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

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Summary

Introduction

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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Conclusion

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