|
Sorption
Studies of Methylene Blue on Activated Carbon Derived from
Agricultural Waste: Achyranthes aspera --
N Balasubramanian and N Sulochana
A
significant amount of Achyranthes aspera is discarded
as agriculture waste weed from paddy field. In the present
investigation, the carbonaceous product obtained by the treatment
of A. aspera with sulphuric acid was used to study
its efficiency as an adsorbent for the removal of methylene
blue from aqueous solution. Batch adsorption of methylene
blue (MB) on A. aspera carbon (AAC) was studied as
a function of agitation time, initial dye concentration, adsorbent
concentration and pH in order to explore the potential use
of this material as low cost adsorbent for dye removal. Among
the isotherm models applied to the equilibrium data, Redlich-Peterson
model better predicted the experimental values. The adsorption
capacity was 204.23 mg/g at an initial pH of 7.0 ± 0.1
and at 32 °C. The kinetics analyses were made by using
pseudo-first order and pseudo-second order models. It was
found that the adsorption kinetics of MB on AAC obeyed pseudo-second
order sorption kinetics. The results indicated the potential
use of AAC as sorbent for the removal of basic dye from aqueous
solution.
©
2008 The Icfai University Press. All Rights Reserved.
A
Theoretical Approach to Increased Ion-Exchange Capacity to
Three-Component Ion-Exchange Materials --
Nafisur Rahman, Lutfullah and Syed Najmul Hejaz Azmi
Zirconium(IV)
selenophosphate, a three-component inorganic ion-exchanger
was synthesized. In most cases, it was found that the ion-exchange
capacity of three-component inorganic ion-exchangers was greater
than those of two-component inorganic ion-exchangers. A theoretical
explanation was given for the enhancement of ion-exchanger
capacity of three-component materials and was found to be
in good agreement with the experimental value.
©
2008 The Icfai University Press. All Rights Reserved.
Kinetic
Behavior of Woody Biomass with Slow Heating Rate --
Jigisha Parikh, S A Channiwala and G K Ghosal
Four
kinds of woody biomassSawdust, Babul, Gulmahor and Eucalyptuswere
pyrolyzed in a nitrogen atmosphere at the heating rate of
10 °C/min. up to 500 °C
in a thermogravimetric analyzer to investigate their pyrolytic
characteristics. Three stagesdehydration, devolatilization
and solid decompositionappeared in the pyrolysis process.
The thermograms could be directly correlated with the thermal
devolatilization. All four materials were mainly devolatilized
in the temperature range of 180-496 °C. A total
volatile yield of about 70% was achieved from each wood. The
pre-exponential factor and activation energies were calculated
using differential method of analysis, assuming different
order of reactions. Linear regression was applied and the
value of order, which gives the highest confidence level,
was considered for the main devolatilization stage (190-370
°C). The value of activation energy found was
in the following order: Eucalyptus>Babul >Gulmahor>Sawdust
and it was same for pre-exponential factor. The experimental
results may provide useful data for the design of pyrolytic
processing systems using woody biomass as feedstock.
©
2008 The Icfai University Press. All Rights Reserved.
Isomers
of Organotin Compounds: Mononuclear
Compounds -- Milan
Melník, Ján Garaj, Aladár Valent and
Mária Kohútová
The
mononuclear organotins cover a huge field as shown by a recent
survey, covering the crystallographic and structural data
of almost 1000 examples. Over 11% of these complexes exist
as isomers and are summarized in this paper. Included are
distortion (88.8%) and ligand (11.2%) isomerism. These are
discussed in terms of coordination about tin atom, and correlations
are drawn between donor atoms, bond lengths and interbond
angles. Distortion isomers differ only by degree of distortion
in Sn-L and L-Sn-L angles, which are the most common. There
are tin atoms in the oxidation states +2 and +4 (most common)
and ligand isomerism (+4 only). The antimicrobial activity
increases with the higher degree of the tetrahedral distortion.
©
2008 The Icfai University Press. All Rights Reserved.
|
September
'08