以稻殼生物炭活化過硫酸鹽降解2,4-二氯酚

Abstract

過單硫酸鹽（PMS）和過二硫酸鹽（PDS）作為常用的氧化劑在地下水污染治理和現地化學氧化處理中得到了廣泛關注。PMS 和 PDS 在水中十分穩定，需要活化產生活性物質以用來降解有機污染物。然而，常見的活化方法如紫外線、微波、加熱以及金屬氧化物，雖然有效，但也面臨著高能耗、金屬溶出導致的二次污染以及高製造成本等問題，限制了這些方法在實際應用中的推廣。農業廢棄物製備的生物炭具有高產量及資源再利用的特點，被認為是一種可持續的碳質材料，可以作為PMS和PDS的活化劑。已有文獻報導，利用生物炭可以有效活化過硫酸鹽，提高有機污染物的降解效率。然而，目前關於生物炭活化過硫酸鹽的活化機制仍有待進一步澄清。本研究選擇用廢棄稻殼為原料分別在熱解溫度400℃、600℃、800℃的條件下製備生物炭（BC400、BC600、BC800）做為活化劑活化過硫酸鹽用以去除水中之 2,4-二氯酚污染物。 研究結果顯示生物炭可以直接吸附2,4-二氯酚，在生物炭活化過二硫酸鹽去除2,4-二氯酚的系統中， BC800對2,4-二氯酚的降解效果最為顯著, 在最佳參數條件下於反應90分鐘內達87%以上的去除。綜合自由基捕捉劑實驗及電子順磁共振分析結果, OH•在 BC800活化過二硫酸鹽降解2,4-DCP中具有關鍵的作用。通過Raman的分析結果，發現吸附在 BC800 表面的 PDS 活化產生的活性過氧化物中間體 S2O82–*，可能有助於 OH•的生成和2,4-DCP 的降解.

Peroxymonosulfate (PMS) and peroxydisulfate (PDS) have garnered widespread attention as common oxidants in groundwater pollution treatments and in-situ chemical oxidation. PMS and PDS are highly stable in water and require activation to generate reactive species for degrading organic pollutants. Common activation methods such as using ultraviolet radiation, microwave irradiation, heating, transition metal ions and metal oxides face challenges such as high energy consumption and metal separation and leaching, which limit their widespread applications. Biochar prepared from agricultural waste, known for its sustainable characteristics and high resource yield, has emerged as a promising activator of persulfate. However, the mechanism involved in persulfate activation by biochar remains unclear. In this study, biochars prepared using waste rice husks as raw materials under different pyrolysis temperatures of 400°C, 600°C, and 800°C (denoted as BC400, BC600, BC800), respectively, were employed to activate persulfate for the removal of 2,4-dichlorophenol (2,4-DCP). The results showed that biochar can directly adsorb 2,4-DCP and BC800 exhibited the best degradation performance for 2,4-DCP removal in the biochar-activated persulfate system, achieving over 87% removal in 90 min. Based on the results of quenching experiments and electron paramagnetic resonance (EPR) analysis, it is concluded that OH• plays a crucial role in the degradation of 2,4-DCP by BC800-activated persulfate. Raman analysis results showed that the active peroxide intermediate S2O8²⁻* generated from the activation of PDS adsorbed on the BC800 surfaces, likely facilitates the formation of OH• and the degradation of 2,4-DCP.