Phytoextraction as a tool for green chemistry

Abstract

Abstract:The unique chemical and physical properties of metals mean that they are extensively utilized by industry in a huge variety of applications, including electronics, materials, industrial catalysts and chemicals. The increased consumer demand from a growing population worldwide with rising aspirations for a better life has resulted in concerns over the security of supply and accessibility of these valuable elements. As such, there is a growing need to develop alternative methods to recover them from waste repositories, current or historic, both for hazard avoidance and potentially, as a new source of metals for industry. Phytoextraction (the use of plants for the recovery of metals from waste repositories) is a green and novel technique for metal recovery, which, if done with the goal of resource supply rather than hazard mitigation, is termed "phytomining". The ability for plants to form metallic nanoparticles as a consequence of phytoextraction could make the recovered metal ideally suited for utilization in green chemical technologies, such as catalysis. This review focuses on a multidisciplinary approach to elemental sustainability and highlights important aspects of metal lifecycle analysis, metal waste sources (including mine tailings), phytoextraction and potential green chemical applications that may result from the integration of these approaches.

Current status and challenges in developing nickel phytomining: an agronomic perspective

“…Nickel phytomining operations consist of growing selected hyperaccumulator plant species ('metal crops') on Ni-rich (ultramafic) soils, followed by harvesting and incineration of the biomass to produce a 'bio-ore' from which Ni salts or Ni metal may be recovered (Anderson et al 1999;Chaney et al 1998;Hunt 2014;Robinson et al 1999b). These operations may be undertaken on: (i) large ultramafic areas with suitable topography, where soils are unsuitable for food production; or (ii) degraded Ni-rich land which includes Ni laterite mine sites, smelter contaminated areas and ore beneficiation tailings (van der Ent et al 2015a).…”

“…Phytomining operations cultivate hyperaccumulator plants on low-grade ore bodies or superficially mineralised (ultramafic) soils, followed by harvesting and a series of post-harvest processing operations to recover target elements such as nickel (Ni) for profit (Anderson et al 1999;Chaney et al 1998;Hunt 2014;Robinson et al 1999a;van der Ent et al 2015). Appropriate agronomic practises are a critical pre-requisite in the development of commercially viable phytomining technology (Li et al 2003a;Rascio and Navari-Izzo 2011).…”

Conservation of Critical Elements of the Periodic Table

“…The concentration of metal found within mine tailings is related to the nature of the ore and how efficient the extraction technology is. Modern mining extraction methods mean that little metal is left in the tailings; however, historic mining sites and their tailings may have concentrations of metals that could be commercially exploited using modern extraction technologies . Throughout every stage of processing there are losses to the environment, and these are frequently chemically complex mixtures of elements, which have significantly lower volumes compared to that of tailings.…”

Phytomining for Artisanal Gold Mine Tailings Management

“…This has been a major impediment to the development of an economically viable biomass processing system to support the commercial roll-out of phytomining [11]. The first step in proposed flow-sheets for biomass processing is to reduce the biomass to ash [13,22], and this first step was employed in the current study (Figure 3).…”