CO2_2016 - page 48

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Chimica Oggi - Chemistry Today
- vol. 34(2) March/April 2016
KEYWORDS: Mesoporous carbon cmk-3, adsorption, heavy metals, pb (ii), cd (ii), ni (ii).
Abstract
The aim of this study is to investigate the ability of CMK-3 to remove heavy metals (Pb (II), Cd (II) and Ni
(II)) from aqueous solution when present singly. CMK-3 was synthesized using the mesoporous SBA-15 silica
as structure template and was characterized by XRD, nitrogen adsorption-desoprtion and FT-IR , FT-IR spectrum shows that there are
many functional groups at the surface of CMK-3. The adsorption process of ions on CMK-3 can be considered very fast, attaining 90%
adsorption efficiency within 5 min for Pb (II) and Ni (II), and 10 min for Cd (II). The adsorption capacity of CMK-3 for the removal of Pb
(II), Ni (II) and Cd (II) was 199,4, 198 and 180 mg/g of CMK-3, respectively. These capacities values are highest among those reported
in the literature. The adsorption capacity was inversely proportional to the hydrated ionic radius of the metals. The effects of the
adsorbent dose, pH and temperature on Pb (II) uptake from aqueous solution have been studied (not shown).The lead removal was
pH dependent, and remained almost unchangeable with the increase in adsorbent dosage, indicating that sufficient adsorption sites
are available at lower CMK-3 dose.The adsorption of Pb (II) when present in binary (Pb (II) + Cd (II), Pb (II) + Ni (II)) or in ternary system
(Pb (II) + Cd (II) + Ni (II)) was also investigated. The results showed that the adsorption of Pb (II) decreased slightly in binary system.
Interestingly, in the ternary system there was a substantial improvement in the removal of Pb (II).
Adsorption of lead (II)
on mesoporous carbon CMK-3 from single,
binary and ternary metal aqueous solution
INTRODUCTION
The release of industrial wastes containing toxic heavy metals
poses a serious threat to the environment and the health of
human populations. The heavy metal ions are stable and
persistent environmental contaminants (1-5). Several studies
have shown that nanomaterials are promising candidates for
pollution treatment (6-29). Mesoporous SBA-15 silica has been
widely studied owing to its 3-D structure with interconnected
pores (30). An interconnected structure is required to use it as
hard template to prepare ordered mesoporous materials as a
stable replica of its structure. SBA-15 is used as hard template
to synthesize mesoporous carbon CMK-3 (31). Mesoporous
carbon has attracted much attention because of its unique
structural features and many promising applications such as
adsorbents, hydrogen storage, catalysts supports in addition
to electrochemical double-layer capacitors (31-36).
The aim of this study is to investigate the ability of CMK-3 to
remove heavy metals (Pb (II), Cd (II) and Ni (II)) from aqueous
solution when present singly. The effects of the contact
time, adsorbent dose, pH and temperature on Pb (II) uptake
from aqueous solution have been studied (not shown). The
adsorption of Pb (II) when present in binary (Pb (II) + Cd (II),
Pb (II) + Ni (II)) or in ternary system (Pb (II) + Cd (II) + Ni (II)) was
also investigated.
EXPERIMENTAL SECTION
Reagents
Tetraethyl orthosilicate (TEOS) (Aldrich), Pluronic P123 (Aldrich,
80%), hydrochloric acid (Riedel-de Haën, 32%), sucrose
(Sigma), sulfuric acid (Aldrich, 97%), sodium hydroxide
(Aldrich), lead nitrate (Aldrich, 99%), cadmium nitrate
tetrahydrate (Aldrich, 99,999%), nickel nitrate hexahydrate
(Aldrich, 99,999%) were used as received.
Materials preparation
Synthesis of SBA-15
The synthesis procedure for mesoporous Silica SBA-15 follows that
published by Zhao et al. (37). In a typical synthesis in this work,
4g of amphiphilic triblock copolymer poly (ethylene oxide)-poly
(propylene oxide)-poly (ethylene oxide) (average molecular
weight 5800, from Aldrich) was dispersed in 120 g of de-
ionized water and 8.64g of 2M HCl solution at 40°C wile stirring
followed by the addition of 8.54g of tetraethyl-orthosilicate
to the homogenous solution with stirring. This gel mixture was
continuously stirred at 40°C for 24h, and finally crystallized in
a Teflon-lined autoclave at 100°C for 2 days. After cooling to
room temperature the solid product was filtered and dried at
room temperature in air. Template removal was achieved by
calcinations in air at 500°C for 4h (heating rate: 1°C/mn).
R. BOURI
1
, L. CHERIF
1
*, R. DENOYEL
2
* Corresponding author
1. Laboratoire de catalyse et synthèse en chimie organique BP 119 , Université de Tlemcen, Algérie
2. Laboratoire des Matériaux Divisés, Revêtements, Electrocéramiques, Thermodynamiques, Cinétiques,
Electrochimie (MADIREL), Centre St-Jérôme 13397, Marseille cedex 20, France
Leila Cherif
CATALYSIS AND BIOCATALYSIS
1...,38,39,40,41,42,43,44,45,46,47 49,50,51,52,53,54,55,56,57,58,...68
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