Abstract
Carbon nanomaterials have a great potential in environmental studies; they are considered as superior adsorbents of pollutants due to their physical and chemical properties. Functionalization and dimension play an important role in many functions of these nanomaterials including adsorption. In this research, adsorption process was achieved with one-dimension nanomaterials: single walled and multiwalled carbon nanotubes were used as received and after oxidation treatment also two-dimensional nanomaterials were used: graphene oxide and reduced graphene oxide. Carbon nanotubes were modified by hydrogen peroxide under microwave irradiation. The reduction of graphene oxide was achieved by using ascorbic acid.R2values obtained with the pseudo-second-order model are higher than 0.99. The results demonstrate that Freundlich isotherm provides the best fit for the equilibrium data (R2>0.94).RLvalues are between 0 and 1; this represents favorable adsorption between carbon nanomaterials and phenol. The adsorption process occurs byπ-πinteractions and hydrogen bonding and not by electrostatic interactions. The results indicate that the adsorption of phenol on carbon nanomaterials depends on the adsorbents’ surface area, and it is negatively influenced by the presence of oxygenated groups.
Highlights
The problem of water pollution is a big challenge in our time
It is clear that MWNTs do not display significant bands, but SWNTs show some signals that indicate the presence of functional groups such as υ(OH) at 3250 cm−1 related to hydroxyl groups, υ(C=O) at 1700 cm−1 associated with carboxylic groups, and υ(C=O) at 1400 cm−1 presented in ketone groups; the peak around 1600 cm−1 corresponds to υ(C=C) of the graphitic sp2 bonds
The formation of functional groups on the SWNTO and MWNTO surface after microwave irradiation is confirmed by the Fourier transform infrared (FTIR)
Summary
Due to rapid population growth, water demand is higher every day [1]. The discharge of wastewater containing large amounts of organic contaminants represents a serious risk to the general population [2]. Wastewater containing organic contaminants such as phenolic compounds implies serious discharge problems, due to their poor biodegradability, high toxicity, and possible accumulation in the environment. It is a fact that phenol and its derivatives found in natural water sources represent a serious risk to human health and water quality [6]. Phenolic compounds represent a serious danger because of their high toxicity and carcinogenicity even at low concentrations. Environmental Protection Agency (EPA) regulations demand lowering phenol content in wastewater to less than 1 mg/L [7].
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