Reduction of oxides obtained from waste Ni-MH battery's positive electrode using waste plastics to produce nickel based alloy. (10th March 2020)

• Record Type: Journal Article
• Authors: Behera, Pravas Ranjan; Farzana, Rifat; Sahajwalla, Veena
• Is Part Of: Journal of cleaner production. Volume 249(2020)
• Publication Date: 2020-03-10
• Subjects: Waste Ni-MH battery -- e-waste plastic -- Nickel alloy -- Waste recycling -- Sustainability; Factory and trade waste -- Management -- Periodicals; Manufactures -- Environmental aspects -- Periodicals; Déchets industriels -- Gestion -- Périodiques; Usines -- Aspect de l'environnement -- Périodiques; 628.5
• DOI: 10.1016/j.jclepro.2019.119407
• Languages: English
• ISSNs: 0959-6526

Abstract

Abstract: Generation of electronic waste (e-waste) is a direct result of the world's dependence on electronics and daily use gadgets. Global consumption of e-waste was around 60 Mt in 2016 and is increasing each year in developed and developing countries. The waste accumulated not only affects the environment (soil and water) but also is detrimental to human health, thereby calling for sustainable recycling solutions. The current work details a novel approach to recover nickel alloy, using two waste streams: positive electrode materials of waste Ni-MH battery as Ni source in oxide form and e-waste plastics as a reductant. As an alternative to the use of conventional carbon, characterization studies, gas evolution kinetics, weight loss, fine black carbon generation were performed on e-waste plastics before carrying out the reduction of Nickel oxide at 1550 °C in an argon atmosphere in a high-temperature horizontal tube furnace. The selected temperature (1550 °C) favors the reduction without the addition of any additives and diminishes the formation of toxic compounds such as dioxins. FTIR gas spectra of the e-waste plastics confirmed the gradual decrease of functional groups, such as poly-methylene, phenol, and styrene as temperature increased from 400 °C to 850 °C. A mechanism of reduction starting from the cold zone of the furnace to hot zone was established which is observed to be predominantly gas based. High metal purity was confirmed by ICP-OES (Inductively coupled plasma optical emission spectroscopy) > 99% and XPS (X-ray photoelectron spectroscopy) 70–84 atomic %. XRD (X-ray powder diffraction) and EDS (Energy Dispersive X-ray spectroscopy) confirmed the formation of nickel alloy in the product phase and morphology was studied by SEM (scanning electron microscopy) which conveyed the uniformity of the product surface. This scientific study of using e-waste plastics as a reducing agent depicts a promising route to produce nickel alloy from the positive electrode of Ni-MH battery while reutilizing e-waste streams in a sustainable way. Graphical abstract: Image 106722 Highlights: Green synthesis of Nickel based alloy by combining two e-waste streams. E-waste plastic as reductant is effective in NiO reduction at 1550 °C. >90% reduction of NiO by waste plastic was achieved within 15 min. Recovered Ni alloy showed high purity with ∼92% Ni and ∼7% Co. XRD, XPS, EDS analysis confirmed the formation of the Nickel alloy.