Sulfur modification of PET fibers and lead ion sorption from wastewaters: kinetics and isotherms studies

This study aims to contribute to the ongoing research into the chemical modification of polyethylene terephthalate (PET) fibers, with a view to enhancing their capacity for adsorbing heavy metals, specifically Pb(II) ions, from aqueous solutions. The PET fibers have been grafted with glycidyl methacrylate (GMA) and further modified with iminodiacetic acid (IDA), sodium hydroxide (NaOH), and carbon disulfide (CS2) to improve sorption efficiency. The modifications introduced functional groups such as hydroxyl, carboxylate, and sulfur-containing moieties, significantly increasing the sorption capacity. The sorption process was evaluated under a range of conditions, including pH, temperature, contact time, and initial ion concentration. The results revealed that Pb(II) ions sorption capacity was maximized at pH 5.0 and a temperature of 35 degrees C. Among the modified PET fibers, those treated with NaOH and CS2 exhibited the highest sorption capacity (94.14 mg/g), demonstrating superior performance. Kinetic studies demonstrated that the sorption process followed a second-order kinetic model. Isotherm analysis indicated that the monolayer sorption mechanism, best described by the Langmuir model, was the most appropriate for the data. The structural and functional changes in the modified fibers were validated through SEM, FTIR, and DSC analyses. This study highlights the potential industrial applications of modified PET fibers as effective adsorbents for removing heavy metals from wastewaters, contributing to environmental pollution control and resource recovery.