Tuesday, September 17, 2019

Chemical Engineering Project Topics

 E-Waste: Recovery of Noble Metal

Rapid developments in Technology lead to increase in diversified production of electrical and electronic items, which is increasing day by day. With increasing population the consumption of such kind of items are also increasing rapidly. Electrical and electronic equipments have its significant impact in various fields in our society due to its higher capabilities, minimum error, and quite faster in operations. Massive use of computer, laptops, cellular phone, television, etc causes the generation of large quantity of e-waste which is a major global problem today. It is one of the fastest growing solid waste streams in the world. In 2005, in the EU, about 8.3 –9.1 million tonnes of waste of electrical and electronic equipments were estimated to be generated and this figure are forecast to reach 12.3 million tonnes by 2020 with an annual growth rate of 2.5–2. 7%. It was also reported that 20 - 50 million tons of waste of electrical and electronic equipments are generating globally in every year. The e-waste generation rate is increasing rapidly day by day. 

          Due to the inadequate recycling infrastructure only about 20% of the total ewaste is possible to recycle, whereas 80% either ending up in land filling or being informally recycled. E-waste in land filling causes the contamination in soil and groundwater. In the present time maximum e-wastes are generating from waste mobile phones and computer parts. Quantitatively it will not be surprised if we say that the existence of number of mobile phones is more than the number of people living on the Earth at present.

            On the basis of chemical composition, the e-waste consists of various metals, metalloids, precious metals, halogenated compounds and radioactive elements. Metals and metalloids include aluminium, arsenic, antimony, barium, beryllium, cadmium, chromium, copper, europium, lead, lithium, iron, manganese, mercury, nickel, selenium, silica, tin, yttrium, zinc, etc. Precious metals include gold, indium, silver, palladium, platinum, etc.

            There is a research scope in this area where the valuable materials (copper, gold, platinum) can be recovered from the e-waste. Some important materials such as copper, gold, platinum, aluminium, palladium, nickel, zinc, and so on are present in the e-waste in different percentage. Recovery of this material from e-waste may be good initiative in the reduction of the e-waste along with the reduction of environmental pollution.

 References:

1.  Huisman, J., Magalini, F., Kuehr, R., Maurer, C., Ogilvie, S., Poll, J., Delgado, C., Artim, E., Szlezak, J., Stevels, A., 2007. 2008 Review of Directive 2002/96 on Waste Electrical and Electronic Equipment. ENV.G.4/ETU/2006/0032. Unite d Nations University, Bonn, Germany 347.

2. UNEP, 2009. Sustainable innovation and technology transfer industri al sector studies, recycling from e-waste to resourc es. United Nations Environment Programme & United Nations University.

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Waste Plastics: Production of Oil

The global production of plastics is increasing rapidly because of their vital role in today’s daily activities. Plastics are widely used because of its advantages such as cheapness, endurance, lightness, hygiene and design adaptability. The sharp rise and mass consumption of plastics produce a great quantity of wastes, which poses a formidable challenge for waste management. Most plastics are not biodegradable and originate from the unsustainable fossil fuels. The disposal of waste plastics has become a major worldwide environmental problem in today’s world. Plastic disposal requires a large land area that otherwise could be used for other more useful purposes. Most of the plastic that is not disposed of properly eventually ends up in water. Some of this waste then accumulates in ocean gyres in the great lakes or in other large water bodies. This accumulated plastic can result in the death of animals and birds from their consumption of it. Thus, it is becoming increasingly challenging to manage and control the use of plastics due to their adverse environmental effects.

            The major sources of plastic waste include agricultural, household, automobile, packaging materials, toys, etc. At present, the disposal processes of plastic wastes are mainly incineration and landfill. The incineration and landfill deposition of municipal waste plastics (MWP) may cause environmental problems and is becoming more expensive. Due to increasing volume of MWP and decreasing landfill capacity for disposal, landfill becomes more challenging. In addition, landfill can release hazardous sub-stances and plastic wastes take long time to degrade. In terms of incineration, it causes hazardous releases such as nitrous oxide, sulphur oxides, dusts, dioxins and other toxins. Especially, incineration of polyvinyl chloride (PVC) plastic causes the environmental pollution and reduces the service life of the incinerator by generating hazardous hydrogen chloride gas and dioxins containing chlorine.

            In this regard, the disposal of plastic wastes has become an important issue all over the world, and recycling is an effective way to solve this problem. Recycling of plastic wastes shows numerous benefits, such as reducing consumption of energy; reducing the amount of solid wastes that go to incineration and landfill and thus decreasing the environmental pollutions; displacing partially virgin plastics produced from refined fossil fuels.

            Research can be focused on the production of oil from the waste plastics, which is more reliable and relatively inexpensive way for suitable applications.

 References

1. Arena, U. Process and technological aspects of municipal solid waste gasification. A review. Waste Manage. 2012, 32, 625–639.

2. Chiu, S.J.; Chen, S.H.; Tsai, C.T. Effect of metal chlorides on thermal degradation of (waste) polycarbonate, Waste Manage. 2006, 26, 252-259.

3. Wang, C. –Q.; Wang, H.; Liu, Y.-N. Separation of polyethylene terephthalate from municipal waste plastics by froth flotation for recycling industry. Waste Manage. 2015, 35, 42-47.

4. Wey, M.Y.; Yu, L. J.; Jou, S.I. The influence of heavy metals on the formation of organics and HCl during incinerating of PVC-containing waste. J. Hazard. Mater. 1998, 60, 259–270.

5. Saisinchai, S. Separation of PVC from PET/PVC mixtures using flotation by calcium lignosulfonate depressant. Eng. J. 2013, 18, 45–54.

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Water Splitting: Hydrogen Production

 A large portion of the world energy demand has been delivered by fossil fuels because of their availability and convenience. But the emissions of CO2, NOx, and SOx to the atmosphere during combustion of fossil fuels causes to the current worldwide air pollution and climate changes. In this scenario there is an increasing demand in the development of renewable energy resources. Hydrogen is considered as an effective alternative energy resources in the near future. Different methods are available for the hydrogen generation, such as electro-catalytic water splitting, steam reforming of hydrocarbons, coal gasification, biomass pyrolysis, etc. 

            One of the most used technologies for electrolytic hydrogen production is the alkaline water electrolysis. But in most industrial electrolysers the cost of production is high because of the high energy consumption. Zero-gap cell geometry, development of new electrocatalytic materials for electrodes and new diaphragm materials are the attempts made to overcome the problems. The conventional nickel electrodes experience extensive deactivation during electrolysis which results in huge current loss. Development of activator electrocatalysts increase the surface area of electrode and reduce hydrogen over potential. Such electrocatalyst toward hydrogen evolution research are cobalt-chrome, nickel-cobalt-molybednum, etc. From the literature it has been shown that electro-catalytic water splitting using solar light is a promising method for hydrogen generation because of high efficiency, purity of the product, large scale production, environmentally friendly and simple process.

            Photocatalytic water splitting using heterogeneous catalysts for hydrogen production attracted recent years because of the material’s favorable electronic energy band structure. Different catalysts, such as SrZrO3, Cu2O, NiW, Nanoscale zero valent iron (nZVI), silver oxides, etc have been used as the photocatalyst during water splitting.

            However, development of highly active and stable catalyst for the photocatalytic water splitting is still a challenging job. Further development in catalyst and modification of method may lead to large scale production of hydrogen for getting sustainable green energy in near future.

 References

1.      Huerta-Flores, A. M.; Torres-Martínez, L. M.; Sánchez-Martínez, D.; Zarazúa-Morín, M. E. Fuel 2015, 158, 66–71.

2.      Chen, K.-F.; Li, S.; Zhang, W.-X. Chem. Eng. J. 2011, 170, 562–567.

3.      Wang, W.; Zhao, Q.; Dong, J.; Li, J. Int. J. hydrogen energy. 2011, 36, 7374 – 7380.



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