336

21 Nanomaterials and Biopolymers for the Remediation of Polluted Sites

oxide hybrid comprising of zinc and copper oxide via acid hydrolysis and sol–gel

method for the effective removal of bacteria and degradation of Rose Bengal dye.

Green synthesis of pure zinc oxide nanoparticles using quince seed mucilage as

stabilizing agent for the photocatalytic degradation of methylene blue has been

reported recently.

Gum polysaccharides are natural polysaccharides which are abundantly available

in nature [29]. In spite of its structural diversity and excellent property, Gum Ara-

bic cannot be used in its native form due to certain limitations such as uncontrolled

rate of hydration and contamination by microbes, drop in viscosity upon storage,

and thickening. In order to overcome these limitations, in most of the cases, it is

modified with different vinyl monomers. Application of Gum Arabic-grafted poly-

acrylamide (GA-cl-PAM) hydrogel as a self-template for the in situ synthesis of zinc

oxide nanoparticles as a potential adsorbent for the degradation of malachite green

dye is well documented.

Hydrogels developed using Gum Arabic are considered as an efficient adsorbent

material for the treatment of contaminated water [30]. Gum olibanum, a natural

oleoresin released from the bark of Boswellia serrata (a native tree of India), has

gained considerable attention (Burseraceae family) in recent times. Many scientists

have exploited this novel material as support for the development of nanobiopolymer

for environmental remediation.

Among the biopolymers used, gelatin is one of the excellent materials ever used

to make films. Gelatin is a biopolymer derived from collagen. Gelatin, derived

from collagen, is hydrophilic in nature, and the strength of the gel is essentially

dependent on its concentration. Films developed using gelatin possess favorable

optical, mechanical, and protective properties against gas, oxygen, and odor at low

relative humidity. Modification of cyclodextrin (oligosaccharide produced from

enzymatic conversion of starch) with nano-TiO2 was found to be effective for the

treatment of wastewater. Likewise, ZnO/carbon black grafted in cellulose acetate

has been used to treat azo dyes such as Congo red, methyl orange, and methylene

blue. MnO2/cellulose nanoparticles of size lesser than 100 nm was effective in

degrading 90% of indigo carmine within 25 minutes duration under optimum

conditions. A novel bionanocomposite comprising of a blend of chitosan–guar gum

incorporated with silver nanoparticle was synthesized using palm shell extract for

catalytic degradation of individual and binary mixture of dyes as well as in the

reduction of 4-nitrophenol to 4-aminophenol [16].

21.3

Soil Remediation

Industrial operations such as metallurgic operations, discharges of smelter slags,

coal, bottom fly ash, and mining activities also contribute to the soil pollution by

releasing effluents to the soil that includes chlorinated compounds, polycyclic aro-

matic hydrocarbon (PAH), toxic heavy metals, and radionuclides. Unlike organic

contaminants, heavy metals do not degrade, becoming a persistent threat to the ter-

restrial environment. These released heavy metals not only pollute soil, sediments,