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21 Nanomaterials and Biopolymers for the Remediation of Polluted Sites

21.2.2

Nanobiopolymers for Water Disinfection and Textile Dye

Degradation

Biopolymers are exceptional materials which are unique in their composition

and possess various physiological properties. Biopolymeric nanomaterials can be

formed by impregnating metals to biopolymers. These materials form a molecular

capsule through intramolecular hydrogen bonding. Incorporation of metals/metal

oxides inside starch/chitosan molecules forms polymeric nanocomposites. Chitosan

is an excellent biomaterial which has found several useful applications in the field

of nanotechnology due to its wide compatibility [16]. Sorption and impregnation

are the two main techniques used for the incorporation of nanomaterials inside

biopolymers [17]. Polymeric nanomaterials are nothing but the solid colloidal

particles ranging from 10 nm to 1 μm. The inorganic counterpart of the composites

has been accountable for their photocatalytic activity and organic counterpart, i.e.

polymers such as pectin, cellulose, guar gum, polyaniline, and polyacrylamide,

etc., act as adsorbent for hazardous organic dyes. The polymeric material acts

as a support and is responsible for increasing the surface area by acting as a

backbone for the attachment to inorganic part. Polymer-based nanocomposites

have attracted several researchers over other composite materials due to their

characteristic properties such as cost-effectiveness, easy processability, renewable

nature, and high-volume applications [18]. Due to the presence of high surface area

nanoparticles in a polymer matrix, polymer nanocomposites possess highly tunable

adsorption behavior.

This optimized adsorption behavior of polymeric nanocomposites makes them

suitable for different applications such as chemical sensor, water purification, drug

delivery, and fuel cell technology. Polymeric nanocomposites have been extensively

used for the removal of various toxic metal ions, dyes, and microorganism from water

bodies (Figure 21.1).

Biopolymers include starch, alginate, chitosan, dextran, and chitin which are

generally present in various organisms such as plants, algae, fungi, bacteria, and

animals. Chitosan, starch, dextran, and cellulose are the polysaccharides which

are commonly used as support for nanomaterials and are derived from plants and

microbes [19].

Owing to its exceptional ability to efficiently adsorb as well as high surface area,

chitosan is considered as an excellent support material for metallic photocatalysis.

Chitosan material helps in reducing the number of intermediates produced during

photocatalytic reactions. Also, chitosan allows quick and trouble-free recovery of the

photocatalyst, which can be recycled with or without any regeneration [20].

Chitosan is one of the most abundantly available, natural, environmentally

benign,

nontoxic,

biodegradable,

low-cost,

and

biocompatible

biopolymer.

Chitosan-based nanocomposites as adsorbents have significant benefits such

as attractive surface area, chemical accessibility, ease of functionalization, and

absence of internal diffusion [21]. Many researchers all over the world are endeav-

oring the application of various chitosan-based materials for removal of heavy

metals as well as dye degradation. Amino and hydroxyl groups present in chitosan