Covalent modification of reduced graphene oxide with piperazine as a novel nanoadsorbent for removal of H 2 S gas
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Covalent modification of reduced graphene oxide with piperazine as a novel nanoadsorbent for removal of H2S gas Masoud Khaleghi Abbasabadi1 · Saeed Khodabakhshi2 · Hamid Reza Esmaili Zand3 · Alimorad Rashidi1 · Pooya Gholami1 · Zahra Sherafati1 Received: 2 June 2020 / Accepted: 6 July 2020 © Springer Nature B.V. 2020
Abstract In the present research, piperazine grafted-reduced graphene oxide RGO-N(piperazine) was synthesized through a three-step reaction and employed as a highly efficient nanoadsorbent for H 2S gas removal. Temperature optimization within the range of 30–90 °C was set which significantly improved the adsorption capacity of the nanoadsorbent. The operational conditions including the initial concentration of H 2S (60,000 ppm) with C H4 (15 vol%), H 2O (10 vol%), O 2 (3 vol%) and the rest by helium gas and gas hour space velocity (GHSV) 4000–6000 h−1 were examined on adsorption capacity. The results of the removal of H 2S after 180 min by RGO-N-(piperazine), reduced graphene oxide (RGO), and graphene oxide (GO) were reported as 99.71, 99.18, and 99.38, respectively. Also, the output concentration of H2S after 180 min by RGO-N-(piperazine), RGO, and GO was found to be 170, 488, and 369 ppm, respectively. Both chemisorption and physisorption are suggested as mechanism in which the chemisorption is based on an acid–base reaction between H2S and amine, epoxy, hydroxyl functional groups on the surface of RGON-(piperazine), GO, and RGO. The piperazine augmentation of removal percentage can be attributed to the presence of amine functional groups in the case of RGO-N(piperazine) versus RGO and GO. Finally, analyses of the equilibrium models used to describe the experimental data showed that the three-parameter isotherm equations Toth and Sips provided slightly better fits compared to the three-parameter isotherms.
* Masoud Khaleghi Abbasabadi [email protected] 1
Nanotechnology Research Center, Research Institute of Petroleum Industry (RIPI), Tehran, Iran
2
Energy Safety Research Institute, Swansea University, Bay Campus, Swansea SA1 8EN, UK
3
Department of Chemistry, Iran University of Science and Technology, Tehran, Iran
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M. Khaleghi Abbasabadi et al.
Graphic Abstract
Keywords Piperazine-reduced graphene oxide · H2S removal · Chemisorption and physisorption · Nanoadsorbent
Introduction Gas emissions are recognized as one of the main sources causing global warming. These emissions, owing to their chronic exposure, can lead to several negative effects such as photochemical smog and greenhouse effect [1–6]. Carbon monoxide (CO), hydrogen sulfide (H2S), and sulfur oxides (SOX) are among these gasses that are harmful, even at low concentrations, for human health and environment [7–12]. Among the above compounds, H2S is highly toxic and correspondingly resulted in irreparable effects in global environment. There are many sources producing and releasing H2S into the atmosphere. As an example, degradation of sulfur-containing compounds
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