Abstract
Hydrogel nanocomposites were synthesized by solution polymerization of acrylic acid in the presence of sodium alginate biopolymer and TiO2nanoparticle. TiO2nanoparticle and N, N-methylene-bis-acrylamide was used as an inorganic and organic crosslinker, respectively. The structure and morphology of the nanocomposites were investigated using X-Ray Diffraction (XRD), Fourier Transform Infra-Red Spectroscopy (FTIR), Scanning Electron Microscopy (SEM), Brunauer-Emmett-Teller (BET) and thermogravimetric analysis techniques. The nanocomposites hydrogel was used for the adsorption of methyl violet dye from water. The influence of TiO2nanoparticle, sodium alginate content and grafting on adsorption were studied. The results showed that a pseudo-second-order adsorption kinetic was predominant in the adsorption of methyl violet onto the nanocomposite hydrogel. The experimental equilibrated adsorption capacity of the nanocomposite hydrogel agrees with Langmuir isotherm. Maximum adsorption capacity of 1156.61 mg g−1and adsorption efficiency of 99.6% towards methyl violet were obtained for the hydrogel nanocomposite.
Highlights
Most dyes and their intermediate products have been known to be toxic, carcinogenic or mutagenic (Rindle et al, 1975; Robinson et al, 2001)
In the initial Methyl violet (MV) concentration range of 650–1100 mg lÀ1, the RL values were determined between 0 and 1 as presented in Figure 6(a), which further confirm the applicability of the Langmuir model. These results demonstrate the homogeneity of Sodium alginate (SA)-g-PAA/TiO2 hydrogel nanocomposite, i.e. each MV molecule requires same energy for adsorption and there is monolayer surface coverage of SA-g-PAA hydrogel nanocomposite
We report the fabrication of SA-g-PAA and SA-g-PAA/TiO2 nanocomposite by a free radical graft copolymerization method
Summary
Most dyes and their intermediate products have been known to be toxic, carcinogenic or mutagenic (Rindle et al, 1975; Robinson et al, 2001). We report the TiO2 NPs incorporated SA-g-PAA hydrogel nanocomposite with high porous structure and high percentage grafting for MV dye removal and successfully achieved high adsorption capacity (1156.61 mg gÀ1). The synthesis of SA-g-PAA hydrogel was similar to SA-g-PAA/TiO2 hydrogel nanocomposite except the presence of TiO2 NPs. To get the maximal percentage grafting of AA onto SA, the following reaction parameters were optimized: initiator concentration, monomer concentration, crosslinker concentration, reaction time, temperature and pH (Table 1).
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