Synthesis Optimization of MCM-41 for CO2 Adsorption Using Simplex-centroid Design

Cíntia De Castro Costa,Rodolfo Luiz Bezerra De Araújo Medeiros,João Andrade Marconi,Marcus Antônio De Freitas Melo,Antonio Eduardo Martinelli,Dulce Maria De Araújo Melo,Joana Maria De Farias Barros

doi:10.1590/1516-1439.017015

Cíntia De Castro Costa, Rodolfo Luiz Bezerra De Araújo Medeiros + Show 5 more

Open Access

https://doi.org/10.1590/1516-1439.017015

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Abstract

There is a growing concern on the relationship between anthropogenic carbon dioxide and climate changes. A promising approach is the adsorption technology using mesoporous MCM-41 materials that can be easily synthesized to depict structures adequate to the flow of gas. The aim of this study was to improve the synthesis of MCM-41 using cationic surfactant mixtures and apply the resulting materials to CO 2 adsorption. To that end, the simplex-centroid design was applied to optimize CO2 adsorption from seven mesoporous MCM-41 materials synthesized by the hydrothermal method using surfactants from hydrophobic chains of different sizes. The cationic surfactants used were tetradecyltrimetylammonium bromide, cetyltrimethylammonium bromide, trimethyloctadecylammonium bromide and their mixture at ratios of 1:1 and 1:1:1. The CO 2 adsorption was investigated using thegravimetric method at 298 K and pressures up to 40 bar. The resulting materials, labelled C17, C19, C21, C17C19, C19C21, C17C21 and C17C19C21, were characterized by XRD, FTIR, TG and SEM and showed significant differences in structure as well as in the mass of CO2 adsorption. The response models showed that the best combination of the surfactants resulted from C 17C19 sample, which presented synergistic interactions reaching the highest value of CO2 adsorption (0.62 g CO2/g adsorbent), compared to other samples

Highlights

According to Scripps of Oceanography Institute, from San Diego University, where the Mauna Loa station is monitored, the average concentration of CO2 in Hawaii in April of 2014 was 401.33 ppm
The surfactants used were tetradecyltrimetylammonium bromide - C17 (C17H38NBr), cetyltrimethylammonium bromide - C19 (C19H42NBr) and trimethyloctadecylammonium bromide - C21 (C21H46NBr). They were mixed in the following ratios: 1:1 C17C19 (C17H38NBr + C19H42NBr); 1:1 C17C21 (C17H38NBr + C21H46NBr), 1:1 e C19C21 (C19H38NBr + C21H46NBr) and 1:1:1 C17C19C21 (C17H38NBr + C19H42NBr + C21H46NBr)
It can be observed that the material which contains a mixture of surfactants in the pores showed higher intensity peaks, especially C17C19

Summary

Introduction

According to Scripps of Oceanography Institute, from San Diego University, where the Mauna Loa station is monitored, the average concentration of CO2 in Hawaii in April of 2014 was 401.33 ppm. For the first time in human history, the concentration of CO2 in the atmosphere remained above 400 ppm during a whole month. The concentration of CO2 at the start of the industrialization period was around 280 ppm, according to the Intergovernamental Panel on Climate Change (IPCC). The new report from IPCC, from April 2014 shows that the emissions of gases from the greenhouse effect increased to unprecedented levels, despite of a series of policies to mitigate them. To decrease the environmental impact from intensified emission of CO2, it is necessary to developmore efficient removal technologies.

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