387
resulting in smaller molecules formation that are removed from industrial effluent.
Chlorine is defined as a strong oxidizing agent used as sodium hypochlorite and
calcium hypochlorite mainly used to remove efficiently direct, acid, reactive, and
metal complex dyes, which are water-soluble, but water-insoluble dyes, such as vat,
and disperse dye, are difficult to remove in this process (Gupta and Suhas 2009)
Advanced oxidation process has become a popular oxidation technique for the
removing dyes from industrial effluents. This is basically the process where above
one simultaneous oxidation processes are involved because the single oxidation
process is insufficient to remove the total dyes at a time (Holkar et al. 2016).
Different types of advanced oxidation processes are developed using different combination of oxidation process such as combination of ozone, hydrogen peroxide,
ultraviolet radiation, titanium dioxide, ultrasound, and electron-beam irradiation.
Among all, ozone/hydrogen peroxide, hydrogen peroxide/ultraviolet, and ozone/
ultraviolet are the promising methods to oxidize the dyes in effluent. The advanced
oxidation process has the potential to remove the dyes, but it is quite expensive
process in industry (Gupta and Suhas 2009; Holkar et al. 2016). Hydrogen peroxide
is a strong oxidizing as well as powerful bleaching agent used for paper bleaching
and making the peroxidase enzymes for dye decolorization (Gupta and Suhas 2009).
Kim et al. (2004) studied 99% dye removal by using Fenton’s oxidation process at
optimum condition (Kim et al. 2004). Ozone has the powerful oxidizing property
that can easily break down the aromatic ring in organic dyes with their cleavage of
conjugated double bonds and decomposes the pollutants. Ozone may react with dye
molecules directly or indirectly. Even at low pH, ozone efficiently reacts with the
dye by direct reactions. The disadvantages are short half-life, i.e., 20 min, quite
expensive, and produce toxic by-products (Ahmad et al. 2015). Photo-chemical oxidation treatment, the presence of hydrogen peroxide increases the efficiency of the
treatment. The ultraviolet-assisted hydrogen peroxide breaks the dye molecules into
smaller parts of organic particles or the ultimate products like carbon dioxide and
water and the other inorganic oxides, etc. The efficiency depends on the pH, ultraviolet radiation, and the structure of dyes. Electrochemical oxidation has attracted
great attention in the wastewater treatment under low temperature and moderate pH
with complete decomposition of dyes. In this process the dye molecules decompose
by non-soluble anodes such as conducting polymer and iron or by electrocoagulation using consumable materials either by direct or indirect oxidation process. The main disadvantages of this process are very costly (Gupta and Suhas
2009). Babu et al. (2011) studied that the methyl red azo dye removal by electrooxidation process was 81% (Babu et al. 2011).
Ion exchange process is the most simple method in dye treatment from industrial
effluent (Gupta and Suhas 2009). In this process, the dyes are removed by the strong
interchange between the charged molecules of dyes and the ion exchange resins.
Resins can be classified as four groups: anion exchange membrane, cation exchange
membrane, cross-linkage membrane, and other ion exchange membrane (Ruan
et al. 2019). Among all, cation exchangers and anion exchangers are mostly used for
dye removal (Ahmad et al. 2015). Cation exchange membrane used the negative
charged groups that helps to pass the cations but prevents anions to pass. The
15 Remediation of Dyes from Industrial Wastewater Using Low-Cost Adsorbents
resulting in smaller molecules formation that are removed from industrial effluent.
Chlorine is defined as a strong oxidizing agent used as sodium hypochlorite and
calcium hypochlorite mainly used to remove efficiently direct, acid, reactive, and
metal complex dyes, which are water-soluble, but water-insoluble dyes, such as vat,
and disperse dye, are difficult to remove in this process (Gupta and Suhas 2009)
Advanced oxidation process has become a popular oxidation technique for the
removing dyes from industrial effluents. This is basically the process where above
one simultaneous oxidation processes are involved because the single oxidation
process is insufficient to remove the total dyes at a time (Holkar et al. 2016).
Different types of advanced oxidation processes are developed using different combination of oxidation process such as combination of ozone, hydrogen peroxide,
ultraviolet radiation, titanium dioxide, ultrasound, and electron-beam irradiation.
Among all, ozone/hydrogen peroxide, hydrogen peroxide/ultraviolet, and ozone/
ultraviolet are the promising methods to oxidize the dyes in effluent. The advanced
oxidation process has the potential to remove the dyes, but it is quite expensive
process in industry (Gupta and Suhas 2009; Holkar et al. 2016). Hydrogen peroxide
is a strong oxidizing as well as powerful bleaching agent used for paper bleaching
and making the peroxidase enzymes for dye decolorization (Gupta and Suhas 2009).
Kim et al. (2004) studied 99% dye removal by using Fenton’s oxidation process at
optimum condition (Kim et al. 2004). Ozone has the powerful oxidizing property
that can easily break down the aromatic ring in organic dyes with their cleavage of
conjugated double bonds and decomposes the pollutants. Ozone may react with dye
molecules directly or indirectly. Even at low pH, ozone efficiently reacts with the
dye by direct reactions. The disadvantages are short half-life, i.e., 20 min, quite
expensive, and produce toxic by-products (Ahmad et al. 2015). Photo-chemical oxidation treatment, the presence of hydrogen peroxide increases the efficiency of the
treatment. The ultraviolet-assisted hydrogen peroxide breaks the dye molecules into
smaller parts of organic particles or the ultimate products like carbon dioxide and
water and the other inorganic oxides, etc. The efficiency depends on the pH, ultraviolet radiation, and the structure of dyes. Electrochemical oxidation has attracted
great attention in the wastewater treatment under low temperature and moderate pH
with complete decomposition of dyes. In this process the dye molecules decompose
by non-soluble anodes such as conducting polymer and iron or by electrocoagulation using consumable materials either by direct or indirect oxidation process. The main disadvantages of this process are very costly (Gupta and Suhas
2009). Babu et al. (2011) studied that the methyl red azo dye removal by electrooxidation process was 81% (Babu et al. 2011).
Ion exchange process is the most simple method in dye treatment from industrial
effluent (Gupta and Suhas 2009). In this process, the dyes are removed by the strong
interchange between the charged molecules of dyes and the ion exchange resins.
Resins can be classified as four groups: anion exchange membrane, cation exchange
membrane, cross-linkage membrane, and other ion exchange membrane (Ruan
et al. 2019). Among all, cation exchangers and anion exchangers are mostly used for
dye removal (Ahmad et al. 2015). Cation exchange membrane used the negative
charged groups that helps to pass the cations but prevents anions to pass. The
15 Remediation of Dyes from Industrial Wastewater Using Low-Cost Adsorbents