Metal biosorption

The equilibrium time required for adsorption of metals on biomass was studied for various initial metal concentrations and the results were shown in Figure 2. The adsorption increases rapidly with time in the initial period of adsorption and approaches an equilibrium at about 120min for all the concentrations studied (10-100 mg/L). The slow but gradual increase of metal biosorption after 120min indicates that the adsorption occurs through a continuous formation of adsorption layer in the final period of adsorption. 

Biosorbent Heavy metal Biosorption heat (kcal-mol" )... 

Current reviews on biosorption are related to general approaches90-93 to diverse types of biomass such as microbial biomass, plant wastes, and agro-based waste materials, or to a specific metal.4-94-98 However, a review on metal biosorption using macrophytes biomass is not available. In this chapter, a review on the current knowledge of biosorption using preferentially nonliving biomass from aquatic plants is presented. 

FIGURE 10.4 Binding mechanisms involved in metal biosorption. 

Davis, T.A., Volesky, B. and Mucci, A. (2003) A review of the biochemistry of heavy metal biosorption by brown algae. Water Research, 37, 4311 1330. 

Chapter 3 Role of Bacteria and Bacteria-Soil Composites in Metal Biosorption and Remediating Toxic Metal-Contaminated... 

Borrok et al. (2004a) used potentiometric titration to measure Cd sorption by different bacterial consortia, and a surface complexation approach to determine thermodynamic stability constants. When the data were modeled by adopting a single set of stability constants, a similar sorption behavior was shown by a wide range of bacterial species. Further, current models that rely on pure strains of laboratory-cultivated bacterial species appear to overestimate the extent of metal biosorption in natural systems. 

Vecchio A, Finoli C, Simine DD, Andreoni V (1998) Heavy metal biosorption by bacterial cells. Fresenius J Anal Chem 361 338-342 Walker SG, Flemming CA, Ferris FG, Beveridge TJ, Bailey GW (1989) Physicochemical interaction of Escherichia coli cell envelopes and Bacillus subtilis cell walls with two clays and ability of the composite to immobililze heavy metals from solution. Appl Environ Microbiol 55 2976-2984 Wightman PG, Fein JB (2001) Ternary interactions in a humic acid-Cd-bacteria system. ChemGeol 180 55-65... 

Fig. 10.8. Simple biogeochemical model for metal mineral transformations in the mycorhizosphere (the roles of the plant and other microorganisms contributing to the overall process are not shown). (1) Proton-promoted (proton pump, cation-anion antiport, organic anion efflux, dissociation of organic acids) and ligand-promoted (e.g. organic adds) dissolution of metal minerals. (2) Release of anionic (e.g. phosphate) nutrients and metal cations. (3) Nutrient uptake. (4) Intra- and extracellular sequestration of toxic metals biosorption, transport, compartmentation, predpitation etc. (5) Immobilization of metals as oxalates. (6) Binding of soluble metal species to soil constituents, e.g. clay minerals, metal oxides, humic substances.

Pagnanelli F, Beolchini F, Di Biase A, and Veglio F. Effect of equilibrium models in the simulation of heavy metal biosorption in single and two-stage UF/MF membrane reactor systems. Biochem Eng J, 2003 15(1) 27-35. 

Chubar, N.. Carvalho, J.R., and Correia, M.J.N., Heavy metals biosorption on cork biomass Effect of the pre-treatment. Colloids Sutf. A, 238, 51, 2004. 

Unfortunately, higher amoimts of some minerals in seaweed have been the result of pollution of the seawater or natural environment. Thus, many studies were conducted with respect to the contamination of seaweed by heavy metals. Because of their high sorption capacity, they were also probed for their utilization as biosorbents to remove heavy metals from the environment and to elucidate mechanisms of metal biosorption by seaweeds (Davis et al., 2003 Murphy et al., 2008 Suzuki et al., 2005). Further, these conclusions could be utilized for the understanding of the uptake mechanisms by seaweed. Finally, endogenous and exogenous factors have participated on the variability of seaweed mineral composition. 

G. Naja and B. Volesky. Multi-metal biosorption in a fixed-bed flow-through column. Colloids and Surfaces A Physicochemical Engineering Aspects 281 194—201, 2006. 

MECHANISM OF METAL BIOSORPTION AND FACTORS AFFECTING ITS PERFORMANCE... 

Gadd, 2009). Biosorption of metal ions is not based on only one mechanism. It is a complicated process and follows complex mechanisms, mainly ion exchange, adsorption by physical forces (e.g., electrostatic), complexation/coordination and precipitation (VoleskyandHolan, 1995). Type of biomaterials, properties of metal solution chemistry and environmental conditions such as pH influence the mechanism of metal biosorption (Das et al, 2008). 

Chang, W.-C., Hsu, C.-H., Chiang, S.-M. Su, M.-C. (2007) Equilibrium and kinetics of metal biosorption by sludge from a biological nutrient removal system. Environmental Technology, 28, 453-462. 

Laurent, J, Casellas, M. Dagot, C. (2019) Heavy metals biosorption on disintegrated activated sludge description of a new equilibrium model. Chemical Engineering Journal, 164, 63-69. 

Yuncu, B., Sanin, ED. Yetis, U. (2006) An investigation of heavy metal biosorption in relation to C/N ratio of activated sludge. Journal of Hazardous Materials, 137, 990-997. 

Metal biosorption-flotation, application to cadmium removal. Appl... 

In the late 1990s and early 2000s certain attempts were made to expand Langmuir and Freundlich-type models to describe two- or multi-metal ions biosorption system to more accurately represent the nature of real effluents. These empirical models hardly reflect the sorption mechanism as they do not take into account all the various processes and parameters which influence the retention of metals and radionuclides by algal cells. Furthermore, a number of attempts were made to consider other mechanism in metal biosorption, e.g. ion exchange between protons in the biomass and/or complexation. Those models considered the sorbate speciation in solution pH and even electrostatic attraction however are not yet widely accepted in the scientific community... 

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