Abstract
Modified activated carbon sorbents (ACP-Zn and ACP-Zn-Fe) had been prepared from the activation of corn husks precursor to increase the chemical activity of the resulting adsorbents by increasing the number of active functional groups and generation of micro-mesoporous structures. Fourier transform infrared (FTIR) assessed the acidic surface properties of the prepared activated carbons that is due to the presence acidic functional groups such as –OH and –COOH which improves the removal efficiency of the produced sorbents. Textural characteristics revealed the generation of micro-mesoporous structures in ACP–Zn and ACP-Zn-Fe. Thus the combination of H3PO4 with Zn or Zn–Fe could enhance the mesoporosity with a considerable decrease in the adsorption of nitrogen. However, the formation of mesopores might be attributed to the template-like effects of the obtained Zn- of Zn-Fe compounds inside the carbon structure. These structures were employed as sorbents for removal of hexavalent chromium Cr(VI) ions from its aqueous solutions, and the removal efficiency reached ~ 86% for ACP-Zn-Fe and ~ 82% for ACP-Zn. The kinetic modeling studies revealed that the sorption process follows the pseudo-second-order model which indicates that the mechanism of process is chemisorptions. Freundlich, Langmuir and Dubinin–Radushkevich (D–R) models were used to express the experimental data. The isotherm modeling studies revealed that the sorption process was fit with both Freundlich and Langmuir models with maximum capacity 24.8 and 30.3 mg/g for ACP-Zn and ACP-Zn-Fe, respectively.
Highlights
The environmental difficulties caused by heavy metal ions in water need the development of new efficient methods for removing these contaminants, especially because their accumulation in living creatures at extremely low concentrations causes significant health problems (Monier et al 2010; Essawy and Ibrahim 2004; Xiao et al 2017)
The optimum removal of Cr (VI) by ACP-Zn and ACPZn-Fe, isotherm and kinetic models were studied through batch adsorption method
All experiments were repeated three times, and the percentage of chromium ions removal by ACP-Zn and ACP-Zn-Fe during a series of batch investigations can be expressed using Eq (2): Three obtained samples were analyzed by Fourier transform infrared (FTIR), which are: the activated carbon impregnated with 50% H 3PO4 and heated at 700 °C (ACP), activated carbon impregnated with 50% H3PO4/ZnCl2 and heated at 700 °C (ACP-Zn) and its counterpart of the activated carbon impregnated with 50% H3PO4/ZnCl2/FeCl3 and pyrolyzed at 700 °C (ACPZn-Fe)
Summary
The environmental difficulties caused by heavy metal ions in water need the development of new efficient methods for removing these contaminants, especially because their accumulation in living creatures at extremely low concentrations causes significant health problems (Monier et al 2010; Essawy and Ibrahim 2004; Xiao et al 2017). Where C0 (mg/L) is the initial concentration of hexavalent chromium, Cf (mg/L) is the equilibrium concentration of Cr(VI) in aqueous solution, V (L) is the volume of solution, M (g) is the mass of the adsorbent and Qt (mg/g) is the calculated Cr(VI) adsorption amount onto ACP,ACP-Zn and ACP-Zn-Fe. The optimum removal of Cr (VI) by ACP-Zn and ACPZn-Fe, isotherm and kinetic models were studied through batch adsorption method.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
