Change search
ReferencesLink to record
Permanent link

Direct link
Textural and hydrogen sulphide adsorption behaviour of double metal-silica modified with potassium permanganate
KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Materials.
Högskolan i Gävle.
Högskolan i Gävle.
Högskolan i Gävle.
2013 (English)In: Journal of porous materials, ISSN 1380-2224, E-ISSN 1573-4854, Vol. 20, no 3, 447-455 p.Article in journal (Refereed) Published
Abstract [en]

A new MgCa-silica material with bimodal pore size is impregnated with KMnO4 for dynamic adsorption of H2S. The MgCa-silica was synthesized using sodium silicate and calcium and magnesium salts as precipitating agents. The KMnO4 impregnation onto MgCa-silica was obtained through either direct addition into MgCa-silica wet coagulum or doping of dried MgCa-silica pellets into KMnO4 solution. These chemisorbents were characterized by nitrogen physisorption, spectrophotometer, microscopy and dynamic H2S adsorption test setup similar to ASHRAE standard I45.I. The results show that impregnation route and KMnO4 wt% cause a reduction of surface area and total pore volume. The decrease in pore volume was slightly more in chemisorbents obtained via post doping compared to direct impregnation. Regardless of pore volume reduction the pore size range, 1-32 nm, was as in the parent MgCa-silica with micro and meso-pore diameter centered at 1.4 and 5.4 nm respectively. Thus obtained chemisorbents have their pore entrances neither blocked nor shifted. The MgCa-silica/KMnO4 chemisorbents exhibits good H2S uptake performance. The chemisorbent with 11.4 wt% KMnO4 and obtained via direct impregnation possesses the highest uptake capacity. The lowest capacity was observed for chemisorbent with 8 wt% KMnO4 and made by direct impregnation. The variations in uptake capacity are likely due to impregnation route, the KMnO4 content and its location in the pore system. The results suggest that the MgCa-silica/KMnO4 chemisorbents can remove H2S from indoor air at room temperature.

Place, publisher, year, edition, pages
2013. Vol. 20, no 3, 447-455 p.
Keyword [en]
Hydrogen sulphide, KMnO4 impregnation, H2S adsorption, Textural properties, Pore size
National Category
Civil Engineering
URN: urn:nbn:se:kth:diva-120460DOI: 10.1007/s10934-012-9614-xISI: 000318369400001ScopusID: 2-s2.0-84877827331OAI: diva2:614997

QC 20130610

Available from: 2013-04-08 Created: 2013-04-08 Last updated: 2016-08-16Bibliographically approved
In thesis
1. Preparation and Evaluation of New Nanoporous Silica Materials for Molecular Filtration and for Core Materials in Vacuum Insulation Panels
Open this publication in new window or tab >>Preparation and Evaluation of New Nanoporous Silica Materials for Molecular Filtration and for Core Materials in Vacuum Insulation Panels
2013 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Nanoporous materials for gas purification and thermal insulation have been studied and developed for application in many areas. It is known that a single adsorbent may not adequately control multiple contaminants. Further the utilization of nanoporous material as thermal insulator in building applications is limited due to high cost. Moreover, in view of the global environmental movement for clean air and reduction of heating energy consumption in built environment, the development of new and better nanoporous materials will not only facilitate major advances in gas adsorption and thermal insulation technology, but also meet the new challenges that cannot be met with the nanoporous materials that are currently available. This thesis presents a synthesis of new nanoporous silica based materials, and the characterization and application of these materials for molecular filtration and thermal insulation. Commercial nanoporous materials have been used for benchmarking for the pore properties, the applicability, and the performance of these new materials.

First a double metal-silica adsorbent has been synthesized. The preparation procedure is based on the use of sodium silicate coagulated with various ratios of magnesium and calcium salts which yields micro-meso porous structures in the resulting material. The results show that molar ratios of Mg/Ca influence the pore parameters as well as the structure and morphology. The bimodal pore size can be tailored by controlling the Mg/Ca ratio.

In the second synthesis, pure mesoporous silica, SNP has been prepared using glycerol as pore forming agent and monovalent salts as coagulant. This leads to material with large surface area and uniformed pore size centred at 43 or 47 nm.  The materials further exhibits a low bulk density in the range of 0.077 to 0.122 g/ml and possess a high porosity in the range of 95-97%. The influence of acid type (organic or inorganic) on the pore parameters and on the tapped density has also been investigated.  

A synthesis method has also been developed for the preparation of carbon-silica composites. The method involves a number of routes, which can be summarised as addition of activated carbon particles to (I) the paste, (II) the salt solution, or (III) with the sodium silicate solution. In route II and III the activated carbon is present before coagulation. The routes presented here leads to carbon-silica composites possessing high micro porosity, meso porosity as well as large surface areas. The results further shows that pore size distribution may be tailored based on the route of addition of the carbon particles. Following route I and III a wide pore size (1-30 nm) was obtained whereas by route II a narrow pore size (1-4 nm) was observed.    

MgCa-silica chemisorbents were also developed using either potassium hydroxide or potassium permanganate as impregnate chemicals. A direct or post-impregnation procedure was employed. The results revealed that the impregnate route and amount cause a reduction in both specific surface area and pore volume.

Finally the thermal conductivity and dynamic adsorption of H2S, SO2 andtoluene were measured. Results show that at room temperature and atmospheric pressure, a thermal conductivity of 28.4 and 29.6 mW/m.K were obtained for the SNP mesoporous silicas. The dynamic adsorption behaviour of the chemisorbents and composites indicate their ability to absorbed H2S, SO2 andtoluene respectively. The highest H2S uptake corresponds to chemisorbents with 11.2-13.6 wt% KMnO4. The effect of impregnation route, amount of KMnO4 and its location in the pore system are likely the key factors in achieving a large H2S uptake. For SO2 adsorption, the highest uptake capacity was observed for MgCa-68/32-KOH. The results further suggest that the key to large SO2 uptake is as a result of the synergetic effect between large mesopore diameter and extensive mesopore volumes. Carbon-silica composites with carbon content 45 wt % exhibits high toluene adsorption with composite via route I having the highest toluene adsorption capacity (27.6 wt % relative to carbon content). The large uptake capacity of this composite was attributed to the presence of high microporosity volume and a wide (1-30 nm) bimodal pore system consisting of extensive mesopore channels (2-30 nm) as well as large surface area. These capacity values of carbon-silica composites are competitive to results obtained for commercial coconut based carbon (31 wt %), and better than commercial alumina-carbon composite (9.5 wt %).

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2013. vii, 57 p.
Meddelande. Institutionen för byggvetenskap, ISSN 1651-5536 ; 211
Adsorbents, activated carbon, MgCa-silica, carbon-silica composite, characterization, porous parameters, molecular filtration, thermal conductivity, thermal insulation
National Category
Architectural Engineering Building Technologies
urn:nbn:se:kth:diva-120330 (URN)978-91-7501-701-3 (ISBN)
Public defence
2013-04-16, Sal B2, Brinellvägen 23, KTH, Stockholm, 13:00 (English)

QC 20130408

Available from: 2013-04-08 Created: 2013-04-04 Last updated: 2013-04-08Bibliographically approved

Open Access in DiVA

No full text

Other links

Publisher's full textScopus

Search in DiVA

By author/editor
Twumasi Afriyie, Ebenezer
By organisation
Building Materials
In the same journal
Journal of porous materials
Civil Engineering

Search outside of DiVA

GoogleGoogle Scholar
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

Altmetric score

Total: 54 hits
ReferencesLink to record
Permanent link

Direct link