dc.description.abstract |
The control of water pollution has become of increasing interests because it
is associated with the life of human beings, animals and the land which is
irrigated with it. Water pollution has many dimensions and types but
pollution due to industrial wastes is commonly metal pollution and
chemical pollution. The present study emphasizes the water pollution and
composites present in waste water like dyes and surfactants. Dyes are the
main component of the dyeing industries so the effluent carrying high
content of dyes along with other composites. It is quite difficult to remove
dyes from effluents since most of them are stable to light, heat and
oxidizing agents and they are biologically non-degradable also. Whereas
the surfactants are the major part of every washing and cleaning agents like
soaps, washing powder, dish washing bars, toothpastes and widely used in
textile industry as softener. So both dyes and surfactants are the major
constituent of domestic and industrial waste water.
The treatment of
contaminated waste water is necessary before it enter into the stream, lake,
river or sea. The disposal of wastes containing dyes and surfactants into
receiving water bodies effects on the values of biological oxygen demand
(BOD) and chemical oxygen demand (COD) which resulted toxicity of
aquatic life. In the current study by employing physical and chemical
treatment methods utilization and removal of surfactant and dyes were
carried out. The physical treatment method like adsorption technique was
adopted by using natural materials and their modified surfaces for the
removal of dyes and surfactant. The physical treatment method is beneficial
for the removal and the regeneration of adsorbed substances. It is also
economical and low cost method and can be employed on industrial scale
before the disposal of waste into the stream and other reservoirs. The
efforts were done by developing a model system for the removal of
surfactant Cetylpyridinum Chloride (CPYCl) and dyes Malachite Green
11
(MG), Methylene blue (MB), Fast Green (FG) from aqueous solution by
adopting batch adsorption method. The Cetylpyridinum Chloride (CPYCl)
is the main constituent of daily washing powder and the dyes Malachite
Green (MG) and Methylene blue (MB)
are used in textile and paper
industries and Fast Green (FG) dye widely used in food industries. The
adsorbents were used for the removal of surfactant and dyes are raw
Charcoal (RC), marine Algea like Ulva Lactuca (UL) and Sargassum
Muticum (SM), Used Black tea (UBT), and impregnated used black tea
(IM-UBT). Raw Charcoal was prepared from coconut dry shells, the algae
Ulva Lactuca (UL) and Sargassum Muticum (SM) were collected from sea
shore near the Clifton beach of Arabian Sea while Used Black tea (UBT)
were collected from tea canteens as it is waste material after making tea
and used for adsorption purposes. The modified surface of UBT were
prepared by impregnation technique and their nano composites were
prepared by impregnation with lead nitrate Pb(NO3)2. The batch adsorption
experiments were run and effect of amount of adsorbents, concentration of
adsorbate,
contact
time
and
temperature
were
investigated.
Spectrophotometric technique was adopted for the measurement of
concentration of dyes before and after adsorption. The adsorption data were
fitted in the adsorption models like Langmuir, Freundlich and Dubinin-
Radushkevich adsorption
isotherm equations and the values of their
respective constants were evaluated. Thermodynamic parameters such as
(ΔG) free energy, (ΔH) enthalpy, and (ΔS) entropy of the system were
calculated. Mean free energy of sorption (Es) was also estimated in order to
get the clear picture of energy exchange between the adsorbate and
adsorbent using D-R adsorption isotherm equation. The values of %
removal show that adsorption of surfactant (CPYCl) and dyes (MG), (MB)
and (FG) on the natural and modified adsorbents show about 70% - 80%
removal tendency.
The chemical treatment method was adopted for the decoloration of dye
effluent by the photoreduction method. The reduction kinetic was studied
for all the dye systems but fast green (FG) show dominating results. It is
evenly widely used for domestic and industrial purposes and also it is a
representative of its acidic group dyes. The rate of the reaction was
determined by varying concentration and temperatures of dye, surfactant
and base (NaOH) at 303K to 323 K at the step of ± 5 °C. It was observed
that the reduction followed pseudo first-order kinetics with respect to dye,
surfactant, and OH– ion concentration .The mechanism for the photo
bleaching of the dye has been proposed and well confirmed by the data
simulation procedure. The activation parameters of the reaction like
entropy of activation (ΔS) and free energy of activation (ΔG) showed the
extremely solvated states of transient complex which was less disorderly
arranged than the oxidized form of dye, whereas energy of activation Ea
values reflects a high amount of energy required for the reduction of dye
with surfactant cetylpyridinum chloride. The % decolorations of dyes were
obtained about 70 to 80%.
It was concluded that if the effluent contains acidic dyes and the cationic
surfactant simultaneously, the dye will reduced by the surfactant and in this
manner that surfactant in waste will also be utilized to reduce the harmful
effects of dyes. It is an economical and cost effective method to utilize
waste material for the purification of effluent also we can regenerate these
adsorbents for the further treatment process. By employing impregnation
technique nano composites were prepared from waste material and they
show better adsorption tendency as compared to commercial adsorbents.
The purification of waste water was carried out by employing physical
method like adsorption and chemical method by reduction kinetics
technique so we can simulate the model for the recycling of solid -liquid
waste and we save the environment with harmful pollutants. |
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