Synthesis and application of a new carboxylated cellulose derivative. Part I : removal of Co2+, Cu2+ and Ni2+ from monocomponent spiked aqueous solution.

A 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 DadsH 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

S?ntese de um novo material adsorvente a base de baga?o de cana-de-a??car para remo??o de ?ons de metais pesados e corantes t?xteis de solu??es aquosas.

Programa de P?s-Gradua??o em Qu?mica. Departamento de Qu?mica, Instituto de Ci?ncias Exatas e Biol?gicas, Universidade Federal de Ouro Preto.A contamina??o qu?mica dos recursos h?dricos por contaminates org?nicos e inorg?nicos tais como corantes t?xteis e metais pesados vem despertando uma grande preocupa??o global devido aos problemas ambientais que a presen?a destes compostos causam. Devido aos m?todos de tratamento f?sico-qu?micos e biol?gicos tradicionalmente empregados gerarem elevados custos, m?todos alternativos como a adsor??o empregando bioadsorventes v?m sendo estudados para substituir e/ou complementar tais m?todos. Neste trabalho, o baga?o de cana-de-a??car (BC) foi modificado com os anidridos ft?lico e succic?nico em uma s?ntese em uma ?nica etapa (one pot). A s?ntese foi avaliada por meio de um planejamento fatorial 23, cujas vari?veis independentes foram temperatura, tempo e fra??o molar de anidrido succ?nico (?AS) e as vari?veis resposta foram as capacidades de adsor??o dos corantes auramina-O (AO) e safranina-T (ST) e dos metais Co+2 e Ni+2 a fim de um melhor conhecimento do sistema. O perfil de desejabilidade indicou a melhor condi??o de s?ntese em 100?C, 660 min e ?AS de 0,2 dentro do dom?nio experimental investigado e tal resultado foi satisfat?rio dentro da proposta deste estudo. O BC modificado foi caracterizado por ganho de massa, quantidade de fun??es ?cidas, PCZ, an?lise elementar, FTIR, TGA/DTG, DRX, RMN 13C em estado s?lido, MEV e EDX. Os estudos de adsor??o monocomponente revelaram que o pH de melhor adsor??o dos corantes foi 7,0 e dos metais foi 5,75. A adsor??o dos corantes seguiu uma cin?tica de Elovich, enquanto a adsor??o dos ?ons Co+2 e Ni+2 seguiu uma cin?tica de pseudo segunda ordem. As isotermas foram modeladas com os modelos de Langmuir, Sips, D-R e R-P. As capacidades m?ximas de adsor??o encontradas experimentalmente foram 1,37, 0,93, 0,53 e 0,49 mmol/g para AO, ST, Co+2 e Ni+2, respectivamente. Medidas de titula??o calorim?trica isot?rmica foram feitas e as varia??es de entalpias de adsor??o encontradas revelaram que a adsor??o dos corantes foi um processo exot?rmico e a de metais endot?rmico. A energia livre de Gibbs calculada revelou que os corantes e metais concentraram-se preferencialmente na superf?cie do baga?o de cana modificado. Os estudos de adsor??o de corantes com o BC in natura revelaram que a modifica??o qu?mica incrementou a capacidade adsortiva deste material. Estudos de dessor??o e re-adsor??o mostraram que ? poss?vel obter efici?ncias de dessor??o superiores a 42%, 54%, 83% e 95% e de re-adsor??o superiores a 98%, 76%, 90% e 100% para AO, ST, Co2+ e Ni2+, respectivamente, e, desta forma, revelaram que o BC modificado pode ser reutilizado sem perda de sua capacidade adsortiva e que o processo de dessor??o usando solu??o ?cida n?o ? agressivo, nas condi??es empregadas, mantendo a integridade das fibras do material e sua funcionalidade qu?mica.The chemical contamination of water resources by organic and inorganic pollutants such as textile dyes and heavy metals has raised a great global concern due to the environmental problems caused by the presence of these compounds. The physico-chemical and biological treatment methods commonly used for treating wastewaters are costly, and therefore, alternative methods such as adsorption using bioadsorbents have been studied to replace and/or improve such methods. In this study, the sugarcane bagasse (SB) was modified with phthalic and succinic anhydrides in a one pot synthesis, which was analized by means of a factorial design of three variables evaluated in two levels (23). The independent variables were temperature, time and mole fraction of succinic anhydride (?AS) and the response variables were adsorption capacities of dyes auramine-O (AO) and safranin-T (ST) and metals Co+2 and Ni+2 for a better understanding of the potential of the adsorbent material. The desirability profile indicated the best synthesis condition at 100?C, 660 min and ?AS of 0,2, which was a condition the experimental data gathered. This result was satisfactory for the prupose of the present study. The modified SB was characterized by weigth gain, amount of acid functions introduced, point of zero charge (PZC), elemental analysis, FTIR, TGA, DRX, solid-state 13C NMR, SEM and EDX. Monocomponent adsorption studies revealed that the pH of the best adsorption for both dyes was 7.0 and for both metal ions was 5.75. The adsorption of dyes was best described by the Elovich model while the adsorption of Co+2 and Ni+2 was best described by a pseudo-second order kinetics. The isotherms were modeled by the Langmuir, Sips, D-R and R-P models. The observed maximum adsorption capacities were 1.37,0.93,0.53 and 0.49 mmol/g for AO, ST, Co+2 and Ni+2, respectively. Isothermal calorimetric titration measurements were performed and the enthalpies of adsorption revealed that the adsorption of dyes is exothermic while the adsorption of metals is endothermic. The estimated free energy of adsorption showed that the dyes and metals concentrate preferentially on the surface of the modified SB. The adsorption studies of dyes on raw SB showed that the chemical modification increased the adsorptive capacity of the material. Desorption and re-adsorption studies showed that it is possible to obtain desorption efficiencies of 42%,54%,83% and 95% and re-adsorption efficiencies of 98%, 76%, 90% and 100% for AO, ST, Co2+ and Ni2+, respectively, and thus revealed that the modified SB can be reused without loss of its adsorptive capacity. It was also showed that the desorption process using acid solution was not aggressive, under the conditions tested, preserving the integrity of the bagasse fibers and the chemical functionality introduced

Quantification of moisture contents in iron and manganese ores.

The moisture contents of several synthetic and natural goethite-bearing samples were determined by the loss-of-mass method and by the Karl-Fischer titration. It was found that drying at 105°C did not remove all the water from these samples, and that temperatures above 200°C would be required to completely remove the adsorbed water. The multiple peaks observed in the TGA and DSC measurements are not due to the dehydroxylation of goethite, but are due to the release of adsorbed water. The decomposition of goethite into hematite occurs with the release of adsorbed water from room temperature up to the onset of the main dehydroxylation peak. The dehydroxylation occurs in a broad range of temperatures due to the existence of a particle-size distribution, surface hydroxyls and formation of a hematite coating. The determination of all adsorbed water is best performed by adding the powdered sample into the Karl- Fischer reaction vessel

Modeling mono- and multi-component adsorption of cobalt(II), copper(II), and nickel(II) metal ions from aqueous solution onto a new carboxylated sugarcane bagasse. Part I: Batch adsorption study.

A new carboxylated-functionalized sugarcane bagasse (STA) was prepared through the esterification of sugarcane bagasse with trimellitic anhydride. The optimized synthesis conditions yield STA with a percent weight gain of 73.9% and the number of carboxylic acid groups accounted for 3.78 mmol/g. STA was characterized by FTIR, elemental analysis, TGA, PZC, and SEM. Adsorption kinetics followed a pseudosecond- order model. The adsorption rate constant showed the following order: k2,Ni 2+ > k2,Cu 2+ > k2,Co 2+. Four mono- and multi-component isotherm models were used to model the adsorption systems. Monocomponent experimental data were fitted to Langmuir and Sips models; whereas, multicomponent data were fitted to modified extended Langmuir and P-factor models. The maximum adsorption capacities (Qmax,mono) obtained from the Langmuir model were 1.140, 1.197, and 1.563 mmol/g for Co2+, Cu2+, and Ni2+, respectively. The competitive studies demonstrated that the multicomponent adsorption capacity (Qmax,multi) was smaller than Qmax,mono, as a result of the interaction between the metal ions. Desorption studies showed that all metal ions could be fully desorbed from STA

Regular article synthesis and application of a new carboxylated cellulose derivative. Part I: Removal of Co 2+ , Cu 2+ and Ni 2+ from monocomponent spiked aqueous solution

A 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 Co^2+, Cu^2+ and Ni^2+ 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 Co^2+, Cu^2+ and Ni^2+, 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

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

In 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

Aminated cellulose as a versatile adsorbent for batch removal of As(V) and Cu(II) from mono- and multicomponent aqueous solutions

International audienceA bioadsorbent (CEDA) capable of adsorbing As(V) and Cu(II) simultaneously was prepared by tosylation of microcrystalline cellulose (MC) and nucleophilic substitution of the tosyl group by ethylenediamine. MC, tosyl cellulose, and CEDA were characterized by elemental C, H, N, and S analysis, infrared spectroscopy, and 13C solid-state nuclear magnetic resonance spectroscopy. The adsorption of As(V) and Cu(II) on CEDA was evaluated as a function of solution pH, contact time, and initial solute concentration. The maximum adsorption capacities of CEDA for As(V) and Cu(II) were 1.62 and 1.09 mmol g−1, respectively. The interactions of As(V) and Cu(II) with CEDA were elucidated using thermodynamic parameters, molecular quantum mechanics calculations, and experiments with ion exchange of Cd(II) by Cu(II), and As(V) by SO4 2−. Adsorption enthalpies were determined as a function of surface coverage of the CEDA, using isothermal titration calorimetry, with ΔadsH° values of −32.24 ± 0.07 and −93 ± 2 kJ mol−1 obtained for As(V) and Cu(II), respectively. The potential to reuse CEDA was evaluated and the interference of other ions in the adsorption of As(V) and Cu(II) was investigated. Multi-component experiments showed that Cd(II), Co(II), Ni(II), and Pb(II) did not interfere in the adsorption of Cu(II), while SO4 2− inhibited As(V) adsorption

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

Sugarcane 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

Synthesis and application of sugarcane bagasse cellulose mixed esters. Part II : removal of Co2+ and Ni2+ from single spiked aqueous solutions in batch and continuous mode.

Sugarcane bagasse cellulose succinate trimellitate (SBST) was prepared by a one-pot synthesis method. The synthesis of this novel mixed ester was investigated by a 23-factorial design. The parameters investigated were time, temperature, and succinic anhydride mole fraction (?SA). The responses evaluated were the adsorption capacity (qCo2+ and qNi2+), weight gain (wg), and number of carboxylic acid groups (nT,COOH). 13C Multiple Cross-Polarization solid-state NMR spectroscopy, 1H NMR relaxometry, and Fourier-transform infrared spectroscopy were used to elucidate the SBST structure. The best SBST reaction conditions were 100??C, 660?min, and ?SA of 0.2, which yielded SBST with a wg of 57.1%, nT,COOH of 4.48?mmol?g?1, and qCo2+ and qNi2+ of 0.900 and 0.963?mmol?g?1, respectively. The maximum adsorption capacities (Qmax) (pH 5.75, 25??C) estimated by the Redlich-Peterson model for Co2+ and Ni2+ were 1.16 and 1.29?mmol?g?1. The ?adsH? values for Co2+ and Ni2+ adsorption obtained by isothermal titration calorimetry were 8.03 and 6.94?kJ?mol?1. Regeneration and reuse of SBST were investigated and the best conditions applied for fixed-bed column adsorption in five consecutive cycles. SBST was fully desorbed and Qmax values for Co2+ (0.95?mmol?g?1) and Ni2+ (1.02?mmol?g?1) were estimated using the Bohart-Adams model