Heavy Metal Adsorption

Demirbas, A., Heavy metal adsorption onto agro-based waste materials A review, Journal of Hazardous Material, 157, 220-229, 2008. 

Cavallaro and McBride (1984a) observed that the removal of Fe oxides from two clay soils reduced Zn adsorption. Shuman (1976) reported that the removal of Fe oxides resulted in an increase or decrease in Zn adsorption, but later in another similar study (1988) he found that the removal of either amorphous or crystalline Fe oxides increased Zn adsorption capacity and decreased Zn-bonding energy. The author explained that adsorption sites on the Fe oxide coatings were not as numerous as those released when the coatings were removed. Elliott et al. (1986) observed that DCB extraction of Fe oxides from two subsoils of the Atlantic Coastal Plain increased heavy metal adsorption. Wu et al. (1999) found that Cu adsorption on the fine clay fraction increased after dithionite treatment with possible exposure of much more high-affinity sites for Cu on the fine clay. 

In summary, the removal of organic matter and Fe oxides significantly changes the physicochemical and surface chemical properties of soils. Thus, this pretreatment affects the overall reactivity of heavy metals in soils. The removal of organic matter and Fe oxides may either increase or decrease heavy metal adsorption. The mechanisms responsible for the changes in metal adsorption in soils with the removal of organic matter and Fe oxides include increases in pH, surface area, CEC and electrostatic attraction, decreases in the ZPC, shifts of positive zeta potentials toward... 

Carrizosa MJ, Hermosin MC, Koskinen WC, Cornejo J (2004) Interactions of two sulfonylurea herbicides with organoclays. Clays Clay Miner 52 643-649 Celis R, Hermosin MC, Cornejo J (2000) Heavy metal adsorption by functionalized clays. Environ Sci Technol 34 4593-4599 Chappell MA, Laird DA, Thompson ML, Li H, Teppen BJ, Johnston CT, Boyd SA (2005) Influence of smectite hydration and swelling on atrazine sorption behavior. Environ. Sci Technol 39 3150-3156 Chiou CT (1989) Theoretical considerations of the partition uptake of nonionic organic compounds by soil organic matter. In Sawhney BL, Brown K (eds) Reactions and movement of organic chemicals in soils. Soil Science Society of America, Madison, WI, pp 1-29... 

Metal cation adsorption processes include exchange, Coulombic, and site-specific adsorption. Heavy metal cations exhibit exchange reactions with negatively charged surfaces of clay minerals. Cationic adsorption is affected by the pH and in an acid environment (pH < 5.5), and some heavy metals do not compete with Ca " (a ubiquitous constituent in the subsurface) for mineral adsorption sites. At a higher pH, heavy metal adsorption increases abruptly and becomes irreversible. 

Ceiis, R. Hermosin, M. C. Cornejo, J. Heavy Metal Adsorption by Functionaiized Clays. Environ. Sci. Technol. 2000, 34, 4593-4599. 

Spark, KM. Johnson, B.B. Wells, J.D. (1995) Characterizing heavy-metal adsorption on oxides and oxyhydroxides. Eur. J. Soil Sd. 46 621-631... 

In summary, the fact that the VSC-VSP model predicts adsorption edge shift and the effect of charge reversal on the pH-dependence of adsorption, neither of which can be accounted for on the basis of the model of James and Healy ( ), lends support to its use in accurately describing heavy metal adsorption. The agreement between theory and experiment shown in Figure 7 additionally supports the use of the VSC-VSP model. 

In this work, the efTect of anodic oxidation treatments on activated carbon fibets (ACFs) was studied in the context of Cr(Vl), Cu( II), and Ni( II) ion adsorption behaviors. Ten wt% phosphoric acid and sodium hydroxide were used for acidic and basic electrolytes, respectively. Surf properties of the ACFs were determined by XPS. The specific surface area and the pore stnicture were evaluated from nitrogen adsorption data at 77 K. The heavy metal adsorption rates of ACFs were measured by using a UV spectrometer and 1C P. As a result, the anodic treatments led to an increase in the amount of total acidity by an increase of acidic functional groups such as carboxyl, lactone, and phenol, in spite of a decrease in specific surface area, due to the pore blocking by increased acidic functional groups. 

In simple adsorption from aqueous solution, Hg has features in contrast and in common with the base metals. The hydroxy-cation is the active species in the model for heavy-metal adsorption and this also appears to be true for Hg. However, in contrast with Cu, Pb and Zn, the adsorption is less efficient and is strongly inhibited by the formation of halide complexes, as has been shown by Forbes et al. (1974) (Fig. 12-1). These authors also demonstrate that the adsorption of Hg to goethite is effective at pH as low as 4, allowing it to be trapped subsequent to sulphide oxidation. Whilst many minerals in weathered rocks and soils may each adsorb Hg, the relative efficiency of the hydrous iron oxides (Andersson, 1979) implies that these phases will be the dominant host in most exploration samples. However, the soil organic matter is also of importance and, although the association with Hg has been described as adsorption, it seems more... 

A. Garca-Sanchez, A. Alastuey, and X. Querol, Heavy Metal Adsorption by Different Minerals Application to the Remediation of Polluted Soils, The Science of the Total Environment, 242(1), 179-188 (1999). 

Griffin, R.A., Frost, R.R., Au, A.K., Robinson, G. and Shimp, N.F., 1977. Attenuation of pollutants in municipal landfill leachate by clay minerals. Part 2. Heavy metal adsorption. Ill. State Geol, Surv, Environ, Geol. Note 79. 47 pp,... 

Criscenti, L. J., and Sverjensky, D. A. (2002). A single-site model for divalent transition and heavy metal adsorption over a range of metal concentrations. J. Colloid Interface Sci. 253, 329-352. 

Gadde. R.R. and Laitinen, H.A., Studies of heavy metal adsorption by hydrous iron and manganese oxides. Anal. Chem., 46, 2022, 1974. 

Early applications were related to industrial processes and focussed on the sampling of metal ions in natural waters [96], the determination of phenylalanine using in-line ion-exchange [97], modelling of heavy metal adsorption [98], use of pulsed flows for nickel removal from acidic solutions [99], investigation of properties inherent to fluidised beds and transport reactors [100], and treatment of radioactive wastes [101]. The characteristics, limitations and applications of fluidised beads are provided elsewhere [102—104],... 

P. Menoud, L. Cavin, A. Renken, Modelling of heavy metals adsorption to a chelating resin in a fluidized bed reactor, Chem. Eng. Process 37 (1998) 89. 

Repo E., Warchol J., Bhatnagar A., Sillanpaa M. Heavy metals adsorption by novel EDTA-modified chitosan-silica hybrid materials. Journal of Colloid Interface Science 2011 358 261-267. 

Recently, WPCs have been used as carriers for biopolymers and microorganisms (Fig. 26.4). Robledo-Ortiz et al. [50] used a composite material of recycled HDPE and agave fibers for bacterial immobilization. According to the results reported, the natural adhesion of Pseudomonas putida FI onto the composite surface is strongly affected by temperature, pH, ionic strength, and initial biomass concentration. Vdzquez et al. [51] coated the same material (agave fibers/HDPE) with chitosan to be applied in heavy-metal adsorption. These studies showed that composite materials represent an attractive low-cost recycled support for bacterial and biopolymers with potential applications in biotechnological and environmental cleanup processes. 

Surface complexation Potentiometric titration FITEQL, MICROQL Heavy metal adsorption on [9] ... 

Wen, X., Q. Du, and H. Tang. 1998. Surface complexation model for the heavy metal adsorption on natural sediment. Environmental Science Technology 32, no. 7 870-875. doi 10.1021/es970098q. 

Ho Y.S., Wase D.A.J., Forster C.F Kinetic studies of competitive heavy metal adsorption by sphagnum moss peat. Environ. Technol., 1996 17 71-77. 

Heavy metal adsorption is a well-known process that utilizes mass transfer technique to remove adsorbates by depositing them on the surface of adsorbent. It can be applied at lower concennations for both continuous and batch operations. Ease of access and cost effectiveness are other advantages of this technique... 

The SCM approach was used to describe the siuface properties and prediction of heavy-metal adsorption on natural aquatic sediment [79]. All of the model parameters were determined from experimental data of potentiometric titration and metal Cu and Cd adsorption isotherm Results showed that all three typical versions (CCM, DLM and TLM) of SCMs can simulate the experimental data very well and provide an acceptable prediction for heavy-metal adsorption to natural sediments. The heavy-metal (Mo, Pb, Cu, Zn, Cd) contaminant leaching from weathered municipal solid waste was successfully modeled by DLM [80]. The leaching of Mo, Pb, and Cu from the weathered ash was well deseribed by surface complexation, whereas the precipitation of formed Zn-hydroxy species had to take into consideration to describe the leaehing data of Zn. 

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