含界面活性劑Tween 80與萘之水溶液Fenton-like氧化之探討

Fenton氧化法已廣泛使用在處理各種工業廢水之技術，其中改良之Fenton-like氧化法，以固相含鐵催化劑催化雙氧水產生氫氧自由基，在中性環境下即可進行，亦可直接應用於土壤地下水整治領域降低對土壤環境之影響。非選擇性氧化之強氧化劑─氫氧自由基，因欲處理之有機物其氧化反應速率不同，導致產生選擇性優先氧化溶液中單一物質的現象，故本研究探討Tween 80與萘之水溶液Fenton-like氧化相互競爭氫氧自由基降解之效率與影響參數，最後篩選最適合處理含Tween 80與萘水溶液之Fenton-like 氧化條件，提供場址界面活性劑沖排法廢水Fenton-like氧化處理之參考。研究結果顯示，Triton X-100與Tween 80可增加萘之水溶解度，但Triton X-100抑制萘被氧化的情況較Tween 80明顯，而且在單次添加雙氧水氧化時界面活性劑抑制效應也與界面活性劑濃度有關，增加雙氧水添加濃度並不會大幅提高萘去除率，在與萘競爭氧化明顯之0.5% 和1.0% Tween 80，則必須提高氧化次數來得到較佳的萘去除率，而增加氧化次數對Tween 80特性變化並不大，催化劑則是在每公升添加1 g針鐵礦會有較好的氧化效率，最後當水溶液中Tween 80接近臨界微胞濃度且萘濃度約1 mg/L和10 mg/L之水溶液以最佳條件氧化後，萘去除率可達60%~70%，Tween 80則減少20%~30%。因此本研究結果說明，在Fenton-like氧化含萘與Tween 80之水溶液中，氫氧自由基會選擇性氧化萘，但使氧化後Tween 80仍能保有增溶特性。此結果可供整治場址所產生之含萘與Tween 80廢水氧化處理，以移除大部分水中污染物，進而回收再使用界面活性劑溶液，並可做為土壤離地清洗時之溶液，以減少界面活性劑使用量與最終廢水處理量，降低整治成本，達到更經濟與環保的全球趨勢。另可將此結果應用在界面活性劑接續進行現地Fenton-like氧化之場址整治參考。

關鍵字

Fenton-like ； Tween 80 ；萘；廢水處理

並列摘要

The Fenton oxidation technology has been widely used in the treatment of various industrial wastewaters. The Fenton-like oxidation is a modified method using iron-containing solid catalysts to catalyze the hydrogen peroxide to generate hydroxyl radicals. This method can be carried out in a neutral pH and can be directly applied to the soil and groundwater remediation, using natural iron in soils as a catalyst. The hydroxyl radical is a non-selective strong oxidant, that reacts preferentially with organic compounds of high KHO• constants. Therefore, this study explores the efficiency and influencing parameters of Fenton-like oxidation of aqueous solutions containing surfactants and pollutants generating from the surfactant enhancing aquifer remediation (SEAR) technology. The most suitable treatment parameters are developed for Fenton-like oxidation of the SEAR wastewater containing Tween 80 and naphthalene. The research results show that Triton X-100 and Tween 80 can increase the water solubility of solid naphthalene, but Triton X-100 inhibits the oxidation of naphthalene more than Tween 80. The oxidation efficiency is better when adding 1 g/L of goethite. In addition, the inhibition effect of surfactants on the oxidation of naphthalene is also related to the concentration of surfactants. Increasing the concentration of hydrogen peroxide does not significantly enhance the naphthalene removal efficiency. Because of the strong competition for oxidation between naphthalene and Tween 80, repeated doses of hydrogen peroxide must be applied to obtain a better naphthalene removal. Using the solubility enhancement capability as an property index for Tween 80, the oxidation did not significantly change the characteristics of Tween 80. Finally, at the Tween 80 concentration is close to its critical cell concentration and naphthalene concentrations are about 1 mg/L and 10 mg/L, naphthalene oxidation is optimal. The naphthalene removal can reach 60%~70%, and Tween 80 property can be reduced by 20~ 30%. Therefore, the results of this study indicate that in Fenton-like oxidation of SEAR aqueous solutions containing naphthalene and Tween 80, hydroxyl radicals will selectively oxidize naphthalene less, whereas Tween 80 will retain its solubilizing properties after oxidation. This result can be used for the oxidation treatment of naphthalene and Tween 80 wastewater generated at the remediation site. After removing most of naphthalene in the water, the surfactant solution can be recycled and reused as a washing solution for ex-situ soil washing. Thus, the cost of surfactant and wastewater treatment can be reduced. This result can also be used for oxidation efficiency evaluation when in-situ Fenton-like oxidation is applied after the SEAR process.