Research Projects

Plastics are essential, and their annual production is rising, but the current recycling rate is very low (9%). The discovery of microplastics in human blood is alarming. Therefore, plastic recycling is essential to establish a circular plastic economy. The efficiency of both mechanical recycling and incineration is very poor, which emphasizes the need for chemical recycling for value-added products. So far, chemical recycling has succeeded for hydrolyzable polymers, but polymers bearing carbon backbone are extremely difficult. The major share includes polyethylene (PE) and polypropylene (PP), which are pyrolyzed to produce crude oil. A mixture of a small amount of halogenated polymers hampers the overall recycling process due to the facile release of corrosive hydrogen halides, which requires a special dehalogenation treatment before recycling to reduce halogen content. On the contrary, halogenated polymers are rich in halogen content and, therefore, can be a halogen source on demand. Chlorinated and fluorinated compounds are extensively used in material sciences, agrochemicals, and pharmaceuticals. Their synthesis often requires hazardous halogenating reagents. Halogen recycling from waste halogenated polymer will solve two problems: polymer recycling and producing halogenated compounds of high demand. Electrochemistry has become a viable tool for green and sustainable synthesis in recent decades. The concept of electro-dechlorination of polyvinyl chloride (PVC) in the presence of additive diethyl hexyl phthalate (DEHP) was used recently for chlorination of aromatic and heteroaromatics. The requirement of a divided cell and DEHP as a stoichiometric mediator for limited substrate scope opens up opportunities for further development. Due to its high barrier properties, polyvinylidene chloride (PVDC) has high-value applications, and its high chlorine content (73%) makes it even more attractive as a chlorine source. Recently we have developed an efficient method for chlorination of aromatic and heteroaromatics using PVDC as a chlorine source without DEHP in an undivided cell, both in batch and continuous flow up to 98% dechlorination. The objective is to efficiently cleave C-Cl and C-F bonds and utilize them for chlorination and fluorination reactions, respectively. Electrophoto catalysis is known to produce super-reductants and oxidants. Furthermore, strong bases can be generated at a slower rate electrochemically, the ‘electrogenerated base’ will do the dehydrohalogenation. Halides, produced from waste halogenated polymers, will be used for halogenation reactions in paired electrolysis. Variations in electrode materials and electrophotocatalysts will significantly improve the efficiency of the process. Along with C(sp2)-H halogenation, C(sp3)-H halogenations will be carried out. Dehalogenated polymers will be characterized first, and then they will be subjected to chemical transformations for value-added chemicals.