microbes (Tsydenova et al. 2015). These statistics indicated that water pollution by
numerous pollutants becomes an alarming issue worldwide. Therefore, developing
sustainable or low-cost alternative pathways for disinfecting pathogenic microorganisms has attracted more attention from policymakers and scientists (Wang et al.
2017c). Different conventional water disinfection methods like ozonation, chlorination, and ultraviolet disinfection were believed to be efficient ways for water
disinfection. Yet, these methods have not been widely applied to water disinfection
due to cost and disposal issues (Foster et al. 2011).
Moreover, these disinfection methods have their own merits and demerits to treat
wastewater. Among the chemical methods, advanced oxidation processes are of
sufficient interest in disinfection process for the effective oxidation of a wide variety
of organic and inorganic pollutants due to the generation of dominant reactive
oxygen species, such as the hydroxyl radical, H 2 O 2 , and superoxide radical
(Nieuwenhuijsen et al. 2000). Among these methods, top priority goes to
semiconductor-assisted photocatalytic disinfection process, which can use sunlight
(Huang et al. 2005). The application of photocatalysis for water disinfection of
Lactobacillus acidophilus, Saccharomyces cerevisiae, and Escherichia coli was
applied for the first time in 1985 by Matsunaga et al. (1985a). After that, more
researches have been carried out in the development of the photocatalytic disinfection process. According to Christensen et al. (2003) and Gong et al. (2011), three
pathogenic microorganisms, namely, Pseudomonas aeruginosa, Candida albicans,
and Enterococcus faecium, using solar/ultraviolet radiation were effectively
inhibited by using titanium as a photocatalyst. Similar results were reported for the
disinfection of Staphylococcus aureus (Makoday et al. 2015), Streptococcus mutants
(Kühn et al. 2003), Salmonella choleraesuis, Vibrio parahaemolyticus, and Listeria
monocytogenes (Melián et al. 2000). Figure 7.1 shows the photocatalytic bacterial
disinfection mechanism involving reactive oxygen species (Maness et al. 1999;
Rahmawati et al. 2010; Spuhler et al. 2010; Dunlop et al. 2011). Recently, Liu
et al. (2017) investigated the effective photocatalytic TiO 2 disinfection of Cryptosporidium and Giardia that are resistant to chlorination.
Recently some resaerches are carrioed out uisng TiO 2 as photocatalyst for the
disinfection of microbes because of having a large bandgap structure, surface
defects, electronic structure, and microstructure by different methods like developing TiO 2 photocatalysts with metal oxides, sulfides, nitrides, and oxynitrides
(Castaneda et al. 2019; Munawar et al. 2020; Cantarella et al. 2018; Zhou et al.
2018; Huang et al. 2017). Other researchers went to the preparation of non-TiO 2
photocatalysts showing fast bacterial disinfection or organic pollutant degradation
from wastewater effluents (Gong et al. 2011; Zhang et al. 2014, 2018; Liu et al.
2018; Yang et al. 2016a, b; Zhou et al. 2014). More recently, research has been
focused on dye sensitization, noble metal deposition, and ion doping (Asahi et al.
2001; Chandran et al. 2014; Chen et al. 2016; Mikolajczyk et al. 2016; Umezawa
and Janotti 2016; Vaiano et al. 2016; Wang et al. 2017c; Yu et al. 2005; Zhang et al.
2016a; Zhao et al. 2016; Li et al. 2017). However, these photocatalytic systems
differed in their photogenerated reactive species leading to the disinfection process.
A recent study by Wang et al. (2011b) reported that H 2 O 2 -reactive species are more
7 Photocatalytic Nanomaterials for Bacterial Disinfection
217
numerous pollutants becomes an alarming issue worldwide. Therefore, developing
sustainable or low-cost alternative pathways for disinfecting pathogenic microorganisms has attracted more attention from policymakers and scientists (Wang et al.
2017c). Different conventional water disinfection methods like ozonation, chlorination, and ultraviolet disinfection were believed to be efficient ways for water
disinfection. Yet, these methods have not been widely applied to water disinfection
due to cost and disposal issues (Foster et al. 2011).
Moreover, these disinfection methods have their own merits and demerits to treat
wastewater. Among the chemical methods, advanced oxidation processes are of
sufficient interest in disinfection process for the effective oxidation of a wide variety
of organic and inorganic pollutants due to the generation of dominant reactive
oxygen species, such as the hydroxyl radical, H 2 O 2 , and superoxide radical
(Nieuwenhuijsen et al. 2000). Among these methods, top priority goes to
semiconductor-assisted photocatalytic disinfection process, which can use sunlight
(Huang et al. 2005). The application of photocatalysis for water disinfection of
Lactobacillus acidophilus, Saccharomyces cerevisiae, and Escherichia coli was
applied for the first time in 1985 by Matsunaga et al. (1985a). After that, more
researches have been carried out in the development of the photocatalytic disinfection process. According to Christensen et al. (2003) and Gong et al. (2011), three
pathogenic microorganisms, namely, Pseudomonas aeruginosa, Candida albicans,
and Enterococcus faecium, using solar/ultraviolet radiation were effectively
inhibited by using titanium as a photocatalyst. Similar results were reported for the
disinfection of Staphylococcus aureus (Makoday et al. 2015), Streptococcus mutants
(Kühn et al. 2003), Salmonella choleraesuis, Vibrio parahaemolyticus, and Listeria
monocytogenes (Melián et al. 2000). Figure 7.1 shows the photocatalytic bacterial
disinfection mechanism involving reactive oxygen species (Maness et al. 1999;
Rahmawati et al. 2010; Spuhler et al. 2010; Dunlop et al. 2011). Recently, Liu
et al. (2017) investigated the effective photocatalytic TiO 2 disinfection of Cryptosporidium and Giardia that are resistant to chlorination.
Recently some resaerches are carrioed out uisng TiO 2 as photocatalyst for the
disinfection of microbes because of having a large bandgap structure, surface
defects, electronic structure, and microstructure by different methods like developing TiO 2 photocatalysts with metal oxides, sulfides, nitrides, and oxynitrides
(Castaneda et al. 2019; Munawar et al. 2020; Cantarella et al. 2018; Zhou et al.
2018; Huang et al. 2017). Other researchers went to the preparation of non-TiO 2
photocatalysts showing fast bacterial disinfection or organic pollutant degradation
from wastewater effluents (Gong et al. 2011; Zhang et al. 2014, 2018; Liu et al.
2018; Yang et al. 2016a, b; Zhou et al. 2014). More recently, research has been
focused on dye sensitization, noble metal deposition, and ion doping (Asahi et al.
2001; Chandran et al. 2014; Chen et al. 2016; Mikolajczyk et al. 2016; Umezawa
and Janotti 2016; Vaiano et al. 2016; Wang et al. 2017c; Yu et al. 2005; Zhang et al.
2016a; Zhao et al. 2016; Li et al. 2017). However, these photocatalytic systems
differed in their photogenerated reactive species leading to the disinfection process.
A recent study by Wang et al. (2011b) reported that H 2 O 2 -reactive species are more
7 Photocatalytic Nanomaterials for Bacterial Disinfection
217