many reports already available in removing arsenic species using MFUF. One of the
studies utilized a cationic surfactant as a source to investigate the efficiency of
arsenic removal (Iqbal et al. 2007). The highest removal efficiency (96%) was
observed on hexadecyl pyridinium chloride (CPC) surfactant. However, it was
reported that the removal efficiency decreases while decreasing pH of the solution.
Besides, in spite of the viable expulsion of arsenic, additional treatment is required
with powdered activated carbon (PAC) to remove the excess concentration of
surfactant in the solution.
If a molecular weight of the dissolved compound is over 300 g/mol, then NF and
RO methods are appropriate for the water filtration (Van der Bruggen et al. 2003).
These filtration systems can reduce the contaminant arsenic from water significantly,
however there should not be any suspended solids in the feed and arsenic should be
in the form of arsenate (Figoli et al. 2010). It was demonstrated that the As
(V) removal efficacy surpassed 85% for all type of NF membrane involved in the
investigation (Sato et al. 2002), whereas the As(III) removal efficacy was extremely
low. This study was sustained by the discoveries of Uddin et al. (2007), who showed
that without oxidation of arsenite to arsenate, NF can’t fulfil to the maximum
concentration level of arsenic present in water. Similar situation for RO as well, as
appeared in many investigations (Brandhuber and Amy 1998).
Diatomaceous earth (DE) is an another filtration system works similar like other
membranes, however, technically it does not come under membrane filtration system
(Bhardwaj and Mirliss 2005). DE filtration system contains pasty sedimentary
material which has microscopic water plants (fossil-like skeletons) that is called as
diatoms (Logsdon et al. 2002). Diatoms are made up of porous structure with a small
opening of around 50 nm in radius and total size of the diatoms in the range of
5–100μm. The consolidated impact of high porosity and small pore sizes present in
DE makes the best channels used to evacuate tiny particles in the water filter system
(Bhardwaj and Mirliss 2005; Logsdon et al. 2002). Moreover, this kind of channel is
tasteless, odourless, and chemically inactive which makes it safe use in drinking
water filtration. There was a method developed by Misra and Lenze utilized the
combination of mixed hydroxides and DE filter system for the effective removal of
arsenic and other heavy metals present in the drinking water (Misra and Lenz 2008).
This development was performed in the lab scale with a reagent loading of 1000 mg/
L and 100 ppb (μg/L) as an initial concentration of arsenic and showed 90% of
removal efficiency. However, the pH alteration, a long conditioning time and
reagents are required which are considered as a drawbacks (Misra and Lenz 2008).
6.4.4 Ion Exchange and Adsorption
In a process where solid materials are used as a medium to remove any substances
from liquids are called “Adsorption process” (Singh et al. 2015). Basically, in the
adsorption process, the substances are isolated from one phase and collected on the
surface of another phase. This adsorption procedure mainly occurs by either
164
T. S. Sakthivel et al.
studies utilized a cationic surfactant as a source to investigate the efficiency of
arsenic removal (Iqbal et al. 2007). The highest removal efficiency (96%) was
observed on hexadecyl pyridinium chloride (CPC) surfactant. However, it was
reported that the removal efficiency decreases while decreasing pH of the solution.
Besides, in spite of the viable expulsion of arsenic, additional treatment is required
with powdered activated carbon (PAC) to remove the excess concentration of
surfactant in the solution.
If a molecular weight of the dissolved compound is over 300 g/mol, then NF and
RO methods are appropriate for the water filtration (Van der Bruggen et al. 2003).
These filtration systems can reduce the contaminant arsenic from water significantly,
however there should not be any suspended solids in the feed and arsenic should be
in the form of arsenate (Figoli et al. 2010). It was demonstrated that the As
(V) removal efficacy surpassed 85% for all type of NF membrane involved in the
investigation (Sato et al. 2002), whereas the As(III) removal efficacy was extremely
low. This study was sustained by the discoveries of Uddin et al. (2007), who showed
that without oxidation of arsenite to arsenate, NF can’t fulfil to the maximum
concentration level of arsenic present in water. Similar situation for RO as well, as
appeared in many investigations (Brandhuber and Amy 1998).
Diatomaceous earth (DE) is an another filtration system works similar like other
membranes, however, technically it does not come under membrane filtration system
(Bhardwaj and Mirliss 2005). DE filtration system contains pasty sedimentary
material which has microscopic water plants (fossil-like skeletons) that is called as
diatoms (Logsdon et al. 2002). Diatoms are made up of porous structure with a small
opening of around 50 nm in radius and total size of the diatoms in the range of
5–100μm. The consolidated impact of high porosity and small pore sizes present in
DE makes the best channels used to evacuate tiny particles in the water filter system
(Bhardwaj and Mirliss 2005; Logsdon et al. 2002). Moreover, this kind of channel is
tasteless, odourless, and chemically inactive which makes it safe use in drinking
water filtration. There was a method developed by Misra and Lenze utilized the
combination of mixed hydroxides and DE filter system for the effective removal of
arsenic and other heavy metals present in the drinking water (Misra and Lenz 2008).
This development was performed in the lab scale with a reagent loading of 1000 mg/
L and 100 ppb (μg/L) as an initial concentration of arsenic and showed 90% of
removal efficiency. However, the pH alteration, a long conditioning time and
reagents are required which are considered as a drawbacks (Misra and Lenz 2008).
6.4.4 Ion Exchange and Adsorption
In a process where solid materials are used as a medium to remove any substances
from liquids are called “Adsorption process” (Singh et al. 2015). Basically, in the
adsorption process, the substances are isolated from one phase and collected on the
surface of another phase. This adsorption procedure mainly occurs by either
164
T. S. Sakthivel et al.