期刊
POLYMERS
卷 13, 期 2, 页码 -出版社
MDPI
DOI: 10.3390/polym13020251
关键词
anionic-cationic dye removal; chitosan; conjugate sponge; karaya gum; sustainable materials; waste-water treatment
资金
- Ministry of Education, Youth and Sports in the Czech Republic [CZ.02.1.01/0.0/0.0/16_019/0000843, LTAUSA19091, 18309/136]
- Ministry of Education, Youth and Sports of the Czech Republic [LM2018124]
- European Union-European Structural and Investment Funds in the framework of the Operational Programme Research, Development, and Education
The Kg-Ch conjugate sponge with high porosity and chemical stability shows good adsorption capacity for anionic and cationic dyes. The sponge's surface features pH-dependent ionizable functional groups, and the adsorption process is influenced by pH, adsorbate concentration, dose, and contact time.
A novel, lightweight (8 mg/cm(3)), conjugate sponge of karaya gum (Kg) and chitosan (Ch) has been synthesized with very high porosity (similar to 98%) and chemical stability, as a pH-responsive adsorbent material for the removal of anionic and cationic dyes from aqueous solutions. Experimental results showed that Kg-Ch conjugate sponge has good adsorption capacity for anionic dye methyl orange (MO: 32.81 mg/g) and cationic dye methylene blue (MB: 32.62 mg/g). The optimized Kg:Ch composition grants access to the free and pH-dependent ionizable functional groups on the surface of the sponge for the adsorption of dyes. The studies on the adsorption process as a function of pH, adsorbate concentration, adsorbent dose, and contact time indicated that the adsorption capacity of MB was decreased with increasing pH from 5 to 10 and external mass transfer together with intra-particle diffusion. The adsorption isotherm of the anionic dye MO was found to correlate with the Langmuir model (R-2 = 0.99) while the adsorption of the cationic MB onto the sponge was better described by the Freundlich model (R-2 = 0.99). Kinetic regression results specified that the adsorption kinetics were well represented by the pseudo-second-order model. The H-bonding, as well as electrostatic interaction between the polymers and the adsorption interactions of dyes onto Kg-Ch sponge from aqueous solutions, were investigated using attenuated total reflection-Fourier transform infrared (ATR-FTIR) spectroscopy, and the highly wrinkled porous morphology was visualized in depth by field-emission scanning electron microscopy (FE-SEM) analysis. Moreover, the samples could be reused without loss of contaminant removal capacity over six successive adsorption-desorption cycles. The hierarchical three-dimensional sponge-like structure of Kg has not been reported yet and this novel Kg-Ch sponge functions as a promising candidate for the uninterrupted application of organic pollutant removal from water.
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