3 Role of Nanofiber in Sensing Water Pollutants
In this section, we will discuss the role of different available nanofiber materials for
detection of various water pollutants categorically depending on the pollutants. We
have limited this review for the detection of three categories of pollutants, with
nanofiber as the sensing material, irrespective of the detection methodology. The
selected pollutant categories are heavy metals, organic impurities and biological
contaminants.
3.1 Heavy Metal Ions Detection
Due to heavy industrialization and increased usage of electronic goods, heavy metal
ions (HMI) induced pollution has reached a grave level. HMIs are one of the micro
pollutants that can cause immense environmental problems [17]. Water pollution by
heavy metal ions is significant issue also because long-term exposure to these metal
ions can result in critical or chronic damage to the brain and the central nervous
system, immune system, reproductive and gastrointestinal systems [31]. Major
sources of these heavy metal ions are fertilizers and other chemicals produced from
industrial or household electronic waste. These HMIs do not decay or degrade with
time and have a tendency to accumulate in living organisms. Among different
heavy metals, lead (Pb), cadmium (Cd), mercury (Hg), chromium (Cr) and arsenic
(As) are considered extremely toxic [32–36]. Even small doses of these highly toxic
metals can lead to severe problems on environment and on human health.
Human beings are mainly exposed to these metal ions from air, water and food.
For example, the major source of mercury contamination in humans is due to
infected fish consumption. Due to the severity of the consequences, it is of utmost
importance to detect these heavy metal ions in natural and drinking water and to
determine their quantities. It is also important to remediate the water after detection
which can be dictated based on the analysis and type and range of contamination.
Several international organizations like World Health Organization (WHO), the US
Environmental Protection Agency (EPA) and the European Union have enlisted
HMIs as the priority substances to be monitored and have set certain permissible
limits for their concentrations in water. The permissible limits of contaminants in
different water categories as per the Environmental protection agency (EPA), USA
and World Health Organization (WHO) are given in Table 1.
The detection of HMIs in water is possible through various different techniques
which include the spectroscopic techniques like atomic absorption spectroscopy
(AAS), inductively coupled plasma mass spectroscopy (ICP-MS), X-ray
Fluorescence Spectrometry (XRF) and others [38, 39]. These techniques are
extremely sensitive and can detect very low concentrations(femtomolar) of metal
ions also. However, they are very expensive and require high end instrumentation
and thus are expensive to manage. Other relatively less intensive techniques include
Nanofiber Based Sensors for Water Pollution Monitoring
303
In this section, we will discuss the role of different available nanofiber materials for
detection of various water pollutants categorically depending on the pollutants. We
have limited this review for the detection of three categories of pollutants, with
nanofiber as the sensing material, irrespective of the detection methodology. The
selected pollutant categories are heavy metals, organic impurities and biological
contaminants.
3.1 Heavy Metal Ions Detection
Due to heavy industrialization and increased usage of electronic goods, heavy metal
ions (HMI) induced pollution has reached a grave level. HMIs are one of the micro
pollutants that can cause immense environmental problems [17]. Water pollution by
heavy metal ions is significant issue also because long-term exposure to these metal
ions can result in critical or chronic damage to the brain and the central nervous
system, immune system, reproductive and gastrointestinal systems [31]. Major
sources of these heavy metal ions are fertilizers and other chemicals produced from
industrial or household electronic waste. These HMIs do not decay or degrade with
time and have a tendency to accumulate in living organisms. Among different
heavy metals, lead (Pb), cadmium (Cd), mercury (Hg), chromium (Cr) and arsenic
(As) are considered extremely toxic [32–36]. Even small doses of these highly toxic
metals can lead to severe problems on environment and on human health.
Human beings are mainly exposed to these metal ions from air, water and food.
For example, the major source of mercury contamination in humans is due to
infected fish consumption. Due to the severity of the consequences, it is of utmost
importance to detect these heavy metal ions in natural and drinking water and to
determine their quantities. It is also important to remediate the water after detection
which can be dictated based on the analysis and type and range of contamination.
Several international organizations like World Health Organization (WHO), the US
Environmental Protection Agency (EPA) and the European Union have enlisted
HMIs as the priority substances to be monitored and have set certain permissible
limits for their concentrations in water. The permissible limits of contaminants in
different water categories as per the Environmental protection agency (EPA), USA
and World Health Organization (WHO) are given in Table 1.
The detection of HMIs in water is possible through various different techniques
which include the spectroscopic techniques like atomic absorption spectroscopy
(AAS), inductively coupled plasma mass spectroscopy (ICP-MS), X-ray
Fluorescence Spectrometry (XRF) and others [38, 39]. These techniques are
extremely sensitive and can detect very low concentrations(femtomolar) of metal
ions also. However, they are very expensive and require high end instrumentation
and thus are expensive to manage. Other relatively less intensive techniques include
Nanofiber Based Sensors for Water Pollution Monitoring
303