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Additive - driven dissolution enhancement of colloidal silica. 1. basic principles and relevance to water treatment / Konstantinos D. Demadis in Industrial & engineering chemistry research, Vol. 50 N° 22 (Novembre 2011) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 50 N° 22 (Novembre 2011) . - pp. 12587-12595 Titre : Additive - driven dissolution enhancement of colloidal silica. 1. basic principles and relevance to water treatment Type de document : texte imprimé Auteurs : Konstantinos D. Demadis, Auteur ; Eleftheria Mavredaki, Auteur ; Maria Somara, Auteur Année de publication : 2012 Article en page(s) : pp. 12587-12595 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Water  treatment  Dissolution  Additive Résumé : The effect of various chemical additives (small molecules and polymers) on the dissolution of two kinds of colloidal silica (Aerosil 200 and laboratory-synthesized, SSD) is systematically studied at pH 10. The silica scale dissolvers tested are 5-carbosybenzotriazole (CBZT), amino-tris(methylene phosphonic acid) (AMP), a phosphino-polycarboxylic acid (PPCA), diethylenetriamine pentacarboxylic acid (DETPA), a proprietary polymer (Genesol 40), poly(acrylic acid) (PAA), ethylenediamine-tetrakis(methylenephosphonic acid) (EDTMP), phosphonobutane-1,2,4-tricarbosylic acid (PBTC), sodium metaborate, and N-phosphonomethylimino-diacetic acid (PMIDA). Of the polymeric additives only Genesol 40 shows some dissolution activity, dissolving ~280 ppm silica at 10000 ppm dosage after 72 h. PBTC and DETPA are the best-performing additives of all those tested. PBTC is effective even at the 2500 ppm dosage, as it solubilizes ~290 ppm silica after 72 h. Its efficiency is dosage-dependent. DETPA is also an effective silica dissolver. Its behavior is similar to that of PBTC. Its best dosage is 7500 ppm, which yields dissolution of 322 ppm silica (after 24 h), 340 ppm (after 48 h), and 333 ppm (after 72 h). SSD silica is a very recalcitrant deposit showing resistance to dissolution even by the most effective additives, PBTC and DETPA. DEWEY : 660 ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=24745734 [article] Additive - driven dissolution enhancement of colloidal silica. 1. basic principles and relevance to water treatment [texte imprimé] / Konstantinos D. Demadis, Auteur ; Eleftheria Mavredaki, Auteur ; Maria Somara, Auteur . - 2012 . - pp. 12587-12595. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 50 N° 22 (Novembre 2011) . - pp. 12587-12595 Mots-clés : Water  treatment  Dissolution  Additive Résumé : The effect of various chemical additives (small molecules and polymers) on the dissolution of two kinds of colloidal silica (Aerosil 200 and laboratory-synthesized, SSD) is systematically studied at pH 10. The silica scale dissolvers tested are 5-carbosybenzotriazole (CBZT), amino-tris(methylene phosphonic acid) (AMP), a phosphino-polycarboxylic acid (PPCA), diethylenetriamine pentacarboxylic acid (DETPA), a proprietary polymer (Genesol 40), poly(acrylic acid) (PAA), ethylenediamine-tetrakis(methylenephosphonic acid) (EDTMP), phosphonobutane-1,2,4-tricarbosylic acid (PBTC), sodium metaborate, and N-phosphonomethylimino-diacetic acid (PMIDA). Of the polymeric additives only Genesol 40 shows some dissolution activity, dissolving ~280 ppm silica at 10000 ppm dosage after 72 h. PBTC and DETPA are the best-performing additives of all those tested. PBTC is effective even at the 2500 ppm dosage, as it solubilizes ~290 ppm silica after 72 h. Its efficiency is dosage-dependent. DETPA is also an effective silica dissolver. Its behavior is similar to that of PBTC. Its best dosage is 7500 ppm, which yields dissolution of 322 ppm silica (after 24 h), 340 ppm (after 48 h), and 333 ppm (after 72 h). SSD silica is a very recalcitrant deposit showing resistance to dissolution even by the most effective additives, PBTC and DETPA. DEWEY : 660 ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=24745734

Additive - driven dissolution enhancement of colloidal silica. / Konstantinos D. Demadis in Industrial & engineering chemistry research, Vol. 50 N° 24 (Décembre 2011) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 50 N° 24 (Décembre 2011) . - pp. 13866–13876 Titre : Additive - driven dissolution enhancement of colloidal silica. : 2. environmentally friendly additives and natural products Type de document : texte imprimé Auteurs : Konstantinos D. Demadis, Auteur ; Eleftheria Mavredaki, Auteur ; Maria Somara, Auteur Année de publication : 2012 Article en page(s) : pp. 13866–13876 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Colloidal  silica Résumé : The effect of various environmentally friendly chemical additives and natural products on the dissolution of amorphous silica (Aerosil 200 and laboratory-synthesized, SSD) is studied. The silica scale dissolvers tested include the following: ascorbic acid (vitamin C, ASC), citric acid (CITR), carboxymethyl inulin (CMI), 3,4-dihydroxybenzoic acid (catechuic acid, DHBA), 3,4,5-trihydroxybenzoic acid (gallic acid, GA), dopamine hydrochloride (DOPA), iminodiacetic acid (IDA), histidine (HIST), phenylalanine (PHALA), and malic acid (MAL). The chemical structures of these chemical additives contain potentially dissolution-active moieties, such as 1,2-dihydroxyethylene (ASC), α-hydroxycarboxylate (MAL and CITR), catecholate (DHBA, GA, and DOPA), α-aminocarboxylate (HIST and PHALA, both aminoacids), and finally carboxy-modified fructofuranose units (CMI). It was found that all studied molecules showed variable dissolution efficiency, with MAL, CMI, HIST, and PHALA being the slowest/least effective dissolvers, and the catechol-containing DHBA, GA, and DOPA being the most effective ones. IDA and CITR have intermediate efficiency. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie201798e [article] Additive - driven dissolution enhancement of colloidal silica. : 2. environmentally friendly additives and natural products [texte imprimé] / Konstantinos D. Demadis, Auteur ; Eleftheria Mavredaki, Auteur ; Maria Somara, Auteur . - 2012 . - pp. 13866–13876. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 50 N° 24 (Décembre 2011) . - pp. 13866–13876 Mots-clés : Colloidal  silica Résumé : The effect of various environmentally friendly chemical additives and natural products on the dissolution of amorphous silica (Aerosil 200 and laboratory-synthesized, SSD) is studied. The silica scale dissolvers tested include the following: ascorbic acid (vitamin C, ASC), citric acid (CITR), carboxymethyl inulin (CMI), 3,4-dihydroxybenzoic acid (catechuic acid, DHBA), 3,4,5-trihydroxybenzoic acid (gallic acid, GA), dopamine hydrochloride (DOPA), iminodiacetic acid (IDA), histidine (HIST), phenylalanine (PHALA), and malic acid (MAL). The chemical structures of these chemical additives contain potentially dissolution-active moieties, such as 1,2-dihydroxyethylene (ASC), α-hydroxycarboxylate (MAL and CITR), catecholate (DHBA, GA, and DOPA), α-aminocarboxylate (HIST and PHALA, both aminoacids), and finally carboxy-modified fructofuranose units (CMI). It was found that all studied molecules showed variable dissolution efficiency, with MAL, CMI, HIST, and PHALA being the slowest/least effective dissolvers, and the catechol-containing DHBA, GA, and DOPA being the most effective ones. IDA and CITR have intermediate efficiency. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie201798e

Catalytic effect of magnesium ions on silicic acid polycondensation and inhibition strategies based on chelation / Konstantinos D. Demadis in Industrial & engineering chemistry research, Vol. 51 N° 26 (Juillet 2012) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 51 N° 26 (Juillet 2012) . - pp. 9032-9040 Titre : Catalytic effect of magnesium ions on silicic acid polycondensation and inhibition strategies based on chelation Type de document : texte imprimé Auteurs : Konstantinos D. Demadis, Auteur ; Antonia Ketsetzi, Auteur ; Eva-Maria Sarigiannidou, Auteur Année de publication : 2012 Article en page(s) : pp. 9032-9040 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Condensation  polymerization  Catalytic  reaction Résumé : The catalytic role of Mg2+ ions in the polycondensation of silicic acid to form amorphous silica has been investigated in detail. This behavior is pH-dependent. As pH increases (herein, the three pH values 8.0, 9.0, and 9.5 were tested), the catalytic effect of Mg2+ ions becomes more pronounced. Also, this behavior is directly proportional to the concentration of Mg2+. Ethylenediaminetetraacetic acid (EDTA) can inhibit this catalytic effect by strongly chelating the Mg2+ ions. This research can be further expanded to other chelating agents that have an affinity for Mg2+ ions. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=26107461 [article] Catalytic effect of magnesium ions on silicic acid polycondensation and inhibition strategies based on chelation [texte imprimé] / Konstantinos D. Demadis, Auteur ; Antonia Ketsetzi, Auteur ; Eva-Maria Sarigiannidou, Auteur . - 2012 . - pp. 9032-9040. Industrial chemistry Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 51 N° 26 (Juillet 2012) . - pp. 9032-9040 Mots-clés : Condensation  polymerization  Catalytic  reaction Résumé : The catalytic role of Mg2+ ions in the polycondensation of silicic acid to form amorphous silica has been investigated in detail. This behavior is pH-dependent. As pH increases (herein, the three pH values 8.0, 9.0, and 9.5 were tested), the catalytic effect of Mg2+ ions becomes more pronounced. Also, this behavior is directly proportional to the concentration of Mg2+. Ethylenediaminetetraacetic acid (EDTA) can inhibit this catalytic effect by strongly chelating the Mg2+ ions. This research can be further expanded to other chelating agents that have an affinity for Mg2+ ions. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=26107461

Controlled release of bis(phosphonate) pharmaceuticals from cationic biodegradable polymeric matrices / Konstantinos D. Demadis in Industrial & engineering chemistry research, Vol. 50 N° 9 (Mai 2011) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 50 N° 9 (Mai 2011) . - pp. 5873-5876 Titre : Controlled release of bis(phosphonate) pharmaceuticals from cationic biodegradable polymeric matrices Type de document : texte imprimé Auteurs : Konstantinos D. Demadis, Auteur ; Maria Paspalaki, Auteur ; Joanna Theodorou, Auteur Année de publication : 2011 Article en page(s) : pp. 5873-5876 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Bis(phosphonate)  Biodegradable  Polymeric Résumé : Herein, the controlled release of etidronic acid (hydroxyethylidene-bis(phosphonic) acid), an important drug for osteoporotic conditions, immobilized onto cationic polymeric matrices, such as polyethyleneimine (PEI) or cationic inulin (CATIN) is reported. Several CATIN- and PEI-etidronate composites have been synthesized at various pH regions and characterized. Tablets with starch as the excipient containing the active ingredient (polymer-etidronate composite) were prepared, and the controlled release of etidronate was studied at aqueous solutions of pH 3 (to mimick the pH of the stomach) for 8 h. All studied composites showed a delayed etidronate release in the first 4 h, compared to the “control” (a tablet containing only starch and etidronic acid, without the polymer). DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie102546g [article] Controlled release of bis(phosphonate) pharmaceuticals from cationic biodegradable polymeric matrices [texte imprimé] / Konstantinos D. Demadis, Auteur ; Maria Paspalaki, Auteur ; Joanna Theodorou, Auteur . - 2011 . - pp. 5873-5876. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 50 N° 9 (Mai 2011) . - pp. 5873-5876 Mots-clés : Bis(phosphonate)  Biodegradable  Polymeric Résumé : Herein, the controlled release of etidronic acid (hydroxyethylidene-bis(phosphonic) acid), an important drug for osteoporotic conditions, immobilized onto cationic polymeric matrices, such as polyethyleneimine (PEI) or cationic inulin (CATIN) is reported. Several CATIN- and PEI-etidronate composites have been synthesized at various pH regions and characterized. Tablets with starch as the excipient containing the active ingredient (polymer-etidronate composite) were prepared, and the controlled release of etidronate was studied at aqueous solutions of pH 3 (to mimick the pH of the stomach) for 8 h. All studied composites showed a delayed etidronate release in the first 4 h, compared to the “control” (a tablet containing only starch and etidronic acid, without the polymer). DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie102546g