Desorption of chromium (VI) and lead (II) ions and regeneration of the exhausted adsorbent

Abstract

The desorption characteristics of previously adsorbed hexavalent chromium [Cr(VI)] and divalent lead [Pb(II)] ions on groundnut husk were tested by various desorption eluents such as tap water, de-ionized water, NaOH, HCl and H2SO4. Among them, HCl and H2SO4 were chosen as the best desorbing agents for Cr(VI) and Pb(II) ions, respectively, due to their high desorption efficiency. The desorption efficiency of HCl and H2SO4 for Cr(VI) and Pb(II) ions was about 76.1% and 82.1%, respectively, at a concentration of 0.1 M for both elution agents. The exhausted groundnut husk was regenerated up to five cycles, and the removal efficiency of Cr(VI) and Pb(II) ions on the recycled groundnut husk could be maintained at 53.5% and 54.6%, respectively, in the third cycle. The successive regeneration cycles resulted in the reduction of the desorption efficiency by 20.0% and 26.7% for Cr(VI) and Pb(II) ions, respectively, after the third cycle. The results show that groundnut husk could be recycled when used to remove Cr(VI) and Pb(II) ions from Cr(VI) and Pb(II)-polluted water and wastewaters.

Adsorptive potential of ZnO/SiO2 nanorods prepared via the sol–gel method for the removal of Pb(II) and Cd(II) from petroleum refinery wastewater

“…This may be ascribed to the fact that an increase in the concentration of HNO 3 caused increases in the number of H + in solution, which increases the concentration gradient of the metal ions and H + and therefore increases the driving force for ion exchange, which favored metal ions during the desorption process. 107 The results in this study corroborate the analysis of Bayuo et al 108 who reported similar values using 0.1 mol L −1 H 2 SO 4 (82.1%) and HCl (74.2%) for desorption of Pb(II). Similar results have been reported by Samson et al, 109 who studied desorption using different concentrations of HCl (0.01, 0.1, 1.0 and 1.20 mol L −1 ).…”

“…Despite the success in the use of nanomaterials for the removal of pollutants from wastewater, the discharge of adsorbents that have been exhausted is a serious environmental issue 27 . As a result, it is critical to regenerate and reuse adsorbents to make the adsorption process economically and environmentally friendly.…”

“…Despite the success in the use of nanomaterials for the removal of pollutants from wastewater, the discharge of adsorbents that have been exhausted is a serious environmental issue. 27 As a result, it is critical to regenerate and reuse adsorbents to make the adsorption process economically and environmentally friendly. Desorption and reutilization of spent adsorbents in adsorption-desorption cycles may significantly minimize the discharge of the spent adsorbent into the environment.…”

Wastewater depollution of textile dyes and antibiotics using unmodified and copper oxide/zinc oxide nanofunctionalised graphene oxide materials

“…Each adsorbent was regenerated by mixing the used adsorbent with 5% HCl (10 mL) as the desorption agent and this desorption of adsorbed contaminant ions from the GO material will restore the adsorbents for future use. 42 The desorption mixture was sonicated for 30 min and the adsorbent material was then washed with M.Q. water 3 times after removing the supernatant, and dried at 50 °C for 6 h. The regeneration cycles proved an ability to remove the dyes and antibiotics from aqueous solutions as a valid reusable material.…”

Polyacrylonitrile Crosslinked with Diethylenetriamine and Its Use for the Removal of Lead Ions from Aquatic Systems

“…Supercapacitor electrodes made of polyacrylonitrile exhibit superior conductivity, high power density, and enhanced capacitance. [29]…”