Adsorptive removal of Hg 2+ from aqueous solutions using amino phenyl-pyrazole-functionalized graphene oxide
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Carbon Letters https://doi.org/10.1007/s42823-019-00119-8
ORIGINAL ARTICLE
Adsorptive removal of Hg2+ from aqueous solutions using amino phenyl‑pyrazole‑functionalized graphene oxide Mobina Alimohammady1 · Mehdi Ghaemi2 Received: 24 August 2019 / Revised: 2 December 2019 / Accepted: 17 December 2019 © Korean Carbon Society 2020
Abstract The aim of this work is to investigate the ability of a new functionalized graphene oxide 3-amino-5-phenylpyrazole (F-GO) in the adsorption and removal of H g2+ from aqueous solution. Both untreated graphene oxide (GO) and F-GO were characterized using FT-IR, EDX, FE-SEM, XRD and TGA analysis. The effects of three operational variables (pH, adsorbent dose and initial metal ion concentrations) on H g2+ adsorption capacity of F-GO were investigated by central composite design. This technique aims to find a simple way to optimize the adsorption process and to analyze the interaction between the significant parameters. A quadratic model suggested for the analysis of variance found that the adsorption of metal ions heavily depend upon pH of the solution. The adsorption mechanism has been determined by pseudo-first-order kinetic models and the adsorption behavior was modeled by Freundlich isotherm. Results demonstrated that the adsorption capacities of F-GO for removal of Hg2+ were generally higher than those of GO, which is attributed to a decrease in the agglomeration of graphene layers due to the presence of amino-functional moieties with their bulky phenyl groups. Thermodynamic data indicated that the functionalization significantly affects the thermostability of the GO precursor materials. The desorption study demonstrated favorable regenerability of the F-GO adsorbent, even after three adsorption–desorption cycles. Keywords Adsorption · Heavy metal · RSM Optimization · Functionalized graphene oxide List of symbols B Constant related to the heat of sorption (J mol−1) b Temkin isotherm constant BD Dubinin–Radushkevich isotherm constants C0 Initial metal ion concentration (mg L−1) Ce Final metal ion concentration (mg L−1) E Activation energy h Initial sorption rate in the pseudo-second-order kinetic model (mg g−1 min−1) k1 Pseudo-first-order adsorption rate constant (min−1) k2 Pseudo-second-order adsorption rate constant (g mg−1 min−1) Electronic supplementary material The online version of this article (https://doi.org/10.1007/s42823-019-00119-8) contains supplementary material, which is available to authorized users. * Mobina Alimohammady [email protected] 1
Department of Chemical Engineering, Golestan University, Gorgan 19395‑3697, Iran
Department of Chemistry, Faculty of Science, Golestan University, Gorgan, Iran
2
Kd Equilibrium constant KF Freundlich isotherm constant KL Langmuir isotherm constant (mg L−1) KT Equilibrium binding constant (L g−1) m The weight of sorbent (g) n Adsorption intensity q Sorption capacity at any time (mg g−1) qD Theoretical Dubinin–Radushkevich isotherm saturation capacity (mg g−1) qe Sorption
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