Plant mediated detoxification of mercury and lead


In recent years, the development of efficient green chemistry methods for detoxification of metal poisoning has become a major focus of researchers. They have investigated in order to find an eco-friendly and recyclable technique for the removal of heavy metal (Pb2+, Hg2+) contamination from the natural resources. One of the most considered methods is the removal of Pb2+, Hg2+ metal using green plants and their wastes. Among these plant wastes seem to be the best candidates and they are suitable for detoxification of heavy metals. Biosorption by plants involve complex mechanisms, mainly ion exchange, chelation, adsorption by physical forces and ion entrapment in inter and intra fibrillar capillaries and spaces of the structural polysaccharide cell wall network. The advantages of using green plants and their wastes for detoxification of heavy metal have interested researchers to investigate mechanisms of metal ion uptake, and to understand the possible utilization. In this review, we discuss the role of plants and their wastes for minimizing mercury and lead pollution with their toxic effect on both human beings and plants.To get more news about Emeramide, you can visit fandachem.com official website.

Environmental chemistry is an area of increasing interest both to chemists and to the general public. Nowadays, more and more people consider that the magnitude of pollution problem in our soils and water calls for immediate action. Among toxic substances reaching hazardous levels are heavy metals, including mercury, lead, chromium, arsenic, zinc, cadmium, uranium, selenium, silver, gold and nickel. The danger of heavy metals is aggravated by their almost indefinite persistence in the environment due to their immutable nature. Unfortunately, the enormous cost associated with the removal of pollutants from soils and water by means of traditional physiochemical methods has been encouraging companies to ignore the problem. Conventional methods for heavy metal removal from aqueous solution and soil include chemical precipitation, electrolytic recovery, ion exchange/chelation, solvent extraction/liquid membrane separation and size exclusion processes (Esalah et al., 2000, Canet et al., 2002, Weirich et al., 2002, Shi et al., 2009, Li et al., 2009, Shao et al., 2010). But these methods are often cost prohibitive having inadequate efficiencies at low metal concentrations (Hammaini et al., 2003). Moreover, the resulting sludge has to be concentrated and its disposal or recovery of metals from the sludge represents an enormous problem (Cheng and Shang, 1994). The conventional technologies for effluent treatment are not economically feasible for small-scale industries that are prevalent in developing economies. Therefore, new technologies are required to reduce heavy metal concentrations to environmentally acceptable levels at affordable costs. Hence, phytoremediation/bioremediation with low-cost materials (industrial, agricultural or urban residues) has emerged as a promising technology for recovering mercury and lead from contaminated sites. The application of phytoremediation/bioremediation in environmental treatment has become a significant research area in the past 15 years.

Heavy metal ions are reported as priority pollutants, due to their mobility in natural water ecosystems and due to their toxicity. Heavy metals cannot be destroyed biologically, but only transformed from one oxidation state or organic complex to another. As a result of the alteration of its oxidation state, the metal may become either: (i) more water soluble and is removed by leaching, (ii) inherently less toxic, (iii) less water soluble so that it precipitates and then becomes less bioavailable or removed from the contaminated site, or (iv) volatilized and removed from the polluted area (Garbisu and Alkorta, 1997). Heavy metals are present in soil as natural components or as a result of human activity. Heavy metals even at low concentrations can cause toxicity to humans and other forms of life, their adverse effects on human health are quite evident from Table 1. The primary sources of metal pollution are the burning of fossil fuels, mining and smelting of metallic resources, downwash from power lines, municipal wastes, fertilizers, pesticides and sewage.