The Effect of Temperatures on the Synergistic Effect between a Magnetic Field and Functionalized Graphene Oxide-Carbon Nanotube Composite for Pb2+ and Phenol Adsorption

Abstract

The effect of temperature on scale inhibition and adsorption properties for Pb2+ and phenol was studied under the synergistic effect of the magnetic field and the adsorbent. The sulfhydryl and amino-modified graphene oxide/oxidized multiwalled carbon nanotubes (NH2-SH-GO/o-MWCNTs) were synthesized and applied as the adsorbent. Additionally, changes in pH, conductivity, molecular activation energy, the relative variation of intramolecular energy and the relative variation in the proportion of free water, and adsorption capacity of the adsorbent were studied under different temperatures of circulating water. The relative variation of the proportion of free water increased with the increasing temperatures. The above results indicated that higher temperature would be detrimental to scale inhibition. The higher the temperatures, the lower the intramolecular energies. And the more stable molecules are formed in the circulating water. Thus, the results reduced the tendency to scale formation. The increased temperatures promoted the adsorption capacity of the adsorbent for Pb2+ and phenol. The adsorption process for Pb2+ and phenol conformed to the pseudo-second-order kinetic model and Freundlich isotherm model under the synergistic effect of magnetic field and NH2-SH-GO/MWCNTs. After five cycles, the adsorption capacities of the adsorbent for Pb2+ and phenol separately decreased by 59.86% and 76.36%. The aforementioned results reveal that temperatures can promote the adsorption process for Pb2+ and phenol, and the synergistic effect between magnetic field and the adsorbent has a potential application for water treatment.