Wood (Bagassa guianensis Aubl) and green coconut mesocarp (cocos nucifera) residues as textile dye removers (Remazol Red and Remazol Brilliant Violet).

In this work the efficiency of two lignocellulosic waste materials, wood residues and coconut mesocarp, were investigated as adsorbents towards two representative textile dyes (Remazol Red, RR and Remazol Brilliant Violet, RBV). The moisture, carbohydrate, protein, lipid, ash and fiber contents of both natural matrices were characterized. The materials were also characterized by infrared spectroscopy, X-ray diffractometry, scanning electron microscopy, specific surface area analysis and thermogravimetry. The adsorption of dyes was monitored by using UV-Vis spectrophotometry. It was verified that both, coconut mesocarp (CM) and wood residues can act as effective adsorbents towards the investigated dyes. It is verified that the maximum adsorption capacity ΓM (mg g-1) for RBV and RR are 7.28 and 3.97 towards CM and 0.64 and 0.71 towrads SD. Furthermore, it was verified that the adsorption is strongly pH dependent and, as a general behavior, an increase in the pH value is associated with a decrease of the total amount of adsorbed dye. The adsorption of violet dye onto coconut mesocarp is well described by the Langmuir model, while all the remazol red fitted better with the Freundlich equation.

Sawdust Derivative for Environmental Application: Chemistry, Functionalization and Removal of textile dye from aqueous solution.

The adsorption of Violet Remazol 5R (VR 5) on wood sawdust modified with succinic anhydride (SSA) as a function of contact time, pH, and initial dye concentrations was investigated using a batch technique under ambient conditions. The SSA obtained was confirmed by IR spectroscopy, thermogravimetry and 13C NMR, and degrees of substitution (DS) were calculated. A study on the effect of the pH on the adsorption of VR 5 showed that the optimum pH was 2.0. The interactions were assayed with respect to the pseudo-first-order and pseudo-second-order kinetic models, and were found to follow closely the pseudo-second-order. The isotherm was adjusted to the Langmuir, the Freundlich and the Temkin sorption models. SSA is a promising material for the removal of dye textile from aqueous solutions, and under conditions studied the removal percentage achieved was 51.7%.

Immobilization of ethylene sulfide in aminated cellulose for removal of the divalent cations.

Cellulose (Cel) was first chemically modified with thionyl chloride to increase its reactivity. In the next step CelCl was reacted with ethylenediamine (CelEn) and subsequently reacted with ethylene sulfide to obtain a solid substance, CelEnEs. The modification reactions were confirmed by elemental analysis, TG, XRD, (13)C NMR and FTIR. The chemically modified biopolymer CelEnEs had an order of divalent metal sorption of Pb(2+)>Cd(2+)>Ni(2+)>Co(2+)>Cu(2+)>Zn(2+), and the maximum adsorption capacities were found to be 6.282±0.023, 5.783±0.015, 5.561±0.017, 4.694±0.013, 1.944±0.062 and 1.733±0.020 mmol g(-1), respectively. The equilibrium data were fitted to Langmuir, Freundlich and Temkin models, and in general, the experimental data best fit the Freundlich model. This newly synthesized biopolymer proved to be a chemically useful material for cations removal from aqueous solution.

Exploring the favorable ion-exchange ability of phthalylated cellulose biopolymer using thermodynamic data.

A phthalylated ion-exchange biopolymer was obtained by adding cellulose to molten phthalic anhydride in a quasi solvent-free procedure. Through this route 2.99+/-0.07 mmolg(-1) of pendant groups containing ester and carboxylic acid moieties were incorporated into the polymeric structure that was characterized by elemental analysis, solid-state carbon nuclear magnetic resonance (CP/MAS), infrared spectroscopy, X-ray diffraction, and thermogravimetry. The chemically modified polysaccharide is able to exchange cations from aqueous solution as demonstrated by batchwise methodology. The data were adjusted to a modified Langmuir equation to give 2.43+/-0.12 and 2.26+/-0.11 mmolg(-1) for divalent cobalt and nickel cations, respectively. The net thermal effects obtained from calorimetric titration measurements were also adjusted to a modified Langmuir equation, and the enthalpy of the interaction was calculated to give endothermic values of 2.11+/-0.28 and 2.50+/-0.31kJmol(-1) for these cations, respectively. The spontaneity of this ion-exchange process is reflected in negative Gibbs energy and with a contribution of positive entropic values. This set of thermodynamic data at the solid-liquid interface suggests a favorable ion-exchange process for this anchored biopolymer for cation exchange from the environment.

Immobilization of ethylenesulfide on babassu coconut epicarp and mesocarp for divalent cation sorption.

A new synthetic methodology route consisted in reacting the natural babassu coconut mesocarp (BCM) and babassu coconut epicarp (BCE) with ethylenesufide, for adding basic sulfur centers in pendant chains that possess high potential activity for coordinating divalent cations from aqueous solution. All biomaterials were characterized by elemental analysis, infrared (IR), (13)C NMR and thermogravimetry. The sulfur elemental analysis gave 2.00+/-0.05 and 8.67+/-0.01% for BCES and BCMS, which correspond to 0.60+/-0.01 and 2.71+/-0.01 mmol of this element per each gram of BCE and BCM, to confer a degree of functionalization of 20.2+/-0.07 and 86.7+/-0.01 mg g(-1). This synthesis enabled from IR weak SH band at 2544 cm(-1) due to the incorporation of the reagent into the structure. The basic centers favor copper sorption with increasing pH from 2 to 6 observed by a batchwise methodology and the data obtained from the chosen pH 6 were adjusted to Freundlich and Langmuir models, favoring fit for the latter equation. The kinetics of sorption was established at 30 min for both biopolymers with a pseudo-second-order model.

Kinetics and thermodynamics of textile dye adsorption from aqueous solutions using babassu coconut mesocarp.

Extracted babassu coconut (Orbignya speciosa) mesocarp (BCM) was applied as a biosorbent for aqueous Blue Remazol R160 (BR 160), Rubi S2G (R S2G), Red Remazol 5R (RR 5), Violet Remazol 5R (VR 5) and Indanthrene Olive Green (IOG) dye solutions. The natural sorbent was processed batchwise while varying several system parameters such as stirring time, pH and temperature. The interactions were assayed with respect to both pseudo-first-order and second-order reaction kinetics, with the latter the more suitable kinetic model. The maximum adsorption was obtained at pH 1.0 for all dyes due to available anionic groups attached to the structures, which can be justified by pH(pzc) 6.7 for the biosorbent BCM. The ability of babassu coconut mesocarp to adsorb dyes gave the order R S2G>VR 5>BR 160>IOG>RR 5, which data were best fit to Freundlich model, but did not well-adjusted for all dyes. The dye/biopolymer interactions at the solid/liquid interface are all spontaneous as given by free Gibbs energy, with exothermic enthalpic values of -26.1, -15.8, -17.8, -15.8 and -23.7 kJ mol(-1) for BR 160, R S2G, RR 5, IOG and VR 5, respectively. In spite of the negative entropic values contribution, the set of thermodynamic data is favorable for all dyes removal. However, the results pointed to the effectiveness of the mesocarp of babassu coconut as a biosorbent for removing textile dyes from aqueous solutions.