SYNTHESIS AND APPLICATION OF PET-DERIVED HYDROGEL ADSORBENTS FOR EFFICIENT TREATMENT OF DYE-CONTAMINATED WATER
Keywords:
Heavy metal removal, Dye removal, Wastewater treatment, Adsorption, Hydrogel, Chemical recycling, Polyethylene terephthalate (PET)Abstract
The accumulation of plastic waste, particularly polyethylene terephthalate (PET), and the discharge of toxic industrial effluents pose significant threats to aquatic ecosystems. This study addresses both challenges by developing a value-added hydrogel adsorbent synthesized from post-consumer PET waste. PET bottles were chemically depolymerized via aminolysis using diethylenetriamine (DETA), and the resulting oligomers were cross-linked with varying concentrations (15–19.5 wt%) of ethylene glycol diglycidyl ether (EDGE) to form a three-dimensional polymeric network. The synthesized hydrogels were characterized by Fourier-transform infrared spectroscopy (FTIR), confirming the successful integration of amide and hydroxyl functional groups, and by scanning electron microscopy (SEM), which revealed a highly porous, interconnected architecture conducive to solute diffusion. The adsorption performance of the hydrogel was systematically evaluated for the removal of the anionic dye Congo Red (CR) and the heavy metal ions Pb(II) and Zn(II) from aqueous solutions. Batch adsorption experiments demonstrated that the adsorption process followed pseudo-second-order kinetics and was well-described by the Langmuir isotherm model, indicating monolayer chemisorption. The hydrogel containing 19.5 wt% EDGE exhibited the highest removal efficiency, achieving up to 99% for CR under optimal conditions (pH 7, 7 h contact time) and maximum adsorption capacities of 383.96 mg/g for Pb(II) and 244.12 mg/g for Zn(II). Furthermore, the material demonstrated excellent reusability, retaining over 85% of its initial adsorption capacity after four consecutive cycles. This study presents a sustainable, circular-economy approach that successfully upcycles plastic waste into an effective, reusable adsorbent, offering significant potential for the remediation of industrial wastewater
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