Modification of Silica Nanoparticles with Cysteine or Methionine Amino Acids for the Removal of Uranium (VI) from Aqueou
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ORIGINAL PAPER
Modification of Silica Nanoparticles with Cysteine or Methionine Amino Acids for the Removal of Uranium (VI) from Aqueous Solution Latifa Ismail 1
&
Fawwaz Khalili 1 & Faten M. Abu Orabi 1
Received: 8 September 2019 / Accepted: 15 December 2019 # Springer Nature B.V. 2020
Abstract Silica nanoparticles (SiO2-NPs), modified silica nanoparticles with cysteine (SiO2-Cys) or methionine (SiO2-Meth) were used for sorption of uranium (VI) ion from aqueous solution. Silica nanoparticles and its modified forms were prepared and characterized by elemental analysis, FTIR, XRD, XRF, TGA, DSC, SEM, TEM, BET and zeta potential. Sorption of uranium(VI) ion using batch technique by silica nanoparticles, SiO2-Cys and SiO2-Meth was studied as a function of initial concentration, sorbent dosage, pH, contact time and temperature. The percent uptakes for silica nanoparticles, SiO2-Cys, SiO2-Meth were 27%, 33%, 30% respectively for U(VI) ion at 25 °C. The kinetic studies show that sorption of U(VI) ion by silica nanoparticles, SiO2-Cys and SiO2-Meth was well described by the pseudo second order equation. Negative values of Gibbs free energy (ΔG°) suggest the spontaneity of the sorption process on silica nanoparticles and its modified forms (SiO2-Cys) and (SiO2-Meth). Positive values of enthalpy (ΔH°) indicate endothermic adsorption process. The sorption isotherm was better fitted by Langmuir model with maximum sorption capacity for silica nanoparticles, SiO2-Cys and SiO2-Meth was found to be 3.6, 4.5, 3.8 mg/g respectively. Desorption studies indicate that the most favorable desorption reagent for uranium(VI) is 0.1 M HNO3 and the highest percent recovery was achieved from silica nanoparticles (~71%) than its modified forms SiO2-Cys and SiO2-Meth. Keywords Modification . Silica nanoparticles . Methionine . Cysteine . Sorption . Uranium(VI)
Abbreviations S i O 2 - Silica nanoparticles NPs Meth Methionine Cys Cysteine S i O 2 - Modified silica nanoparticles with cysteine Cys S i O 2 - Modified silica nanoparticles with methionine Meth Co Initial metal concentration (mg/L) Ce
* Latifa Ismail [email protected] Fawwaz Khalili [email protected] Faten M. Abu Orabi [email protected] 1
Chemistry Department, The University of Jordan, 11942, Amman 9626535000, Jordan
V m KL qm qe qt k2
The residual concentration of the metal ion in solution at equilibrium (mg/L) Volume of solution (L) Mass of SiO2-NPs, SiO2-Cys or SiO2-Meth (g) Langmuir affinity constant (L/mg) Langmuir monolayer adsorption capacity (mg/g) The equilibrium amount of metal ion adsorbed per unit mass of adsorbent (mg/g) The amount of metal ions adsorbed (mg/g) at contact time t The second order reaction constant (g/mg.min)
1 Introduction Pollution with uranium(VI) has been studied for human health and animals. Uranium is the most important natural radioactive elements effecting the environment and caused renal damage then kidney failure and death; therefore removal of uranium from aqueous solution is very important [1, 2]. A variety of techniques
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