5 research outputs found
New use for succinylated sugarcane bagasse containing adsorbed Cu2+ and Ni2+ : efficient catalysts for gas-phase n-hexane and n-heptane oxidation reactions.
This study describes the use of succinylated twice-mercerized sugarcane bagasse containing adsorbed
Cu2+ or Ni2+ ions from spiked aqueous solutions (2MSBA-Cu and 2MSBA-Ni) as heterogeneous catalysts
for the catalytic oxidation of n-hexane and n-heptane in gas phase. To the best of our knowledge, this
is the first study in which a spent adsorbent material based on lignocellulose biomass is used in the
catalytic oxidation of volatile organic compounds. The adsorbent and spent adsorbent materials were
characterized by FTIR, TGA and XRD. The amount of Cu2+ and Ni2+ adsorbed on 2MSBA was 0.49 and
2.49 mmol g?1, respectively. The catalysts were active for total oxidation of n-hexane and n-heptane,
even at low temperatures. 2MSBA-Cu exhibited higher catalytic activity than 2MSBA-Ni and surprisingly
their performances were comparable or superior to those of some catalysts reported in the literature,
including noble metal-based catalysts
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
Synthesis and application of a new carboxylated cellulose derivative. Part II : removal of Co2+, Cu2+ and Ni2+ from bicomponent spiked aqueous solution.
In the second part of this series of studies, the competitive adsorption of three binary systems Cu2+?Co2+,
Cu2+?Ni2+ and Co2+?Ni2+ on a carboxylated cellulose derivative (CTA) was evaluated in binary equimolar
(1:1) metal?ion aqueous solutions. Bicomponent adsorption studies were developed as a function of contact
time and initial metal ion concentration. Bicomponent adsorption kinetic data was modeled by
monocomponent kinetic models of pseudo-first- (PFO) and pseudo-second-order (PSO) and a competitive
kinetic model of Corsel. Bicomponent adsorption isotherm data was modeled by the ideal adsorbed solution
theory (IAST) and real adsorbed solution theory (RAST) models. The monocomponent isotherm models
implemented into the IAST were the Langmuir and Sips models, whereas for the RAST model only the
Langmuir model was implemented because this model provided the best prediction of the bicomponent
isotherm data. The surface of the CTA adsorbent after bicomponent adsorption of metal ions was also
examined by SEM-EDX. The effect of one metal ion on the adsorption capacity of another metal ion
was discussed in detail with basis on the kinetic and thermodynamics parameters. The selectivity and
performance of the CTA adsorbent for the removal of Cu2+, Co2+ and Ni2+ was also evaluated and
discussed
Trimellitated sugarcane bagasse : a versatile adsorbent for removal of cationic dyes from aqueous solution. Part II: batch and continuous adsorption in a bicomponent system.
In the second part of this series of studies, the bicomponent adsorption of safranin-T (ST) and auramine-O (AO) on trimellitated sugarcane bagasse (STA) was evaluated using equimolar dye aqueous solutions at two pH values. Bicomponent batch adsorption was investigated as a function of contact time, solution pH and initial concentration of dyes. Bicomponent kinetic data were fitted by the pseudo-first-order and pseudo-second-order models and the competitive model of Corsel. Bicomponent equilibrium data were fitted by the real adsorbed solution theory model. The antagonistic interactions between ST and AO in the adsorption systems studied contributed to obtain values of maximum adsorption capacity in mono- (Qmax,mono) and bicomponent (Qmax,multi) lower than unity (Qmax,multi/Qmax,mono at pH 4.5 for ST of 0.75 and AO of 0.37 and at pH 7 for ST of 0.94 and AO of 0.43). Mono- and bicomponent adsorption of dyes in a fixed-bed column was evaluated at pH 4.5. The breakthrough curves were fitted by the Thomas and Bohart-Adams original models. Desorption of ST in a fixed-bed column was studied. The results obtained from the bicomponent batch and continuous adsorption showed that the presence of ST most affected the AO adsorption than the presence of AO affected the ST adsorption
Trimellitated sugarcane bagasse : a versatile adsorbent for removal of cationic dyes from aqueous solution. Part I : batch adsorption in a monocomponent system.
Trimellitated-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 energy and entropy of adsorption were calculated. These thermodynamic
parameters were also used to evaluate the adsorption
mechanism at both pH values