Navegando por Autor "Patino Agudelo, Alvaro Javier"
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Item Aggregation of sodium dodecylbenzene sulfonate : weak molecular interactions modulated by imidazolium cation of short alkyl chain length.(2020) Patino Agudelo, Alvaro Javier; Ferreira, Guilherme Max Dias; Ferreira, Gabriel Max Dias; Coelho, Yara Luiza; Hudson, Eliara Acipreste; Pires, Ana Clarissa dos Santos; Silva, Luis Henrique Mendes daIonic liquids (ILs) can modify cooperative process in aqueous solutions to a large extent, including anionic surfactant aggregation. Here, the micellization of sodium dodecylbenzene sulfonate (SDBS) was evaluated in low concentrations of 1-alkyl-3-methylimidazolium chloride (CnmimCl, n = 0, 2, and 4) aqueous solutions through fluorescence spectroscopy, isothermal titration calorimetry, dynamic light scattering, and conductometry. The thermodynamic stability of SDBS aggregates strongly depended on the IL structure and concentration, following the order C4mim+ > C0mim+ ≈ C2mim+. At 1.0 mmol L−1 of the ILs, the increase of the hydrophobicity of the imidazolium cation decreased the enthalpic favorableness, changing from −3.75 ± 0.07 kJ mol−1, for C0mim+, to −2.69 ± 0.01 kJ mol−1, for C4mim+. On the other hand, the entropic feasibility showed an opposite trend, i.e., the higher hydrophobicity of C4mim+ overcame the kosmotropic effect of IL cations in the bulks. We suggested that the imidazolium cations interact with the SDBS monomers on the micellar surface, mainly through hydrophobic, π-π, and electrostatic interactions for C4mim+ and C2mim+, and through electrostatic interactions and hydrogen bonds for C0mim+.Item Batch and continuous adsorption of Cu(II) and Zn(II) ions from aqueous solution on bi‐functionalized sugarcane‐based biosorbent.(2022) Teodoro, Filipe Simões; Soares, Liliane Catone; Filgueiras, Jefferson Gonçalves; Azevedo, Eduardo Ribeiro de; Patino Agudelo, Alvaro Javier; Herrera Adarme, Oscar Fernando; Silva, Luis Henrique Mendes da; Gurgel, Leandro Vinícius AlvesA new one-pot synthesis method optimized by a 23 experimental design was developed to prepare a biosorbent, sugarcane bagasse cellulose succinate pyromellitate (SBSPy), for the removal of Cu(II) and Zn(II) from single-component aqueous solutions, in batch and continuous modes. The bi-functionalization of the biosorbent with ligands of diferent chemical structures increased its selectivity, improving its performance for removing pollutants from contaminated water. The suc- cinate moiety favored Cu(II) adsorption, while the pyromellitate moiety favored Zn(II) adsorption. Sugarcane bagasse (SB) and SBSPy were characterized using several techniques. Analysis by 13C Multi-CP SS NMR and FTIR revealed the best order of addition of each anhydride that maximized the chemical modifcation of SB. The maximum adsorption capacities of SBSPy for Cu(II) and Zn(II), in batch mode, were 1.19 and 0.95 mmol g-1, respectively. Homogeneous surface difusion, intraparticle difusion, and Boyd models were used to determine the steps involved in the adsorption process. Isothermal titration calorimetry was used to assess changes in enthalpy of adsorption as a function of SBSPy surface coverage. Fixed- bed column adsorption of Cu(II) and Zn(II) was performed in three cycles, showing that SBSPy has potential to be used in water treatment. Breakthrough curves were well ftted by the Thomas and Bohart-Adams models.Item Comportamento de fase e aspectos interacionais de sistemas aquosos bifásicos formados por sais de tiocianato e surfactante não iônico triton X.(2022) Gonçalves, Gessyca Rosa Silva; Ferreira, Gabriel Max Dias; Cardoso, Marcus Vinícius Cangussu; Ferreira, Gabriel Max Dias; Cardoso, Marcus Vinícius Cangussu; Patino Agudelo, Alvaro Javier; Virtuoso, Luciano SindraNeste trabalho foram obtidos dados de equilíbrio líquido-líquido para sistemas aquosos bifásicos (SABs) formados por surfactante não iônico triton X (triton X-165 ou triton X- 305) + sal (tiocianato de sódio (NaSCN), tiocianato de amônio (NH4SCN) ou tiocianato de potássio (KSCN) + água, em diferentes temperaturas (298,2, 313,2 e 328,2 K). Os diagramas de fase dos SABs investigados foram obtidos pelo método de quantificação das fases, sendo discutidos os efeitos da mudança de temperatura, do aumento da cadeia hidrofílica do surfactante e da mudança do cátion formador do sal sobre os dados de equilíbrio. Além disso, aspectos interacionais associados com as propriedades dos SABs foram discutidos a partir dos dados de equilíbrio e de análises de RMN. Para os SABs formados com NaSCN ou KSCN, constatou-se que a fase superior foi rica em surfactante (wTX ≥ 25,43% m/m), ao mesmo tempo em que apresentou elevada concentração de sal (wsal ≥ 26,50% m/m), enquanto a fase inferior foi rica em sal (wsal ≥ 35,45% m/m) e com concentrações de surfactante próximas de 0% m/m. Por outro lado, nos SABs formados com NH4SCN foi verificado uma inversão de fase, em que a fase superior passou a ser a fase rica em sal (wsal ≥ 47,59% m/m) e a fase inferior passou a ser a fase rica em surfactante (wTX ≥ 28,63% m/m), com esta última também contendo elevadas concentrações de sal. Foi observado que o tamanho da região bifásica dependeu do cátion formador do sal e aumentou na ordem: K+ > Na+ > NH4 + . Além disso, o aumento da temperatura promoveu um leve aumento da região bifásica dos SABs, sendo a magnitude desse efeito maior no sistema formado por NaSCN. Foi verificado que o surfactante TX– 305 foi mais eficiente para induzir a separação de fases que o surfactante TX–165, sendo este efeito atribuído à maior massa molar do TX–305. Além disso, verificou-se que para determinadas condições termodinâmicas, os SABs formados com NaSCN apresentaram a capacidade de formar sistemas com uma fase líquida em equilíbrio com uma fase de aspecto de gel. A partir dos resultados de RMN, pode-se inferir que a capacidade relativa de indução de fase foi associada ao efeito combinado do cátion com o ânion SCNsobre a estrutura da água, em que a combinação do cátion NH4 + com aqueles ânions é mais eficiente para diminuir a contribuição entrópica que induz o sistema a se separar em duas fases. Os resultados obtidos trazem avanços e perspectivas relevantes para estudos que visem à compreensão dos processos que regem a formação de SABs baseados em surfactantes não iônicos.Item Lactoferrin denaturation induced by anionic surfactants : the role of the ferric ion in the protein stabilization.(2018) Ferreira, Gabriel Max Dias; Ferreira, Guilherme Max Dias; Patino Agudelo, Alvaro Javier; Hudson, Eliara Acipreste; Pires, Ana Clarissa dos Santos; Silva, Luis Henrique Mendes daHere, investigation was made of the interaction between lactoferrin (Lf) and the anionic surfactants sodium dodecyl sulfate (SDS), sodium dodecylbenzene sulfonate (SDBS), and sodium decyl sulfate (DSS), using isothermal titration calorimetry, Nano differential scanning calorimetry (NanoDSC), and fluorescence spectroscopy. The Lf-surfactant interaction was enthalpically favorable (the integral enthalpy change ranged from −5.99 kJ mol−1, for SDS at pH 3.0, to −0.61 kJ mol−1, for DSS at pH 12.0) and promoted denaturation of the protein. The Lf denaturation efficiency followed the order DSS < SDS < SDBS. The adsorption capacity of the protein with respect to surfactant strongly depended on pH and the surfactant structure, reaching a maximum value of 505 SDBS molecules per gram of Lf at pH 3.0. The different efficiencies of the surfactants in denaturing Lf were attributed to the balance of hydrophobic and electrostatic interactions, which also depended on pH and the surfactant structure, highlighting the SDBS-tryptophan residue specific interaction, where SDBS acted as a quencher of fluorescence. Interestingly, the NanoDSC and fluorescence measurements showed that the ferric ion bound to Lf increased its stability against denaturation induced by the surfactants. The results have important implications for understanding the influence of surfactants on structural changes in metalloproteins.Item New insights into the partitioning of phenothiazine dyes in aqueous two-phase systems.(2020) Coelho, Yara Luiza; Patino Agudelo, Alvaro Javier; Ferreira, Guilherme Max Dias; Ferreira, Gabriel Max Dias; Castro, Alan Stampini Benhame de; Hudson, Eliara Acipreste; Pires, Ana Clarissa dos Santos; Silva, Luis Henrique Mendes daAqueous two-phase systems (ATPSs) have proven to be efficient and environmentally safe methods for extracting chemical species. However, the driving forces behind the partition of solutes in these systems are still little understood. A complete thermodynamic partitioning of phenothiazine dyes was investigated in poly(ethylene oxide) (PEO) + salt + water ATPSs. Standard transfer parameters (Gibbs free energy change (ΔtrGo ), enthalpy change (ΔtrHo ) and entropy change (TΔtrSo )) were evaluated, and their dependence on the dye structure, electrolyte nature and tie line length (TLL). All phenothiazine dyes are concentrated predominantly in the polymer enriched phase, with ΔtrGo values ranging from −4.1 up to −13.4 kJ mol−1. Due to the dye-PEO attractive interactions that occur mainly via benzene condensed ring present in the structures of phenothiazine dyes, the partitioning of these dyes was enthalpically driven, with −11.4 ≥ ΔtrHo ≥ −52 kJ mol−1 and −4.93 ≥ TΔtrSo ≥ −38 kJ mol−1.Item Solvophobic effect of 1-alkyl-3-methylimidazolium chloride on the thermodynamic of complexation between β-cyclodextrin and dodecylpyridinium cation.(2019) Patino Agudelo, Alvaro Javier; Coelho, Yara Luiza; Ferreira, Guilherme Max Dias; Ferreira, Gabriel Max Dias; Hudson, Eliara Acipreste; Pires, Ana Clarissa dos Santos; Silva, Luis Henrique Mendes daPreferential solvation participate in various supramolecular self-assembly processes, whose thermodynamic properties can be modulated by the addition of ionic liquids (ILs). However, the effects of these liquids on the thermodynamics of the host-guest complexation process remain unexplored. In this study, the thermodynamic properties of the complexation between 1-dodecylpyridinium cations (C12Py+) and β-cyclodextrin (βCD) species in aqueous solutions with different concentrations of 1-alkyl-3-methylimidazolium halides (CnmimX) were investigated by isothermal titration calorimetry. In water, C12Py+ and βCD form a 1:1 inclusion complex, which is enthalpically ( −9.2 ± 0.1 kJ mol−1) and entropically ( 16.1 ± 0.2 kJ mol−1) favorable. However, in IL aqueous solutions, all the βCD―C12Py+ thermodynamic parameters of the complexation change and this IL effect is dependent on the carbon chain length of Cnmim+ cations. ILs with shorter alkyl chains (Cnmim+, n ≤ 4) decreases the system entropy, while ILs with longer alkyl chains (Cnmim+, n ≥ 6) reduce the enthalpy values. These effects are attributed to i) preferential solvation of surfactant tails by ILs; ii) ability of the ILs to modify the 3D water structure and iii) inclusion of IL molecules into the inner cavities of βCD.