The implementation of green chemistry principles and green technology makes the process of organic synthesis safer. From the green chemistry point of view, E-factor, atom efficiency, or atom economy are generally accepted new criteria to measure the effectiveness of the organic chemical reactions. Green chemistry also enjoys the advantage of catalytic reactions. Catalysts can be of several types including homogeneous catalysts, heterogeneous catalysts, biocatalysts, and as well as phase-transfer catalysts. Chemical synthesis has to be environmentally friendly, whereas the majority of the solvents applied now are volatile organic substances that are inflammable, explosive, and harmful to the environment. In this regard, there are several alternative approaches in green chemistry including solvent less chemistry, use of dimethylcarbonate, carrying out reactions at supercritical conditions, use of ionic liquids, and as well as the use of the fluorous biphasic systems. Green chemistry should have green reactions and technologies. Following the 12 principles of green chemistry which require a certain strategy and expertise, commonly the set of indicators are used for assessing the critical points of the process. The safety analysis is a systematic study of the process, aimed at identifying potential causes of accidents, risk assessment, which they represent, and finding measures to reduce this risk. The substitution of hazardous materials by more benign ones is a core principle of green chemistry, and a key feature in ISD (Inherently safer design).
While apart from the traditional chemistry subjects such as organic chemistry, inorganic chemistry, physical chemistry, analytical chemistry, polymer chemistry, and environmental chemistry, the theories of green chemistry also consists of the latest achievements of sociology, anthropology, macroeconomics, and management. That's why green chemistry is the scientific guidance to set up a new industrial system and reconstruct society in China and Belarus.
Lithium is a significant energy metal. This study focuses on the extraction of lithium from lithium-bearing clay minerals utilizing calcination combined with oxalic acid leaching. The relevant important parameters, leaching kinetics analysis, and the lithium extraction mechanism were deeply investigated. The results demonstrate that a high lithium recovery of 91.35% could be achieved under the optimal conditions of calcination temperature of 600 °C, calcination time of 60 min, leaching temperature of 80 °C, leaching time of 180 min, oxalic acid concentration of 1.2 M, and liquid-to-solid ratio of 8:1. According to the shrinkage core model, the leaching kinetics of lithium using oxalic acid followed a chemical reaction-controlled process. XRD, TG, and SEM analysis showed that the kaolinite, boehmite, and diaspore phases in raw ore transformed into corundum, quartz, and muscovite phase in calcination products when the calcination temperature was higher than 600 °C. Moreover, the expansion of the interlayer spacing of minerals during the calcination process could promote the lithium release. During the leaching process, lithium present in the layered silicates was efficiently recovered through ion exchange with the dissociated H+ from oxalic acid. This study could provide a promising guide for lithium extraction from lithium-bearing clay minerals.
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