Life cycle assessment of Carbon nanodots synthesis from olive solid wastes.
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Abstract Palestine is considered one of the olive oil producing countries. As the world annual production amount of olive and olive oil reaches 120 and 24 thousand tons respectively, this means that the production of pomace will be large and will impose an environmental damage. Therefore, it is important to think of a process to get rid of this waste, one process is to produce carbon nano dots (CNDs) by processing olive solid waste through several stages. In this study the environmental impact of the CNDs synthesis was studied by applying life cycle assessment (LCA), and the cost per unit of 1 kg production of CNDs was estimated. Moreover, CNDs synthesis process was compared in terms of its life cycle environmental impacts with two different scenarios used for the treatment and utilization of olive pomace, the two other scenarios are bio-fuel pallets and compost synthesis. LCA was performed by using Open LCA software, the data base usda 1901009 and the method CML 2001, while the studied environmental aspects were climate change, human toxicity, acidification and eutrophication potential, after that the overall impact scores were estimated to compare between the studied processes. The results obtained showed that the CNDs synthesis affects the climate change due to carbon dioxide and carbon monoxide emissions during the carbonization stage, and it also contributes to photochemical oxidation impact due to phenol emissions produced from the olive solid waste cleaning stage. On the other hand, the comparison results showed that compost synthesis is the one with the highest environmental impact while bio-fuel pellets is the most environmentally friendly option. It is true that CNDs production is not as eco-friendly as bio-fuel pellets synthesis, but it is the most economically efficient option with a moderate overall environmental impact of 0.3 and a highly competitive cost per unit of $ 9626.1 related to 150 kg annual production.