Sorption of Cadmium in Some Soil Amendments for In Situ Recovery of Contaminated Soils

Abstract

Although Cd concentrations in uncontaminated soils are usually low, pollution of soils by Cd from different sources of contamination pose problems. The application of soil amendments to increase plant production has been used as a viable alternative for recovery of soils contaminated with Cd. However, emphasis needs to be placed on the nature of Cd sorption processes in order that the amendments can be managed appropriately. A range of materials including vermicompost, sugarcane filter cake, palm kernel pie, lime, phosphate rock, and zeolite were used for the sorption studies. Total and nonspecific Cd sorption was estimated by batch experiments, and specific sorption was obtained by the difference between the former and the latter. Best adsorbents for specific Cd sorption from soil amendments were lime and zeolite. Langmuir adsorption isotherms fitted reasonably well in the experimental data, and their constants were evaluated, with R 2 values from 0.80 to 0.99. The maximum adsorption capacity of Cd(II) was higher for mineral amendments than for organic amendments and ranged from 0.89 to 10.86 gkg −1. The small value (0.08 Lmg −1) of the constant related to the energy of adsorption indicated that Cd was bound weakly to the palm kernel pie. Thermodynamic parameter, the Gibbs free energy, was calculated for each system, and the negative values obtained confirm that the adsorption processes were spontaneous. The values of separation factor, R L , which has been used to predict affinity between adsorbate and adsorbent were between 0 and 1, indicating that sorption was very favorable for Cd(II).

Immobilizing Metal-Resistant Sulfate-Reducing Bacteria for Cadmium Removal from Aqueous Solutions

“…SRB were prepared as described previously [19]. Briefly, culture media of SRB were composed of (per liter of deionized water): 0.5 g Na 2 The immobilized bacteria used were described elsewhere [13], and immobilized beads were prepared by an entrapping method [20]. Immobilization of biomass via entrapment was carried out as follows: Firstly, the polyvinyl alcohol solution (6%, w/v), silica solution (3%, w/v), and sodium alginate solution (0.5%, w/v) were dissolved in deionized water and mixed thoroughly.…”

“…and refining industries [2][3]. According to World Health Organization guidelines, the permissible Cd content of drinking water is 0.003 mg/L [4][5].…”

Study on Physical Remediation Technology of Polluted Land

“…According to statistics, in recent years, China's production and construction activities and natural disasters destroyed a total of about 8.7 million hectares of land. Among them, about millions of acres of land are newly damaged every year due to production and construction activities such as mineral resources development, 60% of which is cultivated land or other agricultural land [1]. Therefore, in order to ensure the safety of 1.8 billion mu of arable land and construction land, and solve the social and environmental problems caused by land pollution, it is necessary to pay attention to the research and development of land engineering technology, improve the level of land engineering technology, and make it usable land through the restoration and development of defaced land.…”

Biosorption of macronutrients by Brazilian tropical peats

“…Biosorption can be defined as a physicochemical process that occurs naturally in a biomass and enables the binding and/or passive concentration of chemical species such as cations or anions (Gadd 2009). Biosorption has been widely studied in remediation processes, since it offers the advantage of being able to transfer a contaminant to an adsorbent material in a natural fashion, avoiding high expenditure on energy (Zenteno et al 2013;Kamari, Pulford, and Hargreaves 2011). A wide variety of adsorbent materials have been used, ranging from agricultural waste biomass (Garg et al 2008) to compounds naturally present in nature, such as humic substances (Perminova and Hatfield 2005).…”