41
Cellulose’s main feature is an enormous amount of hydroxyl groups consisting
of three groups of hydroxyl: C-2 and C-3 secondary OH andC-6 primary OH
(Fig. 2.2). These groups of hydroxyl have affinities with heavy metal ions. However,
raw agricultural residues are usually low load capacity, comparatively tiny metal ion
binding constants, and low selectivity due to –OH groups engaged in pure cellulose
intermolecular hydrogen bonds (C–H—-O) (Phan et al. 2009). Meanwhile, cellulose’s crystalline structure impacts cellulose’s adsorption characteristics as their
flexibility decreases with a growing proportion of crystalline to cellulose’s amorphous areas. Recent studies have suggested that chemical modifications can be carried out to destroy the hydrogen bonds, decrease the crystalline structure, and make
binding sites more efficient in the form of crystalline cellulose and then create –OH
groups more reactive to attach other functional groups and attain better adsorptive
properties (e.g., ion-exchange properties). Najafabidi et al. prepared chitosan/graphene oxide (GO) nanofibrous, and their adsorption behaviors of Cu
2+
, Pb
2+
were
investigated, and the results are shown in Fig. 2.4.
2.7.2 Biopolymers from Agricultural Recycling
Several agronomic by-products, e.g., straw, coconut husks, rice, wool, used coffee,
waste tea (Boonamnuayvitaya et al. 2004), rice hulls (Ahmaruzzaman and Gupta
2011), cork waste (Psareva et al. 2005), seeds of Ocimum basilicum (Levankumar
et al. 2009), coconut shells (Amuda et al. 2007), soybean keels and cotton (Sud et al.
2008), sawdust of walnut untreated coffee dust (Dahri et al. 2014), papaya
wood(Hameed 2009), peanut hulls (Brown et al. 2000), and citrus peel (Ajmal et al.
2000) were used as adsorbents for heavy metal removal. However, with encouraging outcomes, marine weeds, molds, yeasts, and bacteria were screened for metal
Fig. 2.3 Glycosidic linkage
2 Polymer Absorbents for Heavy Metal Removal
Cellulose’s main feature is an enormous amount of hydroxyl groups consisting
of three groups of hydroxyl: C-2 and C-3 secondary OH andC-6 primary OH
(Fig. 2.2). These groups of hydroxyl have affinities with heavy metal ions. However,
raw agricultural residues are usually low load capacity, comparatively tiny metal ion
binding constants, and low selectivity due to –OH groups engaged in pure cellulose
intermolecular hydrogen bonds (C–H—-O) (Phan et al. 2009). Meanwhile, cellulose’s crystalline structure impacts cellulose’s adsorption characteristics as their
flexibility decreases with a growing proportion of crystalline to cellulose’s amorphous areas. Recent studies have suggested that chemical modifications can be carried out to destroy the hydrogen bonds, decrease the crystalline structure, and make
binding sites more efficient in the form of crystalline cellulose and then create –OH
groups more reactive to attach other functional groups and attain better adsorptive
properties (e.g., ion-exchange properties). Najafabidi et al. prepared chitosan/graphene oxide (GO) nanofibrous, and their adsorption behaviors of Cu
2+
, Pb
2+
were
investigated, and the results are shown in Fig. 2.4.
2.7.2 Biopolymers from Agricultural Recycling
Several agronomic by-products, e.g., straw, coconut husks, rice, wool, used coffee,
waste tea (Boonamnuayvitaya et al. 2004), rice hulls (Ahmaruzzaman and Gupta
2011), cork waste (Psareva et al. 2005), seeds of Ocimum basilicum (Levankumar
et al. 2009), coconut shells (Amuda et al. 2007), soybean keels and cotton (Sud et al.
2008), sawdust of walnut untreated coffee dust (Dahri et al. 2014), papaya
wood(Hameed 2009), peanut hulls (Brown et al. 2000), and citrus peel (Ajmal et al.
2000) were used as adsorbents for heavy metal removal. However, with encouraging outcomes, marine weeds, molds, yeasts, and bacteria were screened for metal
Fig. 2.3 Glycosidic linkage
2 Polymer Absorbents for Heavy Metal Removal