Abstract
Water-soluble hyperbranched polyamine functionalized multiwalled carbon nanotubes nanocomposite (WHPA-OMCNT) was successfully prepared and applied to water remediation in this paper. WHPA-OMCNT was characterized by Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), zeta potential, scanning electron microscopy (SEM) and transmission electron microscope (TEM) analyses. WHPA-OMCNT exhibited excellent adsorption performance for removal of organic dyes e.g., methylene blue (MB), malachite green (MG) and methyl violet (MV). The equilibrium adsorption capacity was 800.0 mg g−1 for MB, 840.3 mg g−1 for MG and 970.9 mg g−1 for MV under the optimal conditions. The pseudo-second order equation and the Langmuir model exhibited good correlation with the adsorption kinetic and isotherm data for all three pollutants, respectively. The thermodynamic results (ΔG < 0, ΔH < 0, ΔS < 0) implied that the adsorption process of MB, MG and MV was feasible, exothermic and spontaneous in nature. A possible adsorption mechanism has been proposed, where H-bonding, electrostatic attraction and π-π stacking interactions dominated the adsorption of the organic dyes. In addition, the excellent reproducibility endowed WHPA-OMCNT with the potential for application in water treatment.
Highlights
Water pollution with toxic organic dyes from developing modern industries, such as textile, plastic, leather, cosmetics, paper, and food, has been a serious environmental issue
water-soluble hyperbranched polyamine (WHPA) can be obtained through a one-pot reaction and its molecular structure was determined by the 1H nuclear magnetic resonance spectroscopy (1H NMR) spectrum (Fig. 2A)
(R2 = 0.9989, R2 = 0.9994, R2 = 0.9991) and methyl violet (MV) (R2 = 0.9888, R2 = 0.9785, R2 = 0.9805) at 298 K, 308 K and 318 K, respectively. These results suggested that the surface of WHPA-oxidized multiwalled carbon nanotubes (OMCNT) was covered by monolayer pollutant, and the reaction interface between methylene blue (MB)/malachite green (MG)/MV and WHPA-OMCNT was nonhomogeneous
Summary
Water pollution with toxic organic dyes from developing modern industries, such as textile, plastic, leather, cosmetics, paper, and food, has been a serious environmental issue. The adsorption technique has proven to be an effective, simple, and economically feasible method for removal of organic dyes from wastewater[4, 5] Various adsorbents, such as activated carbon[6], zeolite[7], clay[8] and sepiolite[9], have been produced to meet different needs. Water-soluble polymers containing desired functional groups are typically chosen to modify CNT for improving dispersion properties in aqueous solutions as well as the adsorption capacity. We combined water-soluble hyperbranched polyamine (WHPA) with high surface area oxidized multiwalled carbon nanotubes (OMCNT) to prepare a novel nanosorbent (WHPA-OMCNT) for the high removal efficiency of organic dyes. To further evaluate the practical applications, the effect of coexisting ions on the adsorption and the regeneration performance of WHPA-OMCNT were investigated
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