Preparation of graphene reinforced poly(lactic acid) nanocompositesviasolution casting approach for packaging applications.

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In this work, batch adsorption experiments are carried out for crystal violet dye using mesoporous MCM-41 synthesized at room temperature and sulfate modified MCM-41 prepared by impregnation method using H 2 SO 4 as sulfatising agent. The surface characteristics, pore structure, bonding behavior and thermal degradation of both the MCM-41 samples are characterized by nitrogen adsorption/desorption isotherms, X-ray diffraction (XRD) patterns, Fourier transform infrared (FT-IR) spectroscopy and thermo gravimetric analysis (TGA). The adsorption isotherm, kinetics and thermodynamic parameters are investigated for crystal violet (CV) dye using the calcined and sulfated MCM-41. Results are analysed using Langmuir, Freundlich and Redlich-Peterson isotherm models. It is found that the Freundlich model is an appropriate model to explain the adsorption isotherm. The highest adsorption capacity achieved is found to be 3.4 × 10 −4 mol g −1 for the sulfated MCM-41. The percentage removal of crystal violet dye increases with increase in the pH for both the MCM-41 adsorbents. Kinetics of adsorption is found to follow the second-order rate equation. From the thermodynamic investigation, it is evident that the adsorption is exothermic in nature. CVCrystal Violet CTAB Cetyltrimethylammonium Bromide TEOS Tetraethylorthosilicate a 0 Unit cell Parameter (nm)Pseudo-first-order rate constant (min −1 ) k 2 Pseudo-second-order rate constant (gmol −1 min −1 ) k d Diffusion coefficient (dimensionless) K F Freundlich isotherm constant (mol/g(dm 3 /mol) 1/n ) K L Langmuir constant (dm 3 mol −1 ) K RP Redlich-Peterson constants (mol g −1 ) m Mass of the adsorbent (g) n Adsorption intensity (dimensionless) q e Amount of dye adsorbed at equilibrium (mol g −1 ) Q max Maximum adsorption capacity (mol g −1 ) S 0 Entropy (KJ mol −1 K −1 ) S BET BET surface area (m 2 g −1 ) V Volume (dm 3 ) V mes Mesoporous volume (cm 3 g −1 )Greek letters βFull width at half maximum (degrees) θAngle of diffraction (degrees) λ Wavelength (nm) λ max Maximum absorbance wavelength (nm) Adsorption (2009) 15: 390-405 391

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