{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,2,18]],"date-time":"2026-02-18T11:14:38Z","timestamp":1771413278941,"version":"3.50.1"},"reference-count":53,"publisher":"MDPI AG","issue":"12","license":[{"start":{"date-parts":[[2020,6,17]],"date-time":"2020-06-17T00:00:00Z","timestamp":1592352000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100001871","name":"Funda\u00e7\u00e3o para a Ci\u00eancia e a Tecnologia","doi-asserted-by":"publisher","award":["SFRH\/BD\/131280\/2017"],"award-info":[{"award-number":["SFRH\/BD\/131280\/2017"]}],"id":[{"id":"10.13039\/501100001871","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100001871","name":"Funda\u00e7\u00e3o para a Ci\u00eancia e a Tecnologia","doi-asserted-by":"publisher","award":["UID\/EQU\/00102\/2019"],"award-info":[{"award-number":["UID\/EQU\/00102\/2019"]}],"id":[{"id":"10.13039\/501100001871","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100001871","name":"Funda\u00e7\u00e3o para a Ci\u00eancia e a Tecnologia","doi-asserted-by":"publisher","award":["UID\/QUI\/00313\/2019"],"award-info":[{"award-number":["UID\/QUI\/00313\/2019"]}],"id":[{"id":"10.13039\/501100001871","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100008530","name":"European Regional Development Fund","doi-asserted-by":"publisher","award":["POCI-01-0145-FEDER-006910"],"award-info":[{"award-number":["POCI-01-0145-FEDER-006910"]}],"id":[{"id":"10.13039\/501100008530","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100008530","name":"European Regional Development Fund","doi-asserted-by":"publisher","award":["POCI-01-0145-FEDER-007630"],"award-info":[{"award-number":["POCI-01-0145-FEDER-007630"]}],"id":[{"id":"10.13039\/501100008530","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100000921","name":"European Cooperation in Science and Technology","doi-asserted-by":"publisher","award":["CA18125"],"award-info":[{"award-number":["CA18125"]}],"id":[{"id":"10.13039\/501100000921","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Molecules"],"abstract":"<jats:p>Heavy metals are common inorganic pollutants found in the environment that have to be removed from wastewaters and drinking waters. In this work, silica-derived aerogels and xerogels were modified via a co-precursor method to obtain functional adsorbents for metal cations. A total of six formulations based upon four different functional precursors were prepared. The materials\u2032 structural characterization revealed a decreased porosity and surface area on modified samples, more prominent in xerogel counterparts. Preliminary tests were conducted, and the prepared samples were also compared to activated carbon. Three samples were selected for in-depth studies. Isotherm studies revealed that the pre-selected samples remove well copper, lead, cadmium and nickel, and with similar types of interactions, following a Langmuir trend. The adsorption kinetics starts very fast and either equilibrium is reached quickly or slowly, in a two-stage process attributed to the existence of different types of active sites. Based on the previous tests, the best sample, prepared by mixing different functional co-precursors, was selected and its behavior was studied under different temperatures. For this material, the adsorption performance at 20 \u00b0C is dependent on the cation, ranging from 56 mg\u00b7g\u22121 for copper to 172 mg\u00b7g\u22121 for lead.<\/jats:p>","DOI":"10.3390\/molecules25122788","type":"journal-article","created":{"date-parts":[[2020,6,18]],"date-time":"2020-06-18T12:21:46Z","timestamp":1592482906000},"page":"2788","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":32,"title":["Silica Aerogels\/Xerogels Modified with Nitrogen-Containing Groups for Heavy Metal Adsorption"],"prefix":"10.3390","volume":"25","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-1025-3488","authenticated-orcid":false,"given":"Jo\u00e3o P.","family":"Vareda","sequence":"first","affiliation":[{"name":"University of Coimbra, CIEPQPF, Department of Chemical Engineering, Rua S\u00edlvio Lima, 3030-790 Coimbra, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-4612-7686","authenticated-orcid":false,"given":"Artur J. M.","family":"Valente","sequence":"additional","affiliation":[{"name":"University of Coimbra, CQC, Department of Chemistry, Rua Larga, 3004-535 Coimbra, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-3336-2449","authenticated-orcid":false,"given":"Luisa","family":"Dur\u00e3es","sequence":"additional","affiliation":[{"name":"University of Coimbra, CIEPQPF, Department of Chemical Engineering, Rua S\u00edlvio Lima, 3030-790 Coimbra, Portugal"}]}],"member":"1968","published-online":{"date-parts":[[2020,6,17]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"55","DOI":"10.1016\/j.jnoncrysol.2013.10.017","article-title":"An overview on silica aerogels synthesis and different mechanical reinforcing strategies","volume":"385","author":"Maleki","year":"2014","journal-title":"J. Non Cryst. 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