With an increasing use of plastic, considerable plastic waste is generated, threatening the environment and public health. In particular, changes in living patterns in urban areas have significantly impacted the rate at which plastic waste increases every year. Thus, governments in many developed countries have implemented numerous policies to reduce plastic waste generation. Among them is the concept of circular economy that aims to protect the environment from plastic pollution and promote growth and innovation in industry and human life through overall changes in designing, producing, using, and recycling plastic products. The Korean government has implemented the Resource Circulation Act (RCA), which includes the concept of circular economy and resource efficiency policy for overall waste management. Following the concept of RCA, the Plastic Waste Control Plan (PWCP) was established for the comprehensive management of plastic waste. Therefore, this study introduces the goals and strategies of PWCP, which has a circulation system of four stages of production, consumption, discharge, and recycling, as well as the major roadblocks in the stages impeding the achievement of the goals and strategies. This study also suggests countermeasures at the government level for solving the major problems in the four stages.

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This study describes a hydrometallurgical process to investigate the cerium recovery from rare earth polishing powder waste (REPPW) containing main elements such as cerium, lanthanum, praseodymium, neodymium, calcium and aluminum. First, dissolution experiments on La 2 O 3 , Pr 2 O 3 , Nd 2 O 3 , CaO and Al 2 O 3 with 5 µm particle size in sulfuric acid solutions were carried out using a batch reactor with various acid concentrations (115 mol/dm 3 ) at different temperatures (30180°C). The effects of these two parameters on the dissolution reaction were studied. The obtained results showed that two sequential leaching steps were needed to separate cerium from the mixture of CeO 2 , La 2 O 3 , Pr 2 O 3 , Nd 2 O 3 , CaO and Al 2 O 3 . The total process for cerium recovery from REPPW via two-stage acid leaching was then developed through the collection of experimental results. Moreover, the dissolution rate of Al 2 O 3 was expressed by a shrinking core kinetics model. The variation of the dissolution rate constant with temperature obeyed the Arrhenius equation with activation energy of 130 kJ·mol ¹1 and reaction rate constant as a function of the acid concentration of C 0.41. On the basis of the above data, a k-T (reaction rate constant-reaction temperature) diagram for a CeO 2 Al 2 O 3 H 2 SO 4 H 2 O system that permits rational extraction of CeO 2 and Al 2 O 3 was devised.

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