ORIGINAL RESEARCH
Modified Clays as an Efficient Adsorbent
for Brilliant Green, Ethyl Violet and Allura Red
Dyes: Kinetic and Thermodynamic Studies
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1
Department of Chemistry, Quaid-i-Azam University, Is-lamabad, 45320, Pakistan
2
Department of Chemistry, University of Education, Attock Campus, Attock, 43600, Pakistan
3
Department of Chemistry, College of Science, University of Bahrain, Sakhir 32038, Bahrain
Submission date: 2019-07-31
Final revision date: 2019-09-07
Acceptance date: 2019-09-15
Online publication date: 2020-04-29
Publication date: 2020-06-08
Corresponding author
Amir Waseem
Chemistry, Quaid-i-Azam University, Islamabad, Pakistan., 3rd Avenue, 87300, Islamabad, Pakistan
Pol. J. Environ. Stud. 2020;29(5):3831-3839
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ABSTRACT
Clay minerals can effectively adsorb contaminants from aqueous effluents due to their good
adsorption and high cation exchange capacity. However, naturally occurring clay materials possessing
hydrophilic features are not especially effective for the removal of organic pollutants. Therefore, in
the present work the issue of hydrophilicity is tackled by modification of the clay (Pakistan origin)
to prepare organoclays. Hexadecylpyridinium chloride, cetyltrimethylammonium bromide, and
sodium dodecyl sulfate were used as clay modifiers. Changes in the basal spacing of clay layers after
modification with surfactants were determined through XRD analysis. Chemical compositions of the
clay and organoclays were determined by FTIR spectroscopy. Surface morphology of the as-prepared
organoclays was assessed from SEM analysis. The modified clays (organoclays) were tested for their
ability as potential adsorbents for three dyes from water: brilliant green, ethyl violet and allura red.
All three modified clays showed high adsorption characteristics by removing (>90 %) of all three dyes
with an adsorption capacity ranging from 35 to 85 mg/g. The time-dependent adsorption experiments
showed that the rates of adsorption of dyes on organoclays were fast, adsorbing maximum amounts of
dyes ranging from 15 to 80 mins of contact time. The adsorption kinetic study revealed that the dye
removal process is mainly governed by a pseudo-1st order mechanism. Thus, surfactant-modified clays
are an excellent choice as cost-effective and efficient adsorbents for the purification of water from dye
contaminants.