Recycling of spent superabsorbent polymer into nitrogen-doped carbon catalyst for enhanced antibiotic degradation in groundwater

초록

Polyacrylate (PA), used as a superabsorbent material, is found in household waste, including diapers, napkins, and ice packs; these items are disposed in landfills, raising concerns regarding their environmental impact and management. The beneficial use of PA -derived waste as a carbon catalyst was examined. Nitrogen -doped superabsorbent polymer -derived carbon (N-SAPC) catalysts were designed to activate peroxymonosulfate (PMS) for the removal of the persistent trimethoprim (TMP) pollutant. N-SAPC carbonized at 800 degrees C (N-SAPC 800 ) exhibited improved adsorption and catalytic performance due to its high specific surface area (216.68 m 2 g -1 ), pore volume (0.070 cm 3 g -1 ), and graphitic degree (89.56 %). A 97.78 % removal of TMP (10 mg L -1 ) was achieved in 180 min using N-SAPC 800 (0.1 g L -1 ) and PMS (1.0 mM) at pH 6.8. N-SAPC 800 was effective over a pH range of 5 -11. The breakdown of TMP using N-SAPC 800 /PMS was primarily due to improved electron transfer and the production of non -radical species ( 1 O 2 ) on the reactive sites of N-SAPC 800 . These sites include defects and functional groups like C -- O and C - N within the graphitic structures, which were created by N -doping. TMP degradation pathways were proposed according to the by-products formed, and the toxicity of these intermediates was assessed. TMP degradation was slightly inhibited in natural groundwater (NGW), which was overcome by increasing the PMS and/or N-SAPC 800 concentrations. The catalyst also demonstrated successful removal of other antibiotics such as ciprofloxacin, tetracycline, and sulfamethoxazole with removal percentages of 88.92%, 100%, and 94.82 %, respectively. This study emphasizes the potential of N-SAPC 800 /PMS in addressing antibiotic contamination in groundwater.

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