張夢文,陳菊香,,楊 靜,高乃云

UV/Oxone降解水中撲熱息痛的效能及影響模型

張夢文1,陳菊香1,2*,楊 靜1,高乃云2*

(1.新疆大學建筑工程學院,新疆 烏魯木齊 830047；2.同濟大學,污染控制與資源化研究國家重點實驗室,上海 200092)

采用UV、oxone和UV/Oxone3種工藝降解ACE,同時對體系中氧化活性物質(zhì)種類和貢獻率進行鑒別和計算.采用響應面曲線法研究HCO3?、Cl?、NO3?、pH值和溫度5因素、3水平條件下UV/Oxone對ACE的去除效果的綜合影響,并選用3種實際水體作為原水水質(zhì)背景來評價UV/Oxone降解ACE的實際降解值和模型預測值的差距,最后比較了3種工藝的效能.結(jié)果表明UV、oxone、UV/Oxone3種工藝對ACE的去除率分別為2.1 %、53.7 %和98.3 %.活性物質(zhì)的鑒別實驗發(fā)現(xiàn)UV激活oxone會產(chǎn)生?OH、SO4?–和活性氯3種活性物質(zhì),且對ACE降解的貢獻率分別為37.05 %、19.22 %和43.73 %.通過響應面曲線法得到影響降解ACE效果的回歸方程式,該回歸方程對應的p值小于0.0001,擬合缺失項不顯著,校正決定系數(shù)R2＞0.8,說明該模型可信度高.選用實際水體進行實際降解和模型預測比較時發(fā)現(xiàn)實際降解值基本符合模型預測值.最后對兩種不同工藝進行效能比較發(fā)現(xiàn)在同等時間和降解率的情況,UV/Oxone耗能最低,是一種高效、快速、可行的降解工藝.

撲熱息痛；UV/Oxone；動力學；響應面曲線法；效能評價

撲熱息痛(ACE)是一種非抗炎解熱鎮(zhèn)痛藥,由于其適用性廣、價格低廉等優(yōu)點,得到廣泛使用.據(jù)調(diào)查,國內(nèi)外多種水體中已檢測到ACE的存在[1-3].其中我國天然水體中檢測到ACE的濃度可達6~ 10μg/L[4],歐洲某污水處理廠檢測到ACE的濃度達6~11.3μg/L[5],ACE濃度較高時具有肝毒性和其他副作用,可能通過富集作用進入生物鏈,長此以往會對人類的健康以及生態(tài)系統(tǒng)造成潛在的不利影響[6-7].因此水體中ACE的檢測和去除得到國內(nèi)外環(huán)境學界的廣泛關注[8-9].傳統(tǒng)水處理工藝對ACE降解效果不理想,現(xiàn)亟需研究開發(fā)一種高效、經(jīng)濟的處理技術來去除水體中的ACE.

UV/PMS(過硫酸氫鹽)和UV/PS(過硫酸鹽)是近年來水處理領域高級氧化工藝的研究熱點之一,其可以產(chǎn)生羥基自由基×OH和硫酸根自由基SO4??[10-13],其中SO4?–的氧化還原電位為2.5~3.1V,可降解水中大多數(shù)的污染物[14],所以基于SO4?–的高級氧化技術成為研究重點之一.本文采用的氧化劑水王子(oxone)為一種復合型氧化劑,主要成分為PMS,還包含輔助劑、絡合劑和穩(wěn)定劑等[15].本實驗中考察了UV、oxone和UV/Oxone 3種氧化體系降解水中ACE的動力學以及UV/Oxone體系中活性物質(zhì)的鑒別及其貢獻率的計算,采用響應面曲線法研究了不同水體中ACE的去除效果和降解ACE的效能.

1 材料與方法

1.1 實驗材料

ACE(399.9%)和oxone(399.7%)購買于阿拉丁貿(mào)易有限公司.甲醇(MeOH399.9%),叔丁醇(TBA399.9%),硫代硫酸鈉(Na2S2O3399.0%)購買于國藥集團化學試驗有限公司.碳酸氫鈉(NaHCO3399.5%),硝酸鈉(NaNO3399.0%)和氯化鈉(NaCl399.9%)均購買于海信玻璃有限公司.高效液相色譜儀(HPLC)檢測所需流動相乙腈為色譜純,購自美國Sigma-Aldrich有限公司,試驗中所用樣本溶液均采用Milli-Q超純水(18MΩ·cm) 配制.

分別從橫山水庫、錫東水廠和西氿水庫進水口取樣作為不同水質(zhì)背景,于2018年7,8,9,10,11月各調(diào)查采樣一次,取其5次采樣的平均值,具體水質(zhì)參數(shù)見表1.

表1 實際水體的水質(zhì)參數(shù)表

1.2 分析方法

采用高效液相色譜儀(HPLC2010)對ACE濃度進行定量,裝配有C18色譜柱(250nm′4.6nm′5μm, Waters)和UV可見光檢測器.流動相采用乙腈(15%)和水(85%),流速為1.0mL/min,紫外裝置采用準平行光束儀,檢測波長為242nm,柱溫維持在35℃,檢測時間為10min.

1.3 實驗方法

在實驗條件下,用超純水配制100mL的目標污染物加入到200mL的結(jié)晶皿中,再加入所需的氧化劑溶液oxone,然后將結(jié)晶皿放置在紫外裝置臺上(紫外裝置已提前預熱30min),反應開始并計時,在指定的反應時間采用移液槍取樣0.8mL加至預先放置了足量的淬滅劑硫代硫酸鈉的液相棕色小瓶中,保證殘余氧化劑反應完畢.平行實驗進行3次,取其平均值,見式(1).采用方差分析實驗數(shù)據(jù)的誤差棒,見式(2).

式中:1,2,3—3次實驗后ACE的濃度;C—3次平行實驗的平均值;2—實驗方差.

2 結(jié)果與分析

2.1 不同氧化工藝降解ACE

圖1 3種工藝降解ACE的效果及動力學擬合

如圖1所示,采用UV單獨降解ACE15min后降解效果不明顯,僅為2.1%,這一結(jié)果與唐敏康[16]的研究結(jié)果較為一致,證實了ACE的光穩(wěn)定性.而oxone和UV/Oxone對ACE的去除率分別為53.7%和98.3%,產(chǎn)生這種現(xiàn)象是因為oxone單獨降解ACE時,Cl-可以與PMS發(fā)生反應生成活性氯從而達到降解ACE的目的,具體反應如下式(3~4)所示.此結(jié)論與徐蕾等[17]降解2,4,6-三氯苯酚的結(jié)論相似. UV/Oxone協(xié)同工藝降解ACE時,降解率高達98.3%,充分說明oxone在紫外光照激活下產(chǎn)生了其他活性物質(zhì),從而使ACE的降解效率大大提高.分別對oxone和UV/oxone 2種工藝降解ACE的數(shù)據(jù)進行動力學擬合,均遵循擬一級反應動力學,具體動力學參數(shù)見表2.

表2 oxone和UV/Oxone工藝降解ACE的擬一級動力學速率常數(shù)

2.2 活性物質(zhì)的鑒別

之前報道表明PMS在紫外激活下可產(chǎn)生×OH和SO4?–[10-13],且oxone的主要成分為PMS.為了鑒別UV/Oxone工藝中起氧化作用的活性物質(zhì),分別向系統(tǒng)溶液中加入MeOH和TBA. MeOH可有效淬滅?OH和SO4?–,而TBA只能作為×OH的有效淬滅劑[18-19],如式(5~8)所示.從圖2可以看出:加入MeOH/TBA之后反應速率常數(shù)顯著降低,且加入MeOH的系統(tǒng)比加入TBA下降得更快.同時隨著MeOH/TBA濃度的增加,反應速率常數(shù)不斷降低,但降低幅度逐漸減小.這是因為:×OH和MeOH/TBA的反應速率快,加入低濃度的MeOH或TBA時,主要淬滅系統(tǒng)中的×OH,導致ACE的降解速率下降.隨著MeOH或TBA的濃度逐漸增大,相繼開始淬滅系統(tǒng)中的SO4?–,導致體系中ACE降解速率減小,進而說明oxone在UV激活下可以產(chǎn)生活性自由基(×OH和SO4?–).從圖2看出隨著MeOH濃度增加,ACE仍有一定程度的降解,說明體系中除了生成×OH和SO4?–,還有其他活性物質(zhì). 古振川等人[20]在研究Cl-/PMS降解甲氧芐啶時發(fā)現(xiàn)其反應系統(tǒng)中的活性物質(zhì)主要是活性氯.為了進一步的驗證活性氯的存在,設計驗證實驗:在反應體系中同時加入足量的MeOH和NH4+,ACE無降解.在反應體系中加入MeOH,再加入氯離子時,反應速率變慢.以上結(jié)果表明,在UV/Oxone工藝降解ACE過程中起氧化作用的活性物質(zhì)有3種:×OH、SO4?–和活性氯.

為了計算出各活性物質(zhì)的貢獻率,分別向系統(tǒng)中加入足量的淬滅劑MeOH、TBA和NH4+,得到如圖3所示的ACE降解圖.由圖3可知分別加入不同淬滅劑后ACE的降解率分別為52.39%、75.41%和67.41%,得到不同活性物質(zhì)降解ACE的降解率方程.通過聯(lián)立方程可求解×OH、SO4?–.和活性氯單獨對ACE的降解率,進而計算出各活性物質(zhì)對ACE降解的貢獻率分別為37.05%、19.22%和43.73%.

圖3 MeOH、TBA和NH4+對ACE降解率的影響

2.3 響應面曲線法實驗模型

在實際背景水體中存在多種因素,可能對ACE降解產(chǎn)生影響,例如實際水體中包含各種類型的無機陰離子(如HCO3-、Cl?、NO3-), pH值和溫度()等.采用響應面曲線法[21](5因素3水平)探究3種陰離子、pH值和溫度等因素在不同水平條件下的ACE降解效果及模型方程,詳見表3.對應的響應值為ACE的去除率(),水平響應面實驗設計及響應值見表4,基于響應面曲線法得到如圖4所示的三維模型圖.通過方差分析法(ANOVA)驗證模型的準確和適用性,結(jié)果見表5,的值為11.96,對應的值小于0.0001,模型顯著.擬合缺失項不顯著,校正決定系數(shù)2>0.8,說明該模型可信度高,能夠很好的預測實際水體中ACE的降解效果.

表3 因素水平

表4 5因素、3水平響應面實驗設計及響應值

續(xù)表4

表5 方差分析結(jié)果

圖4 響應面曲線圖

基于上述響應面曲線法可以得到如式(9)所示的5因素、3水平的影響模型方程式:

2.4 模型預測值與實驗降解值的比較

為了驗證響應面曲線法(RSM)設計影響模型的準確性和適用性,特選取不同原水水質(zhì)進行研究.圖5將ACE實驗降解值和模型預測值進行比較,如圖5所示,模型預測值與實際降解值接近,略小于實際降解值,這可能是因為在實際水體中還存在其他因素(例如其他微生物,溴離子等)會影響ACE的降解效果.但模型預測值和實驗值誤差不大,說明該模型可以較好的預測不同水質(zhì)背景下ACE的降解率.

圖5 ACE實測去除率和RSM模型預測值的比較

2.5 不同工藝效能比較

采用單位電能效率(EE/O)比較oxone和UV/Oxone2種工藝降解水中ACE時所消耗的能量.單位電能效率(EE/O kW×h/m3/order)可以采用式(10)進行計算[22]:

式中:代表總輸入電量,kW;為反應時間,0.25h;溶液的體積,1′10-4m3.在實際工藝中還包含藥劑的投加費用,而上式10僅能用來表示直接消耗的電能,所以在具體計算時將藥劑投加費用換算為間接消耗的電能來綜合考察.表6為在同等時間和降解率的條件下2種工藝降解ACE的能耗(控制反應時間均為15min,降解率均為98.3%,此時單獨oxone的投加量為UV/oxone的3.2倍). EE/O1和EE/O2分別表示為:直接和間接消耗的電能.從表6中可以看出在同等時間和相同降解率條件下UV/Oxone工藝降解ACE的能耗最小,最為經(jīng)濟.所以UV/Oxone效率最高,是一種高效可行的降解方法.

表6 2種工藝電能消耗

注:Cost1為系統(tǒng)化學試劑的投加費用,Cost2為系統(tǒng)化學試劑投加費用根據(jù)電費折算成的用電量.電價取0.1元/(kW?h),化學試劑oxone的價格取0.054元/g.

3 結(jié)論

3.1 Oxone 在UV激活下生成了其他高效的氧化活性物質(zhì),大大提高oxone降解ACE的去除率;通過活性物質(zhì)鑒別實驗可知UV/Oxone降解ACE時起氧化作用的活性物質(zhì)有3種:×OH、SO4?–和活性氯,對ACE降解的貢獻率分別為37.05%、19.22%和43.73%.

3.2 通過響應面曲線法得到ACE降解回歸方程式,通過方差分析可知該模型可信度高.選用實際水體背景降解發(fā)現(xiàn)實際降解值略接近于模型預測值,基本符合模型預測值誤差范圍,進一步證明該模型方程的可信度高.

3.3 對兩種工藝進行效能比較分析,發(fā)現(xiàn)在同等反應時間和降解率的情況下,UV/Oxone更為高效、經(jīng)濟可行.

[1] Ternes T A. Occurrence of drugs in German sewage treatment plants and rivers 1Dedicated to Professor Dr. Klaus Haberer on the occasion of his 70th birthday. 1 [J]. Water Research, 1998,32(11):3245–3260.

[2] Sui Q, Lv M, Hu A Y, et al. Seasonal variation in the occurrence and removal of pharmaceuticals and personal care products in a wastewater treatment plant in Xiamen, China [J]. Journal of hazardous materials, 2014,277:69–75.

[3] Roberts P H, Thomas K V. The occurrence of selected pharmaceuticals in wastewater effluent and surface waters of the lower Tyne catchment [J]. Science of the Total Environment, 2005,356(1-3):143–153.

[4] Kolpin D W, Furlong E T, Meyer M T, et al. Pharmaceuticals, hormones, and other organic wastewater contaminants in U.S. streams, 1999-2000: a national reconnaissance [J]. Environmental Science & Technology, 2002,36(6):1202-1211.

[5] Jones O A H, Green P G, Voulvoulis N, et al. Questioning the excessive use of advanced treatment to remove organic micropollutants from wastewater [J]. Environmental Science & Technology, 2007,41(14):5085-5089.

[6] Zhang G Y, Sun Y B, Zhang C X, et al. Decomposition of acetaminophen in water by a gas phase dielectric barrier discharge plasma combined with TiO2-rGO nanocomposite: Mechanism and degradation pathway [J]. Journal of hazardous materials, 2017(B), 323:719-729.

[7] Carballa M, Omil F, Lema J M, et al. Behavior of pharmaceuticals, cosmetics and hormones in a sewage treatment plant [J]. Water Research, 2004,38(12):2918-2926.

[8] Vogna D, Marotta R, Napolitano A, et al. Advanced oxidation chemistry of paracetamol. UV/H2O2-induced hydroxylation/ degradation pathways and15N-aided inventory of nitrogenous breakdown products [J]. The Journal of Organic Chemistry, 2002, 67(17):6143-6151.

[9] 高 穎,楊 曦,劉 鈺.含碳酸鹽水溶液中撲熱息痛的光解研究 [J]. 環(huán)境科學, 2008,29(3):643-649. Gao Y, Yang X, Liu Y. Photodegradation of Paracetamol in Carbonate Solution [J]. Environmental Science, 2008,29(3):643-649.

[10] Luo C W, Ma J, Jiang J, et al. Simulation and comparative study on the oxidation kinetics of atrazine by UV/H2O2, UV/HSO5-and UV/S2O82-[J]. Water Research, 2015,80:99-108.

[11] Lu X, Shao Y S, Gao N Y, et al. Degradation of diclofenac by UV-activated persulfate process: Kinetic studies, degradation pathways and toxicity assessments [J]. Ecotoxicology and Environmental Safety, 2017,141:139-147.

[12] Xie P C, Ma J, Liu W, et al. Impact of UV/persulfate pretreatment on the formation of disinfection byproducts during subsequent chlorination of natural organic matter [J]. Chemical Engineering Journal, 2015,269:203-211.

[13] 陳菊香,高乃云,楊 靜,等.UV/PS降解水中2,4-二氯苯酚的特性研究 [J]. 中國環(huán)境科學, 2017,38(6):2145-2149. Chen J X, Gao N Y, Yang Y, et al. Study on the characteristics of 2,4-dichlorophenol in water degraded by UV/PS [J]. China Environmental Science, 2017,38(6):2145-2149.

[14] Zhang Q, Chen J B, Dai C M, et al. Degradation of carbamazepine and toxicity evaluation using the UV/persulfate process in aqueous solution [J]. Journal of Chemical Technology and Biotechnology, 2015, 90(4):701-708.

[15] Xiong Y Y, ASCE A M, Melching C S, et al. Comparison of kinematic-wave and nonlinear reservoir routing of urban watershed runoff [J]. Journal of Hydrologic Engineering, 2005,10(1):39-49.

[16] 唐敏康,莊珍珍,高乃云,等.基于紫外的高級氧化工藝降解水溶液中撲熱息痛研究 [J]. 水處理技術, 2014,40(12):39-43+47. Tang M K, Zhuang Z Z, Gao N Y, et al. Degradation of paracetamol in aqueous solution by advanced oxidation process (AOP) based on ultraviolet (UV) [J]. Technology of Water Treatment, 2014,40(12): 39-43+47.

[17] 徐 蕾,袁瑞霞,郭耀廣,等.氯離子對鈷/單過氧硫酸鹽體系降解2,4,6三氯苯酚的影響 [J]. 武漢大學學報(理學版), 2013,59(1):51-56. Xu L, Yuan R X, Guo Y G, et al. Effects of chloride ions on degradation of 2, 4, 6-trichlorophenol by Co(Ⅱ)/peroxymonosulfate (Co/PMS) system [J]. Journal of Wuhan University (Natural Science Edition), 2013,59(1):51-56.

[18] Neta P, Huie R E, Ross A B. Rate constants for reactions of inorganic radicals in aqueous-solution [J]. Journal of Physical and Chemical Reference Data, 1988,17(3):1027-1284.

[19] Buxton G V, Greenstock C L, Helman W P, et al. Critical-review of rate constants for reactions of hydrated electrons, hydrogen-atoms and hydroxyl radicals (×OH/O-in aqueous-solution [J]. Journal of Physical and Chemical Reference Data, 1988,17(2):513-886.

[20] 古振川,高乃云,安 娜,等.Cl-/PMS體系降解甲氧芐啶的效能與機理 [J]. 中國環(huán)境科學, 2018,38(3):977-984. Gu Z Z, Gao N Y, An N, et al. Efficiency and mechanism of trimethoprim degradation in Cl-/PMS system [J]. China Environmental Science, 2018,38(3):977-984.

[21] Amiri H, Nabizadeh R, Silva M S, et al. Response surface methodology modeling to improve degradation of chlorpyrifos in agriculture runoff using TiO2solar photocatalytic in a raceway pond reactor [J]. Ecotoxicology and Environmental Safety, 2018,147:919- 925.

[22] Tan C Q, Gao N Y, Zhou S Q, et al. Kinetic study of acetaminophen degradation by UV-based advanced oxidation processes [J]. Chemical Engineering Journal, 2014,253:229-236.

Efficiency and effect model of acetaminophen degradation by UV/Oxone.

ZHANG Meng-wen1, CHEN Ju-xiang1,2*, YANG Jing1, GAO Nai-yun2*

(1.College of Architecture and Civil Engineering, Xinjiang University, Xinjiang Urumqi 830047, China；2.State Key Laboratory of Pollution Control and Resource Reuse, Tongji University, Shanghai 200092, China)., 2019,39(8)：3293~3299

This work reported the efficiency of degradation ACE used three degradation processes (i.e. UV、oxone and UV/Oxone). Meanwhile, the kinds of oxidative active substances and contribution in the system were identified and calculated. Response surface curve method (RSM) was used to study the comprehensive effect of UV/Oxone on ACE removal under five factors including HCO3-, Cl-, NO3-, pH and T and three levels. Furthermore, three kinds of actual water were chosen as the quality indicator of raw water to evaluate the difference between actual degradation values and model predictive values of degradation ACE by UV/Oxone. Finally, the degradation efficiencies of three processes were evaluated. The results showed that the degradation rates of UV、oxone and UV/Oxone were 2.1%, 53.7% and 98.3%, respectively. Identification experiments of active substances found that three active substances were produced by UV activation of oxone, such as?OH、SO4?–and reactive chlorine, and the contribution of three active substances to ACE degradation were 37.05%、19.22% and 43.73%, respectively. The regression equation of ACE degradation was obtained by RSM. The p value was less than 0.0001, the missing fitting term was not obvious and2>0.8, which indicated that the model was highly reliable. Actual waters, as degradation substance, were selected to compare the actual and model predicted and found that two values were matched basically. Compared with the efficiency of two different processes, the result showed that UV/Oxone was an effective, rapid and feasible degradation process with the lowest energy consumption at the same time and degradation rate.

acetaminophen；UV/Oxone；dynamics；RSM；effectiveness evaluation

X703

A

1000-6923(2019)08-3293-07

張夢文(1994-),女,陜西咸陽人,碩士研究生,主要從事水處理研究.發(fā)表論文3篇.

2019-02-12

國家自然科學基金資助項目(51768067)

* 責任作者, 陳菊香, 副教授, chenyu1816@126.com; 高乃云, 教授, gaonaiyun@126.com