26
M. Al-Sahari et al.
most common natural coagulants in environmental science where it contains watersoluble substance and edible oil (James and Zikankuba 2017; Hauwa et al. 2018).
Moringa parts have been used in many applications such as food and medicinal in
the rural areas (Gopalakrishnan et al. 2016), but this point will discuss the usage of
the Moringa seed extracts as coagulants. It has been reported that the M. oleifera
seed extracts were used in some countries to treat the river water turbid (Hoa and
Hue 2018). Furthermore, many recent and ancient studies have emphasized the
natural coagulating characteristic of the M. oleifera seed extracts (Petersen et al.
2016; Sulaiman et al. 2017). M. oleifera coagulation depends on the mechanism
of charge neutralization (Al-Gheethi et al. 2016). Various suggestions and research
have been provided to specify the coagulating agent of Moringa, while most of these
researches agreed that the active agent is cationic protein and it has been suggested
that the cationic protein molecular mass of 12–14 kDa with an isoelectric point (pI)
between 10 and 11 (Camacho et al. 2017). On the other hand, Okuda et al. (2001),
reported that the active coagulating agent from the aqueous salt extraction is not
a protein, polysaccharide or lipid but an organic polyelectrolyte with a molecular
weight of approximately 3.0 kDa. As a concussion, the coagulation mechanism of
the M. oleifera seed extracts can be defined as the interaction process between the
negatively charged colloids particles at the contaminated water and the positively
charged protein molecules in the active ingredients (Camacho et al. 2017).
2.6 Natural Coagulants Animal-Based
Animal-based coagulant/flocculants is one of the most environmentally benign
and less expensive coagulants/flocculants, where it is an effective polysaccharide
employed to remove the water contaminants such as the Chitosan.
2.6.1 Chitosan
Chitosan is one of the most widely used coagulants among the animal-based coagulants. Chitosan is an amine-based polysaccharide that is derived via deacetylation of chitin and considered as a biopolymer. The chitin is the second most abundant polysaccharide in nature after cellulose. Chitosan has been used as a singlecomponent coagulant in different studies and applications, such as the settling of
clay suspensions (Ferhat et al. 2016), water turbidity and color removal (Momeni
et al. 2018), and the treatment of industrial wastewater (Negm et al. 2015). Many
studies have been reported that chitosan coagulants depend on the charge neutralization mechanism while there are other studies reported that inter-particle bridging
occurs in conjunction with charge neutralization (Fig. 2.3). However, Li et al. (2013)
has been suggested to use the patch mechanism because of the high concentration of
the positive charges on the chitosan compared to the negative charges in the water
M. Al-Sahari et al.
most common natural coagulants in environmental science where it contains watersoluble substance and edible oil (James and Zikankuba 2017; Hauwa et al. 2018).
Moringa parts have been used in many applications such as food and medicinal in
the rural areas (Gopalakrishnan et al. 2016), but this point will discuss the usage of
the Moringa seed extracts as coagulants. It has been reported that the M. oleifera
seed extracts were used in some countries to treat the river water turbid (Hoa and
Hue 2018). Furthermore, many recent and ancient studies have emphasized the
natural coagulating characteristic of the M. oleifera seed extracts (Petersen et al.
2016; Sulaiman et al. 2017). M. oleifera coagulation depends on the mechanism
of charge neutralization (Al-Gheethi et al. 2016). Various suggestions and research
have been provided to specify the coagulating agent of Moringa, while most of these
researches agreed that the active agent is cationic protein and it has been suggested
that the cationic protein molecular mass of 12–14 kDa with an isoelectric point (pI)
between 10 and 11 (Camacho et al. 2017). On the other hand, Okuda et al. (2001),
reported that the active coagulating agent from the aqueous salt extraction is not
a protein, polysaccharide or lipid but an organic polyelectrolyte with a molecular
weight of approximately 3.0 kDa. As a concussion, the coagulation mechanism of
the M. oleifera seed extracts can be defined as the interaction process between the
negatively charged colloids particles at the contaminated water and the positively
charged protein molecules in the active ingredients (Camacho et al. 2017).
2.6 Natural Coagulants Animal-Based
Animal-based coagulant/flocculants is one of the most environmentally benign
and less expensive coagulants/flocculants, where it is an effective polysaccharide
employed to remove the water contaminants such as the Chitosan.
2.6.1 Chitosan
Chitosan is one of the most widely used coagulants among the animal-based coagulants. Chitosan is an amine-based polysaccharide that is derived via deacetylation of chitin and considered as a biopolymer. The chitin is the second most abundant polysaccharide in nature after cellulose. Chitosan has been used as a singlecomponent coagulant in different studies and applications, such as the settling of
clay suspensions (Ferhat et al. 2016), water turbidity and color removal (Momeni
et al. 2018), and the treatment of industrial wastewater (Negm et al. 2015). Many
studies have been reported that chitosan coagulants depend on the charge neutralization mechanism while there are other studies reported that inter-particle bridging
occurs in conjunction with charge neutralization (Fig. 2.3). However, Li et al. (2013)
has been suggested to use the patch mechanism because of the high concentration of
the positive charges on the chitosan compared to the negative charges in the water