Photovoltaic panel recycling: from type-selective processes to flexible apparatus for simultaneous treatment of different types.

Photovoltaic (PV) technology for renewable energy utilization is constantly growing throughout the world. This widespread application is going to determine the disposal of large amounts of wastes (as end of life panels): only in Europe about 500,000 ton/year are expected in the next 20 years. European Union issued the Guideline 2012/19/EU in order to fix rules about end of life photovoltaic panel’s treatment establishing both collecting rates and minimum recovery targets. Currently the dominant PV technology uses crystalline silicon (monocrystalline and polycrystalline) as semiconductor, but the thin film photovoltaic modules using cadmium telluride (CdTe), amorphous silicon, Copper Indium Gallium Selenide (CIGS) and Copper Indium Selenide (CIS) are recently getting much more importance. Wastes of PV installations are secondary raw materials which could be treated in order to recover glass and Al, but also other metals such as Cu, Ti, Ag, Te, In, Se, Ga, along with plastic and metallic components of electronic equipment. Many recent efforts were devoted to the treatment of end of life panels, but only two full scale processes were developed for crystalline silicon modules (Deutsche Solar) and CdTe panels (First Solar). Furthermore, recent developments concerned with new technologies designed for treating together more kinds of photovoltaic panels by automated processes. In this work a picture of the PV world in terms of market, typology, waste dynamics and recoverable materials will be given. A description of full scale processes will be reported evidencing products and yields of recovery. A case study of process development for the simultaneous treatment of different kinds of PV panels will be presented. In particular experimental results in lab and pilot scale will be described regarding the development and optimization of a process including both physical pre-treatment and hydrometallurgical recovery of target metal concentrates. The process will be validated in pilot scale within the activities of the Photolife project (LIFE13 ENV/IT/001033) financed by European Community in the LIFE+ program

Synthesis of cobalt nanoparticles by electrodeposition onto aluminium foils

In this contribution a study of electrochemical deposition of cobalt nanoparticles onto aluminium foils is presented. The study is aimed at deriving information required for design and control of cobalt nanoparticles electrodeposition onto aluminium foams employed as catalysts support in ethanol reforming. A thorough experimental analysis was in this perspective conducted to determine the influence of applied potential and amount of electric charge passing thorough the cell (amount of charge), on number density and size of the synthesized nanoparticles. Chronoamperometric tests were for this purpose performed in a three electrode cell to determine the current responses to variations in the selected operating parameters. Mathematical models accounting for charge transfer and diffusion limitations were implemented to attain fitting of the derived data, leading to an estimation of the number density of active sites. Scanning electron microscopy of cathode aluminium foils was performed to validate the predictions of the employed mathematical models and characterize the influence of the considered operating parameters on the size and number density of the electrodeposited nanoparticles

Development and Techno-Economic Analysis of an Advanced Recycling Process for Photovoltaic Panels Enabling Polymer Separation and Recovery of Ag and Si

Photovoltaic panels were included in EU Directive as WEEE (Wastes of Electric and Electronic Equipment) requiring the implementation of dedicated collection schemes and end-of-life treatment ensuring targets in terms of recycling rate (80%) and recovery rate (85%). Photovoltaic panels are mainly made up of high-quality solar glass (70–90%), but also metals are present in the frames (Al), the cell (Si), and metallic contacts (Cu and Ag). According to the panel composition, about $72 per 100 kg of panels can be recovered by entirely recycling the panel metal content. The PhotoLife process for the treatment of end-of-life photovoltaic panels was demonstrated at pilot scale to recycle high value glass, Al and Cu scraps. A process upgrade is here reported allowing for polymer separation and Ag and Si recycling. By this advanced PhotoLife process, 82% recycling rate, 94% recovery rate, and 75% recoverable value were attained. Simulations demonstrated the economic feasibility of the process at processing capacity of 30,000 metric ton/y of end-of-life photovoltaic panels

Valorisation of Olive Pomace for the Production of Bio-Composite Adsorbents Applied in as Removal from Drinking Waters

Arsenic is a toxic metalloid representing a serious threat to human health, reaching a concentration in drinking water above the limit of 10 µg/L in many regions of the world. Although adsorption technologies are available today to remove arsenic from water, the employed adsorbents are expensive, which severely hinders the possibility of water treatment in marginal and rural areas. In this study, a two-stage process is investigated in which an adsorbent for the removal of arsenic from water is produced by hydrothermal carbonization (HTC) of olive pomace followed by iron precipitation. In the first part of the study, the kinetics of solid mass variation during the HTC process were analyzed to derive indications about the mechanisms driving the thermochemical conversion of olive pomace to hydrochar. It was thus verified that a satisfactory hydrochar yield could be attained after 30 min through the polymerization of hydrolysis products released during the early stages of HTC. Adsorption isotherms were determined for the Fe-hydrochar and the Fe-biochar produced by iron precipitation onto the hydrochar and the pyrolyzed olive pomace (biochar). Fe hydrochar showed higher adsorption capacity (qmax=8.7 mg/g) compared to the Fe-biochar (qmax= 5.3 mg/g). Fe-hydrochar was finally tested in a fixed-bed adsorption column for As removal, evidencing the ability to maintain the arsenic concentration below the 10 µg/L limit when employed in the configuration conventionally adopted for water treatment. However, in this configuration, the apparent adsorption capacity was reduced, indicating the need for an optimization of the fixed bed-column desig

Regeneration of Exhausted Palladium-Based Membranes: Recycling Process and Economics

The aim of the present work is the recycling treatment of tubular α-Al2O3-supported ceramic membranes with a Pd/Ag selective layer, employed in hydrogen production with integrated CO2 capture. A nitric acid leaching treatment was investigated, and recovered ceramic supports were characterized, demonstrating their suitability for the production of novel efficient membranes. The main objective was the metal dissolution that preserved the support integrity in order to allow the recovered membrane to be suitable for a new deposition of the selective layer. The conditions that obtained a satisfactory dissolution rate of the Pd/Ag layer while avoiding the support to be damaged are as follows: nitric acid 3 M, 60 °C and 3.5 h of reaction time. The efficiency of the recovered supports was determined by nitrogen permeance and surface roughness analysis, and the economic figures were analysed to evaluate the convenience of the regeneration process and the advantage of a recycled membrane over a new membrane. The experimentation carried out demonstrates the proposed process feasibility both in terms of recycling and economic results.This research has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement no. 760944 (MEMBER project)

Synthesis of MnCO3 nanoparticles by microemulsions: statistical evaluation of the effects of operating conditions on particle size distribution

Manganese carbonate nanoparticles were produced by microemulsion method. The effects of different operating conditions on nanoparticles' morphology, size, and polydispersity were determined. The reference system was made of cetyl trimethylammonium bromide, cyclohexane (as solvent), pentanol (as cosurfactant), and reactants MnCl2 and (NH4)(2)CO3. Investigated operating conditions were reaction time (30 and 60 min), solvent's type (isooctane and hexane), cosurfactant's dosage (3 and 4.5 g), and reactant's concentration (1.0 and 0.25 mol/L). Produced nanoparticles were characterized by X-ray diffraction, scanning electron microscope, while particle size distribution was determined by image analysis. Significance of investigated factors was assessed by statistical analysis. Cubic-rhombohedral stacked particles with average size of 69 nm and standard deviations of 31 nm were obtained. Morphology was maintained in all the investigated conditions except when cosurfactant's dosage was raised to 4.5 g. Statistical analysis showed that nanoparticles' average size can be significantly increased with respect to the reference condition by augmenting reaction time (+49 nm), by increasing the cosurfactant's dosage (+67 nm) and also by decreasing the reactant's concentration when using hexane as solvent (+110 nm). Conversely, significant diminution of average size was obtained by using isooctane (-30 nm) and hexane (-26 nm) as solvents. Polydispersity of particle size distribution can be significantly diminished by using isooctane (8 nm) and hexane (13 nm) instead of cyclohexane, by decreasing reactant's concentration in the reference condition (10 nm) and by raising cosurfactant's dosage (12 nm)

Non-electrostatic surface complexation models for protons and lead(II) sorption onto single minerals and their mixture

Potentiometric titrations and lead sorption tests were conducted using muscovite, clinochlore, hematite, goethite, quartz, and a mixture of these same minerals. Mechanistic models were developed to represent and interpret these data. The aim was isolating the specific contribution of each mineral in proton and lead binding. Acid-base properties of each single mineral as well as their mixture were represented by discrete models, which consider the dissociation of n monoprotic sites (n-site/n-K-H models). A one-site/one-K-H model (logK(H1) = 10.69) was chosen for quartz (dissociation of SiOH edge hydroxyl groups). Goethite and hematite (FeOH groups) were represented by the same one-site/one-K-H model (logK(H1) = 10.35). Three-site/three-K-H models were used for muscovite (logK(H1) = 4.18; logK(H2) = 6.65; log K-H3 = 9.67) and clinochlore (log K-H1 = 3.84; log K-H2 = 6.57; log K-H3 = 9.71) assuming that SiOH and AlOH of the alummosilicate matrix dissociate in the acid-neutral pH range while SiOH groups of quartz inclusions dissociate in the basic range. Similarly, the mixture of these minerals was represented by a three-site/three-K-H model (log K-H1= 3.39; log K-H2 = 6.72; log K-H3 10.82). According to crossed comparisons with single minerals, the first two sites of the mixture were associated with the aluminosilicate matrix (SiOH and AlOH respectively) and the third site with iron oxides (FeOH) and quartz groups. Additivity of proton binding in the mixture was demonstrated by simulating the mixture's titration curve. A unified model for the entire set of titration curves (single minerals and mixture) was also developed introducing a three-peak distribution function for proton affinity constants. Experimental data for lead sorption onto the mixture and individual minerals in 3-5 pH range denoted the competition between protons and metallic ions. The entire set of lead isotherms (individual mineral and mixture data) was represented adequately by a unified model taking into account both monodentate and bidentate complexes with the three active sites (additivity of lead binding). Experimental data of metal distribution in solid and liquid phases were successfully simulated by implementing the protonation and the surface complexation constants into the database of a dedicated software for chemical equilibria. (c) 2005 Elsevier Ltd. All rights reserved

Sequential extraction of heavy metals in river sediments of an abandoned pyrite mining area: Pollution detection and affinity series

In this paper heavy metal pollution at an abandoned Italian pyrite mine has been investigated by comparing total concentrations and speciation of heavy metals (Fe, Cu, Mn, Zn, Pb and As) in a red mud sample and a river sediment. Acid digestions show that all the investigated heavy metals present larger concentrations in the sediment than in the tailing. A modified Tessier's procedure has been used to discriminate heavy metal bound to organic fraction from those originally present in the mineral sulphide matrix and to detect a possible trend of metal mobilisation from red mud to river sediment. Sequential extractions on bulk and size fractionated samples denote that sediment samples present larger percent concentrations of the investigated heavy metals in the first extractive steps (I-IV) especially in lower dimension size fractionated samples suggesting that heavy metals in the sediment are significantly bound by superficial adsorption mechanisms. A modified Tessier's procedure, discriminating organic and sulphide bound metals, was used to detect pollutant mobilisation from red mud to river sediment in an abandoned pyrite mine. © 2004 Elsevier Ltd. All rights reserved

Photovoltaic panel recycling: from type selective processes to flexible apparatus for simultaneous treatment of different types

Photovoltaic (PV) technology for renewable energy utilisation is constantly growing throughout the world. Many recent efforts were devoted to the treatment of end-of-life panels, but only two full-scale processes were developed for crystalline silicon modules (Deutsche Solar) and CdTe panels (First Solar). Furthermore, recent developments concerned with new technologies designed for treating together more kinds of PV panels by automated processes. In this work, a picture of the PV world in terms of market, typology, waste dynamics and recoverable materials was given. A description of full-scale processes will be reported evidencing products and yields of recovery. A case study of process development for the simultaneous treatment of different kinds of PV panels was presented. In particular, experimental results in lab and pilot scale were described regarding the development and optimisation of a process including both physical pre-treatment and hydrometallurgical treatment for the recovery of target metal. © 2016 The Australasian Institute of Mining and Metallurgy