Some New Data for Metal Desorption on Inorganic–Organic Hybrid Materials

Cestari, Antonio R.; Vieira, Eunice F.S.; Bruns, Roy E.; Airoldi, Cláudio

doi:10.1006/jcis.2000.6841

Cited by 17 publications

(14 citation statements)

References 30 publications

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“…The adsorption and thermochemical data acquired can give important information on the quantity and energetics of dye interactions with chitosan. The adsorption capacity is mainly due to the protonated amine groups of chitosan, since the hydroxyl groups did not contribute to this kind of adsorption, whereas they are strongly solvated in aqueous solution (1,2,23).…”

Section: Resultsmentioning

confidence: 99%

“…where C s is the final concentration (mol/L) in the supernatant at each concentration at equilibrium, N s is the amount of necessary dye for the formation of the monolayer, and b is a constant related to the intensity of the adsorption (12,18,(20)(21)(22)(23). The isotherms of adsorption, N f versus C s , are shown in Fig.…”

Section: Treatment Of the Isotherms Datamentioning

confidence: 99%

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Interaction of Indigo Carmine Dye with Chitosan Evaluated by Adsorption and Thermochemical Data

Anjos

Vieira

Cestari

2002

Journal of Colloid and Interface Science

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Section: Resultsmentioning

confidence: 99%

Section: Treatment Of the Isotherms Datamentioning

confidence: 99%

Interaction of Indigo Carmine Dye with Chitosan Evaluated by Adsorption and Thermochemical Data

Anjos

Vieira

Cestari

2002

Journal of Colloid and Interface Science

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“…This is a clear evidence of the pH effect and confirms definitively the importance of pH. The optimum pH varies with the source of enzyme and also depends on the phenolic substrate chosen for the assay, 2,25,26 but it can also be affected by the type of buffer and the purity of the enzyme. 1 The observed antagonistic principal effect for the kind of PVP results from the best extraction conditions at low pH values, near to 4.0, where the hydrogen bonding PVPbiophenols are maximized.…”

Section: Multivariate Studiesmentioning

confidence: 53%

“…Univariate procedures, often used in studies involving the performance of several enzymes, are not capable of recognizing these important interactive effects. 4,17,20,24,25 Despite the best univariate results for SB-100, the kind of Polyclar seems not to have significant importance for PPOcatalyzed reactions. Additional information on the interaction PVP-enzymes can be found by specific references in this field.…”

Section: Discussionmentioning

confidence: 99%

“…17,24 The principal and interactive effects (E f(i) ) of the factors on the PPO activity can be calculated from the results in Table 2, using the following equation: 17,24,25 (2) where R +,i and R -,i are average values of the enzymatic activity for the high (+) and low (-) levels of each of the three factors i=1-3. Since independent duplicate experiments were performed as indicated in Table 2, standard error for principal and interactive effect values (E) can be calculated as follows: 17,20 (3)…”

Section: Multivariate Studiesmentioning

confidence: 99%

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Factorial Design Evaluation of Some Experimental Factors for Phenols Oxidation using Crude Extracts from Jackfruit (Artocarpus integrifolia)

Cestari

Vieira

Nascimento

et al. 2002

J. Braz. Chem. Soc.

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Este estudo apresenta algumas informações adicionais sobre a utilização alternativa do extrato bruto da jaca, em reações de oxidação seletivas de fenóis. Foram avaliados os substratos catecol, o-, me p-cresóis e pirogalol. Estudaram-se também os efeitos do pH, da concentração do tampão fosfato, bem como a utilização de alguns tipos de agentes extratores de biofenóis. Utilizando-se o procedimento convencional univariado, a atividade enzimática foi maior com o substrato catecol, em tampão fosfato pH 5,0, de concentração 0,10 mol L -1 e agente comercial extrator de fenóis Polyclar SB-100 â . Usando-se um planejamento fatorial, do tipo 2 3 , constatou-se que os melhores desempenhos catalíticos foram em pH 5,0 e concentração de tampão 0,050 mol L -1 , para o substrato catecol. A variação no tipo de extrator não mostrou importância estatística. Pelo método multivariado, obtiveram-se os melhores resultados para a oxidação seletiva do catecol. Assim, conclui-se que para aumentar o desempenho catalítico do extrato, deve-se utilizar preferencialmente a metodologia multivariada.This study presents some additional information on the alternative utilization of Jackfruit crude extracts in selective phenol oxidation reactions, using catechol and the o-, m-e p-cresols and pyrogallol substracts. The effects of pH, concentration of phosphate buffer and kinds of natural phenol extractors are evaluated. By using the conventional univariate procedure, the best enzymatic activities were obtained with the catechol substract, phosphate buffer (pH 5.0) at a concentration 0.10 mol L -1 , and the commercial polymer Polyclar SB-100 â as natural phenol extractor. Using a full 2 3 factorial design the best catalytic results were obtained by employing phosphate buffer at pH 5.0 and it 0.050 mol L -1 . However, the kind of phenol extractor was not statistically important. The best results for selective catechol oxidation were obtained by using the multivariate technique. In this way, the multivariate methodology is indicated to increase the performance of the crude extract in the selective oxidation reactions.Keywords: homogeneous enzymatic catalysis, jackfruit, phenol oxidations, factorial designs IntroductionRecently, an increasing trend has been observed in the use of new biocatalytic materials in place of pure enzymes, for the development of several different research lines, especially those related to the development of biosensors 1 and enzyme-catalyzed methods of analysis. 2 The use of such materials offers some advantages with regard to those procedures based on the use of pure and isolated enzymes, especially by providing a better lifetime and lower cost. 3,4 Natural and undesirable browning reactions, using atmospheric oxygen as oxidant, occur by the catalysis of, mainly, the enzyme polyphenol oxidase (PPO). 3-5 PPO is a copper-containing oxidase having catecholase and/or cresolase activity. PPO catalyses o-hydroxylation of monophenols to give o-diphenols (cresolase activity) and o-diphenols to o-quinones (catecholase activity). For P...

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Selective Ion Pair Adsorption of Cobalt and Copper Salts on Cationically Produced Poly(1,3-divinylimidazolid-2-one)/Silica Hybrid Particles

Meyer

Prause

Spange

et al. 2001

Journal of Colloid and Interface Science

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Some New Data for Metal Desorption on Inorganic–Organic Hybrid Materials

Cited by 17 publications

References 30 publications

Interaction of Indigo Carmine Dye with Chitosan Evaluated by Adsorption and Thermochemical Data

Interaction of Indigo Carmine Dye with Chitosan Evaluated by Adsorption and Thermochemical Data

Factorial Design Evaluation of Some Experimental Factors for Phenols Oxidation using Crude Extracts from Jackfruit (Artocarpus integrifolia)

Selective Ion Pair Adsorption of Cobalt and Copper Salts on Cationically Produced Poly(1,3-divinylimidazolid-2-one)/Silica Hybrid Particles

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