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15.4.1 Natural Materials
Natural materials are used as cheap adsorbents due to their abundant existence in
nature. The materials used as low-cost adsorbents are:
Natural coal can easily eliminate rhodamine B and methylene blue (basic dyes)
and sandola rhodine (acidic dye). Prior to the use as adsorbent, coal is prepared by
sulfonating and heating in water bath (Mittal and Venkobachar 2014). Different
types of coal are used as adsorbents such as lignite coal, bituminous coal, and char
fines. Because of the existence of acidic groups such as carboxyl and hydroxyl in
coal, it has chemisorption mechanism. As the coal is not a pure material, various
sorption properties are also found due to its various surface properties. Its sorption
properties are determined after some physicochemical pretreatment process
(Karaca 2006).
Clay is naturally obtained adsorbent that has been widely used for dye removal.
It is a mineral with the combination of silica and alumina with bound water. Due to
their availability, low-cost, higher capacity of adsorption, and good mechanical and
chemical strength, with good capacity of ion exchange, clay is very effective adsorbent for the treatment of wastewater. Clay particles have strong affinity to cations
and anions because of its surface area consisting of exchangeable ions. Various kind
of clay is used for dye removal present in aqueous medium such as kaolin clay,
bentonite clay, and Algerian clay (Sharma and Kaur 2018; Raval et al. 2017). Nandi
et al. (2009) used low cost kaolin clay for rhodamine-B, malachite green, and safranin- O dyes removal with 5%, 7%, and 2% (Nandi et al. 2009). Anirudhan and
Ramachandran (2015) used bentonite clay as low-cost adsorbent and found the
adsorption efficiency of methylene blue and rhodamine-B was 99.9% and 83%,
respectively (Anirudhan and Ramachandran 2015).
Surfactant-modified clay is actually the naturally obtained montmorillonite clay
modified with the cationic surfactant such as hexadecylpyridinium chloride and
hexadecyltrimethyl ammonium bromide. This product can be used as adsorbent and
efficiently remove dyes from industrial wastewater. It has been found that the
removal efficiency of malachite green and methylene blue by using this product is
30% and 28% (Sharma and Kaur 2018).
Surfactant-modified alumina is also modified with sodium dodecyl sulfate for
better efficiency in the treatment of wastewater. It effectively removes crystal violet
dye with 99% efficiency (Adak et al. 2005).
Siliceous materials are actually sedimentary rocks which consist with silica as
major constituent. Diatomite is one of the most convenient siliceous rocks in the
form of diatoms, radiolarians, and different types of sponges. Silica, perlite, alunite,
and glass fibers are the natural siliceous materials with low cost and easily available,
mainly used as adsorbent in removing malachite green for the treatment of wastewater (Raval et al. 2017). Andrzejewska et al. (2007) studied by using aminosilane
modified silica for removing anionic reactive color index reactive blue 19 dye with
90% removal efficiency (Andrzejewska et al. 2007).
15 Remediation of Dyes from Industrial Wastewater Using Low-Cost Adsorbents
15.4.1 Natural Materials
Natural materials are used as cheap adsorbents due to their abundant existence in
nature. The materials used as low-cost adsorbents are:
Natural coal can easily eliminate rhodamine B and methylene blue (basic dyes)
and sandola rhodine (acidic dye). Prior to the use as adsorbent, coal is prepared by
sulfonating and heating in water bath (Mittal and Venkobachar 2014). Different
types of coal are used as adsorbents such as lignite coal, bituminous coal, and char
fines. Because of the existence of acidic groups such as carboxyl and hydroxyl in
coal, it has chemisorption mechanism. As the coal is not a pure material, various
sorption properties are also found due to its various surface properties. Its sorption
properties are determined after some physicochemical pretreatment process
(Karaca 2006).
Clay is naturally obtained adsorbent that has been widely used for dye removal.
It is a mineral with the combination of silica and alumina with bound water. Due to
their availability, low-cost, higher capacity of adsorption, and good mechanical and
chemical strength, with good capacity of ion exchange, clay is very effective adsorbent for the treatment of wastewater. Clay particles have strong affinity to cations
and anions because of its surface area consisting of exchangeable ions. Various kind
of clay is used for dye removal present in aqueous medium such as kaolin clay,
bentonite clay, and Algerian clay (Sharma and Kaur 2018; Raval et al. 2017). Nandi
et al. (2009) used low cost kaolin clay for rhodamine-B, malachite green, and safranin- O dyes removal with 5%, 7%, and 2% (Nandi et al. 2009). Anirudhan and
Ramachandran (2015) used bentonite clay as low-cost adsorbent and found the
adsorption efficiency of methylene blue and rhodamine-B was 99.9% and 83%,
respectively (Anirudhan and Ramachandran 2015).
Surfactant-modified clay is actually the naturally obtained montmorillonite clay
modified with the cationic surfactant such as hexadecylpyridinium chloride and
hexadecyltrimethyl ammonium bromide. This product can be used as adsorbent and
efficiently remove dyes from industrial wastewater. It has been found that the
removal efficiency of malachite green and methylene blue by using this product is
30% and 28% (Sharma and Kaur 2018).
Surfactant-modified alumina is also modified with sodium dodecyl sulfate for
better efficiency in the treatment of wastewater. It effectively removes crystal violet
dye with 99% efficiency (Adak et al. 2005).
Siliceous materials are actually sedimentary rocks which consist with silica as
major constituent. Diatomite is one of the most convenient siliceous rocks in the
form of diatoms, radiolarians, and different types of sponges. Silica, perlite, alunite,
and glass fibers are the natural siliceous materials with low cost and easily available,
mainly used as adsorbent in removing malachite green for the treatment of wastewater (Raval et al. 2017). Andrzejewska et al. (2007) studied by using aminosilane
modified silica for removing anionic reactive color index reactive blue 19 dye with
90% removal efficiency (Andrzejewska et al. 2007).
15 Remediation of Dyes from Industrial Wastewater Using Low-Cost Adsorbents