A sustainable novel approach of recycling end-of-life reverse osmosis (RO) membrane as additives in concrete and mathematical model with response surface methodology (RSM).

This study investigates a novel method of recycling end-of-life reverse osmosis (RO) membranes to enhance the mechanical properties of concrete. Reverse osmosis (RO) is a widely used technology for water purification and desalination, but it has various environmental problems that require attention. RO membranes have a short service life, resulting in the generation of end-of-life (E-o-L) RO membrane trash in thousands of tons each year, which is typically disposed of in landfills, polluting land resources. The RO membrane primarily comprises a thin-film composite of polyamide (TFC PA) as a filter medium. The material properties of TFC PA are studied and added to the concrete as an additive in the cement volume at 1 to 20%. The optimum mix is identified at 3.4% of TFC PA, and the mechanical properties are nearly 17% greater than the control mix. SEM/EDX shows a higher bonding between TFC PA and the concrete, and TGA results exhibit the mass loss increasing with the increase in TFC PA. MIP analysis shows that the volume of cumulative pores and intruded volume is increased with increasing TFC PA. A sustainability study was carried out to evaluate the energy consumed and embodied CO₂ in the mixes and _compared them with the control mix. The mathematical model for compressive strength at 7 days, 14 days, and 28 days is done using response surface methodology (RSM) with the independent variables of TFC PA, slump, and superplasticizer. The adopted regression illustrates a significant relationship between the response and variables, proving a higher R² for all the models and optimal p-values for the responses. They show that TFC PA influences the enhancement of properties of concrete. The residual also proves to be very minimal in the model. [ABSTRACT FROM AUTHOR]