Hybrid Hydrate-Based Strategy for Petrochemical Effluent Purification and Sustainable Water Management

Abstract

This study highlights the need for sustainable purification of petrochemical effluents to enable water recycling, economic benefits, and ecosystem preservation. The petrochemical effluent, characterized by high concentrations of pollutants (e.g., total dissolved solids (TDS) of 155,360 mg/L, chemical oxygen demand (COD) of 4826 mg/L, and pH 14), poses significant treatment challenges due to its complex composition. To address this, we introduce HyPurif, a novel hydrate-based purification method that employs propane (C₃H₈) and 1,1,1,2-tetrafluoroethane (HFC134a) as hydrate formers along with graphene oxide-doped silica aerogel. The mechanism involves the selective encapsulation of water molecules into hydrate structures, effectively excluding contaminants from the solid phase. Comprehensive analyses, including phase equilibrium studies, spectroscopy, and atomic absorption spectrometry, confirm the efficient separation of pollutants (≥95% removal) during hydrate formation with a water-to-hydrate conversion of 42.4% and an overall water recovery exceeding 60%. Postpurification using the aerogel further reduces contaminant levels in recovered water to a TDS of 5427 mg/L, a COD of 141 mg/L, and a residual chlorine of 0.3 mg/L. The process is energy-efficient, requiring just 0.074 kWh/kg of the effluent purified. This study not only demonstrates the high removal efficiency and water recovery of HyPurif but also provides mechanistic insights into hydrate-based purification, advancing sustainable industrial wastewater purification technologies.