Abstract
Mesoporous carbons (MPC) and modified mesoporous carbons (MMPC) were prepared from asphalt for the adsorption of several metal ions from the aqueous solution. In this study, we investigated the adsorption efficiency of Cesium (Cs+) and Strontium (Sr2+) ions using mesoporous and modified mesoporous carbons. The optimum conditions for the removal of Cs+ and Sr2+ were at 10.0 pH, 1.00 ppm (1000.0 µg/L) concentration, 20.0 min contact time, 0.20 g/L adsorbent dose, 25.0 °C temperature with more than 95.0% removal of Cs+ and Sr2+ ions using MMPC. The limit of detection (LOD) was found to be 0.030 ppb and 10.00 ppb for Sr2+ and Cs+ metals ions, respectively, while the Limit of quantification (LOQ) was calculated to be 0.10 ppb for Sr2+ and 35.00 ppb for Cs+ metals ions. The functionalization of the MPC was performed using potassium permanganate to get MMPC, which were characterized by FT-IR spectroscopy. The nature of the X-ray diffraction peaks suggests that the MPC and MMPC carbons are amorphous and semi-crystalline materials. The scanning electron microscope (SEM) and transition electron microscope (TEM) studies showed the changes in the morphology due to the adsorption on the surface of the carbons. The TEM analysis clearly showed that the metal ions blocked most of the pores on the surface. The surface area, by N2 adsorption isotherm (BET), of MPC and MMPC were 937 and 667 m2·g−1, respectively. Among the adsorption isotherms, Langmuir isotherm showed the best linearity. The Langmuir isotherm indicates that the adsorption is monolayer and homogeneous with a finite number of ions. Adsorption kinetics showed better linearity with pseudo-second-order plots and obeys this order. This process indicates that the chemical interaction, such as covalent or ionic bonding, took place between the metal ions and the carbon adsorbents.
Highlights
Clean water resources are vital to humans, animals, and plants
The adsorption capacity of these carbonaceous adsorbents was significantly enhanced by the treatment of acids/bases, which leads to the functionalization of the carbonaceous material
The following reagents were purchased and used in this work; which includes potassium hydroxide (85%, Sigma Aldrich, Louis, MO, USA), hydrochloric acid (37%, Merck, Kenilworth, NJ, USA), sulfuric acid (95%–97%, Merck), potassium permanganate (99.5%, Sigma Aldrich). 1.0 and 0.1 M solution were prepared by using nitric acid, ACS reagent 70% from Sigma-Aldrich Company. 1.0 and 0.1 M solution were prepared by using sodium hydroxide pellets from Fluka
Summary
Clean water resources are vital to humans, animals, and plants. the extensive use of these resources, especially in the industrial process, leads to lower water quality and the availability of clean water [1,2,3]. Carbon nanomaterials have been wildly investigated in water treatment due to the unique properties of these materials These materials have shown an excellent adsorption ability to organic and inorganic pollutants through a different mechanism, physiosorption and chemisorption with different adsorption capacity depend on adsorbents’ active sites and available surface area [15]. The adsorption capacity of these carbonaceous adsorbents was significantly enhanced by the treatment of acids/bases, which leads to the functionalization of the carbonaceous material. A simple approach to prepare high surface area functionalized mesoporous carbon from an inexpensive petroleum matrix source, asphalt, was adopted and was tested for the adsorption of Sr2+ and Cs+ metal ions from aqueous solution. The thermodynamic parameters such as entropy (∆S), enthalpy (∆H), and the Gibbs free energy of the processes were calculated and confirmed that the metal ions removal process is exothermic and spontaneous
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