Heavy Metals Remediation of Water Using Plants and Lignocellulosic Agrowastes

Toxic heavy metals and metalloids are constantly released into the environment, and their removal is a very difficult task because of the high cost of treatment methods. Various methods exist for the removal of toxic metal ions from aqueous solutions. Among these are adsorption using activated carbon, by far the most versatile and widely used method for the removal of toxic metals; however, it is relatively expensive and less feasible to use in developing countries. Furthermore, activated carbon loaded with toxicants is generally incinerated or disposed of on land, thereby causing environmental pollution through different routes. There is an urgent need to develop low-cost, effective, and sustainable methods for their removal or detoxification. The use of lignocellulosic agrowastes is a very useful approach, because of their high adsorption properties, which results from their ion-exchange capabilities. Agricultural wastes can be made into good sorbents for the removal of many metals, which would add to their value, help reduce the cost of waste disposal, and provide a potentially cheap alternative to existing commercial carbons. Although the abundance and very low cost of lignocellulosic wastes from agricultural operations are real advantages that render them suitable alternatives for the remediation of heavy metals, further successful studies on these materials are essential to demonstrate the efficacy of this technology.