蒽醌衍生物於光催化降解聚苯乙烯之應用

Abstract

聚苯乙烯廢棄物對環境造成嚴重污染，因此將其轉化為有經濟價值的產物具有重要意義，其中光降解被認為是一種溫和、安全且經濟的解決方法。本研究針對聚苯乙烯的光催化降解，使用多種官能基修飾的蒽醌衍生物，系統性探討其對降解效率與產物選擇性的影響。研究結果顯示，2-溴蒽醌（AQBr）在多項指標上均表現最佳，不僅總轉化率最高，並少見的在光催化降解過程中觀察到苯乙烯單體的生成，凸顯其對C–C選擇性斷鍵的特殊活性。透過優化光照時間、光強度及催化劑濃度，發現延長照射時間至48小時可使總轉化率達81%以上，苯甲酸產率亦顯著提升，可達到30%。本研究進一步結合紫外-可見光吸收光譜、光致發光光譜、循環伏安法、瞬態光電流及電化學阻抗等技術，確認AQBr具備優異的光生電子-電洞分離與電荷傳輸效率。自由基捕捉實驗與電子順磁共振分析顯示，羥基自由基及超氧陰離子為主導光降解的主要活性氧物種。除了基礎聚苯乙烯樣品外，本研究亦將光催化策略應用於市售塑膠產品（塑膠杯蓋、保麗龍及塑膠湯匙）的降解，證實該方法對真實複雜塑膠廢棄物仍具有效性。實驗結果顯示，塑膠杯蓋降解最為顯著，產生較多氣相產物，保麗龍則經凝膠滲透層析分析確認分子鏈斷裂，而塑膠湯匙因表面處理影響而降解效果相對較低。綜合而言，本研究提出以無金屬光催化方式分解聚苯乙烯並生成高價值小分子化合物的策略，為未來塑膠廢棄物資源化與綠色循環利用提供新思路。

Polystyrene (PS) waste poses a severe environmental threat, making its conversion into value-added products of significant importance. Among various approaches, photodegradation is considered a mild, safe, and economical solution. In this study, we systematically investigate the photocatalytic degradation of PS using a series of anthraquinone (AQ) derivatives with different functional group modifications, focusing on their effects on degradation efficiency and product selectivity. The results reveal that 2-bromoanthraquinone (AQBr) exhibits the best performance across multiple metrics. Notably, the generation of styrene monomers is validated during the photocatalytic process, highlighting AQBr’s unique ability for selective C–C bond cleavage. By optimizing the light irradiation time, light intensity, and catalyst concentration, the total conversion rate reaches over 81%, with benzoic acid yield significantly increased to 30% after 48 hours of irradiation. Furthermore, UV-Vis absorption spectroscopy, photoluminescence spectroscopy, cyclic voltammetry, transient photocurrent, and electrochemical impedance spectroscopy confirm that AQBr possesses excellent electron–hole separation and charge transfer efficiency. Radical scavenging experiments and EPR analyses identify hydroxyl radicals and superoxide radicals as the dominant reactive oxygen species in the photodegradation process. This study also applies the photocatalytic strategy to commercial PS products (plastic cup lids, polystyrene foam, and plastic spoons), demonstrating its effectiveness on real-life plastic waste. The results show that plastic cup lids exhibit the highest degradation extent with significant gas-phase product formation. Polystyrene foam displays clear molecular chain cleavage confirmed by GPC analysis, whereas plastic spoons show relatively lower degradation efficiency due to surface treatment. Overall, this study proposes a metal-free photocatalytic method capable of efficiently decomposing PS into valuable small-molecule compounds, providing new insights into plastic waste valorization and sustainable recycling.