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Item Remoção dos corantes Reactive Blue 21 e Direct Red 80 utilizando resíduos de sementes de Mabea fistulifera Mart. como biossorvente(Revista Ambiente & Água, 2012-01) Silveira Neta, Julieta de Jesus da; Silva, Carlos Juliano da; Moreira, Guilherme Costa; Reis, César; Reis, Efraim LázaroNeste estudo empregou-se resíduos de Mabea fistulifera Mart. como bioadsorvente para a remoção dos corantes Reactive Blue 21 (RB 21) e Direct Red 80 (DR 80) em soluções aquosas e em amostras de efluentes reais fortificados com estes corantes. Foram investigados os ensaios da influência do pH, cinéticos e adsortivos para a remoção dos corantes por meio de uma série de experimentos de batelada. O bioadsorvente exibiu máxima adsorção em pH = 2,0 para ambos os corantes. O tempo de equilíbrio da adsorção foi estabelecido em 300 minutos para o DR 80 e 120 minutos para o RB 21. O modelo de Langmuir descreveu com maior fidelidade o comportamento do sistema sortivo, apresentando coeficiente de determinação (R 2 ) superior a 0,98. Por meio da Isoterma de Langmuir, foi possível obter a capacidade máxima de adsorção dos corantes Direct Red 80 e Reactive Blue 21 pelo bioadsorvente sendo encontrados os valores de 4,92 mg g-1 e 11,13 mg g-1 , respectivamente. O modelo cinético de pseudo-segunda ordem melhor descreveu o processo de adsorção do corante RB 21 sob o bioadsorvente, embora a difusão intra-partícula também esteja envolvida no mecanismo de adsorção. Já para o corante DR 80 o modelo de difusão de Morris e Weber sugeriu que a difusão intra-partícula é predominante em todo o processo de adsorção. Depois de otimizadas as condições adsortivas, o bioadsorvente foi empregado a amostras de efluentes têxteis reais fortificadas com soluções aquosas dos corantes, obtendo-se 85 % de remoção do RB 21 e 94 % de remoção do DR 80 na matriz do efluente.Item Synthesis and application of sugarcane bagasse cellulose mixed esters. Part I: Removal of Co2+ and Ni2+ from single spiked aqueous solutions in batch mode using sugarcane bagasse cellulose succinate phthalate(Journal of Colloid and Interface Science, 2019-01-01) Silva, Luis Henrique Mendes da; Elias, Megg Madonyk Cota; Ferreira, Gabriel Max Dias; Almeida, Francine Tatiane Rezende de; Rosa, Nathália Cristina Martins; Silva, Isabela Almeida; Filgueiras, Jefferson Gonçalves; Azevedo, Eduardo Ribeiro de; Melo, Tânia Márcia Sacramento; Gil, Laurent Frédéric; Gurgel, Leandro Vinícius AlvesSugarcane bagasse cellulose mixed ester succinate phthalate (SBSPh) was synthesized by a novel one-pot reaction method. The effects of temperature, time and mole fraction of succinic anhydride (χSA) on the responses weight gain (wg), number of carboxylic acid groups (nT,COOH), and adsorption capacity (q) of Co2+ and Ni2+ were evaluated by a 23 experimental design. The chemical structure of the material was elucidated by Fourier transform infrared, 13C Multiple Cross-Polarization solid-state NMR spectroscopy and 1H NMR relaxometry. The best SBSPh synthesis condition (100 °C, 11 h, χSA of 0.2) yielded a wg of 59.1%, nT,COOH of 3.41 mmol g−1, and values of qCo2+ and qNi2+ of 0.348 and 0.346 mmol g−1, respectively. The Sips model fitted better the equilibrium data, and the maximum adsorption capacities (pH 5.75 and 25 °C) estimated by this model were 0.62 and 0.53 mmol g−1 for Co2+ and Ni2+, respectively. The ΔadsH° values estimated by isothermal titration calorimetry were 8.43 and 7.79 kJ mol−1 for Co2+ and Ni2+, respectively. Desorption and re-adsorption efficiencies were evaluated by a 22 experimental design, which showed that SBSPh adsorbent can be recovered and reused without significant loss of adsorption capacity.Item Evaluation of direct red 80 dye adsorption by chitosan microspheres(The Journal of Engineering and Exact Sciences – JCEC, 2018) Rocha, Thaynara Mendonça; Puiatti, Gustavo Alves; Cruz, Felipe Santana de Oliveira; Moreira, Renata Pereira Lopes; Oliveira, Andre Fernando deThe damage caused to the environment by the textile industry creates a demand for simple and inexpensive methods to remove dyes from wastewaters. In this sense, the objective of this work was to evaluate and optimize the adsorption of the Direct Red 80 azo dye by chitosan microspheres. The SEM and FTIR techniques were used to characterize the materials. The results confirmed the occurrence of the adsorption phenomenon by the detection of characteristic bands and changes on the surface of the adsorbent, caused by the fixing of the dye. The response surface methodology in association with a Doehlert matrix was applied to optimize the adsorption process. The obtained response surface presented a saddle point, indicating that the optimal condition is outside of the experimental domain. Isotherms were constructed to describe the adsorption phenomenon. The experimental data presented a better regression adjustment (R 2 > 0.98) to the Freundlich nonlinear model. The results demonstrate that the chitosan microspheres presented high color removal efficiency (97% in 24h) and operational ease in its usage.Item Synthesis and application of a new carboxylated cellulose derivative. Part I: Removal of Co2+, Cu2+ and Ni2+ from monocomponent spiked aqueous solution(Journal of Colloid and Interface Science, 2016-12) Ferreira, Gabriel Max Dias; Silva, Luis Henrique Mendes da; Teodoro, Filipe Simões; Ramos, Stela Nhandeyara do Carmo; Elias, Megg Madonyk Cota; Mageste, Aparecida Barbosa; Gil, Laurent Frédéric; Gurgel, Leandro Vinícius AlvesA new carboxylated cellulose derivative (CTA) was prepared from the esterification of cellulose with 1,2,4-Benzenetricarboxylic anhydride. CTA was characterized by percent weight gain (pwg), amount of carboxylic acid groups (nCOOH), elemental analysis, FTIR, TGA, solid-state 13C NMR, X-ray diffraction (DRX), specific surface area, pore size distribution, SEM and EDX. The best CTA synthesis condition yielded a pwg and nCOOH of 94.5% and 6.81 mmol g−1, respectively. CTA was used as an adsorbent material to remove Co2+, Cu2+ and Ni2+ from monocomponent spiked aqueous solution. Adsorption studies were developed as a function of the solution pH, contact time and initial adsorbate concentration. Langmuir model better fitted the experimental adsorption data and the maximum adsorption capacities estimated by this model were 0.749, 1.487 and 1.001 mmol g−1 for Co2+, Cu2+ and Ni2+, respectively. The adsorption mechanism was investigated by using isothermal titration calorimetry. The values of ΔadsH° were in the range from 5.36 to 8.09 kJ mol−1, suggesting that the mechanism controlling the phenomenon is physisorption. Desorption and re-adsorption studies were also performed. Desorption and re-adsorption efficiencies were closer to 100%, allowing the recovery of both metal ions and CTA adsorbent.Item Preparation and application of self-assembled systems containing dodecylammonium bromide and chloride as corrosion inhibitors of carbon-steel(Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2012-03-20) Gurgel, Alexandre; Wanderley Neto, Alcides de Oliveira; Moura, Everlane Ferreira; Scatena Júnior, Hélio; Dantas, Tereza Neuma de Castro; Dantas Neto, Afonso AvelinoThe application of surfactant systems as inhibitors of corrosion on metallic surfaces is discussed in this work. The focus is now driven to the influence of cationic surfactants’ counterions on the adsorption mechanism at carbon-steel surfaces. The surfactants dodecylammonium bromide (DDAB) and dodecylammonium chloride (DDAC) have been synthesized and used to prepare micellar and microemulsion formulations. The surfactants were dissolved in aqueous hydrochloric acid as micellar solutions, and in microemulsions containing n-hexane as oil phase and butan-1-ol as cosurfactant. After characterization by phase behavior studies, a number of these formulations with varying surfactant concentration have been tested against acidic corrosion on carbon-steel surfaces. Potentiometry assays were carried out to determine the extent of coverage on the metallic surface, and the adsorption mechanism was modeled with the Frumkin isotherm. Efficiencies of corrosion inhibition as high as 98% were obtained for the DDAC systems, and 96% for the DDAB systems. The results suggest that the protective surfactant film could resist changes in pH, salinity and temperature that might occur during typical applications involving metallic equipment or ducts under a broad range of experimental conditions. This is particularly interesting for industrial applications of microemulsions and other self-assembled systems, which could be used as templates for novel formulations of corrosion inhibitors.Item Trimellitated sugarcane bagasse: A versatile adsorbent for removal of cationic dyes from aqueous solution. Part I: Batch adsorption in a monocomponent system(Journal of Colloid and Interface Science, 2018-01-06) Fideles, Renata Aparecida; Ferreira, Gabriel Max Dias; Teodoro, Filipe Simões; Adarme, Oscar Fernando Herrera; Silva, Luis Henrique Mendes da; Gil, Laurent Frédéric; Gurgel, Leandro Vinícius AlvesTrimellitated-sugarcane bagasse (STA) was used as an environmentally friendly adsorbent for removal of the basic dyes auramine-O (AO) and safranin-T (ST) from aqueous solutions at pH 4.5 and 7.0. Dye adsorption was evaluated as a function of STA dosage, agitation speed, solution pH, contact time, and initial dye concentration. Pseudo-first- and pseudo-second-order, Elovich, intraparticle diffusion, and Boyd models were used to model adsorption kinetics. Langmuir, Dubinin-Radushkevich, Redlich-Peterson, Sips, Hill-de Boer, and Fowler-Guggenheim models were used to model adsorption isotherms, while a Scatchard plot was used to evaluate the existence of different adsorption sites. Maximum adsorption capacities for removal of AO and ST were 1.005 and 0.638 mmol g−1 at pH 4.5, and 1.734 and 1.230 mmol g−1 at pH 7.0, respectively. Adsorption enthalpy changes obtained by isothermal titration calorimetry (ITC) ranged from −21.07 ± 0.25 to −7.19 ± 0.05 kJ mol−1, indicating that both dyes interacted with STA by physisorption. Dye desorption efficiencies ranged from 41 to 51%, and re-adsorption efficiencies ranged from 66 to 87%, showing that STA can be reused in new adsorption cycles. ITC data combined with isotherm studies allowed clarification of adsorption interactions.Item Synthesis and application of a new carboxylated cellulose derivative. Part III: Removal of auramine-O and safranin-T from mono- and bi-component spiked aqueous solutions(Journal of Colloid and Interface Science, 2017-10-25) Teodoro, Filipe Simões; Elias, Megg Madonyk Cota; Ferreira, Gabriel Max Dias; Adarme, Oscar Fernando Herrera; Savedra, Ranylson Marcello Leal; Siqueira, Melissa Fabíola; Silva, Luis Henrique Mendes da; Gil, Laurent Frédéric; Gurgel, Leandro Vinícius AlvesIn the third part of this series of studies, the adsorption of the basic textile dyes auramine-O (AO) and safranin-T (ST) on a carboxylated cellulose derivative (CTA) were evaluated in mono- and bi-component spiked aqueous solutions. Adsorption studies were developed as a function of solution pH, contact time, and initial dye concentration. Adsorption kinetic data were modeled by monocomponent kinetic models of pseudo-first- (PFO), pseudo-second-order (PSO), intraparticle diffusion, and Boyd, while the competitive kinetic model of Corsel was used to model bicomponent kinetic data. Monocomponent adsorption equilibrium data were modeled by the Langmuir, Sips, Fowler-Guggenhein, Hill de-Boer, and Konda models, while the IAST and RAST models were used to model bicomponent equilibrium data. Monocomponent maximum adsorption capacities for AO and ST at pH 4.5 were 2.841 and 3.691 mmol g−1, and at pH 7.0 were 5.443 and 4.074 mmol g−1, respectively. Bicomponent maximum adsorption capacities for AO and ST at pH 7.0 were 1.230 and 3.728 mmol g−1. Adsorption enthalpy changes (ΔadsH) were obtained using isothermal titration calorimetry. The values of ΔadsH ranged from −18.83 to −5.60 kJ mol−1, suggesting that physisorption controlled the adsorption process. Desorption and re-adsorption of CTA was also evaluated.Item Modeling, kinetic, and equilibrium characterization of paraquat adsorption onto polyurethane foam using the ion-pairing technique(Journal of Environmental Management, 2015-06-01) Vinhal, Jonas O.; Lage, Mateus R.; Carneiro, Jose Walkimar M.; Lima, Claudio F.; Cassella, Ricardo J.We studied the adsorption of paraquat onto polyurethane foam (PUF) when it was in a medium containing sodium dodecylsulfate (SDS). The adsorption efficiency was dependent on the concentration of SDS in solution, because the formation of an ion-associate between the cationic paraquat and the dodecylsulfate anion was found to be a fundamental step in the process. A computational study was carried out to identify the possible structure of the ion-associate in aqueous medium. The obtained data demonstrated that the structure is probably formed from four units of dodecylsulfate bonded to one paraquat moiety. The results showed that 94% of the paraquat present in 45 mL of a solution containing 3.90 × 10^−5 mol L^−1 could be retained by 300 mg of PUF, resulting in the removal of 2.20 mg of paraquat. The experimental data were reasonably adjusted to the Freundlich isotherm and to the pseudo-second-order kinetic model. Also, the application of Morris–Weber and Reichenberg models indicated that both film-diffusion and intraparticle-diffusion processes were active during the control of the adsorption kinetics.Item Adsorption of the herbicides diquat and difenzoquat on polyurethane foam: kinetic, equilibrium and computational studies(Ecotoxicology and Environmental Safety, 2017-08-09) Vinhal, Jonas O.; Nege, Kassem K.; Lage, Mateus R.; Carneiro, José Walkimar de M.; Lima, Claudio F.; Cassella, Ricardo J.This work reports a study about the adsorption of the herbicides diquat and difenzoquat from aqueous medium employing polyurethane foam (PUF) as the adsorbent and sodium dodecylsulfate (SDS) as the counter ion. The adsorption efficiency was shown to be dependent on the concentration of SDS in solution, since the formation of an ion-associate between cationic herbicides (diquat and difenzoquat) and anionic dodecylsulfate is a fundamental step of the process. A computational study was carried out to identify the possible structure of the ion-associates that are formed in solution. They are probably formed by three units of dodecylsulfate bound to one unit of diquat, and two units of dodecylsulfate bound to one unit of difenzoquat. The results obtained also showed that 95% of both herbicides present in 45 mL of a solution containing 5.5 mg L^−1 could be retained by 300 mg of PUF. The experimental data were well adjusted to the Freundlich isotherm (r^2 ≥ 0.95) and to the pseudo-second-order kinetic equation. Also, the application of Morris-Weber and Reichenberg equations indicated that an intraparticle diffusion process is active in the control of adsorption kinetics.Item Hydrotalcite-TiO2 magnetic iron oxide intercalated with the anionic surfactant dodecylsulfate in the photocatalytic degradation of methylene blue dye(Journal of Environmental Management, 2015-04-07) Miranda, Liany D.L.; Bellato, Carlos R.; Milagres, Jaderson L.; Moura, Luciano G.; Mounteer, Ann H.; Almeida, Marciano F. deThe new magnetic photocatalysts HT/TiO2/Fe and HT-DS/TiO2/Fe, modified with the anionic surfactant sodium dodecylsulfate (DS) were successfully synthesized in this work. Titanium dioxide (anatase) followed by iron oxide were deposited on the hydrotalcite support. Several catalyst samples were prepared with different amounts of titanium and iron. The photocatalysts were characterized by infrared and Raman spectroscopy, X-ray diffraction, scanning electron microscopy. Photocatalytic performance was analyzed by UV–visible radiation (filter cutoff, λ > 300 nm) of an aqueous solution (24 mg/L) of methylene blue (MB). The most efficient catalyst was obtained at an iron oxide:TiO2 molar ratio of 2:3. This catalyst showed high photocatalytic activity, removing 96% of the color and 61% of total organic carbon from the MB solution after 120 min. It was easily removed from solution after use because of its magnetic properties. The reuse of the HT-DS/TiO2/Fe23 catalyst was viable and the catalyst was structurally stable for at least four consecutive photocatalytic cycles.