Sulfonated plastic waste: A solution for water hardness reduction

This study focused on the utilisation of waste plastic as an ion exchanger to reduce water hardness. The three identical glass columns R1, R2, and R3 were used, each containing different types of waste plastic resin, such as styrofoam resin (SR), air bubble plastic resin (AR), or a mixture of both resins (MR), respectively. The plastics underwent a sulfonation process after crushing and sieving; their sulfonation was confirmed using FTIR analysis. For lab-scale experiments, each glass column was filled with sand, gravel, and coconut fiber as supporting media and equipped with a pump and flow-control valves. Groundwater collected from an urban area was passed through the columns at different flow rates and contact times. The process takes place by exchanging the Na+ ions of resins with polluting ions present in hard water. The treatment parameters involved are total hardness, calcium hardness, magnesium hardness, chloride, TDS, and pH. During the treatment process, pH was maintained between 7 and 8.5. All the parameters were tested twice, and the average of the observations was noted. The results showed that the maximum total hardness reduction achieved in reactors R1, R2, and R3 was 63%, 52%, and 58.6%, respectively, at a contact time of 24 h.