a b s t r a c tA 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: k 2,Ni 2+ > k 2,Cu 2+ > k 2,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 (Q max,mono ) obtained from the Langmuir model were 1.140, 1.197, and 1.563 mmol/g for Co 2+ , Cu 2+ , and Ni 2+ , respectively. The competitive studies demonstrated that the multicomponent adsorption capacity (Q max,multi ) was smaller than Q max,mono , as a result of the interaction between the metal ions. Desorption studies showed that all metal ions could be fully desorbed from STA.
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 (χ) on the responses weight gain (wg), number of carboxylic acid groups (n), and adsorption capacity (q) of Co and Ni were evaluated by a 2 experimental design. The chemical structure of the material was elucidated by Fourier transform infrared, C Multiple Cross-Polarization solid-state NMR spectroscopy andH NMR relaxometry. The best SBSPh synthesis condition (100 °C, 11 h, χ of 0.2) yielded a wg of 59.1%, n of 3.41 mmol g, and values of q and q of 0.348 and 0.346 mmol g, 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 for Co and Ni, respectively. The ΔH° values estimated by isothermal titration calorimetry were 8.43 and 7.79 kJ mol for Co and Ni, respectively. Desorption and re-adsorption efficiencies were evaluated by a 2 experimental design, which showed that SBSPh adsorbent can be recovered and reused without significant loss of adsorption capacity.
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, and at pH 7.0 were 5.443 and 4.074 mmol g, respectively. Bicomponent maximum adsorption capacities for AO and ST at pH 7.0 were 1.230 and 3.728 mmol g. Adsorption enthalpy changes (ΔH) were obtained using isothermal titration calorimetry. The values of ΔH ranged from -18.83 to -5.60 kJ mol, suggesting that physisorption controlled the adsorption process. Desorption and re-adsorption of CTA was also evaluated.
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