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of yeast were studied using various forms, including free vs. immobilized cells, dead vs. live cell, engineered vs. non‐engineered cell, etc. (Park et al., 2003). The yeast cells in free form are not suitable for biosorption as there is a problem in solid‐fluid phase separation. In flocculating cells, this problem tends less effective (Veglio and Beolchini, 1997). Yeast cells must be pretreated to increase the surface‐to‐volume ratio of metal binding sites (Mapolelo, 2004).

Table 2.3 Biosorption of heavy metals by different fungi.

Fungal biomass (biosorbent)	Metal ions (biosorbate)	Functional groups	References
Pleurotus ostreatus	Chromium	Carboxyl, amine groups	(Arbanah et al., 2013)
Hydrilla verticillata	Cadmium	Carboxyl, hydroxyl, amine groups	(Acosta Rodríguez et al., 2013)
Aspergillus terreus	Copper	Carboxyl groups	(Gulati et al., 2002)
Trametes versicolor	Nickel	Carboxyl, hydroxyl, amine groups	(Subbaiah and Yun, 2013)
Penicillium chrysogenum	Arsenic	Carboxyl, amino groups	(Mamisahebei et al., 2007)
Phanerochaete chrysosporium	Lead	Hydroxyl, amino groups	(Haluk Ceribasi and Yetis, 2004)
Pencillium simpliccium	Zinc	Carboxyl, amino groups	(Fan et al., 2008)
Aspergillus fumigatus	Mercury	Amino, hydroxyl groups	(Mamisahebei et al., 2007)

Different parameters of metal ions such as valency, diameter, cell age, culture conditions, concentration of metals, temperature, and pH influence the process of biosorption (Wang and Chen, 2006). Biosorption involves amino, carboxyl, and hydroxyl functional groups. The isothermal model of Langmuir was better adapted to a biosorption ion exchange mechanism (Luo et al., 2010). Yeasts’ huge size, on the other hand, makes them potential candidates for metal bioremediation. Table 2.4 lists the many yeast strains utilized in biosorption.

      Biosorbents Derived from Plant and Animal Waste

      Solid wastes derived from flora and fauna are plentiful, low‐cost, renewable resources. They're made in vast quantities every year, and disposing of them is usually a problem. An important area of research is to find meaningful uses for these materials. They can be used to minimize waste and create cost‐effective products (Kulkarni, 2014).

Plants disposed of as agricultural waste and food industry waste can be used as biosorbents. This is a method of repurposing and recycling discarded materials, so using plant materials has no significant cost (Ali Redha, 2020). Plant‐derived wastes are predominantly made up of cellulose, with structural components such as lignin, proteins, hemicellulose, carbohydrates, lipids, and starch (Rajapaksha et al., 2015). Plant biosorbents can absorb water because of the presence of carboxylic and phenolic functional groups in the cellulosic matrix and components linked with cellulose, such as hemicellulose and lignin (Abdi and Kazemi, 2015). Based on cation exchange between binding sites and metal ions, the metal ions bind with functional groups, resulting in biosorption and, therefore, the removal of the metal ions from media (Abdi and Kazemi, 2015). Table 2.5 lists the various plants employed as biosorbents.

Table 2.4 Biosorption of heavy metals by different yeasts.

Yeast biomass(biosorbent)	Metal ions(biosorbate)	References
Candida utilis	Chromium	(Anaemene, 2012)
Saccharomyces cerevisiae	Cadmium	(Das et al., 2008)
Saccharomyces cerevisiae	Cobalt	(Arakaki et al., 2011)
Candida pelliculosa	Copper	(Apinthanapong and Phensaijai, 2009)
Mucor rouxii	Lead	(Muraleedharan et al., 1991)
Saccharomyces cerevisiae	Mercury	(Anaemene, 2012)
Saccharomyces cerevisiae	Nickel	(Siñeriz et al., 2009)
Thiobacillusthiooxidans	Zinc	(Nagashetti et al., 2013)

Table 2.5 Biosorption of heavy metals by different plant materials.

Plant waste	Metal	Adsorption capacity	Reference
Wheat bran	Mercury	82%	(Farajzadeh and Monji, 2004)
Black gram husk	Lead	93%	(Saeed et al., 2005)
Rice bran	Cadmium	80%	(Montanher et al., 2005)
Baggase	Zinc	90–95%	(Mohan and Singh, 2002)
Activated carbon of peanut shells	Nickel	75%	(Wilson et al., 2006) Скачать книгу В начало < 14 15 16 17 18 19 20 21 22 23 > В конец