Modification and Characterization of Cross-linked Chitosan/Titania Nanocomposites as Adsorbents and their Applications for Textile Dyes Remova

Abstract

In this study, the chitosan cross-linked/TiO2 nanocomposites are synthesized by loading different ratios of TiO2 nanoparticles into the polymeric matrix of crosslinked chitosan to be a promising bio-adsorbent for methyl orange (MO) and reactive orange (RO16) dyes. Box–Behnken design (BBD) in response surface methodology (RSM) is used to optimize the loading of TiO2 nanoparticles into crosslinked chitosan-glyoxal (CCGLY) polymeric matrix and crosslinked chitosan-TPP (CCTPP) polymeric matrix to be a potential biosorbents for the removal of MO and RO16 from aqueous solution. The samples have been characterized by scanning electron microscope with energy dispersive X-ray analyzer (SEM EDX), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and, N2 adsorption-absorption analysis. The analyses proved the mesostructure of composites and interaction of TiO2 nanoparticles in polymeric matrix of crosslinked chitosan and. Box– Behnken design (BBD) in response surface methodology (RSM) is applied to optimize various process parameters, viz., loading of TiO2 nanoparticles into the polymeric matrix of chitosan (A: 0% - 50%), adsorbent dose (B: 0.04 – 0.14 g/50 mL), solution pH (C: 4–10), and temperature (D: 30–50 oC). The optimum conditions of adsorption process for MO and RO16 dyes were 50% TiO2 loading, 0.09 g/50 mL, pH = 4.0, and 40 oC. Statistical and graphical of the BBD model are analyzed to obtain on optimum levels of the main effective parameters. The isotherm and kinetic models are performed to obtain on maximum adsorption capacity and find out adsorption mechanism. The results show that the highest MO and RO16 removal efficiency by CCGLY/TNC-50 was 75.9% and 93.23% respectively. The results show that the highest MO and RO16 removal efficiency by CCTPP/TNC-50 were 87.27 % and 92.7 %, respectively. The adsorption capacity of CCGLY/TNC-50 was 416.1 mg/g and 390.5 mg/g XIV for MO and RO16, respectively. The adsorption capacity of CCTPP/TNC 50 was 636.2 mg/g and 618.7 mg/g for MO and RO16, respectively. This study reveals that the loading of TiO2 nanoparticles into polymeric matrix of CCGLY is responsible for enhancing surface area by ~ 45 times and improving adsorptive property toward MO and RO16. This study reveals that the loading of TiO2 nanoparticles into polymeric matrix of CCTPP is responsible for enhancing surface area by ~ 18 times and improving adsorptive property toward MO and RO16. The adsorption mechanism includes electrostatic attractions, n-π stacking interactions, dipole–dipole hydrogen bonding interactions, and Yoshida H-bonding.