{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,1,19]],"date-time":"2026-01-19T14:17:43Z","timestamp":1768832263345,"version":"3.49.0"},"reference-count":66,"publisher":"MDPI AG","issue":"11","license":[{"start":{"date-parts":[[2017,11,16]],"date-time":"2017-11-16T00:00:00Z","timestamp":1510790400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"FCT\u2014Funda\u00e7\u00e3o para a Ci\u00eancia e a Tecnologia","award":["UID\/MULTI\/00612\/2013"],"award-info":[{"award-number":["UID\/MULTI\/00612\/2013"]}]},{"name":"FCT\u2014Funda\u00e7\u00e3o para a Ci\u00eancia e a Tecnologia","award":["PTDC\/QUI-QUI\/109970\/2009"],"award-info":[{"award-number":["PTDC\/QUI-QUI\/109970\/2009"]}]},{"name":"FCT\u2014Funda\u00e7\u00e3o para a Ci\u00eancia e a Tecnologia","award":["SFRH\/BD\/78289\/2011"],"award-info":[{"award-number":["SFRH\/BD\/78289\/2011"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Metals"],"abstract":"<jats:p>Electrical and electronics equipment and automotive and industrial catalysts are some examples of top technological devices whose functioning rely on the use of platinum-group metals (PGMs). The PGMs\u2019 high economic value and difficult to replace technological properties, together with their scarcity in the Earth\u2019s crust, justify concerns about their critical condition and reinforce the importance of developing recycling practices for PGM end-of-life materials. This article presents and discusses recent advances regarding the use of hydrometallurgical solvent extraction to recover one PGM, palladium, from spent catalysts. Two different tendencies are implicit in the literature concerning Pd(II) extraction: a few groups focus on the adjustment and optimization of current commercial extractants, while others prefer to design new extracting compounds. Actually, the leach solutions obtained from the treatment of anthropogenic materials generally exhibit different compositions when compared to those coming from the primary resources. The pros and cons of both approaches are critically discussed, and the assumptions backing some of the reported achievements are also appraised.<\/jats:p>","DOI":"10.3390\/met7110505","type":"journal-article","created":{"date-parts":[[2017,11,16]],"date-time":"2017-11-16T11:10:02Z","timestamp":1510830602000},"page":"505","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":51,"title":["Recycling of Palladium from Spent Catalysts Using Solvent Extraction\u2014Some Critical Points"],"prefix":"10.3390","volume":"7","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-3858-9386","authenticated-orcid":false,"given":"Ana","family":"Paiva","sequence":"first","affiliation":[{"name":"Centro de Qu\u00edmica e Bioqu\u00edmica, Faculdade de Ci\u00eancias, Universidade de Lisboa, Campo Grande C8, 1749-016 Lisbon, Portugal"}]}],"member":"1968","published-online":{"date-parts":[[2017,11,16]]},"reference":[{"key":"ref_1","unstructured":"Ndlovu, J. (2015, January 12\u201313). Anglo American Platinum\u2014Precious Metals Supply. Proceedings of the Exchange of Good Practices on Metal By-Products Recovery\u2014Technology and Policy Challenges, Brussels, Belgium. Available online: https:\/\/ec.europa.eu\/growth\/tools-databases\/eip-raw-materials\/en\/content\/international-conference-%E2%80%9Cexchange-good-practices-metal-products-recovery-technology-and."},{"key":"ref_2","unstructured":"Ad-Hoc Working Group on Defining Critical Raw Materials (European Commission) (2017, July 06). Report on Critical Raw Materials for the EU. Available online: http:\/\/ec.europa.eu\/DocsRoom\/documents\/10010\/attachments\/1\/translations."},{"key":"ref_3","unstructured":"Matthey, J. (2017, July 06). Precious Metals Management. Available online: http:\/\/www.platinum.matthey.com\/about-pgm\/applications."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"406","DOI":"10.1007\/s11837-014-1263-x","article-title":"Potential of a hydrometallurgical recycling process for catalysts to cover the demand for critical metals, like PGMs and cerium","volume":"67","author":"Steinlechner","year":"2015","journal-title":"JOM"},{"key":"ref_5","doi-asserted-by":"crossref","unstructured":"Rydberg, J., Cox, M., Musikas, C., and Choppin, G.R. (2004). Solvent extraction in hydrometallurgy. Solvent Extraction Principles and Practice, Marcel Dekker Inc.. [2nd ed.].","DOI":"10.1201\/9780203021460-17"},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"210","DOI":"10.1002\/jctb.503290403","article-title":"Solvent extraction in platinum-group metal processing","volume":"29","author":"Cleare","year":"1979","journal-title":"J. Chem. Technol. Biotechnol."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"205","DOI":"10.1016\/j.reactfunctpolym.2005.05.011","article-title":"A review of separation of the platinum-group metals through their chloro-complexes","volume":"65","author":"Bernardis","year":"2005","journal-title":"React. Funct. Polym."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"25","DOI":"10.1080\/07366290701784126","article-title":"Solvent extraction of rhodium from chloride media by N,N\u2032-dimethyl-N,N\u2032-diphenyltetradecylmalonamide","volume":"26","author":"Malik","year":"2008","journal-title":"Solvent Extr. Ion Exch."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1016\/j.hydromet.2010.03.013","article-title":"Separation of platinum and palladium from chloride solution by solvent extraction using Alamine 300","volume":"104","author":"Swain","year":"2010","journal-title":"Hydrometallurgy"},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"2684","DOI":"10.1007\/s11814-016-0123-5","article-title":"Selective recovery of Fe(III), Pd(II), Pt(IV), Rh(III) and Ce(III) from simulated leach liquors of spent automobile catalyst by solvent extraction and cementation","volume":"33","author":"Nguyen","year":"2016","journal-title":"Korean J. Chem. Eng."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"105","DOI":"10.1080\/19443994.2012.696803","article-title":"Recovery of palladium(II) from acidic chloride solution using kerosene containing tri-n-octyl\/decyl amine (Alamine 336)","volume":"47","author":"Peng","year":"2012","journal-title":"Desalin. Water Treat."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"1101","DOI":"10.1080\/19443994.2013.826616","article-title":"Solvent extraction of palladium(II) from acidic chloride solutions using tri-octyl\/decyl ammonium chloride (Aliquat 336)","volume":"52","author":"Peng","year":"2014","journal-title":"Desalin. Water Treat."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"238","DOI":"10.1016\/j.jiec.2015.08.022","article-title":"Separation of platinum(IV) and palladium(II) from concentrated hydrochloric acid solutions by mixtures of amines with neutral extractants","volume":"32","author":"Nguyen","year":"2015","journal-title":"J. Ind. Eng. Chem."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"1502","DOI":"10.1134\/S0036023609090277","article-title":"Palladium extraction by a Cyanex 301-based binary extractant from chloride solutions","volume":"54","author":"Zhidkova","year":"2009","journal-title":"Russ. J. Inorg. Chem."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"826","DOI":"10.1134\/S0040579509050376","article-title":"Extraction of platinum and palladium from hydrochloric solutions by trioctymethylammonium dinonylnaphthalenesulfonate","volume":"43","author":"Zhidkova","year":"2009","journal-title":"Theor. Found. Chem. Eng."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"54","DOI":"10.1016\/j.hydromet.2006.04.005","article-title":"Study on the extraction of palladium(II) and platinum(IV) using LIX 84I","volume":"84","author":"Rane","year":"2006","journal-title":"Hydrometallurgy"},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"253","DOI":"10.1016\/j.jhazmat.2010.04.022","article-title":"Process for the separation and recovery of palladium and platinum from spent automobile catalyst leach liquor using LIX 84I and Alamine 336","volume":"180","author":"Raju","year":"2010","journal-title":"J. Hazard. Mat."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"143","DOI":"10.1016\/S0304-386X(01)00152-9","article-title":"Extraction separation studies of Rh, Pt and Pd using Cyanex 921 in toluene\u2014A possible application to recovery from spent catalysts","volume":"61","author":"Mhaske","year":"2001","journal-title":"Hydrometallurgy"},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"11","DOI":"10.1016\/j.hydromet.2013.01.001","article-title":"Extraction and separation of platinum, palladium and rhodium using Cyanex 923 and their recovery from real samples","volume":"134\u2013135","author":"Gupta","year":"2013","journal-title":"Hydrometallurgy"},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"135","DOI":"10.1016\/S1383-5866(97)00041-5","article-title":"Recovery of platinum, palladium and rhodium from industrial process leaching solutions by reactive extraction","volume":"12","author":"Nowottny","year":"1997","journal-title":"Sep. Purif. Technol."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"213","DOI":"10.1016\/j.seppur.2010.04.003","article-title":"Solvent extraction separation and recovery of palladium and platinum from chloride leach liquors of spent automobile catalyst","volume":"73","author":"Lee","year":"2010","journal-title":"Sep. Purif. Technol."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"202","DOI":"10.1016\/j.seppur.2010.04.001","article-title":"Extraction of palladium(II) from chloride solutions with Cyphos\u00aeIL 101\/toluene mixtures as novel extractant","volume":"73","author":"Cieszynska","year":"2010","journal-title":"Sep. Purif. Technol."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"385","DOI":"10.1016\/j.seppur.2011.05.025","article-title":"Selective extraction of palladium(II) from hydrochloric acid solutions with phosphonium extractants","volume":"80","author":"Cieszynska","year":"2011","journal-title":"Sep. Purif. Technol."},{"key":"ref_24","first-page":"621","article-title":"Removal of palladium(II) from aqueous chloride solutions with cyphos phosphonium ionic liquids as metal ion carriers for liquid-liquid extraction and transport across polymer inclusion membranes","volume":"51","author":"Rzelewska","year":"2015","journal-title":"Physicochem. Probl. Miner. Process."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"62717","DOI":"10.1039\/C6RA09328K","article-title":"Highly selective separation of individual platinum group metals (Pd, Pt, Rh) from acidic chloride media using phosphonium-based ionic liquid in aromatic diluent","volume":"6","author":"Nguyen","year":"2016","journal-title":"RSC Adv."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"15162","DOI":"10.1039\/C6DT02384C","article-title":"Quantitative extraction of Rh(III) using ionic liquids and its simple separation from Pd(II)","volume":"45","author":"Svecova","year":"2016","journal-title":"Dalton Trans."},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"20131","DOI":"10.1039\/C5DT03791C","article-title":"Possibilities and limitations in separating Pt(IV) from Pd(II) combining imidazolium and phosphonium ionic liquids","volume":"44","author":"Papaiconomou","year":"2015","journal-title":"Dalton Trans."},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"79","DOI":"10.1016\/j.hydromet.2011.12.006","article-title":"Extractive recovery of palladium(II) from hydrochloric acid solutions with Cyphos\u00aeIL 104","volume":"113\u2013114","author":"Cieszynska","year":"2012","journal-title":"Hydrometallurgy"},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"164","DOI":"10.1016\/j.hydromet.2014.05.016","article-title":"Extraction mechanism, behavior and stripping of Pd(II) by pyridinium-based ionic liquid from hydrochloric acid medium","volume":"147\u2013148","author":"Tong","year":"2014","journal-title":"Hydrometallurgy"},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"206","DOI":"10.1134\/S1070427216020075","article-title":"Propiconazole and penconazole as effective extractants for selective recovery and concentration of platinum(IV) and palladium(II) from hydrochloric acid solutions formed in leaching of spent aluminoplatinum and aluminopalladium catalysts","volume":"89","author":"Anpilogova","year":"2016","journal-title":"Russ. J. Appl. Chem."},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"159","DOI":"10.1016\/S0304-386X(02)00201-3","article-title":"New pyridinecarboxamides for rapid extraction of palladium from acidic chloride media","volume":"68","year":"2003","journal-title":"Hydrometallurgy"},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"337","DOI":"10.1016\/j.seppur.2006.08.005","article-title":"Selective extraction of palladium(II) from hydrochloric acid solutions with pyridinecarboxamides and ACORGA\u00ae CLX50","volume":"53","author":"Wisniewski","year":"2007","journal-title":"Sep. Purif. Technol."},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"206","DOI":"10.1080\/07366299.2013.838498","article-title":"Fatty imidazolines: A novel extractant for the recovery of palladium(II) from hydrochloric acid solutions","volume":"32","author":"Anpilogova","year":"2014","journal-title":"Solvent Extr. Ion Exch."},{"key":"ref_34","unstructured":"Narita, H., Tanaka, M., and Tamura, K. (2009). Extractants for Palladium and Method of Rapidly Separating and Recovering Palladium Using the Same. (2009\/0178513 A1), U.S. Patent."},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"3636","DOI":"10.1021\/ie404363b","article-title":"Extraction properties of palladium(II) in HCl solution with sulfide-containing monoamide compounds","volume":"53","author":"Narita","year":"2014","journal-title":"Ind. Eng. Chem. Res."},{"key":"ref_36","unstructured":"Narita, H., Tanaka, M., and Morisaku, K. (2005, January 19\u201323). Extraction properties of platinum group metals with diamide compounds. Proceedings of the International Solvent Extraction Conference, Beijing, China."},{"key":"ref_37","doi-asserted-by":"crossref","first-page":"12","DOI":"10.1080\/07366299.2012.700588","article-title":"Liquid-liquid extraction of platinum from chloride media by N,N\u2032-dimethyl-N,N\u2032-dicyclohexyltetradecylmalonamide","volume":"31","author":"Costa","year":"2013","journal-title":"Solvent Extr. Ion Exch."},{"key":"ref_38","doi-asserted-by":"crossref","first-page":"966","DOI":"10.1080\/01496395.2013.878721","article-title":"The solvent extraction performance of N,N\u2032-dimethyl-N,N\u2032-dibutylmalonamide towards platinum and palladium in chloride media","volume":"49","author":"Paiva","year":"2014","journal-title":"Sep. Sci. Technol."},{"key":"ref_39","doi-asserted-by":"crossref","first-page":"40","DOI":"10.1016\/j.hydromet.2016.03.012","article-title":"A bridge between liquid-liquid extraction and the use of bacterial communities for palladium and platinum recovery as nanosized metal sulphides","volume":"163","author":"Matos","year":"2016","journal-title":"Hydrometallurgy"},{"key":"ref_40","doi-asserted-by":"crossref","first-page":"483","DOI":"10.1016\/j.mineng.2008.01.011","article-title":"Palladium extraction with N,N,N\u2032,N\u2032-tetra-n-octyl-thiodiglycolamide","volume":"21","author":"Narita","year":"2008","journal-title":"Min. Eng."},{"key":"ref_41","doi-asserted-by":"crossref","first-page":"576","DOI":"10.1016\/j.hydromet.2017.03.005","article-title":"Precious metal extraction by N,N,N\u2032,N\u2032-tetraoctyl-thiodiglycolamide and its comparison with N,N,N\u2032,N\u2032-tetraoctyl-diglycolamide and methylimino-N,N\u2032-dioctylacetamide","volume":"169","author":"Sasaki","year":"2017","journal-title":"Hydrometallurgy"},{"key":"ref_42","doi-asserted-by":"crossref","first-page":"399","DOI":"10.4028\/www.scientific.net\/AMR.878.399","article-title":"Extraction of precious metals with a new amide extractant","volume":"878","author":"Huang","year":"2014","journal-title":"Adv. Mater. Res."},{"key":"ref_43","doi-asserted-by":"crossref","first-page":"78","DOI":"10.1080\/07366299.2013.810969","article-title":"Recovery of platinum and palladium from chloride solutions by a thiodiglycolamide derivative","volume":"32","author":"Paiva","year":"2014","journal-title":"Solvent Ext. Ion Exch."},{"key":"ref_44","doi-asserted-by":"crossref","first-page":"363","DOI":"10.1016\/j.seppur.2015.10.023","article-title":"Liquid-liquid extraction of palladium(II) from chloride media by N,N\u2032-dimethyl-N,N\u2032-dicyclohexylthiodiglycolamide","volume":"156","author":"Ortet","year":"2015","journal-title":"Sep. Purif. Technol."},{"key":"ref_45","doi-asserted-by":"crossref","first-page":"394","DOI":"10.1016\/j.hydromet.2017.06.014","article-title":"Recovery of palladium from a spent industrial catalyst through leaching and solvent extraction","volume":"171","author":"Paiva","year":"2017","journal-title":"Hydrometallurgy"},{"key":"ref_46","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1016\/j.seppur.2016.06.021","article-title":"Palladium(II) and N,N\u2032-dimethyl-N,N\u2032 dicyclohexylthiodiglycolamide\u2014The extracted species from concentrated chloride solutions","volume":"170","author":"Ortet","year":"2016","journal-title":"Sep. Purif. Technol."},{"key":"ref_47","doi-asserted-by":"crossref","first-page":"151","DOI":"10.1016\/j.seppur.2014.01.001","article-title":"Evaluation of novel ligand dithiodiglycolamide (DTDGA) for separation and recovery of palladium from simulated spent catalyst dissolver solution","volume":"125","author":"Das","year":"2014","journal-title":"Sep. Purif. Technol."},{"key":"ref_48","doi-asserted-by":"crossref","first-page":"1322","DOI":"10.1134\/S1070427216080176","article-title":"Evaluation of unsymmetrical dithiodiglycolamide as novel extractant for application in selective separation of palladium(II) from aqueous solutions","volume":"89","author":"Mohamed","year":"2016","journal-title":"Russ. J. Appl. Chem."},{"key":"ref_49","doi-asserted-by":"crossref","first-page":"1144","DOI":"10.1246\/cl.2004.1144","article-title":"Rapid separation of palladium(II) from platinum(IV) in hydrochloric acid solution with thiodiglycolamide","volume":"33","author":"Narita","year":"2004","journal-title":"Chem. Lett."},{"key":"ref_50","doi-asserted-by":"crossref","first-page":"2303","DOI":"10.3390\/met5042303","article-title":"Palladium(II) recovery from hydrochloric acid solutions by N,N\u2032-dimethyl-N,N\u2032-dibutylthiodiglycolamide","volume":"5","author":"Paiva","year":"2015","journal-title":"Metals"},{"key":"ref_51","unstructured":"Paiva, A.P., and Ortet, O. (2014, January 7\u201311). Solvent extraction of palladium from hydrochloric acid media by N,N-disubstituted thioamides. Proceedings of the International Solvent Extraction Conference, W\u00fcrzburg, Germany."},{"key":"ref_52","doi-asserted-by":"crossref","first-page":"33","DOI":"10.1016\/j.hydromet.2014.11.001","article-title":"Development of tertiary thioamide derivatives to recover palladium(II) from simulated complex chloride solutions","volume":"151","author":"Ortet","year":"2015","journal-title":"Hydrometallurgy"},{"key":"ref_53","first-page":"1461","article-title":"Palladium(II) extraction from concentrated chloride media: Reactions involving thioamide derivatives","volume":"51","author":"Ortet","year":"2016","journal-title":"Sep. Sci. Technol."},{"key":"ref_54","doi-asserted-by":"crossref","first-page":"8914","DOI":"10.1021\/acs.iecr.6b02135","article-title":"Comparative study on palladium(II) extraction using thioamide-modified acyclic and cyclic extractants","volume":"55","author":"Yamada","year":"2016","journal-title":"Ind. Eng. Chem. Res."},{"key":"ref_55","doi-asserted-by":"crossref","first-page":"1243","DOI":"10.1039\/C5RA23146A","article-title":"Rapid and selective extraction of Pd(II) ions using the SCS type pincer ligand 1,3-bis(dimethylthiocarbamoyloxy)benzene, and its Pd(II) extraction mechanism","volume":"6","author":"Gandhi","year":"2016","journal-title":"RSC Adv."},{"key":"ref_56","doi-asserted-by":"crossref","first-page":"521","DOI":"10.1252\/jcej.16we335","article-title":"Extraction and stripping behavior of platinum group metals using an amic-acid-type extractant","volume":"50","author":"Yoshida","year":"2017","journal-title":"J. Chem. Eng. Jpn."},{"key":"ref_57","first-page":"1","article-title":"Recent research in solvent extraction of platinum group metals","volume":"81","author":"Narita","year":"2017","journal-title":"J. Jpn. Inst. Met. Mater."},{"key":"ref_58","doi-asserted-by":"crossref","first-page":"359","DOI":"10.1081\/SEI-120004810","article-title":"Solvent extraction of platinum-group metals from hydrochloric acid solutions by dialkyl sulphoxides","volume":"20","author":"Preston","year":"2002","journal-title":"Solvent Ext. Ion Exch."},{"key":"ref_59","doi-asserted-by":"crossref","first-page":"1271","DOI":"10.1016\/j.mineng.2009.07.006","article-title":"Solvent extraction and separation of palladium(II) and platinum(IV) from hydrochloric acid medium with dibutyl sulfoxide","volume":"22","author":"Pan","year":"2009","journal-title":"Min. Eng."},{"key":"ref_60","doi-asserted-by":"crossref","first-page":"57","DOI":"10.2298\/JMMB120117037P","article-title":"Solvent extraction of palladium(II) and effective separation of palladium(II) and platinum(IV) with synthetic sulfoxide MSO","volume":"49","author":"Pan","year":"2013","journal-title":"J. Min. Metall. Sect. B-Metall."},{"key":"ref_61","doi-asserted-by":"crossref","first-page":"2341","DOI":"10.1002\/ejic.201101406","article-title":"Complexation of palladium(II) with unsaturated dithioethers\u2014A systematic development of highly selective ligands for solvent extraction","volume":"14","author":"Traeger","year":"2012","journal-title":"Eur. J. Inorg. Chem."},{"key":"ref_62","doi-asserted-by":"crossref","first-page":"30","DOI":"10.1016\/j.hydromet.2012.07.002","article-title":"Development of a solvent extraction system with 1,2-bis(2-methoxyethylthio)benzene for the selective separation of palladium(II) from secondary raw materials","volume":"127\u2013128","author":"Traeger","year":"2012","journal-title":"Hydrometallurgy"},{"key":"ref_63","doi-asserted-by":"crossref","first-page":"1036","DOI":"10.1021\/acs.iecr.6b03874","article-title":"New heterocyclic dithioether ligands for highly selective separation and recovery of Pd(II) from acidic leach liquors of spent automobile catalyst","volume":"56","author":"Senthil","year":"2017","journal-title":"Ind. Eng. Chem. Res."},{"key":"ref_64","doi-asserted-by":"crossref","first-page":"8709","DOI":"10.1038\/s41598-017-09053-z","article-title":"Synthesis of pincer-type extractants for selective extraction of palladium from PGMs: An improved liquid-liquid extraction approach to current refining processes","volume":"7","author":"Gandhi","year":"2017","journal-title":"Sci. Rep."},{"key":"ref_65","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1007\/s10847-016-0616-1","article-title":"Thiacalixarenes: Emergent supramolecules in crystal engineering and molecular recognition","volume":"85","author":"Yamada","year":"2016","journal-title":"J. Incl. Phenom. Macrocycl. Chem."},{"key":"ref_66","doi-asserted-by":"crossref","first-page":"1052","DOI":"10.1002\/slct.201601981","article-title":"Calix[4]arene-based n-dialkylamino extractants for selective platinum group metal separation from automotive catalysts","volume":"2","author":"Yamada","year":"2017","journal-title":"ChemistrySelect"}],"container-title":["Metals"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2075-4701\/7\/11\/505\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T18:49:42Z","timestamp":1760208582000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2075-4701\/7\/11\/505"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2017,11,16]]},"references-count":66,"journal-issue":{"issue":"11","published-online":{"date-parts":[[2017,11]]}},"alternative-id":["met7110505"],"URL":"https:\/\/doi.org\/10.3390\/met7110505","relation":{},"ISSN":["2075-4701"],"issn-type":[{"value":"2075-4701","type":"electronic"}],"subject":[],"published":{"date-parts":[[2017,11,16]]}}}