On the desiccant capacity of the mesoporous RF-xerogels

Isabel D Alonso-Buenaposada,Ana Arenillas,J Angel Menéndez

doi:10.1016/j.micromeso.2017.04.014

Isabel D Alonso-Buenaposada, Ana Arenillas + Show 1 more

Open Access

https://doi.org/10.1016/j.micromeso.2017.04.014

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Journal: Microporous Materials	Publication Date: Apr 9, 2017
Citations: 5	License type: cc-by

Affiliation: Instituto Nacional del Carbón

Abstract

Resorcinol-formaldehyde xerogels are ideal desiccant materials since the high concentration of hydroxyl groups on their surfaces confers on them a high hydrophilicity, which adsorbs moisture from their surroundings and their large porosity provides them with a high water sorption capacity. In this study, the porosity of organic xerogels was tailored by adjusting the proportion of methanol in the precursor solution in order to optimize their desiccant capability. It was found that, although an increase in microporosity improves the performance of the desiccant, mesoporosity is a more important property for this application. Organic xerogels are excellent desiccants which are able to adsorb more than 80% of their own weight in moisture and function efficiently for more than 3000 h, when their porosity is optimized. This is a great improvement on the commonly used silica gels that become saturated after only 150 h and can only adsorb a maximum of 40 wt % of their own weight in moisture. Moreover, RF xerogels have the advantage that they are organic materials resistant to acid attack and this allows them to be used in processes where conventional inorganic desiccants would rapidly deteriorate.

Highlights

Resorcinol-formaldehyde (RF) gels have been the most widely studied nanoporous organic gels in recent years [1,2,3]
Resorcinol-formaldehyde xerogels are ideal desiccant materials since the high concentration of hydroxyl groups on their surfaces confers on them a high hydrophilicity, which adsorbs moisture from their surroundings and their large porosity provides them with a high water sorption capacity
Organic xerogels are excellent desiccants which are able to adsorb more than 80 % of their own weight in moisture and function efficiently for more than 3000 h, when their porosity is optimized

Summary

Introduction

Resorcinol-formaldehyde (RF) gels have been the most widely studied nanoporous organic gels in recent years [1,2,3]. The widely recognized advantage of RF xerogels is that it is possible to obtain materials whose porosity can be designed for a specific application by adjusting the variables used during the synthesis process (i.e., the pH of the precursor solution, dilution ratio, RF molar ratio, etc.) [13,14,15,16] This versatility, in combination with the fact that they are light and cheap to produce, makes them suitable for a wide range of applications [1721]. In the case of RF xerogels, the high concentration of hydroxyl groups on their surfaces provides them with a high hydrophilicity that attracts surrounding moisture through hydrogen bonding, and their large porosity gives them their high water sorption capacity Their hydrophilicity and suitability for use as desiccant materials have been demonstrated in a previous work [22]. In this work the influence of porous properties, in the mesopore range, on the water adsorption capacity of RF xerogels is studied in order to optimize their effectiveness as light-weight organic desiccants

Synthesis of organic xerogels

Results and Discussion

Conclusions