Chemical modifications in lignocellulosic fibers to obtain and use in biosensor array phenolic derivative of LCC and the biosorption of metals / Modificações químicas em fibras lignocelulósicas para obtenção e aplicação em biocompósitos de matriz fenólica derivada de LCC e na biossorção de metais

AUTOR(ES)

Antônio César Honorato Barreto

DATA DE PUBLICAÇÃO

2008

RESUMO

In this work, lignocellulosic fibers from two sources (sisal and banana pseudo stem) were used as reinforcing agents in the preparation of phenolic matrix composites derived from cashew nut shell liquid (CNSL) and as material to adsorb toxic metals (Pb+2, Ni+2, Cd+2, Zn+2 and Cu+2). Surface changes were induced in the sisal fibers by immersion in alkali solutions at 5% and 10% concentrations, while for the banana stem material the concentrations were 0.25%, 0.5% and 1%. Then the fibers were treated with sodium hypochlorite (NaClO/H2O 1:1) to bleach and soften them. Scanning electron microscopy showed significant improvement in the fiber surfaces after chemical treatment. All treatments made the fibers more adsorbent than the untreated material. However, the treatments with NaOH 5% and NaOH 0.25% were more effective than the others. For the composites of these fibers, after the alkali treatment was verified an improved interface between the reinforcement agent and phenolic matrix. The following techniques were used to characterize the lignocellulosic fibers: atomic absorption spectrophotometry, thermogravimetry (TG), X-ray diffraction (XRD), X-ray fluorescence (XRF), measurement of electric properties (dielectric permittivity, loss tangent and dielectric conductivity), infrared spectroscopy (IR), biodegradation in simulated soil and scanning electron microscopy (SEM). The composites obtained were characterized by dynamic mechanical analysis (DMA), differential scanning calorimetrry (DSC), TG and SEM. The results revealed that the sisal composites performed better as reinforcement of phenolic matrixes than banana tree composites, possibly due to the higher content of cellulose, which is the component of lignocellulosic fibers that provides mechanical resistance.

ASSUNTO(S)

cardanol adsorção quimica inorganica bananeira adsorption cardanol, sisal, banana sisal

Documentos Relacionados

• Fibras lignocelulósicas como agente de reforço de compósitos de matriz fenólica e lignofenólica
• Sodium lignosulphonate as agent of modification of lignocellulosic fiber surface and formulation of phenolic thermoset
• Caracterização de fibras lignocelulósicas pré-tratadas por meio de técnicas espectroscópicas e microscópicas ópticas de alta resolução
• Microalgae; Proteins; Functional properties; Chemical modifications;
• Modifications chemical, biochemical and sensory s hybrid of tilapia stored in ice