Advancing Sustainable PVC Polymerization: Direct Water Recycling, Circularity, and Inherent Safety Optimization

Polyvinyl chloride (PVC) remains one of the most widely used synthetic polymers worldwide, primarily due to its versatility, cost-effectiveness, and broad applicability across construction, healthcare, automotive, and consumer goods industries. However, its production involves hazardous chemicals, particularly vinyl chloride monomer (VCM), which requires rigorous safety assessments. In this context, the present study applies the Inherent Safety Index (ISI) methodology to evaluate the safety performance of a suspension polymerization process for PVC production that incorporates direct water recycling as a sustainability measure. The integration of water reuse reduces the fractional water consumption index from 2.8 to 2.2 and achieves a recovered water purity of 99.6%, demonstrating clear environmental benefits in terms of resource conservation. Beyond water savings, the core objective is to assess how this integration influences the inherent risks associated with the process. The key operational stages—polymerization, VCM recovery, product purification, and water recirculation—were modeled and analyzed using computer-aided process engineering (CAPE) tools. The ISI analysis yielded a score of 33, surpassing the threshold typically associated with inherently safer designs, with VCM hazards alone contributing a score of 19 due to its high flammability and carcinogenicity. These findings reveal a critical trade-off between environmental performance and inherent safety, underscoring that resource integration measures, while beneficial for sustainability, may require complementary safety improvements. This study highlights the necessity of incorporating inherently safer design principles alongside process integration strategies to achieve balanced progress in operational efficiency, environmental responsibility, and risk minimization in PVC manufacturing.