Leachate is produced from the seepage of water from external sources, such as drainage and rainwater through landfill's refuse. It contains high concentrations of suspended and dissolved solid pollutants, including ammonia, nitrates, nitrites, sulfides, heavy metals, nitrogen, and others. With such high pollutant concentrations, leachate has the potential to contaminate groundwater and the environment. Chemical coagulation is a widely used method for removing suspended solids and pollutants in leachate remediation. The focus of this study was the polymerization of copperas, a by-product of the titanium production process, into polyferric sulfate (PFS). The objective was to optimize the synthesis conditions of PFS and evaluate its efficiency as a coagulant for leachate treatment. Hydrogen peroxide was utilized as an oxidizing agent in the polymerization process. The properties of the synthesized PFS, including morphology, structure, functional groups, and material constitution, were characterized via SEM, FTIR analysis, and XRD, respectively. The pH, COD, and color of untreated landfill leachate obtained from a specific landfill site were determined. Jar test was conducted to evaluate the effectiveness of the synthesized PFS in treating leachate, considering dosage, initial pH, and stirring speed as variables. Out of all the coagulants synthesized, PFS B (synthesized using 1.0 M copperas) was the most effective coagulant, demonstrating optimum performance at dosage of 500 ppm, initial pH of 8 and stirring speed of 200 rpm. The results of this study shed light on the feasibility of polymerized copperas as PFS for leachate remediation. These findings may contribute to the development of more efficient and sustainable methods for protecting human health and mitigating the environmental impact of landfill leachate.