Page 451 - Polymer-based Nanocomposites for Energy and Environmental Applications

408 Polymer-based Nanocomposites for Energy and Environmental Applications

coagulation, precipitation, oxidation, evaporation, distillation, adsorption, reverse
osmosis (RO), ion exchange, electrolysis, electrodialysis, etc. Due to some virtuous
features, like easy operation, low cost, eco-friendliness, fast and effective adsorbents,
and also the accessibility of many adsorbents into open market, adsorption is consid-
ered the most effective technique for treatment of the wastewater. Using adsorption
technique in batch mode process, a lot of research work has been carried out on
the removal of different pollutants from water [12]. Apart from that, the removal
of soluble and insoluble organic, inorganic, and biological pollutants is also
treated/possible using adsorption technique. Initially, activated carbon was used for
the treatment of wastewater, and later on, this activated carbon is substituted by some
economical other adsorbents [13,14].
Among the all twinkling and emerging technologies, the advancement in nano-
technology has proved an incredible potential for the remediation of wastewater
and various other environmental problems [15]. During the last few decades, nano-
technology has gained widespread attention, and various nanomaterials have been
developed for the water remediation with its applications in almost every field of
science and technology. As a matter of fact, various new and novel materials and tech-
nologies for water remediation have been developed, and numerous studies have been
reviewed highlighting the importance of various newly developed nanomaterials [16].
Nanotechnology has been mentioned, as one of the most innovative technologies
for wastewater treatment, in different texts. According to the nature of nanomaterials,
it may be categorized into three main sections: nanoadsorbents, nanocatalysts, and
nanomembranes.
Various studies have been conducted presenting the importance and effectiveness
of various newly prepared nanomaterials. The present review focused on three main
categories of nanomaterials in application of wastewater treatment. These include
nanocatalysts, nanomembranes, and integration of aforementioned nanotechnologies
with biological methods.
The first class of the nanotechnology is the nanoadsorption technique. In this
regard, a tremendous research has been conducted, and a lot of data have been pub-
lished to investigate the decontamination of the wastewater using nanoadsorbent
materials [17,18]. In that nanoadsorption technology, the most and frequently used
materials are the activated carbon. However, other materials for the improvement
of nanoadsorbents comprise clay materials, metal oxides, silica (SiO 2 ), and other
modified compounds in the form of composites [19].
The second class of the nanotechnology is the nanocatalyst technology. Around the
world, nanomaterials like metal oxide and semiconductors are the main focus for the
wastewater treatment in the researchers. A variety of nanocatalysts have been used for
the degradation of pollutants in wastewater, for example, electrocatalysts [20],
Fenton-based catalysts [21], and those catalysts having antimicrobial nature [22].
The third class of the nanotechnology, employed for the wastewater treatment, is
the nanomembrane. A variety of membrane filtration are used; however, the nano-
filtration (NF) is the widely used technology for the treatment of wastewater
due to some remarkable characteristics, for instance, most effective, eco-friendly,
pore sizes, and low operational cost [23–25]. Nanomembranes can be prepared