Polyvinylidene fluoridemultiwalled carbon nanotubes membrane for methylene blue dye removal via adsorption
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Date
2018-06
Authors
Munesh Daniel Rajendren
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Abstract
The polyvinylidene fluoride (PVDF) membrane is fabricated by phase inversion method
for the adsorption of methylene blue dye from its solution. The functionalized multiwalled carbon
nanotubes (MWCNTs) containing carboxylic groups (-COOH) functional groups are incorporated
into the PVDF membrane to improve the mechanical strength as well as the adsorption qualities
of the membrane. The MWCNTs act as a bridge that would provide more vacant adsorption sites
compared to PVDF membrane by itself to assist in the adsorption of the methylene blue dye. The
adsorption process is then tested with 3 different factors which are temperature, contact time and
the initial concentration of the methylene blue (MB) dye solution to observe which factors affect
the PVDF as well as the PVDF/MWCNT membrane most. The study of the effect of temperature
showed that the efficiency of the adsorption decreases as the temperature of the mixture increases.
This leads to the conclusion that the adsorption process between PVDF as well as PVDF/MWCNT
and the MB dye is an endothermic process. The study of the contact time between the membrane
and the MB dye showed that the process begins rapidly when the concentration of the solution
decreases by 5.66% in the first hour and slowly reduces in efficiency when the concentration only
reduced about 2% over the next 3 hours due to the vacant adsorption sites being filled. The study
of the initial concentration of MB dye solution revealed that both PVDF and PVDF/MWCNT
membrane is able to accommodate MB dye solution of 1-2 mg/l without loss of efficiency. The
PVDF membrane starts losing efficiency at MB dye concentration of 3 mg/l whereas
PVDF/MWCNT membrane starts losing efficiency at MB dye concentration of 4 mg/l. The study
of the adsorption isotherms showed that the best fit isotherm for the adsorption process between
the PVDF and PVDF?MWCNT membrane with the methylene blue solution would be the
Langmuir isotherm.