Production of zinc and manganese oxide particles by pyrolysis of alkaline and Zn-C battery waste

Microrecycled zinc oxide nanoparticles (ZnO NP) recovered from spent Zn-C batteries for VOC detection using ZnO sensor

Non-intrusive techniques for diagnosis and biomonitoring - for example, breath testing to detect biomarkers - have the potential to support the advancement of versatile and remote point-of-care (PoC) diagnostics. This paper investigates tuning the sensitivity and selectivity performance of chemo-resistive sensors to detect volatile organic compound (VOC) biomarkers using a hybridized material of pristine graphene (pG) and zinc oxide nanoparticles (ZnO NP) recovered from spent Zn-C batteries. This hybridized graphene nanocomposite material of ZnO nanoparticles showed enhanced sensing performance because of high conductive property of graphene along with the synergetic interplay between graphene composite materials and ZnO NPs. The elevated surface area as well as adsorption capability of ZnO NPs provided improved sensitivity and selectivity for particular VOCs. It was proposed that this hybridized material could be used to fabricate chemo-resistive sensors with sensing performances tailored for VOC biomarker detection. To test this hypothesis, the ability of graphene hybrid nanocomposites with ZnO NPs to improve the sensing characteristics and efficiency of distinguishing diverse VOC biomarkers such as ethanol, acetone, methanol, chloroform, acetonitrile and terahydrofuran (THF) was investigated. Results demonstrated that the microrecycled ZnO based hybrid sensor has good selectivity along with the sensitivity towards ethanol and chloroform VOCs at room temperature (20 °C).

A novel process on the recovery of zinc and manganese from spent alkaline and zinc-carbon batteries

Spent alkaline and zinc-carbon batteries contain valuable elements (notably, Zn and Mn), which need to be recovered to keep a circular economy. In this study, the black mass materials from those spent batteries are pyrometallurgically treated via a series of process steps in a pilot-scale KALDO furnace to produce an Mn-Zn product, a ZnO product, and an MnO (manganese monoxide) product, toward applications of Mn-Zn micronutrient fertilizer, zinc metal, and manganese alloy, respectively. After an oxidative roasting step, an Mn-Zn product, containing 43% Mn, 22% Zn, and negligible amounts of toxic elements (notably, Cd, Hg, and Pb), could be produced, being suitable for the micronutrient fertilizer application. After a reductive roasting step, a ZnO product and an MnO product are produced. The attained ZnO product, containing up to 84.6% ZnO, is suitable for zinc metal production when the leaching steps are taken to remove most of the Cl and F in the product. The attained MnO product, containing up to 91.7% MnO, is of premium quality for manganese alloy production, preferably for SiMn alloy production due to its low phosphorus content. The proposed application scenarios could substantially improve the recovery efficiency of those spent batteries.

Turning carbon-ZnMn2O4 powder in primary battery waste to be an effective active material for long cycling life supercapacitors: In situ gas analysis

A simple and chemical-free recycled carbon-ZnMn₂O₄ powder (composite) from the spent Zn-carbon batteries is proposed as an effective active material for the supercapacitor. This approach may amplify the economic and environmental benefits of the recycling process. We also synthesized the spherical MnO_x nanoparticles by the calcination followed by the chemical treatment. Recycled composite and the MnO_x nanoparticles were comprehensively characterized. Symmetrical supercapacitors with the composite and the MnO_x nanoparticles show specific capacitances of 118 F g^-1 and 88 F g^-1 at 0.1 A g^-1, respectively. Also, the supercapacitor with the composite offers a specific energy of 8.0Whkg^-1 at 0.1A g^-1 while 4.3Whkg^-1 is obtained for MnO_x nanoparticles. The stable cell potential limits of 1.4 V and 1.2 V were established for the supercapacitors of the composite and MnO_x nanoparticles with the capacitance retention of 83% and 96%, respectively at the end of 100,000 cycles at 2.5Ag^-1. Also, the excellent energy efficiencies of 80% and 72% with the coulombic efficiency of 100% are estimated for the supercapacitors of the composite and the MnO_x nanoparticles, respectively. Finally, in situ gas analysis of the symmetrical supercapacitors are carried out using the differential electrochemical mass spectrometry. The proposed approach may be more economical and the environmentally benign recycling of spent Zn-carbon battery for circular economy and sustainability.

Thermal degradation behaviors and evolved products analysis of polyester paint and waste enameled wires during pyrolysis

The thermal degradation behaviors and evolved products analysis of polyester paint and waste enameled wires during pyrolysis were studied. Thermogravimetric (TG) and differential thermogravimetric (DTG) analyses were performed to investigate the mass loss characteristics. The pyrolysis solid residues generated during the process under optimal condition were detailedly analyzed by Fourier-transform infrared spectroscopy (FTIR). Meanwhile, the pyrolysis gas and oil generated were analyzed by gas chromatography-mass spectrometry (GC-MS). Kinetic analysis adopted the Ozawa-Flynn-Wall (OFW) model to confirm the reaction series by the variation pattern of activation energy. The results indicated that the pyrolysis of polyester paint and waste polyester enameled wires can be divided into three stages. The average activation energy of polyester paint and waste polyester enameled wires pyrolysis was 323.34 kJ/mol and 215.95 kJ/mol, respectively. The optimized pyrolysis temperature for polyester paint and waste polyester enameled wires was 500 °C and 900 °C, respectively. The chemical compositions of the pyrolysis residues of polyester paint and waste polyester enameled wires were basically same, mainly containing the compounds with CH, CO, aromatic ring, methyl, and aromatics bonds. The pyrolysis gas of polyester paint was mainly composed of C₂H₆, while that of waste polyester enameled wires mainly consisted of C₂H₆ and C₄H₈O. The main components of the pyrolysis oil polyester paint and waste polyester enameled wires were basically same, mainly containing long chain hydrocarbons, long chain alkenes, alcohols, phenol, ketone, aldehyde, and aromatic.

Energy efficient electrodes for lithium-ion batteries: Recovered and processed from spent primary batteries

In an attempt to develop low cost, energy efficient and advanced electrode material for lithium-ion batteries (LIBs), waste-to-wealth derived as well as value added spent battery materials as potential alternatives assume paramount importance. By combining the low lithiation potential advantages, one can arrive at energy efficient electrodes bestowed with cost effective and eco-friendly benefits required for practical LIB applications. In the present study, Zn and Mn-salts along with C were successfully extracted from the spent zinc carbon batteries through a simple and efficient hydrometallurgy approach and decomposed thermally to obtain ZnMn₂O₄ at 350 °C for 12 h and 450 °C for 3 h. Further, C-ZnMn₂O₄ nanocomposites were prepared and demonstrated for appreciable electrochemical performance in LIB assembly. Our results show that C-ZnMn₂O₄ composites prepared at 350 °C and 450 °C demonstrate better performance than pristine ZnMn₂O₄ anode due to the improved electronic conductivity rendered by the added carbon obtained from spent primary battery. In particular, C-ZnMn₂O₄ at 350 °C @12 h exhibits appreciable electrochemical performance by showing a stable and higher capacity of 600 mAhg^-1 at a current density of 50 mAg^-1 in the voltage range of 0.01-3.0 V and qualifies it as a better performing cost-effective anode for LIBs.

Manganese oxide synthesized from spent Zn-C battery for supercapacitor electrode application

Manganese oxide (Mn₃O₄) nanomaterials have promising potential to be used as supercapacitor electrode materials due to its high energy storage performance and environmental compatibility. Besides, every year huge volume of waste batteries including Zn-C battery ends up in landfill, which aggravates the burden of waste disposal in landfill and creates environmental and health threat. Thus, transformation of waste battery back into energy application, is of great significance for sustainable strategies. Compared with complex chemical routes which mostly apply toxic acids to recover materials from Zn-C battery, this study establishes the recovery of Mn₃O₄ particles via thermal route within 900 °C under controlled atmosphere. Synthesized Mn₃O₄ were confirmed by XRD, EDS, FTIR, XPS and Raman analysis and FESEM micrographs confirmed the coexistence of spherical and cubic Mn₃O₄ particles. Mn₃O₄ electrode derived from waste Zn-C battery demonstrate compatible electrochemical performance with standard materials and conventional synthesis techniques. Mn₃O₄ electrode exhibited highest capacitance value of 125 Fg⁻¹ at 5 mVs⁻¹ scan rate. The stability of the electrode showed good retention in discharge and charge capacity by about 80% after 2100 cycles. This study demonstrates that waste Zn-C battery can be further utilized for energy storage application, providing sustainable and economic benefits.

Recovery of industrial valuable metals from household battery waste

The modern community is dependent on electronic devices such as remote controls, alarm clocks, electric shavers, phones and computers, all of which are powered by household batteries. Alkaline, zinc-carbon (Zn-C), nickel metal hydride, lithium and lithium-ion batteries are the most common types of household energy storage technologies in the primary and secondary battery markets. Primary batteries, especially alkaline and Zn-C batteries, are the main constituents of the collected spent battery stream due to their short lifetimes. In this research, the recycling of main battery components, which are steel shells, zinc (Zn) and manganese oxides, was investigated. Household batteries were collected in Gothenburg, Sweden and mechanically pretreated by a company, Renova AB. The steel shells from spent batteries were industrially separated from the batteries themselves and the battery black mass obtained. A laboratory-scale pyrolysis method was applied to recover the Zn content via carbothermic reduction. First, the carbothermic reaction of the battery black mass was theoretically studied by HSC Chemistry 9.2 software. The effect of the amount of carbon on the Zn recovery was then examined by the designed process at 950°C. The recovery efficiency of Zn from battery black mass was over 99%, and the metal was collected as metallic Zn particles in a submicron particle size range. The pyrolysis residue was composed of mainly MnO₂with some minor impurities such as iron and potassium. The suggested recycling process is a promising route not only for the effective extraction of secondary resources, but also for the utilization of recovered products in advanced technology applications.

Zinc Oxide Nanoparticles from Waste Zn-C Battery via Thermal Route: Characterization and Properties

Disposable batteries are becoming the primary sources of powering day-to-day gadgets and consequently contributing to e-waste generation. The emerging e-waste worldwide is creating concern regarding environmental and health issues. Therefore, a sustainable recycling approach of spent batteries has become a critical focus. This study reports the detail characterization and properties of ZnO nanoparticles recovered from spent Zn-C batteries via a facile thermal synthesis route. ZnO nanoparticles are used in many applications including energy storage, gas sensors, optoelectronics, etc. due to the exceptional physical and optical properties. A thermal treatment at 900 °C under an inert atmosphere of argon was applied to synthesize ZnO nanoparticles from a spent Zn-C battery using a horizontal quartz tube furnace. X-ray diffraction (XRD), selected area electron diffraction (SAED) and X-ray photoelectron spectroscopy (XPS) results confirmed the formation of crystalline ZnO nanoparticles. Field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) analysis confirmed that the size of synthesised ZnO particles were less than 50 nm and mainly composed of sphere shaped nanoparticles. Synthesized ZnO exhibited BET surface area of 9.2629 m²/g and showed absorption of light in the UV region. Excitation of ZnO by UV light showed photoluminescence in the visible range. This study will create an opportunity for potential applications of ZnO nanoparticles from spent batteries and will benefit the environment by reducing the volume of e-waste in landfills.

Simultaneous recovery of Zn and Mn from used batteries in acidic and alkaline mediums: A comparative study

A parallel study of acidic and alkaline leaching for the recovery of Mn and Zn from spent alkaline batteries is outlined. Using H₂SO₄ as solvent and selecting appropriate conditions of temperature and concentration, all residues were dissolved except carbon. The separation and recovery of the two components were performed by electrodeposition with satisfactory results at pH values above 4 (current efficiency above 70% for Zn and Mn) but rather lower efficiencies as the pH decreased. Most of the Zn was selectively dissolved by alkaline leaching using a 6.5M NaOH solution, and its recovery was examined by means of both electrochemical and chemical processes. The expected formation of pure Zn by electrowinning failed due to the formation of ZnO, the content of which was highly dependent on the electrodeposition time. For short periods, Zn was the main component. For longer periods the electrodeposit consisted of agglomerated microparticles of ZnO with a minor fraction of Zn metal (barely 3% as measured by X-ray diffraction). A chemical reaction of the element with oxygen released at the anode surface might be responsible for its conversion to ZnO. A simple chemical route is described for the first time for the direct conversion of Zn(OH)₄^2- solution to nanostructured ZnO by lowering the pH to values around 12 using 2M HCl solution.

Recovery of zinc and cadmium from spent batteries using Cyphos IL 102 via solvent extraction route and synthesis of Zn and Cd oxide nanoparticles

The overall aim of this study is to separate and recover zinc and cadmium from spent batteries. For this purpose Cyphos IL 102 diluted in toluene was employed for the extraction and recovery of Zn and Cd from Zn-C and Ni-Cd batteries leach liquor. The influence of extractant concentration for the leach liquors of Zn-C (0.01-0.05mol/L) and Ni-Cd (0.04-0.20mol/L) batteries has been investigated. Composition of the leach liquor obtained from Zn-C/Ni-Cd spent batteries is Zn - 2.18g/L, Mn - 4.59g/L, Fe - 4.0×10^-3g/L, Ni - 0.2×10^-3g/L/Cd - 4.28g/L, Ni - 0.896×10^-1g/L, Fe - 0.148g/L, Co - 3.77×10^-3g/L, respectively. Two stage counter current extraction at A/O 1:1 and 3:2 with 0.04mol/L and 0.2mol/L Cyphos IL 102 for Zn and Cd, respectively provide more than 99.0% extraction of both the metal ions with almost negligible extraction of associated metal ions. A stripping efficiency of around 99.0% for Zn and Cd was obtained at O/A 1:1 using 1.0mol/L HNO₃ in two and three counter current stages, respectively. ZnO and CdO were also synthesized using the loaded organic phase and characterized using XRD, FE-SEM and EDX techniques. XRD peaks of ZnO and CdO correspond to zincite and monteponite, respectively. The average particle size was ∼27.0nm and ∼37.0nm for ZnO and CdO, respectively. The EDX analysis of ZnO and CdO shows almost 1:1 atomic percentage.

A facile chemical route for recovery of high quality zinc oxide nanoparticles from spent alkaline batteries

Recycling of spent domestic batteries has gained a great environmental significance. In the present research, we propose a new and simple technique for the recovery of high-purity zinc oxide nanoparticles from the electrode waste of spent alkaline Zn-MnO2 batteries. The electrode material was collected by the manual dismantling and mixed with 5M HCl for reaction with a phosphine oxide reagent Cyanex 923® at 250°C for 30min. The desired ZnO nanoparticles were restored from the Zn-Cyanex 923 complex through an ethanolic precipitation step. The recovered particle product with about 5nm diameter exhibited fluorescent properties (emission peak at 400nm) when excited by UV radiation (excitation energy of 300nm). Thus, the proposed technique offered a simple and efficient route for recovering high purity ZnO nanoparticles from spent alkaline batteries.