Estudio de la remoción de cromo y zinc de aguas sintéticas empleando carbón activado impregnado con nanotubos de carbono

Abstract

The project studied the chromium hexavalent (Cr VI) and zinc (Zn) adsorption in synthetic solutions by using a composite of activated carbon impregnated with multiwalled carbon nanotubes in the range of particle sizes from 38 μm to 125 μm, 125 μm at 210 μm and 210 μm at 300 μm with 0.5, 1.0 and 2.0% impregnation. Before impregnation, the multiwalled carbon nanotubes were oxidized in a solution of ammonium hydroxide and hydrogen peroxide by reflux heating. The multiwalled carbon nanotubes were impregnated by wet impregnation with nickel nitrate as oxidant and catalyst. All adsorbents were characterized using instrumental techniques such as: iodine number, SEM (scanning electron microscope), TEM (transmission electron microscopy), FTIR (Fourier transform infrared spectroscopy), BET (Brunauer–Emmett–Teller), TGA (thermogravimetric analysis), to determine they morphological and surface characteristics. The adsorption analyses were executed in batch tests, at pH between 3.0 and 3.5, varying the parameters of particle size, percentage of impregnation, adsorbent dose and contact time. The best adsorbent was the activated carbon composite of 125 μm with 2% of oxidized carbon nanotubes for both pollutants. The maximum removal obtained was 28.08 mg/g in a contact time of 90 minutes and with a dose of adsorbent of 400 mg/L for Cr (VI) and 1111.11 mg/g in a contact time of 45 minutes and with a dose of adsorbent of 400 mg/L for Zn. The adsorption of Cr (VI) was adjusted to the Langmuir isotherm model, while the Zn was adjusted to the Freundlich isotherm model. The correlation coefficients were 0.9987 and 0.9934, respectively.