Irshad Mansuri

Growth of NiO nanorods, SiC nanowires and monolayer graphene via a CVD method

Green approaches for producing high purity advanced materials have always been a challenging task. Conventional methods for converting waste materials into char by heat treatment can have limitations in making defect free and pure materials for practical applications. Herein, we report a Green-Chemical Vapor Deposition (G-CVD) method to transform waste into functional materials in various forms by condensation of gases generated from waste on a chosen substrate. The flow of gases, mainly CO2, CH4 and CO, can be controlled via a regulated flow of a carrier gas and by controlling the temperature, gases can react/recombine on the substrate forming a crystalline lattice of semiconducting materials. Such a versatile green method can be sustainable and at the same time help in reducing the burden of landfill waste. We present how an appropriate control of the gas mixture resulting from the heat-treatment of waste rubber tyres and plastics leads to the growth of various types of functional materials on substrates. The growth mechanism of materials on substrates in this method is similar to the conventional CVD method. However, the utilization of waste to generate these gases adds the green and sustainable feature to this method and its high degree of reproducibility offers practical applicability. Once established for NiO nanorods, we tested the versatility of this technique to grow SiC nanowires, SiC nanoparticles and monolayer graphene. This highly reproducible G-CVD method of making advanced materials solely involves waste materials as the solid carbon source at atmospheric pressure without any other synthetic reagents.

Disentanglement of random access memory cards to regenerate copper foil: A novel thermo-electrical approach

This paper reports the development of a novel process combining thermal and electrical treatments, which are optimised to provide efficient recovery of copper foil from Random Access Memory cards (RAMs). A primary thermal transformation at 900 °C facilitates a highly efficient recovery of copper foils from RAMs during the secondary processing in the electrical fragmenter, using only 10 pulses at 150 kV. The process yield was 98% and inductively coupled plasma (ICP) analysis showed that the copper foils had 98% purity. X-ray diffraction (XRD) confirmed the presence of copper in a crystalline face-centred cubic (FCC) form. Scanning electron microscopy (SEM) - energy dispersive spectroscopy (EDS) analysis of the foils assisted in understanding the underlying mechanism of electrical separation. Transmission electron microscopy (TEM) gave a new perspective on the regeneration of copper foils wherein new copper grains depicted a ribbon like growth pattern. The copper foils had an electrical conductivity similar to that of commercially available pure copper sheets. Thus, the mechanism of thermo-electrical transformation was studied in detail and regenerated copper foils of high electrical conductivity were afforded from end-of-life RAMs.

High voltage pulses to recover copper from waste printed circuit boards

Electronic waste (e-waste) is one of the rapidly growing solid waste streams around the world. Advancement in technology, increase in usage of electronic products and rise in population during the last decade is causing the rapid obsolescence of e-waste. E-waste generation is around 40 million tonnes each year and increasing at the rate of 3–5% per annum. E-waste is heterogeneous in nature and contains both valuable and hazardous materials. Printed circuit boards (PCBs), a key component is used in most of the electronics and contributes 3% by weight to the total e-waste. PCBs contain copper and gold 20 times more than their respective ores hence various physical, chemical, electrostatic, pyrolysis and metallurgical techniques are investigated to recover copper. But due to disadvantages such as (a) release of toxic gases during crushing (b) non-selective fragmentation between metals and non-metals (c) use of chemicals or acids (d) high energy utilization demands the environmental friendly and sustainable technique to recover copper from waste PCBs. In this study, we have used high voltage pulse technology to recover copper from waste PCBs. To achieve high recovery, operating conditions such as voltage and number of pulses were optimised. The results signify that applied electric voltage and number of high energy pulse were the important factors to segregate copper from waste PCBs. Reduction of noxious gases, high recovery of copper and negligible mechanical damage were the advantages of using high voltage pulse technology to recover copper from waste.

Waste to Value in Steelmaking

The high temperature environment of steelmaking process, offers sustainable pathways for utilizing chemical reactions to re-purpose waste materials as resources. The use of waste polymeric materials in steelmaking is not only a solution for end-of-life products, which currently impose a serious burden on overstretched landfills but it also results in reduction of resource consumption and energy saving. This paper presents industrial plant results on the effect of the utilization of waste polymeric materials in steelmaking on coke and energy consumption.

Wettability of Carbonaceous Materials with Molten Iron at 1550°C

In the direct iron smelting process, interfacial reactions of carbonaceous materials with molten iron are among some of the key factors that dictate the rate of carbon transfer into molten iron and establish a carbon concentrated melt to reduce iron oxide in the slag phase. Detailed wettability investigations on a range of carbonaceous materials, e.g. synthetic graphite, natural graphite, coke, coal-chars, coke-polymer blends, waste plastics in contact with molten iron at 1550°C were carried out using the sessile drop method. Experimental results on dynamic contact angles are presented in this chapter and are discussed in terms of the basic characteristics of carbons and the changing composition of the interfacial region as a function of time. The influence of carbon and sulfur content in Fe-C-S melts on the wettability of synthetic graphite was investigated. The initial melt carbon content was in the range of 0.13 to 2.24 wt %, and the melt sulfur content was in the range of 0.05 to 0.37 wt %. It was found that the contact of solid graphite with Fe-C-S melts resulted in a nonequilibrium reactive wetting. It involved the transfer of carbon from the solid to the liquid and iron transfer from the liquid to the solid. The Fe-C-S melts exhibited relatively poor wetting in the absence of such a material exchange. The wetting of natural graphite, which contained 8.8 pct ash, by iron was investigated to establish a fundamental understanding of the influence of ash on interactions between graphite and iron. It was found that the formation of an ash interfacial layer between the carbonaceous material and liquid iron had a strong influence on the mass transfer and interfacial reaction. Wetting investigations of pure liquid iron with three types of metallurgical cokes at 1550°C showed a non-wetting behaviour for all cokes with contact angles ranging from 123° – 126° initially, which marginally decreased to 109°-114° after 60 minutes