabetic patients: A randomized double-blind, placebo-controlled clinical trial”, Journal of Ethnopharmacology, 152 (3), 451 (2014).
[69]  Pereira, J. A., Oliveira, I., Sousa, A., Valentão, P., Andrade, P. B., Ferreira, I. C. F. R., Ferreres, F., Bento, A., Seabra, R. and Estevinho, L., “Walnut (Juglans regia L.) leaves: Phenolic compounds, antibacterial activity and antioxidant potential of different cultivars”, Food and Chemical Toxicology, 45 (11), 2287 (2007).
[70]  Hassanshahi, M. R., Eghbali, H. and Hosseini Zijoud, S., “Study of the effects of walnut leaf on some blood biochemical parameters in hypercholesterolemic rats”, Biochem. Anal Biochem., 1 (103), 1 (2011).
[71]  Wei, Q., Ma, X. and Dong, J., “Preparation, chemical constituents and antimicrobial activity of pyroligneous acids from walnut tree branches”, Journal of Analytical and Applied Pyrolysis, 87 (1), 24 (2010).
[72]  Solar, A., Colarič, M., Usenik, V. and Stampar, F., “Seasonal variations of selected flavonoids, phenolic acids and quinones in annual shoots of common walnut (Juglans regia L.)”, Plant Science, 170 (3), 453 (2006).
[73]  Nirmla Devi, T., Apraj, V., Bhagwat, A., Mallya, R., Sawant, L. and Pandita, N., “Pharmacognostic and phytochemical investigation of Juglans regia Linn. bark”, Pharmacognosy Journal, 3 (25), 39 (2011).
[74]  Zakavi, F., Golpasand Hagh, L., Daraeighadikolaei, A., Farajzadeh Sheikh, A., Daraeighadikolaei, A. and Leilavi Shooshtari, Z., “Antibacterial effect of Juglans Regia bark against oral pathologic bacteria”, International Journal of Dentistry, 2013, (2013).
[75]  Srinivasan, A. and Viraraghavan, T., “Oil removal from water using biomaterials”, Bioresource Technology, 101 (17), 6594 (2010).
[76]  Srinivasan, A. and Viraraghavan, T., “Removal of oil by walnut shell media”, Bioresource Technology, 99 (17), 8217 (2008).
[77]  Nethaji, S. and Sivasamy, A., “Removal of hexavalent chromium from aqueous solution using activated carbon prepared from walnut shell biomass through alkali impregnation processes”, Clean Technology and Environmental Policy, 16, 361 (2014).
[78]  Ac¸ıkalın, K., “Thermogravimetric analysis of walnut shell as pyrolysis feedstock”, Journal of Thermodynamics and Analytical Calorimetry, 105, (2011).
[79]  Alighardashi, A. and Shahali, S., “Removal of nitrate from synthetic aqueous solution and groundwater in a continuous pilot system using chemical activated carbon derived from walnut shell”, Water Practice and Technology, 11 (4), 784 (2016).
[80]  Feizi, M. and Jalali, M., “Removal of heavy metals from aqueous solutions using sunflower, potato, canola and walnut shell residues”, Journal of the Taiwan Institute of Chemical Engineers, 54, 125 (2015).
[81]  Ghasemi, M., Ghoreyshi, A. A., Younesi, H. and Khoshhal, S., “Synthesis of a high characteristics activated carbon from walnut shell for the removal of Cr (VI) and Fe (II) from aqueous solution: Single and binary solutes adsorption”, Iranian Journal of Chemical Engineering, 12 (4), 28 (2015).
Jafari-Mansoorian, H., Farzadkia, M., Ansari, M., Ahmadi, E., Majidi, G., Amraie, A. and Joghataie, A., “Evaluating the activated carbon prepared from walnut in removal of arsenic from aqueous solution”, Journal of Safety Promotion and Injures Preventation, 3 (4), 287 (2016).
[82]  Kar, Y., “Co-pyrolysis of walnut shell and tar sand in a fixed-bed reactor”, Bioresource Technology, 102 (20), 9800 (2011).
[83]  Karatas, H. and Akgun, F., “Experimental results of gasification of walnut shell and pistachio shell in a bubbling fluidized bed gasifier under air and steam atmospheres”, Fuel, 214, 285 (2018).
[84]  Kim, J. -W., Sohn, M. -H., Kim, D. -S., Sohn, S. -M. and Kwon, Y. -S., “Production of granular activated carbon from waste walnut shell and its adsorption characteristics for Cu2+ ion”, Journal of Hazardous Materials, 85 (3), 301 (2001).
[85]  Kuśmierek, K. and Świątkowski, A., “Removal of chlorophenols from aqueous solutions by sorption onto walnut, pistachio and hazelnut shells”, Polish Journal of Chemical Technology, 17 (1), 23 (2015).
[86]  Soleimani, M. and Kaghazchi, T., “Low-cost adsorbents from agricultural by-products impregnated with phosphoric acid” Adv. Chem. Eng. Res., 3 (1), 34 (2014).
[87]  Xie, R., Wang, H., Chen, Y. and Jiang, W., “Walnut shell-based activated carbon with excellent copper (II) adsorption and lower chromium (VI) removal prepared by acid-base modification”, Environmental Progress and Sustainable Energy, 32 (3), 688 (2013).
[88]  Yang, J. and Qiu, K., “Preparation of activated carbons from walnut shells via vacuum chemical activation and their application for methylene blue removal”, Chemical Engineering Journal, 165 (1), 209 (2010).
[89]  Zabihi, M., Haghighi Asl, A. and Ahmadpour, A., “Studies on adsorption of mercury from aqueous solution on activated carbons prepared from walnut shell”, Journal of Hazardous Materials, 174 (1), 251 (2010).
[90]  Zhu, M., Yao, J., Dong, L. and Sun, J., “Adsorption of naphthalene from aqueous solution onto fatty acid modified walnut shells”, Chemosphere, 144, 1639 (2016).
[91]  Demirbas, A., “Effect of temperature on pyrolysis products from four nut shells”, Journal of Analytical and Applied Pyrolysis, 76 (1), 285 (2006).
[92]  Yang, W., Shimizu, I., Ono, T. and Kimura, Y., “Preparation of biodegradable foam from walnut shells treated by subcritical water”, Journal of Chemical Technology and Biotechnology, 90 (1), 44 (2015).
[93]  Bansal, R. and Goyal, M., Activated carbon adsorption, Taylor and Francis Group, CRC Press, (2005).
[94]  Gonzalez, J. F., Roman, S., Gonzalez-Garcıa, C. M., Valente Nabais, J. M. and Luis Ortiz, A., “Porosity development in activated carbons prepared from walnut shells by carbon dioxide or steam activation”, Industrial Engineering and Chemical Research, 48, 7474 (2009).
[95]  Arjmand, S., Kaghazchi, T., Latifi, S. M. and Soleimani, M., “Chemical production of activated carbon from nutshells and date stones”, Journal of Chemical Engineering and Technology, 29, 986 (2006).
[96]  Hayashi, J. I., Horikawa, T., Takeda, I., Muroyama, K. and Nasir Ani, F., “Preparing activated carbon from various nutshells by chemical activation with K2CO3”, Carbon, 40 (13), 2381 (2002).
[97]  Moreno-Barbosa, J. J., López-Velandia, C., del Pilar Maldonado, A., Giraldo, L. and Moreno-Piraján, J. C., “Removal of lead (II) and zinc (II) ions from aqueous solutions by adsorption onto activated carbon synthesized from watermelon shell and walnut shell”, Adsorption, 19 (2-4), 675 (2013).
[98]  Yu, Q., Li, M., Ji, X., Qiu, Y., Zhu, Y. and Leng, C., “Characterization and methanol adsorption of walnut shell activated carbon prepared by KOH activation”, Journal of Wuhan University of Technology-Mater. Sci. Ed., 31 (2), 260 (2016).
[99]  Nowicki, P., Pietrzak, R. and Wachowska, H., “Sorption properties of active carbons obtained from walnut shells by chemical and physical activation”, Catalysis Today, 150 (1), 107 (2010).
[100]       Teimouri, Z., Salem, A. and Salem, S., “Clean and new strategy for catalytic conversion of agriculture waste shells to activated carbon via microwave-assisted impregnation: Applied and eco-friendly aspect for decoloration of industrial corn syrup and process identifications”, Journal of Environmental Chemical Engineering, 7 (3), 103161 (2019).
[101]       Abbas, S. H., Ismail, I. M., Mostafa, T. M. and Sulaymon, A. H., “Biosorption of heavy metals: A review”, Journal of Chemical Science and Technology, 3 (4), 74 (2014).
[102]       Krstić, V., Uroševoć, T. and Pešovski, B., “A review on adsorbents for treatment of water and wastewaters containing copper ions”, Chemical Engineering Science, 192 (31), 273 (2018).
[103]       Kazemipour, M., Ansari, M., Tajrobehkar, S., Majdzadeh, M. and Kermani, H. R., “Removal of lead, cadmium, zinc, and copper from industrial wastewater by carbon developed from walnut, hazelnut, almond, pistachio shell, and apricot stone”, Journal of Hazardous Materials, 150 (2), 322 (2008).
[104]       Milenković, D., Milosavljević, M. and Bojić, A., “Optimization of ultrasonically assisted adsorption of Cu (II) on carbonized and activated walnut shells”, Facta Universitatis, Series: Working and Living Environmental Protection, 15 (1), 35 (2018).
[105]       Mishra, S., “Adsorption–desorption of heavy metal ions”, Current Science, 601 (2014).
[106]       Altun, T. and Pehlivan, E., “Removal of Cr (VI) from aqueous solutions by modified walnut shells”, Food Chemistry, 132 (2), 693 (2012).
[107]       Lu, X., Duan, J. and Huang, Y., “Adsorption of Cr (VI) in water with phosphoric acid modified and ordinary walnut shell”, Agricultural Science and Technology, 16 (9), 1989 (2015).
[108]       Gondhalekar, S. C. and Shukla, S. R., “Biosorption of cadmium metal ions on raw and chemically modified walnut shells”, Environmental Progress and Sustainable Energy, 34 (6), 1613 (2015).
[109]       Qiu, Z., Chen, J., Tang, J. and Zhang, Q., “A study of cadmium remediation and mechanisms: Improvements in the stability of walnut shell-derived biochar”, Science of the Total Environment, 636, 80 (2018).
[110]       Saffari, M., “Optimization of cadmium removal from aqueous solutions using walnut-shell residues biochar supported/unsupported by nanoscale zero-valent iron through response surface methodology”, Journal of Chemical Health Risks, 8, 19 (2018).
[111]       Yi, Z. -J., Yao, J., Kuang, Y. -F., Chen, H. -L., Wang, F. and Yuan, Z. -M., “Removal of Pb(II) by adsorption onto Chinese walnut shell activated carbon”, Water Science and Technology, 72 (6), 983 (2015).
[112]       Zbair, M., Ahsaine, H. A., Anfar, Z. and Slassi, A., “Carbon microspheres derived from walnut shell: Rapid and remarkable uptake of heavy metal ions, molecular computational study and surface modeling”, Chemosphere, 231, 140 (2019).
[113]       Khani, H., Rofouei, M. K., Arab, P., Gupta, V. K. and Vafaei, Z., “Multi-walled carbon nanotubes-ionic liquid-carbon paste electrode as a super selectivity sensor: Application to potentiometric monitoring of mercury ion (II)”, Journal of Hazardous Materials, 183 (1-3), 402 (2010).
[114]       Zabihi, M., Ahmadpour, A. and Haghighi Asl, A., “Removal of mercury from water by carbonaceous sorbents derived from walnut shell”, Journal of Hazardous Materials, 167 (1), 230 (2009).
[115]       Davidi, S., Lashanizadegan, A. and Sharififard, H., “Walnut shell activated carbon: optimization of synthesis process, characterization and application for Zn (II) removal in batch and continuous process”, Materials Research Express, 6 (8), 085621 (2019).
[116]       Olafadehan, O., Akpo, O., Enemuo, O., Amoo, K. O. and Abatan, O. G., “Equilibrium, kinetic and thermodynamic studies of biosorption of zinc ions from industrial wastewater using derived composite biosorbents from walnut shell”, African Journal of Environmental Science and Technology, 12 (9), 334 (2018).
[117]       Mohammadi, N., Khani, H., Gupta, V. K., Amereh, E. and Agarwal, S., “Adsorption process of methyl orange dye onto mesoporous carbon material–Kinetic and thermodynamic studies”, Journal of Colloid and Interface Science, 362 (2), 457 (2011).
[118]       Hall, W. A., Bellamy, D. E. and Walse, S. S., “Activated carbons from end-products of tree nut and tree fruit production as sorbents for removing Methyl Bromide in ventilation effluent following postharvest chamber fumigation”, Journal of Agricultural and Food Chemistry, 63, 3094 (2015).
[119]       Almasi, A., Mousavi, S. A., Hesari, A. and Janjani, H., “Walnut shell as a natural adsorbent for the removal of Reactive Red 2 form aqueous solution”, International Research Journal of Applied and Basic Sciences, 10 (5), 551 (2016).
[120]       Hajialigol, S. and Masoum, S., “Optimization of biosorption potential of nano biomass derived from walnut shell for the removal of Malachite Green from liquids solution: Experimental design approaches”, Journal of Molecular Liquids, 286, 110904 (2019).
[121]       Ojo, T. A., Ojedokun, A. T. and Bello, O. S., “Functionalization of powdered walnut shell with orthophosphoric acid for congo red dye removal”, Particulate Science and Technology, 37 (1), 74 (2019).
[122]       Nazari, G., Abolghasemi, H. and Esmaieli, M., “Batch adsorption of cephalexin antibiotic from aqueous solution by walnut shell-based activated carbon”, Journal of the Taiwan Institute of Chemical Engineers, 58, 357 (2016).
[123]       Nazari, G., Abolghasemi, H. and Esmaieli, M., “Study of mass transfer coefficient of cephalexin adsorption onto walnut shell-based activated carbon in a fixed-bed column”, Chemistry and Chemical Technology, 10 (1), 81 (2016).
[124]       Nazari, G., Abolghasemi, H., Esmaieli, M. and Sadeghi Pouya, E., “Aqueous phase adsorption of cephalexin by walnut shellbased activated carbon: A fixed-bed column study”, Applied Surface Science, 375, 144 (2016).
[125]       Nazari, G., Abolghasemia, H., Esmaieli, M. and Assar, M., “Theoretical and experimental study of cephalexin batch adsorption dynamics using walnut shell-based activated carbon”, Desalination and Water Treatment, 57 (56), 27339 (2016).
[126]       Teixeira, S., Delerue-Matos, C. and Santos, L., “Application of experimental design methodology to optimize antibiotics removal by walnut shell based activated carbon”, Science of The Total Environment, 646, 168 (2019).
[127]       Ghanbari Pakdehi, S. and Rezaei, F., “Adsorption of liquid fuel dimethyl amino ethyl azide from dilute aqueous solution on activated carbon prepared from walnut shell”, Desalination and Water Treatment, 57 (39), 27726 (2016).
[128]       Mataji, M. and Khoshandam, B., “Benzene adsorption on activated carbon from walnut shell”, Chemical Engineering Communications, 201 (10), 1294 (2014).
[129]       Guo, J. -X., Fan, L., Peng, J. -F., Chen, J., Yin, H. -Q. and Jiang, W. -J., “Desulfurization activity of metal oxides blended into walnut shell based activated carbons”, Journal of Chemical Technology and Biotechnology, 89, 1565 (2014).
[130]       Yu, Q., Li, M., Ning, P., Yi, H. and Tang, X., “Preparation and phosphine adsorption of activated carbon prepared from walnut shells by KOH chemical activation”, Separation Science and Technology, 49, 2366 (2014).
[131]       Yu, Q., Li, M., Ning, P., Yi, H. and Tang, X., “Characterization of metal oxide-modified walnut-shell activated carbon and its application for phosphine adsorption: Equilibrium, regeneration, and mechanism studies”, Journal of Wuhan University of Technology-Mater. Sci. Ed., 34 (2), 487 (2019).
[132]       Bayat, M., Alighardashi, A. and Sadeghasadi, A., “Fixed-bed column and batch reactors performance in removal of diazinon pesticide from aqueous solutions by using walnut shell-modified activated carbon”, Environmental Technology & Innovation, 12, 148 (2018).
[133]       Taghizadeh, M. M. and Vahdati, R., “Study about efficiency of nitrate removal from water by activated carbon prepared by pistachio, walnut and almond shells”, International Journal of Biosciences, 6 (2), 375 (2015).
[134]       Ding, S., Jia, L. and Qu, Z., “Study on the adsorption of ammonia nitrogen in wastewater by modified walnut shell”, Proceedings of World Automation Congress (WAC), 2012 IEEE, pp 1-5 (2012).
[135]       Zheng, X., Lin, H., Tao, Y. and Zhang, H., “Selective adsorption of phenanthrene dissolved in Tween 80 solution using activated carbon derived from walnut shells”, Chemosphere, 208, 951 (2018).
[136]       Soleimani, M. and Kaghazchi, T., “Low-cost adsorbents from agricultural by-products impregnated with phosphoric acid”, Advanced Chemical Engineering Research, 3 (1), 34 (2014).
[137]       Saqib, A. N. S., Waseem, A., Khan, A. F., Mahmood, Q., Khan, A., Habib, A. and Khan, A. R., “Arsenic bioremediation by low cost materials derived from blue pine (Pinus wallichiana) and walnut (Juglans regia L.)”, Ecological Engineering, 51, 88 (2013).
[138]       Almasi, A., Omidi, M., Khodadadian, M., Khamutian, R. and Gholivand, M. B., “Lead (II) and cadmium (II) removal from aqueous solution using processed walnut shell: Kinetic and equilibrium study”, Toxicological and Environmental Chemistry, 94 (4), 660 (2012).
[139]       Cheng, L., Sun, L., Xue, W., Zeng, Z. and Li, S., “Adsorption equilibrium and kinetics of Pb (II) from aqueous solution by modified walnut shell”, Environmental Progress and Sustainable Energy, 35 (6), 1724 (2016).
[140]       Saadat, S., Karimi-Jashni, A. and Doroodmand, M. M., “Synthesis and characterization of novel single-walled carbon nanotubes-doped walnut shell composite and its adsorption performance for lead in aqueous solutions”, Journal of Environmental Chemical Engineering, 2 (4), 2059 (2014).
[141]       Cao, J. -S., Lin, J. -X., Fang, F., Zhang, M. -T. and Hu, Z. -R., “A new absorbent by modifying walnut shell for the removal of anionic dye: Kinetic and thermodynamic studies”, Bioresource Technology, 163, 199 (2014).
[142]       Ashrafi, M., Bagherian, G., Arab Chamjangali, M. and Goudarzi, N., “Removal of brilliant green and crystal violet from mono- and bi-component aqueous solutions using NaOH-modified walnut shell”, Analytical and Bioanalytical Chemistry Research, 5 (1), 95 (2018).
[143]       Naghizadeh, A., Khosravi, R., Derakhshani, E., Shahabi, H. and Ghasemi, F., “Application of walnut shell modified with Zinc Oxide (ZnO) nanoparticles in removal of natural organic matters (NOMs) from aqueous solution”, Archives of Hygiene Sciences, 4 (4), 187 (2015).