Production of silica gel from Tunisian sands and its adsorptive properties
authors Lazaar, K; Hajjaji, W; Pullar, RC; Labrincha, JA; Rocha, F; Jamoussi, F
nationality International
journal JOURNAL OF AFRICAN EARTH SCIENCES
author keywords Tunisian quartz sands; Silica gel; Retention; Methylene blue; Dye absorption
keywords REMOVAL; ADSORBENT; KINETICS; MATRIX; GREEN; DYE; PH
abstract Thanks to its highly absorbent character, silica gel is used in several applications, such as air moisture removal, as a treatment agent for effluents. In this study, silica gels were synthesised from Tunisian sands, collected from the Fortuna and Sidi Aich Formations in northern and central Tunisia. The collected quartz sand raw materials, as well as the prepared silica gels, were characterised by different techniques, such as X-ray diffraction (XRD), X-ray fluorescence (XRF) and scanning electron microscopy (SEM). XRD patterns of quartz sands showed quartz as main phase (86.1-98%), with lower contents of potassic feldspars, along with kaolinite and calcite. These quartz sands presented relatively small quantities of Fe2O3 (0.3%-0.5%) and TiO2 (0.1%-0.6%). The synthesised silica gels exhibited pore diameters exceeding 20 A and surface areas up to 194 m(2)/g, comparable with those described in the literature and commercial silica gel. N-2 adsorption isotherms showed that the silica gels prepared from Tunisian sands are meso-porous materials with high adsorption capacities. To understand better their adsorbent properties and applicability on an industrial scale, these gels were tested for methylene blue (MB) absorption. Maximum decolourisation rates (up to 96% after a contact time of 180 min) occurred with products synthesised at pH 3. The adsorption mechanism fitted better with a Langmuir model, revealing a monolayer coverage process of MB molecules over the gel surface, and the adsorption kinetics of the dye on these materials is well described by the second order model. The corresponding equilibrium adsorption capacities obtained from experimental data (Q(exp) = 292-214 mg/g) were close to the estimated maximum adsorption capacities (Q(e) = 333-250 mg/g), and to that of an industrial silica gel (250 mg/g). (C) 2017 Elsevier Ltd. All rights reserved.
publisher PERGAMON-ELSEVIER SCIENCE LTD
issn 1464-343X
year published 2017
volume 130
beginning page 238
ending page 251
digital object identifier (doi) 10.1016/j.jafrearsci.2017.03.017
web of science category Geosciences, Multidisciplinary
subject category Geology
unique article identifier WOS:000403515500019
  ciceco authors
  impact metrics
journal analysis (jcr 2017):
journal impact factor 1.532
5 year journal impact factor 1.784
category normalized journal impact factor percentile 36.053
dimensions (citation analysis):
altmetrics (social interaction):



 


Sponsors

1suponsers_list_ciceco.jpg