Selective formation of copper nanoparticles from acid mine drainage using nanoscale zerovalent iron particles

This is the author accepted manuscript. The final version is available from Elsevier via the DOI in this record.Nanoscale zerovalent iron (nZVI) has been investigated for the selective formation of Cu nanoparticles from acid mine drainage (AMD) taken from a legacy mine site in the UK. Batch experiments were conducted containing unbuffered (pH 2.67 at t=0) and pH buffered (pH <3.1) AMD which were exposed to nZVI at 0.1-2.0 g/L. Results demonstrate that nZVI is selective for Cu, Cd and Al removal (>99.9% removal of all metals within 1 h when nZVI ≥1.0 g/L) from unbuffered AMD despite the coexistent of numerous other metals in the AMD, namely: Na, Ca, Mg, K, Mn and Zn. An acidic pH buffer enabled similarly high Cu removal but maximum removal of only <1.5% and <0.5% Cd and Al respectively. HRTEM-EDS confirmed the formation of discrete spherical nanoparticles comprised of up to 68% wt. Cu, with a relatively narrow size distribution (typically 20-100 nm diameter). XPS confirmed such nanoparticles as containing Cu0, with the Cu removal mechanism therefore likely via cementation with Fe0. Overall the results demonstrate nZVI as effective for the one-pot and selective formation of Cu0-bearing nanoparticles from acidic wastewater, with the technique therefore potentially highly useful for the selective upcycling of dissolved Cu in wastewater into high value nanomaterials.This work was financially supported by the Natural Environmental Research Council (grant number: NE/L013908/1) and the Camborne School of Mines Trust

Towards sustainable mass production of metallic nanoparticles: selective synthesis of copper nanoparticles directly from malachite ore

This is the author accepted manuscriptContinued industrial development and burgeoning pressure to solve global challenges, including climate change and non-pharmaceutical pathogen management, will drive an urgent up-scaling in global nanoparticle production this Century. Conventional nanoparticle synthesis is typically a linear multistage approach comprising mining, benefaction, refining, reagent synthesis and then nanoproduct synthesis, which is both energy and resource intensive. Herein we present a new approach using nanoscale Cu (nCu) as an example: the translocation of nanoparticle synthesis into the subsurface and into one step. Malachite ore was first leached with H2SO4 or CH3COOH (0.5M, 1:10 solid-liquid ratio), partially neutralised using 0.01-0.5M NaOH or NaCO3 respectively and then exposed to nanoscale zerovalent iron (nZVI) (4.0 g/L), which acted as both a selective and rapid (<240 s) chemical reducing agent but also a magneto-responsive nCu recovery vehicle. Conversion of Cu from ore to discrete Cu0 35 /Cu2O nanoparticles was up to 31.1 wt.% with purities of up to 81.70 wt.% Cu (or 98.59 wt.% Cu and O) detected using HRTEM. This work therefore provides a first proof-of-concept of a new direct and one-pot “in situ” nanoparticle mass production route, which is conceptually possible for a wide range of engineered nanomaterials, including those containing Ni, Cr, U, Pb, Ag and Au, and therefore has the potential to yield transformative environmental and economic benefit across mining and raw material synthesis industries.Natural Environment Research Counci

Versatile Catalytic Hydrogenation Using A Simple SnIV Lewis Acid

Despite the rapid development of frustrated Lewis pair (FLP) chemistry over the last ten years, its application in catalytic hydrogenations remains dependent on a narrow family of structurally similar early main-group Lewis acids (LAs), inevitably placing limitations on reactivity, sensitivity and substrate scope. Herein we describe the FLP-mediated H2 activation and catalytic hydrogenation activity of the alternative LA iPr3SnOTf, which acts as a surrogate for the trialkylstannylium ion iPr3Sn+, and is rapidly and easily prepared from simple, inexpensive starting materials. This highly thermally robust LA is found to be competent in the hydrogenation of a number of different unsaturated functional groups (which is unique to date for main-group FLP LAs not based on boron), and also displays a remarkable tolerance to moisture

Versatile catalytic hydrogenation using a simple tin(IV) Lewis acid

Despite the rapid development of frustrated Lewis pair (FLP) chemistry over the last ten years, its application in catalytic hydrogenations remains dependent on a narrow family of structurally similar early main‐group Lewis acids (LAs), inevitably placing limitations on reactivity, sensitivity and substrate scope. Herein we describe the FLP‐mediated H2 activation and catalytic hydrogenation activity of the alternative LA iPr3SnOTf, which acts as a surrogate for the trialkylstannylium ion iPr3Sn+, and is rapidly and easily prepared from simple, inexpensive starting materials. This highly thermally robust LA is found to be competent in the hydrogenation of a number of different unsaturated functional groups (which is unique to date for main‐group FLP LAs not based on boron), and also displays a remarkable tolerance to moisture

Physicochemical composition of wastes and co-located environmental designations at legacy mine sites in the south west of England and Wales: Implications for their resource potential

This is the author accepted manuscript. The final version is available from the publisher via the DOI in this recordThis work examines the potential for resource recovery and/or remediation of metalliferous mine wastes in the south west of England and Wales. It does this through an assessment of the physicochemical composition of several key metalliferous legacy mine waste piles and an analysis of their co-location with cultural, geological and ecological designations. Mine waste samples were taken from 14 different sites and analysed for metal content, mineralogy, paste pH, particle size distribution, total organic carbon and total inorganic carbon. The majority of sites contain relatively high concentrations (in some cases up to several % by mass) of metals and metalloids, including Cu, Zn, As, Pb, Ag and Sn, many of which exceed ecological and/or human health risk guideline concentrations. However, the economic value of metals in the waste could be used to offset rehabilitation costs. Spatial analysis of all metalliferous mine sites in the south west of England and Wales found that around 70% are co-located with at least one cultural, geological and ecological designation. All 14 sites investigated are co-located with designations related to their mining activities, either due to their historical significance, rare species assemblages or geological characteristics. This demonstrates the need to consider the cultural and environmental impacts of rehabilitation and/or resource recovery on such sites. Further work is required to identify appropriate non-invasive methodologies to allow sites to be rehabilitated at minimal cost and disturbance.Natural Environment Research Council (NERC