Green Synthesis of S- and N-Codoped Carbon Nanospheres and Application as Adsorbent of Pb (II) from Aqueous Solution

Nadia Hussain,Salam Alwan,Ibrahim Sahib,Hassan Alshamsi

doi:10.1155/2020/9068358

Abstract

In this paper, green and facile synthesis of sulfur- and nitrogen-codoped carbon nanospheres (CNs) was prepared from the extract of Hibiscus sabdariffa L by a direct hydrothermal method. Finally, sulfur-carbon nanospheres (CNs) were used as the adsorbent to remove Pb+2 ions from aqueous solutions because of the high surface area of S-CNs from CNs and N-CNs. The synthesized nanospheres were examined by Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), field emission scanning electron microscopy, transmission electron microscopy (TEM), and nitrogen adsorption-desorption isotherms. The results show spherical shapes have a particle size of up to 65 nm with a high surface area capable of absorbing lead ions efficiently. Additionally, the factors affecting the process of adsorption that include equilibrium time, temperature, pH solution, ionic intensity, and adsorbent dose were studied. The equilibrium removal efficiency was studied employing Langmuir, Freundlich, and Temkin isotherm forms. The kinetic data were analyzed with two different kinetic models, and both apply to the adsorption process depending on the values of correlation coefficients. The thermodynamic parameters including Gibbs free energy (ΔG°), standard enthalpy change (ΔH°), and standard entropy change (ΔS°) were calculated for the adsorption process.

Highlights

IntroductionAfter discovering various forms of carbon, for instance, fullerenes and carbon nanotubes, researchers went on to use the carbon material in a broader form [1]
After discovering various forms of carbon, for instance, fullerenes and carbon nanotubes, researchers went on to use the carbon material in a broader form [1]. Including these nanodesigned carbon substances, the carbon nanospheres have drawn large considerations owing to their various uses in catalyst supports, anodes for lithium-ion batteries, electrodes for supercapacitors, lubricants, polymer, and rubber additives, which result from their exceptional properties, for instance, superior chemical stability, thermal insulation, low density, and high compressive strength [2,3,4,5,6,7,8]. ere are many different methods to synthesis the carbon nanospheres involving arc plasma technique [9], catalyzed pyrolysis [10], self-generated template manner [11], hydrothermal reaction [12], spray pyrolysis [13] and chemical vapor deposition (CVD) [14], etc
The study of the development procedure of carbon nanospheres (CNs) manufactured by hydrothermal methods is comparatively elusive. e major problem in conception of this mechanism is that the reaction takes place in a closed inaccessible vessel, and some experiments have been made to study the hydrothermal reaction in situ using Raman spectroscopy, but further performance is necessary to gain a conception of the growth process [20]

Summary

Introduction

After discovering various forms of carbon, for instance, fullerenes and carbon nanotubes, researchers went on to use the carbon material in a broader form [1] Including these nanodesigned carbon substances, the carbon nanospheres have drawn large considerations owing to their various uses in catalyst supports, anodes for lithium-ion batteries, electrodes for supercapacitors, lubricants, polymer, and rubber additives, which result from their exceptional properties, for instance, superior chemical stability, thermal insulation, low density, and high compressive strength [2,3,4,5,6,7,8]. Ere are many different methods to synthesis the carbon nanospheres involving arc plasma technique [9], catalyzed pyrolysis [10], self-generated template manner [11], hydrothermal reaction [12], spray pyrolysis [13] and chemical vapor deposition (CVD) [14], etc. Batch studies were performed by varying the contact time, temperature, pH solution, and ionic intensity, where the size of the samples prepared and the morphology were identified using the characterization techniques mentioned

Experimental Section

Characterization

Adsorption Experiments

Conclusions